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Abstract

Polyester, Polyethylene, and Polypropylene are the materials widely used as geosynthetics. The utilization of such plastic products causes significant environmental issues due to their degradation. Addressing the environmental issues arising from the challenges associated with the direct degradation of conventional plastic geogrid. This study evaluated the tensile performance of additively manufactured different-shaped biodegradable Polylactic acid (PLA) geogrids, printed three-dimensionally using the material fused deposition modelling (FDM) technique. The printed specimens underwent tensile loading at rates ranging from 2 to 20 mm/min until failure. The parameters investigated include the shape of the grid (uniaxial, biaxial, and Inter AX), the filling pattern, filling ratio, filling form, and tensile rate. The findings indicated that the specimens’ failure was brittle and not contingent upon any particular geometrical configuration or alterations. The onset of failure consistently stemmed from the junctions. The InterAX geogrid exhibited the lowest tensile strength and highest strain, while uniaxial and biaxial strengths are dependent on the tensile rate. The tensile strength of Gyroid patterns of all shapes of grid increases with increasing filling ratio. With the increase in filling ratios, the tensile strength of the line pattern first increased and then decreased. The line 0⁰ attained peak strength at 50% filling ratio and Gyroid 0⁰ at 30% filling ratio, with common ultimate strength at 38% (line 0^o & 45^o) and 51% (Gyroid 0^o &45^o). InterAX geogrid shows the lowest stiffness as compared to Uniaxial and Biaxial geogrids.

Keywords

Polylactic acid tensile test additive manufacturing 3D printing fused deposition modelling

Introduction

Geogrids, a geosynthetic material, are typically made from polymers such as polyester, high-density polyethylene, and high-density polypropylene. They are widely used in civil engineering to reinforce soils, retaining walls, and concrete pavements, as well as in road construction and other structural applications. Geogrids play a crucial role in improving soil conditions by reducing settlements and wall deformation in retaining wall and by enhancing the stiffness of the sub-base in pavement, which can lead to a reduction in pavement structure thickness. This characteristic is especially advantageous for upgrading existing infrastructure, as it improves the stability of the wall and enables the use of a thinner layer of asphalt in pavements and helps to prevent potential failures. The popularity of geogrids in construction is attributed to their ease of handling, favourable mechanical properties, and environmental benefits.

Geogrids come in various structures, including woven, non-woven, or composite fabrics, each offering specific advantages depending on the application. Their ability to provide cost-effective and efficient solutions for soil reinforcement and infrastructure stability makes them a valuable component in modern engineering projects. However, most conventional geogrids are composed of polypropylene, polyvinyl chloride, and other polymers, manufactured by thermoplastic processes or molding techniques. Polypropylene and polyvinyl chloride are challenging to break down naturally and pose significant environmental pollution concerns.¹ These materials resist biodegradation, leading to their accumulation in the environment, which can have detrimental effects on ecosystems and wildlife. Their persistent nature means they can remain in landfills and natural habitats for extended periods, contributing to long-term pollution issues and complicating waste management efforts. Over the past decade, biodegradable materials such as biopolymers have garnered increasing global attention as alternatives to synthetic materials. This growing interest has prompted the scientific community and industry to seek efficient and cost-effective methods to substitute traditional materials in various engineering applications.² Singh et al.³ successfully recycled thermoplastic materials to fabricate energy storage devices (ESDs) using advanced 3D printing technology. Their research demonstrated that the ESDs exhibited superior thermal stability and enhanced mechanical properties. This innovative approach also highlights the potential of recycling thermoplastics for high-performance applications and underscores the effectiveness of 3D printing in creating robust and reliable energy storage solutions. The findings confirm the viability of using recycled materials in manufacturing processes that demand stringent thermal and mechanical standards. Multiple researchers^4–6 have explored the extraction of bamboo fibres for the synthesis of geosynthetics and conducted studies to investigate this innovative approach. Their work focuses on utilizing the natural strength and sustainability of bamboo fibres to create geosynthetic materials, offering a promising alternative to traditional synthetic fibres. By harnessing the unique properties of bamboo, these researchers aim to develop environmentally friendly and efficient geosynthetic solutions for various engineering applications. Their efforts contribute to advancing sustainable materials in the field of civil engineering. Zhang et al.⁷ assessed the applicability of bamboo reinforcement through tendon tensile tests and reinforced soil interface friction tests, subsequently selecting bidirectional plastic geogrid as the reinforcing material for comparative analysis. Hegde and Sitharam^8,9 performed a comprehensive examination of the ultimate bearing capacity of a clay bed reinforced with bamboo cells and geogrids. Their findings indicated that this combination of reinforcements enhanced the ultimate bearing capacity of the clay bed by a factor of 1.3, in comparison to a clay bed reinforced exclusively with geocells and geogrids. This notable enhancement highlights the efficacy of incorporating bamboo cells into geosynthetic applications. They also identified polylactic acid as an eco-friendly material, underscoring its potential for sustainable engineering applications. This study enhances the understanding of the role of natural materials, such as bamboo, in improving the performance and sustainability of geosynthetic-reinforced structures. Polylactic acid, often known as polylactide, is undeniably the most promising among the entirely biodegradable polymers.² Polylactic acid is a thermoplastic polymer characterized by its high strength and high modulus. It has been commercialized and is utilized in large-scale production across multiple industries. Its notable versatility renders it appropriate for applications in food technology, medical engineering, pharmaceuticals, packaging, and agriculture.

Since its inception in the mid-1980s, 3D printing has emerged as a transformative technology.¹⁰ Palaniyappan et al.¹¹ conducted a study examining the impact of process parameters, including filling density, layer thickness, and printing temperature, on the structural characteristics of hexagonal lattice structures in 3D-printed PLA polymer materials. Recently, 3D printing has been utilized in geotechnical research. Although numerous scholars have employed 3D printing technology for the fabrication of geogrids, research on the techniques for material filling within these structures remains scarce.¹² employed 3D printing technology to create a uniaxial prototype geogrid made from a PLA-based polymer integrated with titanium dioxide. They explored the potential of biopolymers in geogrid production, highlighting the feasibility and benefits of using these materials for such applications. 3D printing is currently best suited for small-scale, customized, or experimental applications. However, as 3D printing technology continues to advance through faster printing speeds, the development of cheaper and stronger materials including the use of recycled waste, and industrial-scale automation, it has the potential to become economically viable for mass production of geogrid products. Nabeel and Marius¹³ utilized 3D printing technology to create a lightweight porous composite structure incorporating continuous carbon fibres. They conducted tensile tests to analyse and investigate the fracture interface of the composite. The environmental challenges associated with the slow degradation of conventional geogrid raw materials have led to significant research focusing on the mechanical properties of uniaxial, biaxial, and triaxial 3D-printed geogrids. The studies on the mechanical characteristics of InterAX geogrids remain relatively underdeveloped. Within the domain of 3D printed geogrids, the majority of researchers predominantly utilize 3D printing technology to fabricate geogrid models for investigating their mechanical characteristics like tensile strength, and joint strength. There has been limited studies on the stiffness characteristic of these 3D printed geogrid as Giroud & Han¹⁴ demonstrated that geogrid stiffness significantly affects the load transfer efficiency in reinforced soil structures, influencing the deformation behavior and long-term stability. Also, there has been a restricted examination of the influence of printing parameters like filling form, filling ratio and filling pattern on tensile and stiffness characteristics of geogrid. The filling ratios, filling patterns, and filling forms of consumables are crucial elements in 3D printing. The filling ratio quantifies the percentage of consumables contained within the printed solid model.¹⁵ Various filling methods result in a distinct internal structure of the model. Currently, various geogrid tensile test specifications do not consistently specify uniform tensile rates.⁶

The present study intends to utilize 3D printing to fabricate model geogrids with properly scaled shapes and tensile properties for small-scale laboratory experimentation. The research focuses on the influence of 3D printing parameters like filling ratio, filling form and filling pattern on the tensile and stiffness properties of uniaxial, biaxial and InterAX geogrid. This research aims to enhance the application of 3D printing technology through the use of the fused deposition modelling (FDM) technique in this field. A series of tensile experiments has been designed to investigate the influence of printing parameters and tensile rate on the mechanical properties of geogrids, highlighting their significance in engineering applications.

Materials

Polylactic acid (PLA) shown in Figure 1 is a sustainable polymer material known for its outstanding mechanical properties and its ability to completely biodegrade.^16–19 This environmentally friendly polymer is not only robust and durable, making it suitable for a wide range of applications, but it also offers a significant ecological advantage by breaking down fully over time, reducing environmental impact. The combination of high performance and complete degradability renders PLA an appealing option for individuals seeking to balance functionality with environmental responsibility, as evidenced by its extensive application in geotechnical engineering and other domains.²⁰ The properties of the material are given in Table 1.

Figure 1.

Sustainable PLA filament.²¹

Table 1.

Properties of PLA material.

Material	PLA filament
Tensile strength (MPa)	25
Diameter (mm)	1.75
Elongation (%)	4.5
Print temperature (°C)	195-220
Tolerance (mm)	±0.02

3D Printer

A Raise3D Pro2 3D printer prepared the 3D-printed geogrid models. The machine size was 620 mm (length) × 590 mm (width) × 760 mm (height) and the build volume of the printer was 305 mm (length) × 305 mm (width) × 300 mm (height) as shown in Figure 2. The Pro2 Series included safety precautions for work preservation, a 7-inch touchscreen for effective monitoring of the 3D printing process, and a HEPA air filter. The printer demonstrated a printing accuracy of 0.01 mm and was capable of processing various filaments at temperatures up to 300°C. The specific 3D printer parameters are summarized in Table 2. It uses the material fused deposition modelling (FDM) technique. Fused Deposition Modelling (FDM) is a prevalent additive manufacturing process that constructs three-dimensional objects through the sequential deposition of melted material onto a build platform. The process employs thermoplastic polymers, typically in filament form, which are extruded through a temperature-regulated nozzle to create the specified part based on digital CAD data. The tensile test was conducted in accordance with ASTM D6637-15-2023,²² which outlines the standard test method for determining the tensile properties of geogrid using either the single or multi-rib tensile method. A Universal Testing Machine (UTM) was utilized, featuring a control accuracy of ±0.1 N and a capacity of 50 kN. The geogrid was clamped to the fixture’s edge with a wooden strip and the grip of UTM to prevent damage to the sample, as illustrated in Figure 3.

Figure 2.

Raise3D pro2 printer.²³

Table 2.

3D printer specification.

Name	Raise3D Pro2 3D printer
Machin size (L × W × H)	620 mm × 590 mm × 760 mm
Build volume (L × W × H)	305 mm × 305 mm × 300 mm
Print technology	Fused deposition modelling (FDM)
Filament diameter (mm)	1.75
Print speed (mm/s)	70
Build plate	Heated aluminium with magnetic holding
Build plate temperature (°C)	56
Layer height (mm)	0.2
Nozzle diameter (mm)	0.4
Nozzle temperature (°C)	216
Connectivity	Wi-Fi
Filter	HEPA filter with activated charcoal
Filament run-out sensor	Available

Figure 3.

Clamping in UTM.

Geogrid Model

The preliminary stage of sample preparation entailed the design of geometry utilizing SolidWorks software. Figure 4(a) illustrates 3D designs created with SolidWorks, which were scaled to reduce geometry. Subsequently, the second phase involved importing the STL file of the SolidWorks 3D model, which was configured with the necessary printing parameters, into the IdeaMaker software. The slicing process was then executed to produce the gcode. Figure 4(b) presents the 3D-printed geogrid model following the slicing process. The G-code of the sliced model was transmitted to the 3D printer via Wi-Fi to initiate the printing process. The printing process for various shapes of the geogrid model requires 2-3 hours. Upon removal from the bed, the final model specimen is obtained, as illustrated in Figure 4(c).

Figure 4.

Geogrid modelling of the printing process.

Three distinct types of geogrids were prepared, with their precise specifications and technical parameters presented in Table 3. The three geogrids exhibit distinct shapes and aperture sizes, as illustrated in Figure 5.

Table 3.

Detailed specification and technical parameters.

	Geogrid
Parameters	Uniaxial geogrid	Biaxial geogrid	InterAX geogrid
Mesh shape	Rectangular	Square	Hexagonal unit with trapezoidal and triangular aperture
Mesh size (inner dimensions)	50 mm × 10 mm	10 mm × 10 mm	The hexagon of 25 mm side contains 6 trapezoids (a = 9 mm, b = 25 mm)^a and equilateral triangles of side 25 mm on edge b
Node width	3.0 mm	3.0 mm	5.0 mm
Node thickness	1.0 mm	1.0 mm	1.0 mm
Node length	3.0 mm	3.0 mm	5.0 mm
Rib length	270 mm	270 mm	220 mm
Rib width	3.0 mm	3.0 mm	3.0 mm
Rib thickness	1.0 mm	1.0 mm	1.0 mm

^aa and b are the opposite side of the trapezoid.

Figure 5.

Different shaped geogrid.

Experimental Program

This experiment involved the design of geogrid models using five different filling ratios (5%, 10%, 30%, 50%, and 80%) as per²⁴ and four separate filling forms (Line 45⁰ filling, Line 0⁰ filling, Gyroid 45⁰ filling, and Gyroid 0⁰ filling) as illustrated in Figure 6. In addition, three geometric shapes were taken into account: uniaxial geogrids, biaxial geogrids, and InterAX geogrids (specification shown in Table 3). The models undergo tensile tests at three distinct rates: 2 mm/min, 10 mm/min, and 20 mm/min. Table 4 contains a comprehensive summary of the test cases. This comprehensive approach aimed to evaluate the performance of various geogrid configurations under different conditions, ensuring a thorough assessment of their tensile properties.

Figure 6.

Different filling forms and pattern used in 3D printing.

Table 4.

Experimental program.

Number	Materials	Filling ratio (%)	Filling pattern	Filling form	Geometric form	Tensile rate (mm/min)
A	PLA	5, 10, 30, 50, 80	Line	45⁰, 0⁰	Biaxial	2
A		5, 10, 30, 50, 80	Gyroid	45⁰, 0⁰	Biaxial	2
B		50	Line	0⁰	Uniaxial, biaxial and InterAX	2
B		30	Gyroid	0⁰	Uniaxial, biaxial and InterAX	2
C		50	Line	0⁰	Uniaxial, biaxial and InterAX	2, 10, 20
C		30	Gyroid	0⁰	Uniaxial, biaxial and InterAX	2, 10, 20

Calculations

The primary performance indicators of a geogrid’s mechanical properties are its tensile strength, elongation, and tensile stiffness. Tensile strength, measured in kN/m, indicates the tensile load the material can withstand per unit width and is the most crucial performance index for majority of geogrid applications, such as GRS walls, tension is the predominant mechanism. Therefore, compression is not considered in this study. In some cases, such as basal reinforcement, bending may influence the overall performance; however, it is typically neglected in most design applications, as its effect is generally not significant. Strain is quantified as the percentage change in the length of a geogrid when subjected to tension. The tensile stiffness measures the geogrid’s resistance to deformation when subjected to tensile force. It is represented at a particular strain (ɛ). The tensile strength, elongation, and tensile stiffness of geogrid are calculated using the following formula as per Gao et al..²⁴

T = \frac{F \times N}{n}

(1)

ε = \frac{Δ l}{l}

(2)

J_{ɛ} = \frac{f}{ε}

(3)Where, T represents the tensile strength of the geogrid; F is the maximum tensile force the geogrid can withstand; n denotes the actual number of ribs in the geogrid; N signifies the number of ribs per meter width of the geogrid; ε stands for the strain of the geogrid in percentage; Δl is the amount of elongation; l is the distance between the edges of two clamps holding the geogrid in a pre-tensioned state; J_ɛ represents the tensile stiffness of the geogrid at strain ɛ%; and f indicates the tensile force at strain ɛ%.

Results and discussion

Effect of filling ratio and filling pattern

The results of tensile testing on geogrids having two different filling forms and two filling patterns at varying filling ratios are presented in Table 5. Figure 7 depicts the correlation between tensile strength and elongation for the geogrids across various filling forms and patterns. As the filling ratio increased from 5% to 80%, the slope of the tensile strength versus strain curve first increased and then decreased in most of the geogrids. This indicates that the geogrid’s tensile strength capacity initially increased and then decreased with higher filling ratios, reaching its peak when the filling ratio was 50%, 30%, 50%, and 30% for line 0^°, line 45^°, Gyroid 0^°, and Gyroid 45^° respectively. Line 0^° filling form (Figure 7(b)) at 50% filling ratio has higher strength than Line 45^° filling form (Figure 7(a)) at any filling ratio. Similarly, Gyroid 0^° filling (Figure 7(d)) has a higher strength at 30% filling ratio than Gyroid 45^° Filling (Figure 7(c)) at any filling ratio. This suggests that the geogrid’s tensile strength capacity is maximized at this filling ratio within the specified filling pattern.

Table 5.

Range of ultimate tensile strength and elongation at break of geogrids.

Filling patterns of geogrid	Filling ratio (%)	Ultimate tensile strength (kN/m)	Elongation at break (%)
Line 45^°	5	3.25 ± 0.13	1.52 ± 0.11
	10	3.32 ± 0.19	1.17 ± 0.09
	30	3.63 ± 0.31	1.06 ± 0.12
	50	3.10 ± 0.17	1.37 ± 0.13
	80	2.14 ± 0.16	1.12 ± 0.09
Line 0^°	5	2.68 ± 0.12	0.96 ± 0.10
	10	2.83 ± 0.21	0.81 ± 0.08
	30	2.91 ± 0.31	0.65 ± 0.07
	50	4.22 ± 0.39	1.17 ± 0.06
	80	4.06 ± 0.26	1.06 ± 0.06
Gyroid 45^°	5	3.11 ± 0.20	0.81 ± 0.13
	10	3.89 ± 0.12	1.11 ± 0.11
	30	3.99 ± 0.30	1.16 ± 0.14
	50	4.22 ± 0.38	1.02 ± 0.10
	80	3.89 ± 0.29	1.16 ± 0.12
Gyroid 0^°	5	3.27 ± 0.17	0.91 ± 0.09
	10	4.04 ± 0.21	0.92 ± 0.10
	30	4.59 ± 0.41	0.92 ± 0.05
	50	4.26 ± 0.24	0.96 ± 0.04
	80	2.40 ± 0.38	0.61 ± 0.08

Figure 7.

Tensile strength curve of different patterns at different filling ratios.

Figure 8(a) and (c) show the line diagram of average ultimate tensile strength with different filling ratios obtained by tensile testing of multiple number of geogrids of different filling forms of line and Gyroid pattern respectively. It can be seen that in both filling patterns with different filling forms, the ultimate tensile strength first increases up to a certain filling ratio and then decreases after reaching the maximum value.

Figure 8.

Strain at break versus filling ratio of different geogrid patterns.

As shown in Figure 8(a), for the line-filling pattern, as the filling ratio increases from 5% to 50%, the ultimate tensile strength of the line 0^o printed geogrid increases by 57.46 %. Similarly, as the filling ratio increases from 5% to 30%, the ultimate tensile strength of line 45⁰ printed geogrid increases by 11.69%. The ultimate tensile strength of line 0⁰ printed geogrid decreases when the filling ratios increase from 50% to 80% by 3.7%. Similarly, the ultimate tensile strength of line 45⁰ printed geogrid decreases when the filling ratios increase from 30% to 80% by 41.04 % Line 0^o printed geogrid shows maximum ultimate tensile strength at 50% filling ratio whereas line 45^o printed geogrid shows maximum ultimate tensile strength at 30% filling ratio. At a filling ratio of 38%, it is noteworthy that line 0⁰ and line 45⁰ exhibit identical ultimate tensile strength.

From Figure 8(b), it can be seen that the stain versus filling ratio follows the same trend for both line forms. Also, by advancing the filling ratio from 5% to 30%, the stain decreases by about 31.33% while the tensile strength increases in both line forms, which indicates that increasing the filling ratio within this range may substantially enhance tensile strength performance while reducing strain. Further increasing the filling ratio from 30% to 50%, strain in geogrid increases to 80% in line 0^o geogrid with increasing strength and in line 45^o printed geogrid, strain decreases to 29.4% with decreasing strength, whereas strain and strength both decrease on increasing filling ratio from 50% to 80%. Greater strain is found in the line 0^o filling form at all filling ratios.

In the Gyroid filling pattern Figure 8(c), as the filling ratio increases from 5% to 30%, the ultimate tensile strength of the Gyroid 0^o printed geogrid increases by 40.36%. Similarly, as the filling ratio increases from 5% to 50%, the ultimate tensile strength of a 45^o printed Gyroid geogrid increases by 35.69%. The ultimate tensile strength of 0^o printed Gyroid geogrid decreases when the filling ratios increase from 30% to 80% with the average values reaching to 47.71%. Similarly, the ultimate tensile strength of 45^o printed Gyroid geogrid decreases when the filing ratios increase from 50% to 80% with the average values reaching 7.81%. In both the filling patterns, the ultimate tensile strength of the geogrid did not continuously increase with increasing the filling ratios, but there exists an optimum filling ratio value that maximizes the ultimate tensile strength of the printed geogrid. Gyroid 0^o printed geogrid has a maximum ultimate tensile strength at 30% filling ratio, whereas Gyroid 45^o printed geogrid has a maximum ultimate tensile strength at 50% filling ratio. At a filling ratio of 51%, it is noteworthy that both Gyroid 0^o and Gyroid 45^o printed geogrids exhibit identical ultimate tensile strength.

From Figure 8(d), it can be seen that by increasing the filling ratio from 5% to 30%, the stain increases by about 1.43%, and ultimate strength also increases in this range for Gyroid 0^o printed geogrid. For Gyroid 45^o printed geogrid, the strain increases to 43.21% and ultimate tensile strength increases to 28.30% with increasing filling ratio from 5% to 30%. This suggests that enhancing the filling ratio within this range may substantially elevate tensile strength performance as strain increases. Increasing the filling ratio from 30% to 50% strain in Gyroid 0° printed geogrid results in a 4.35% increase, accompanied by a decrease in strength within this range. In Gyroid 45° printed geogrid, the strain decreases to 12.07% with a reduction in strength as the filling ratio increases from 30% to 50%. When the filling ratio increases from 50% to 80%, the strain decreases in Gyroid 0° printed geogrid but increases to 13.72% in Gyroid 45° printed geogrid, with both cases showing a decline in strength. Greater strain is found in the Gyroid 45^o filling form as compared to Gyroid 0^o as the filling ratios are greater than 5%.

In conclusion, the ultimate tensile strength of 3D printed geogrid was maximized for the line pattern at a filling ratio of 50% and a filling form of 0°, while the ultimate tensile strength was maximized for the Gyroid pattern at a filling ratio of 30% and a filling form of 0°.

Effect of different grid forms

Table 6 presents the test results of three forms of 3D-printed grids (or geogrids) with two filling patterns subjected to varying tensile rates. The tensile strength versus strain curves for three types of line-printed grids, featuring a 50% filling ratio and a 0° filling pattern, at various tensile rates are illustrated in Figure 9 (a, b, and c), obtained from the experimental data. Figure 9 (d, e, and f) illustrates the tensile strength variation curves as a function of strain for the three forms of 3D-printed Gyroid grids exposed to different tensile rates. Figure 9 illustrates the considerable variety in the tensile properties of several geogrid configurations. The tensile strength versus strain curves of the three distinct grid forms exhibited a decline in the slope of the tangent line as the tensile test progressed until the peak tensile strength was attained, culminating in a brittle fracture in both filling patterns.

Table 6.

Average ultimate tensile strength and elongation at break at different tensile rate and form of geogrid.

Filling pattern and filling ratio (%)	Forms of grid/geogrid	Tensile rate (mm/min)	Ultimate tensile strength (kN/m)	Elongation at break (%)
Line 0° (50%)	Uniaxial geogrid	2	4.74 ± 0.13	1.15 ± 0.10
		10	5.21 ± 0.16	1.15 ± 0.08
		20	5.52 ± 0.31	1.11 ± 0.12
	Biaxial geogrid	2	4.22 ± 0.39	1.17 ± 0.06
		10	4.79 ± 0.14	1.33 ± 0.10
		20	5.68 ± 0.35	1.41 ± 0.11
	InterAX geogrid	2	3.8 ± 0.40	2.11 ± 0.17
		10	4.51 ± 0.31	2.11 ± 0.19
		20	5.02 ± 0.37	2.48 ± 0.21
Gyroid 0^° (30%)	Uniaxial geogrid	2	4.79 ± 0.12	1.00 ± 0.05
		10	4.68 ± 0.15	0.92 ± 0.10
		20	4.74 ± 0.31	1.00 ± 0.12
	Biaxial geogrid	2	4.59 ± 0.41	0.91 ± 0.05
		10	5.20 ± 0.24	1.03 ± 0.09
		20	4.52 ± 0.21	1.32 ± 0.07
	InterAX geogrid	2	3.99 ± 0.25	1.89 ± 0.14
		10	3.94 ± 0.21	1.71 ± 0.11
		20	4.74 ± 0.31	1.89 ± 0.18

Figure 9.

Tensile strength versus strain curve for different forms of geogrid of various patterns.

In-Line pattern

At a tensile rate of 2 mm/min, the slopes of the tensile force versus strain curves for the three types of grids exhibited minimal variation, with biaxial grids displaying slightly lower values than uniaxial grids, yet greater than those of InterAX grids. The tensile strength of the biaxial grid is less to that of the uniaxial grid but superior to the InterAX grid. In terms of strain at the break point, uniaxial grids exhibited the lowest strain, while InterAX grids displayed the highest strain at the break point. At a tensile rate of 10 mm/min, the initial slope of the tensile strength versus strain curve for uniaxial and biaxial grids was similar; however, the biaxial grid exhibited a lower slope. The lowest slope is observed for InterAX grids, suggesting that uniaxial and biaxial geogrids exhibit comparable tensile strength resistance during the initial loading phase; however, InterAX grids demonstrate the least tensile strength capacity. The uniaxial grid exhibited the maximum tensile strength, while the InterAX grid had the lowest tensile strength, as illustrated in Figure 9(b). This discrepancy may be attributed to the geometry, which enables the uniaxial grid to attain more strength at less strain. When it comes to strain at the break point, uniaxial grids had the lowest values, whereas InterAX grids demonstrated the greatest. At a tensile rate of 20 mm/min, there was no notable difference in the slopes of the tangents of the relationship curves between tensile force and strain for both uniaxial and biaxial grids during the initial loading phase; however, the InterAX grid exhibited the lowest slope throughout the tensile test. Regarding tensile strength, the uniaxial grid exhibited the maximum tensile strength, followed by the biaxial grid, but the InterAX grid had the lowest tensile strength (Figure 9(c)). The uniaxial grid had the lowest elongation at break, whereas the InterAX grid demonstrated the highest elongation at break.

In gyroid pattern

At a tensile rate of 2 mm/min, the slopes of the tensile force versus strain curves for the three types of Gyroid printed grids exhibited no significant variation (as illustrated in Figure 9(d)), with biaxial grids displaying somewhat lower values than uniaxial grids, although greater than InterAX grids. The tensile strength of the biaxial geogrid is inferior to that of the uniaxial geogrid but superior to that of the InterAX geogrid. Biaxial grids had the lowest strain at the break point, whereas InterAX grids demonstrated the highest strain at the break point. At a tensile rate of 10 mm/min, the slope of the tensile strength versus strain curve was similar for both uniaxial and biaxial grids over the whole test (Figure 9(e)). The InterAX grids have the lowest slope, signifying that uniaxial and biaxial geogrids possess comparable tensile strength resistance under loading, however InterAX grids demonstrate the least tensile strength capacity. The biaxial grid exhibited the maximum tensile strength, whereas the InterAX grid demonstrated the lowest tensile strength. Regarding strain at the break point, uniaxial grids had the lowest values, whereas InterAX grids demonstrated the greatest. The uniaxial and biaxial grids had similar slopes of the tangents of the relationship curves between tensile force and strain during a loading rate of 20 mm/min, but InterAX had the lowest slope (Figure 9(f)). The uniaxial grid has the highest tensile strength, followed by the biaxial and InterAX grids. Uniaxial and InterAX grids had the lowest and largest elongation at break point, respectively.

Effect of the rate of tensile loading

Figure 10 presents a scatter plot depicting the correlation between ultimate tensile strength and tensile rate across various sets of parallel experiments. Furthermore, it encompasses a graph illustrating the average ultimate tensile strength obtained from these experiments and the variation in the result. This graphic illustrates the correlation between ultimate tensile strength and tensile rate across several geogrid types.

Figure 10.

Tensile rate curve for three forms of geogrid different filling patterns.

For line patterns

Figure 10(a) shows that uniaxial, biaxial, and InterAX geogrids’ ultimate tensile strength rises with tensile rates.²⁵ The rate of increase of ultimate tensile strength of uniaxial, biaxial, and InterAX geogrids is almost constant from 2 to 10 mm/min, but from 10 to 20 mm/min, biaxial geogrid has the highest rate and uniaxial the lowest. This explained why tensile rate affects geogrids’ ultimate tensile strength differently. The uniaxial geogrid’s ultimate tensile strength rose by 16.45% when the tensile rate increased from 2 mm/min to 20 mm/min. The mean ultimate tensile strength of biaxial and InterAX geogrid rose from 2 mm/min to 20 mm/min, reaching 34.59% and 43.43%, respectively.

A scatter plot of strain at break point versus tensile rate across many parallel testing is shown in Figure 10(b). A curve showing the average strain at break point from these tests shows the link between strain at break point and tensile rate for different geogrids. Figure 10(b) shows that as tensile rates increase, the strain at the break for uniaxial and InterAX grids first remains constant, then increases for InterAX and decreases for uniaxial, while biaxial grids continuously increase. Varying grids exhibited varying elongation at break due to different tensile rates. When tensile rates were less than 10 mm/min, the elongation at break of uniaxial and InterAX geogrids remained constant, but when they exceeded 10 mm/min, it increased by 15.63% for InterAX and decreased by 3.47% for uniaxial. Biaxial grids increased to 25.64% on average. InterAX grid strain is highest at all tensile rates, followed by biaxial and uniaxial. The strain at break was greatest for InterAX geogrids and least for uniaxial geogrids at 20 mm/min, demonstrating the considerable effect of tensile rate on geogrid mechanical properties. Also, Biaxial and InterAX geogrid shows high variation in tensile strength and strain that may be due to their complex geometry.

In conclusion, the ideal tensile rate for geogrid tensile is 20 mm/min, which complies with the tensile rates outlined in SL-235-2012, “Specification for test and measurement of Geosynthetics.”²⁶

For gyroid pattern

Figure 10(c) illustrates that the ultimate tensile strength of uniaxial, biaxial, and InterAX geogrids does not conform to the trend indicated by the line pattern as tensile rates increase. The ultimate tensile strength of biaxial and InterAX geogrids diminishes as the tensile rate increases from 2 to 10 mm/min and from 10 to 20 mm/min. The rate of increase in ultimate tensile strength is greater in InterAX geogrid compared to uniaxial geogrid as tensile rates rise. In a biaxial geogrid, the ultimate tensile strength increases with a tensile rate from 2 mm/min to 10 mm/min, but thereafter falls when the tensile rate rises from 10 mm/min to 20 mm/min. The ultimate tensile strength of several geogrids was influenced differentially by the tensile rate. For the uniaxial geogrid, an increase in the tensile rate from 2 mm/min to 10 mm/min resulted in a mean drop of 2.35% in ultimate tensile strength, followed by a mean rise of 1.28% when the tensile rate was further elevated from 10 mm/min to 20 mm/min. The ultimate tensile strength of InterAX geogrid exhibits a similar trend to that of uniaxial geogrid at tensile rates ranging from 2 mm/min to 10 mm/min, with a drop of 1.25% in ultimate tensile strength. As the tensile rate rose from 10 mm/min to 20 mm/min, the ultimate tensile strength of the InterAX geogrid augmented by 20.30%. It is noteworthy that in biaxial geogrid, the ultimate tensile strength initially rises by 13.28% when the tensile rate is increased from 2 mm/min to 10 mm/min, followed by a fall of 13.07% when the tensile rate is elevated from 10 mm/min to 20 mm/min.

A scatter plot of strain at break point with different tensile rates throughout numerous parallel tests is shown in Figure 10(d). This chart shows the average strain at break point determined from these tests and the relationship between elongation at break and tensile rate for different geogrids. Figure 10(b) illustrates that when tensile rates increase, uniaxial and InterAX geogrid strain at the break point reduces and then increases, while biaxial strain grows continuously. The strain at the break point of several geogrids was affected by tensile rates differently. The strain at break point of uniaxial and InterAX geogrids reduced with tensile rates less than 10 mm/min, but increased with average values of 10.53% and 8.69% with tensile rates greater than 10 mm/min. Biaxial geogrids increased to 45.05% on average. InterAX geogrid strain is highest at all tensile rates, followed by biaxial and uniaxial. The strain at break was greatest for InterAX geogrids and least for uniaxial geogrids at 20 mm/min, demonstrating the considerable effect of tensile rate on geogrid mechanical properties.

In conclusion, the optimal tensile rate for gyroid printed geogrids is 10 mm/min for biaxial geogrids and 20 mm/min for uniaxial and InterAX geogrids.

Effect of filling ratio, geometry form, and tensile rate on tensile stiffness

Geogrid stiffness is typically reported at specific strain levels, referred to as scant stiffness. For PET or PVA geogrids, stiffness is commonly measured at 5% strain, as these materials exhibit high strain under greater tensile strength. Additionally, geogrid stiffness can be evaluated at lower strain levels, such as 1% and 2%.²⁷ In contrast, PLA demonstrates brittle behavior with low strain at peak loading. Figure 10 presents the effect of filling ratio, filling form, and tensile rate on stiffness at 0.5% strain.

Figure 11(a) shows the stiffness follows a similar trend for Line 45^o and Gyroid 0^o printed geogrids whereas Line 0^o shows a continuous increment in stiffness with the filling ratio. Gyroid 0^o shows first decrement in stiffness with filling ratio then increment and then again decrement. Figure 11(b) shows that InterAX has the lowest stiffness for both Line 0^o and Gyroid 0^o printed geogrid. Figure 11(c) shows that as the tensile rate increases the stiffness of InterAX geogrid first decreases and then increases for Line 0^o whereas uniaxial and biaxial geogrid shows almost equal stiffness. Uniaxial and biaxial geogrid have stiffness in the range of 440 kN/m to 520 kN/m whereas stiffness of InterAX lies between 280 kN/m to 310 kN/m. Figure 11(d) shows that InterAX has almost constant stiffness as the tensile strain increases for Gyroid 0^o. Biaxial shows lower stiffness as compared to Uniaxial at 20 mm/min tensile rate. Figure 12(a) presents the variation of tensile strength of InterAX geogrid versus strain with the variation of tensile rate. It can be observed that as the tensile rate increases, tensile strength increases. Figure 12(b) presents the variation of stiffness of InterAX geogrid with time, which indicates that as the tensile test proceeds, stiffness at a particular strain (ɛ_t) decreases.

Figure 11.

Effect of filling ratio, filling form, and tensile rate on stiffness of geogrid.

Figure 12.

Variation of tensile strength and stiffness for InterAX geogrid.

Failure pattern analysis

Failure initiation primarily stemmed from the junctions and progressed by involving additional junctions, as shown in Figure 13, rather than being driven by the ribs. These locations experience higher stress concentration and localized strain, leading to the onset of cracking and subsequent propagation, similar observation has be reported in literature.²⁹ Uniaxial and biaxial geogrids failed largely at the rib-node junction. The rib breaks or falls when uniaxial geogrids are broken. Due to the minimal number of transverse ribs in uniaxial geogrid, transverse ribs did not constrain longitudinal ribs.²⁴ Figure 13 shows that most InterAX geogrid joints broke cleanly. The link between ribs and nodes was the weakest location in the tensile process of both uniaxial and biaxial geogrids, confirming.²⁸ The strength of the rib-node connection in uniaxial and biaxial geogrids largely affected their tensile capacity, while the node in InterAX geogrids greatly affected it. All three geogrids had clean failure points with few sharp edges and fibers. This observation demonstrates that all three geogrids had brittle failure. The pristine fracture surfaces indicate that the geogrids experienced minimal stretching or distortion prior to failure. This pattern is commonly seen in materials that exhibit more rigidity and reduced ductility, substantiating the conclusion that the three geogrids failed in a brittle fashion. Fluctuations in tensile rates and printing settings exerted negligible influence on the damage morphology of geogrids. The principal factors affecting the damage morphology were the material composition and the configuration of the geogrid. This indicates that the intrinsic characteristics of the materials and the geogrid design were more pivotal in influencing their failure under stress.

Figure 13.

Geogrid failure pattern from tensile test.

Stress analysis at the joint

To explore the tensile mechanism of grids or geogrids, test findings showed that the geogrid forms significantly affected damage modes. As indicated in Figure 14, this work analyses node force in three geogrid types. The transverse ribs perpendicular to tension are the main geometric difference between uniaxial and biaxial geogrids. Longitudinal ribs convey tension forces to nodes. Biaxial geogrids’ nodes are protected from direct pulling by the transverse ribs’ bonding force F'.

Figure 14.

Force acting on different types of geogrid joints.

Uniaxial geogrids’ few transverse ribs and low bonding force were considered (Figure 14(a)). Since there are 15 longitudinal ribs, the theoretical force on each may be determined. Since transverse ribs are rare, longitudinal ribs bear most of the forces. This computation clarifies the geogrid structure’s force distribution, enabling a more precise assessment of its tensile behavior under applied forces, described below.

F_{1} = \frac{T_{1}}{15}

(4)where F₁ and T₁ represent the force on each longitudinal rib of the geogrid and the tensile strength of the uniaxial geogrid, respectively.

Biaxial geogrids possess a greater number of transverse ribs, resulting in a more intricate network structure (Figure 14(b)). This configuration increases the geogrid’s resistance to damage and improves its load-bearing capability due to the bonding force F’. The theoretical force exerted on each longitudinal rib must satisfy the following requirements.

F_{2} > \frac{T_{1}}{15}

(5)where F′, F₂, and T₁ were the bonding force generated by the cross ribs to the nodes, the Force on each longitudinal rib of biaxial geogrid, and the tensile strength of uniaxial geogrid, respectively. In the InterAX geogrid, the force distribution diagram is shown in Figure 14(c). Four hexagons are coming in the tensile test; if T is the force taken by the geogrid, then the force carried by a single unit will be T/4. The larger side of the trapezoid perpendicular to the direction of loading is in compression. Calculation of forces in ribs gives the following relations-

T = 4 F_{4} + 3.46 F_{3}

(6)

F_{3} > F_{4}

(7)

F_{4} = F_{5} = F_{6}

(8)

F_{7} = 0.5 F_{3} + 0.5 F_{4}

(9)

F_{7} > F_{5}

(10)

All the sides of the hexagon and the leg of the trapezoid have equal tension as per equation (8). From equation (7), it is clear that the triangular portion will get higher tension than the hexagonal portion. From equation (10), it is clear that the larger side of the horizontal trapezoid gets more compressive force than the smaller one, which is in tension. It is exciting to note that in InterAX geogrid in tensile testing, some strips are in compression.

Regression analysis

A regression study was performed to evaluate the relationship between ultimate tensile strength and filling form for biaxial geogrids, with the correlation coefficient used to represent the relationship. The investigation indicated that polynomial regression of orders 2 and 3 had the most robust connections with ultimate tensile strength and filling shape related to ultimate elongation. Ultimately, the third-order polynomial had the highest efficacy. This method for assessing the influence of filling form on the ultimate tensile strength of geogrid will yield a uniform solution in their respective patterns, as illustrated in Figure 8(a) and (c). Table 7 presents the regression equation and correlation coefficient, which can be utilized to determine ultimate tensile strength at any filling ratio. The regression equations of line 0° and line 45° possess a singular common solution; thus, gyroid 0° and gyroid 45° also share one common solution.

Table 7.

Regression equation of ultimate tensile strength (y) and filling form (x).

		Polynomial regression
		Polynomial of order 2		Polynomial of order 3
Filling pattern	Filling form	Regression equation	R²	Regression equation	R²
Line	0⁰	y = 2.412 + 0.038х – 2.0367 × 10⁻⁴ х²	0.818	y = 3.168 – 0.087х + 0.367 × 10⁻²х – 0.305 × 10⁻⁴х³	0.966
Line	45⁰	y = 3.144 + 0.026х – 4.822 × 10⁻⁴ х²	0.969	y = 2.921 + 0.063х – 0.002х² + 9.005 ×10⁻⁶ х³	0.991
Gyroid	0⁰	y = 3.096 + 0.0829х – 0.001х²	0.964	y = 2.777 + 0.136х – 0.003х² + 1.280 × 10⁻⁵х³	0.983
Gyroid	45⁰	y = 3.163 + 0.0423х – 4.255 × 10⁻⁴	0.735	y = 2.950 + 0.078х – 0.002х² + 8.580 × 10⁻⁶х³	0.774

Design requirement-commercial versus 3D printed geogrid

Commercially available geogrids used in practice are typically manufactured from PVA, PET, and PP. These materials have well-established design requirements such as aperture size (grid spacing), tensile strength, stiffness, and characteristic stress–strain behaviour. The 3D-printed geogrids are particularly suited for customized applications and small-scale experimental studies. Table 8 presents a summary of the key design properties of commercially available geogrids in comparison with the 3D-printed grids. The comparison indicates that the mechanical properties of the 3D-printed geogrids fall within the range of values typically required for commercial geogrids used in field applications.

Table 8.

Comparison of commercially and scaled geogrid.

Geogrids		Aperture size (mm)			Strength at 1% strain (kN/m), MD	Stiffness. (kN/m) at 1% strain
Geogrids		Uniaxial	Biaxial	InterAX	Strength at 1% strain (kN/m), MD	Stiffness. (kN/m) at 1% strain
Commercial geogrids	PP	20-150	25-65	a = 30-100	4.1–6.6	410–700
	PP	20-150	25-65	b = 100-280	4.1–6.6	410–700
	PVA	20-200	25-120	-	15–21	1500–2100
	PET	20-400	25-120	-	9–12	900–1200
Prototype value of 3D printed geogrid (scaled up from 1:10 model)	PLA material	100 × 500	100 × 100	a = 90	15–41	1000–4000
	PLA material	100 × 500	100 × 100	b = 250	15–41	1000–4000

Figure 15 shows the representative stress–strain curves for 3D printed geogrids. The results are also compared with the commercially available values as reported in the literature.^30–32 3D-printed geogrids show brittle behavior at lower strain (1-3 %) at failure as compared to commercial geogrids (10%). The brittle failure characteristics of 3D printed geogrids have been also reported in previous studies.^29,24 However, this does not adversely affect their use in small-scale model studies of GRS walls. Stathas et al.³³ have shown that the performance of geosynthetic-reinforced soil (GRS) structures is primarily governed by soil–reinforcement interaction at low to moderate strain levels (less than 3%). GRS walls reach serviceability limits such as facing displacement of about 1% - well before the reinforcement approaches its ultimate tensile strain. Consequently, the strains mobilized in the reinforcement remain small, and does not approach to the failure strain during wall deformation. Therefore, within the strain range, the printed geogrids exhibit performance that is effectively comparable to commercial geogrids. However, their performance strongly depends on the printing parameters, particularly the infill pattern, infill ratio, grid geometry, and loading rate. It is observed that the primary points of failure initiation are the crossover (junction) locations, which can be attributed to the local stress concentration and the reduced effective cross-section at the printed intersections. A similar observation has been reported by Shirdel and Farzam.²⁹ The strengthening of junctions is possible through modifications such as increased junction thickness, altered infill orientation, or localized reinforcement, however this is beyond the scope of the present work.

Figure 15.

Comparison of commercial versus scaled 3D printed PLA geogrid.

For the majority of geogrid applications, such as GRS walls, tension is the predominant mechanism. Therefore, compression is not considered in this study. In some cases, such as basal reinforcement, bending may influence the overall performance; however, it is typically neglected in most design applications, as its effect is generally not significant.

Limitation and future scope

In the present study, regression analysis was applied to the biaxial geogrids, as they exhibited the highest strength, to examine the relationship between filling form, filling pattern, and tensile capacity (see Table 7). One limitation of this approach is that the regression model is valid only within the range of geometries tested. However, the broader vision for future work is to integrate stress analysis with local failure criteria, which would help overcome this limitation and provide a more general predictive framework. While physical testing would still be essential for validation, such a predictive framework could enable estimation of stress–strain response and ultimate strength for a wide range of geogrid geometries without relying entirely on repeated fabrication and testing. This approach would be particularly useful for early-stage design, geometry optimization, and comparative evaluation in a virtual environment. Also, the failure initiation is from the junction so, the strengthening of junctions is possible through modifications such as increased junction thickness, altered infill orientation, or localized reinforcement, however this is beyond the scope of the present work. The current study focuses on low-strength, scaled geogrids intended for physical model testing, where the priority is to satisfy similitude requirements rather than to enhance full-scale mechanical performance. Future work may explore junction optimization to mitigate failure initiation at these points.

Conclusion

This study examines tensile tests conducted on two filling patterns and three different configurations of 3D-printed grids at various filling ratios, filling forms, and tensile rates to analyze the impact of tensile rates and filling ratios on the mechanical properties of the geogrids.

Additionally, the study explores the tensile failure mechanism of these geogrids. The key conclusions are as follows.

1. The geogrid’s tensile strength increased and then decreased as the filling ratio rose from 5% to 80%, peaking at specific filling ratios depending on the pattern. The highest tensile strength was observed at 50% for Line 0°, 30% for Line 45°, 50% for Gyroid 0°, and 30% for Gyroid 45°. Line 0° at 50% and Gyroid 0° at 30% showed superior strength compared to their respective counterparts, indicating that these filling ratios and patterns optimize the geogrid’s tensile strength.

2. The ultimate tensile strength of the geogrid does not consistently increase with higher filling ratios. Instead, there is an optimal filling ratio that maximizes strength. Gyroid 0° peaks at 30%, Gyroid 45° at 50%, and both Line 0° and Line 45° show equal strength at 38%, while Gyroid 0° and Gyroid 45° show equal strength at 51%.

3. The strain versus filling ratio trends similarly for both line and Gyroid patterns. In the line forms, increasing the filling ratio from 5% to 30% decreases strain by about 31.33% and boosts tensile strength, while further increases yield mixed results, with Line 0° showing more strain at all ratios. In the Gyroid forms, strain generally increases with higher filling ratios up to 30%, improving tensile strength, but this reverses at higher ratios. Gyroid 45° exhibits greater strain beyond a 5% filling ratio.

4. When tested at different tensile rates, the slope of strain versus tensile force curves for line-printed geogrids showed minimal differences across forms. At 2 mm/min, biaxial geogrids had slightly lower tensile strength than uniaxial but higher than InterAX, with uniaxial having the least strain at break and InterAX the most. At 10 mm/min, uniaxial and biaxial geogrids initially had similar slopes, but biaxial eventually showed a lower slope, while InterAX had the lowest. At 20 mm/min, the uniaxial geogrid consistently had the highest tensile strength, while InterAX had the lowest, with similar trends in strain at break across all rates.

5. For Gyroid-printed geogrids at a tensile rate of 2 mm/min, the slopes of strain versus tensile force curves were similar across forms, with biaxial geogrids slightly smaller than uniaxial and larger than InterAX. Biaxial geogrids had lower tensile strength than uniaxial but higher than InterAX, and the lowest strain at break, while InterAX had the highest. At 10 mm/min, uniaxial and biaxial geogrids showed similar slopes and tensile strength, with InterAX showing the lowest in both. At 20 mm/min, uniaxial geogrids had the highest tensile strength, followed by biaxial, with InterAX having the smallest tensile strength and highest elongation at break.

6. In line pattern, the ultimate tensile strength of uniaxial, biaxial, and InterAX geogrids increased as tensile rates increased from 2 to 10 mm/min, with biaxial geogrids exhibiting the most significant improvement from 10 to 20 mm/min. Strength increased by 16.45% for uniaxial, 34.59% for biaxial, and 43.43% for InterAX geogrids. Elongation trends expressed variability: uniaxial and InterAX maintained the stability initially but diverged beyond 10 mm/min, with InterAX increasing by 15.63% and uniaxial decreasing by 3.47%. Biaxial elongation regularly increased, averaging 25.64%. InterAX had the most elongation at 20 mm/min, whereas uniaxial shown the least. This indicates that different geogrids respond differently to changes in tensile rates.

7. The tensile strength trends of geogrids in the Gyroid pattern diverge from those in the line pattern. Biaxial and InterAX strength decreases from 2 to 10 mm/min, however InterAX increases significantly (20.30%) from 10 to 20 mm/min. Biaxial strength first increases by 13.28% but then decreases by 13.07% at higher rates. The uniaxial strength decreases by 2.35% prior to a modest increase of 1.28%. The strain at break first decreases for uniaxial and InterAX, thereafter increases, averaging gains of 10.53% and 8.69%, respectively. Biaxial elongation regularly rises by 45.05%. At a rate of 20 mm/min, InterAX exhibits the most elongation, whilst uniaxial displays the least.

8. The tensile properties of Gyroid-printed grids are highest at a tensile rate of 10 mm/min for biaxial geogrids and 20 mm/min for uniaxial and InterAX geogrids.

9. Uniaxial and Biaxial Geogrids show high stiffness at 0.5% strain, whereas InterAX shows low stiffness.

10. As the tensile rate increases, the tensile strength of InterAX geogrid generally increases. At a particular strain, the stiffness decreases as the tensile test proceeds.

11. The points of failure across all three geogrid types were relatively clean with minimal sharp edges and fibres, and variations in tensile rates and printing parameters had little effect on the damage form. Biaxial geogrids exhibited greater strength than uniaxial geogrids due to their higher number of transverse ribs. Conversely, in InterAX geogrids, the larger side of the trapezoid perpendicular to the loading experiences compression.

12. A third-order polynomial regression provided the best fit for the ultimate tensile strength versus filling ratio curve, with similar solutions observed across the different filling patterns.

Footnotes

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.

ORCID iDs

Shivshankar Maurya

Shantanu Patra

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Effect of 3D printing parameters and grid shape on geogrid’s tensile and stiffness properties using FDM technique

Abstract

Keywords

Introduction

Materials

3D Printer

Geogrid Model

Experimental Program

Calculations

Results and discussion

Effect of filling ratio and filling pattern

Effect of different grid forms

In-Line pattern

In gyroid pattern

Effect of the rate of tensile loading

For line patterns

For gyroid pattern

Effect of filling ratio, geometry form, and tensile rate on tensile stiffness

Failure pattern analysis

Stress analysis at the joint

Regression analysis

Design requirement-commercial versus 3D printed geogrid

Limitation and future scope

Conclusion

Footnotes

Declaration of conflicting interests

Funding

ORCID iDs

References