Influence of patch length and thickness on strength and stiffness of patched laminates

Abstract

Composite laminates made of fiber patches offer a large flexibility in terms of layup design. Geometrical layup parameters such as patch length and patch thickness are unique for this type of laminates. This article presents results on the investigation of the influence of patch length and patch thickness on the tensile strength and stiffness properties of patched laminates to contribute to the material understanding. The results show that an increasing of patch thickness leads to a drastic reduction in tensile strength of up to 48.7% for a triplication in patch thickness. The patch length was varied between 20 and 120 mm. Up to 60 mm, the tensile strength increased by 11.5%, further increase did not contribute to a further improved tensile strength. The influence of patch length and patch thickness on the stiffness was found to have only a minor effect. A three-dimensional numerical model that accounts for delamination failure using cohesive zone elements shows very good correlation with the experimental results. This shows its potential for virtual testing to determine tensile strength and stiffness properties of patched laminates without additional testing effort.

Keywords

Delamination discontinuous plies patch laminate cohesive zone modeling

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References

Götz K. Die innere Optimierung der Bäume als Vorbild für technische Faserverbunde – eine lokale approximation. Dissertation, Forschungszentrum Karlsruhe, Karlsruhe, 2000.

Khani

IJsselmuiden

Abdalla

et al.

Design of variable stiffness panels for maximum strength using lamination parameters. Compos Part B Eng 2011; 42: 546–552.

Lopes

Gürdal

Camanho

. Variable-stiffness composite panels: buckling and first-ply failure improvements over straight-fibre laminates. Comput Struct 2008; 86: 897–907.

Lukaszewicz

Ward

Potter

. The engineering aspects of automated prepreg layup: history, present and future. Compos Part B Eng 2012; 43: 997–1009.

Kim BC, Hazra K, Weaver P and Potter K. Limitations of fibre placement techniques for variable angle tow composites and their process-induced defects. In: Proceedings of the 18th international conference on composite materials, Jeju, 21–26 August 2011, pp. 1–6.

Snudden

Ward

Potter

. Reusing automotive composites production waste. Reinforced Plastics 2014; 58: 20–27.

Zogg M. Gepatchte Laminate – ein Weg zum Recycling und zur Vermeidung von Produktionsabfällen. In: inspire ics (ed.) Jahrbuch 2012. Zürich, pp. 7–12.

Meyer O. Kurzfaser-preform-technologie zur kraftflussgerechten Herstellung von Faserverbundbauteilen. Dissertation, Universität Stuttgart. Stuttgart, 2008.

Baucom

Thomas

Pogue

et al.

Tiled composite laminates. J Compos Mater 2010; 44: 3115–3132.

10.

Pimenta

Robinson

. An analytical shear-lag model for composites with ‘brick-and-mortar’ architecture considering non-linear matrix response and failure. Compos Sci Technol 2014; 104: 111–124.

11.

Czél

Pimenta

Wisnom

et al.

Demonstration of pseudo-ductility in unidirectional discontinuous carbon fibre/epoxy prepreg composites. Compos Sci Technol 2015; 106: 110–119.

12.

Malkin

Yasaee

Trask

et al.

Bio-inspired laminate design exhibiting pseudo-ductile (graceful) failure during flexural loading. Compos Part A Appl Sci Manuf 2013; 54: 107–116.

13.

Krueger

. Virtual crack closure technique: history, approach, and applications. Appl Mech Rev 2004; 57: 109–143.

14.

Wisnom

. Modelling discrete failures in composites with interface elements. Compos Part A Appl Sci Manuf 2010; 41: 795–805.

15.

Turon

Camanho

Costa

et al.

Accurate simulation of delamination growth under mixed-mode loading using cohesive elements: definition of interlaminar strengths and elastic stiffness. Compos Struct 2010; 92: 1857–1864.

16.

Camanho PP, Lopes C, Turon A and Trias D. Technical Note 2: Best Practice Analysis Methods. DELAT-INE-TN-410, 2011.

17.

Deutsches Institut für Normnung e.V. 527-4. Bestimmung der Zugeigenschaften.

18.

Hafellner R, Pichler M and Wörndle R. Faserschädigung und Faserlöngeneinfluss auf die Materialeigenschaften bei LFT: Lange Fasern spritzgießen. Kunststoffe international 2000; 2: 44–48.

19.

Brewer

Lagace

. Quadratic stress criterion for initiation of delamination. J Compos Mater 1988; 22: 1141–1155.

20.

Benzeggagh

Kenane

. Measurement of mixed-mode delamination fracture toughness of unidirectional glass/epoxy composites with mixed-mode bending apparatus. Compos Sci Technol 1996; 56: 439–449.

21.

Dassault Systèmes Simulia Corporation. ABAQUS 6.14: Abaqus/CAE User’s Guide, 2014 –> Could not find further details, other publications cited it this way since it is only a manual of the software.

22.

Hashin

. Failure criteria for unidirectional fiber composites. J Appl Mech 1980; 47: 329–334.

23.

Deutsches Institut für Normnung e.V. 14130. Bestimmung der scheinbaren Interlaminaren Scherfestigkeit nach dem Dreipunktverfahren mit kurzem Balken.

24.

Kaddour

Hinton

Smith

et al.

Mechanical properties and details of composite laminates for the test cases used in the third world-wide failure exercise. J Compos Mater 2013; 47: 2427–2442.

25.

Horn B, Ebel C and Drechsler K. Strategies to increase the mechanical performance of long fiber patch preforms. In: Proceedings of the 17th European conference on composite materials, München, 26–30 June, pp. 1–7.

26.

Chakraborty

Pradhan

. Effect of ply thickness and fibre orientation on delamination initiation in broken ply composite laminates. J Reinf Plast Compos 1999; 18: 735–758.