The present work investigates the enhancement of the flexural strength-to-weight ratio on the lattice structure of additively manufactured Inconel-718 parts made using the powder bed fusion (PBF) process. ASTM-E290 standard three-point bending experiments and finite element modeling were conducted on solid and lattice structure parts. Four novel lattice structure unit cells with positive Maxwell’s number for stretch-dominant mechanical behavior were designed and used in the three-point bending specimens. The different lattice structure types investigated are strengthened-cubic (named Model_1), strengthened-cubic + kagome (named Model_2), strengthened-cubic + octet truss (named Model_3), and strengthened-cubic + kagome+octet truss (named as Model_4). Results obtained for the lattice structure specimens were compared with those obtained for solid specimens. The study revealed significant differences in strength-to-weight ratio among them, proving the tremendous potential of lattice structures in flexural loading applications by giving higher strength-to-weight ratios than solid specimens. Out of the four lattice structures and one solid structure investigated, Model_2 with only angular beams and Model_3 with only interior beams gave a better strength-to-weight ratio than solid specimens. Model_2 and Model_3 have beams along the unit cell’s body diagonal, leading to better performance. Out of all the lattice-structured specimens, Model_2 showed the highest strength-to-weight ratio. In the finite element model, the maximum equivalent strain was used as the criterion for failure. The failure sites found by finite element simulation coincided with those in the experiments.
RosenDW. Computer-Aided Design for Additive Manufacturing of Cellular Structures. Comput Aided Des Appl2007; 4(5): 585–594.
9.
NageshaBKDhinakaranVVarsha ShreeM, et al. Review on characterization and impacts of the lattice structure in additive manufacturing. Mater Today Proc2020; 21(1): 916–919.
10.
GorguluarslanRM. Multi-objective design optimization of additively manufactured lattice structures for improved energy absorption performance. Proc IMechE, Part C: J Mechanical Engineering Science2022; 236(1): 3–15.
11.
WeiKYangQYangX, et al. Mechanical analysis and modeling of metallic lattice sandwich additively fabricated by selective laser melting. Thin-Walled Struct2020; 146: 106189.
12.
ConcliFGilioliANalliF. Experimental–numerical assessment of ductile failure of additive manufacturing selective laser melting reticular structures made of Al A357. Proc IMechE, Part C: J Mechanical Engineering Science2021; 235(10): 1909–1916.
13.
XiaoLXuXFengG, et al. Compressive performance and energy absorption of additively manufactured metallic hybrid lattice structures. Int J Mech Sci2022; 219: 107093.
14.
AlkhaderMNazzalMLoucaK. Design of bending dominated lattice architectures with improved stiffness using hierarchy. Proc IMechE, Part C: J Mechanical Engineering Science2019; 233(11): 3976–3993.
15.
LiCLeiHZhangZ, et al. Architecture design of periodic truss-lattice cells for additive manufacturing. Addit Manuf2020; 34: 101172.
16.
MahbodMAsgariM. Multiobjective optimization of a newly developed additively manufactured functionally graded anisotropic porous lattice structure. Proc IMechE, Part C: J Mechanical Engineering Science2020; 234(11): 2233–2255.
17.
SeharingAAzmanAHAbdullahS. A review on integration of lightweight gradient lattice structures in additive manufacturing parts. Adv Mech Eng2020; 12(6): 1–21.
18.
JinXLiGXZhangM. Design and optimization of nonuniform cellular structures. Proc IMechE, Part C: J Mechanical Engineering Science2018; 232(7): 1280–1293.
19.
KimHWKimYSLimJY. Design of a double-optimized lattice structure using the solid isotropic material with penalization method and material extrusion additive manufacturing. Proc IMechE, Part C: J Mechanical Engineering Science2020; 234(17): 3447–3458.
20.
MantovaniSCampoGAGiacaloneM. Steering column support topology optimization including lattice structure for metal additive manufacturing. Proc IMechE, Part C: J Mechanical Engineering Science2022; 236(21): 10645–10656.
21.
HanZWeiK. Multi-material topology optimization and additive manufacturing for metamaterials incorporating double negative indexes of Poisson’s ratio and thermal expansion. Addit Manuf2022; 54: 102742.
22.
ChengLLiangXBelskiE, et al. Natural frequency optimization of variable-density additive manufactured lattice structure: Theory and experimental validation. Trans ASME j manuf sci eng2018; 140: 1–16.
23.
DongGTangYLiD, et al. Design and optimization of solid lattice hybrid structures fabricated by additive manufacturing. Addit Manuf2020; 33: 101116.
24.
ParkSYKimKSAlMangourB, et al. Effect of unit cell topology on the tensile loading responses of additive manufactured CoCrMo triply periodic minimal surface sheet lattices. Mater Des2021; 206: 109778.
25.
ParkSYKimKSAlMangourB, et al. Compressive deformation behavior and energy absorption characteristic of additively manufactured sheet CoCrMo triply periodic minimal surface lattices. J Mater Res Technol2022; 18: 171–184.
26.
ParkSYKimKSAlMangourB, et al. Effect of microstructure and unit cell’s geometry on the compressive mechanical response of additively manufactured Co-Cr-Mo sheet I-WP Lattice. Arch Metall Mater2022; 67(4): 1525–1529.
27.
TeimouriMAsgariM. Mechanical performance of additively manufactured uniform and graded porous structures based on topology-optimized unit cells. Proc IMechE, Part C: J Mechanical Engineering Science2021; 235(9): 1593–1618.
28.
KorshunovaNAlaimoGHosseiniSB, et al. Bending behavior of octet-truss lattice structures: modelling options, numerical characterization and experimental validation. Mater Des2021; 205: 109693.
29.
LozanovskiBLearyMTranP, et al. Computational modelling of strut defects in SLM manufactured lattice structures. Mater Des2019; 171: 107671.
30.
DongGZhaoYF. Numerical and experimental investigation of the joint stiffness in lattice structures fabricated by additive manufacturing. Int J Mech Sci2018; 148: 475–485.
31.
GavazzoniMBoniottiLFolettiS. Influence of specimen size on the mechanical properties of microlattices obtained by selective laser melting. Proc IMechE, Part C: J Mechanical Engineering Science2021; 235(10): 1774–1787.
32.
JinoopANPaulCPMishraSK, et al. Laser additive manufacturing using directed energy deposition of Inconel-718 wall structures with tailored characteristics. Vacuum2019; 166: 270–278.
33.
CakmakEKirkaMMWatkinsTR, et al. Microstructural and micromechanical characterization of IN718 theta shaped specimens built with electron beam melting. Acta Mater2016; 108: 161–175.
34.
YangHYangJHuangW, et al. The printability, microstructure, crystallographic features and microhardness of selective laser melted inconel 718 thin wall. Mater Des2018; 156: 407–418.
35.
SchirraJJCalessRHHatalaRW. The effect of laves phase on the mechanical properties of wrought and cast + HIP inconel 718. The Minerals, Metals and Materials Society, 1991, pp.375–388.
36.
PopovichVABorisovEVPopovichAA, et al. Impact of heat treatment on mechanical behaviour of Inconel 718 processed with tailored microstructure by selective laser melting. Mater Des2017; 131: 12–22.
37.
GallmeyerTGMoorthySKappesBB, et al. Knowledge of process-structure-property relationships to engineer better heat treatments for laser powder bed fusion additive manufactured Inconel 718. Addit Manuf2020; 31: 100977.
38.
Ansys Inc. LS-DYNA theory manual. Hyderabad: Ansys/LST, 2006.
39.
Renishaw Inc. Data sheet: In718-0405 powder for additive manufacturing, Renishaw part number: H-5800-052. Bangalore, India: Renishaw.
