Effects of hybridization and ply thickness on the strength and toughness of composite laminates

This work presents the results of an experimental study performed in carbon/epoxy composite materials manufactured using a ply-level hybridization technique. The aim of the study is to investigate the potential of such hybridization technique to promote pseudo-ductile failure, and to enhance fracture toughness. Two thin-ply carbon-epoxy systems and three different carbon-carbon hybrid lay-ups are considered. Both strength and fracture tests are performed on the manufactured laminates and the properties of the hybrid materials are compared to those of the baseline non-hybrid composites. Digital Image Correlation and post-mortem X-ray imaging are used to analyze the fracture process of the different materials. The comparison of the mechanical response of the different materials demonstrates that, by means of thin ply hybridization, a pseudo-ductile failure in tension can be obtained, associated with fibre fragmentation. However, the hybridization seems not to be responsible for the increased fracture toughness that is ascribable to the ply-thickness effect.

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The Thickness Effect of PSF Nanofibrous Mat on Fracture Toughness of Carbon/Epoxy Laminates

Materials ◽

10.3390/ma14133469 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3469

Author(s):

Hamed Saghafi ◽

Ali Nikbakht ◽

Reza Mohammadi ◽

Dimitrios Zarouchas

Keyword(s):

Fracture Toughness ◽

Composite Laminates ◽

Double Cantilever Beam ◽

Thickness Effect ◽

Toughening Mechanism ◽

Geometrical Features ◽

Electrospinning Method ◽

Fracture Tests ◽

Mat Thickness ◽

First Time

The geometrical features of nanofibers, such as nanomat thickness and the diameter of nanofibers, have a significant influence on the toughening behavior of composite laminates. In this study, carbon/epoxy laminates were interleaved with polysulfone (PSF) nanofibrous mats and the effect of the PSF nanomat thickness on the fracture toughness was considered for the first time. For this goal, the nanofibers were first produced by the electrospinning method. Then, double cantilever beam (DCB) specimens were manufactured, and mode-I fracture tests were conducted. The results showed that enhancing the mat thickness could increase the fracture toughness considerably (to about 87% with the maximum thickness). The toughening mechanism was also considered by presenting a schematic picture. Micrographs were taken using a scanning electron microscope (SEM).

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Improvement of Vibration Damping Capacity and Fracture Toughness in Composite Laminates by the Use of Polymeric Interleaves

10.1115/imece1999-0213 ◽

1999 ◽

Author(s):

Ronald F. Gibson ◽

Hui Zhao

Keyword(s):

Fracture Toughness ◽

Composite Laminates ◽

Critical Thickness ◽

Vibration Damping ◽

Thickness Effect ◽

Damping Capacity ◽

Mode Ii ◽

Interlaminar Fracture Toughness ◽

Interlaminar Fracture ◽

Mode Ii Fracture Toughness

Abstract It is shown that simultaneous improvement of vibration damping capacity and interlaminar fracture toughness in composite laminates can be achieved by using polymeric interleaves between the composite laminae. The specific case of Mode II interlaminar fracture toughness and flexural damping capacity of interleaved composite laminates is studied. Graphite/epoxy, E-glass/epoxy and E-glass/polyetherimide composite laminates with polymeric interleaves of several different thicknesses and materials were tested using both the end notch flexure (ENF) test for Mode II fracture toughness and the impulse-frequency response test for flexural damping capacity. The Mode II energy release rate GIIc for all three composites increased linearly with increasing interleaf thickness up to a critical thickness, then dropped off with further increases in thickness. The damping loss factor η for all three composites increased linearly with increasing interleaf thickness up to the maximum thickness. Analytical models for predicting the influence of interleaves on GIIc and η are developed, along with a hypothesis for the critical thickness effect with regard to fracture toughness.

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Improvement of Vibration Damping Capacity and Fracture Toughness in Composite Laminates by the Use of Polymeric Interleaves

Journal of Engineering Materials and Technology ◽

10.1115/1.1370385 ◽

2001 ◽

Vol 123 (3) ◽

pp. 309-314 ◽

Cited By ~ 22

Author(s):

Ronald F. Gibson ◽

Yu Chen ◽

Hui Zhao

Keyword(s):

Fracture Toughness ◽

Composite Laminates ◽

Critical Thickness ◽

Vibration Damping ◽

Thickness Effect ◽

Damping Capacity ◽

Mode Ii ◽

Interlaminar Fracture Toughness ◽

Interlaminar Fracture ◽

Mode Ii Fracture Toughness

It is shown that, under certain conditions, simultaneous improvement of vibration damping capacity and interlaminar fracture toughness in composite laminates can be achieved by using polymeric interleaves between the composite laminae. The specific case of Mode II interlaminar fracture toughness and flexural damping capacity of interleaved composite laminates is studied. Graphite/epoxy, E-glass/epoxy and E-glass/polyetherimide composite laminates with polymeric interleaves of several different thicknesses and materials were tested using both the end notch flexure (ENF) test for Mode II fracture toughness and the impulse-frequency response test for flexural damping capacity. The Mode II energy release rate GIIc for all three composites increased linearly with increasing interleaf thickness up to a critical thickness, then dropped off with further increases in thickness. The damping loss factor η for all three composites increased linearly with increasing interleaf thickness up to the maximum thickness. Analytical models for predicting the influence of interleaves on GIIc and η are developed, along with a hypothesis for the critical thickness effect with regard to fracture toughness.

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Is there a ply thickness effect on the mode I intralaminar fracture toughness of composite laminates?

Theoretical and Applied Fracture Mechanics ◽

10.1016/j.tafmec.2020.102473 ◽

2020 ◽

Vol 107 ◽

pp. 102473 ◽

Cited By ~ 1

Author(s):

C. Furtado ◽

A. Arteiro ◽

P. Linde ◽

B.L. Wardle ◽

P.P. Camanho

Keyword(s):

Fracture Toughness ◽

Composite Laminates ◽

Thickness Effect ◽

Mode I

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Determination of crack tip position by digital image correlation at static and cyclic fracture toughness tests of aluminum alloys

Deformation and Fracture of Materials ◽

10.31044/1814-4632-2018-7-30-38 ◽

2018 ◽

pp. 30-38 ◽

Cited By ~ 1

Author(s):

V. V. Avtayev ◽

◽

N. O. Yakovlev ◽

V. S. Yerasov ◽

N. Yu. Podzhivotov ◽

...

Keyword(s):

Fracture Toughness ◽

Aluminum Alloys ◽

Digital Image Correlation ◽

Digital Image ◽

Crack Tip ◽

Image Correlation ◽

Cyclic Fracture ◽

Cyclic Fracture Toughness ◽

Tip Position

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Ductile failure analysis of epoxy resin plates containing multiple circular arc cracks by means of the equivalent material concept

International Journal of Mechanical and Materials Engineering ◽

10.1186/s40712-020-00123-1 ◽

2021 ◽

Vol 16 (1) ◽

Author(s):

M. Pourseifi ◽

A. S. Rahimi

Keyword(s):

Ductile Failure ◽

Equivalent Material ◽

Circular Arc ◽

Equivalent Material Concept ◽

Crack Tips ◽

Fracture Tests ◽

Polymeric Samples ◽

Cracked Specimens ◽

Brittle Fracture Criterion ◽

Material Concept

AbstractDuctile failure of polymeric samples weakened by circular arc cracks is studied theoretically and experimentally in this research. Various arrangements of cracks with different arc angles are considered in the specimens such that crack tips experienced the mixed mode I/II loading conditions. Fracture tests are conducted on the multi-cracked specimens and their fracture loads are achieved. To provide the results, the equivalent material concept (EMC) is used in conjunction of dislocation method and a brittle fracture criterion such that there is no necessity for performing complex and time-consuming elastic-plastic damage analyses. Theoretical and experimental stress intensity factors are computed and compared with each other by employing the fracture curves which demonstrate the appropriate efficiency of proposed method to predict the tests results.

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Linear translaminar fracture characterization of additive manufactured continuous carbon fiber reinforced thermoplastic

Journal of Thermoplastic Composite Materials ◽

10.1177/08927057211021462 ◽

2021 ◽

pp. 089270572110214

Author(s):

Weiller M Lamin ◽

Flávio LS Bussamra ◽

Rafael TL Ferreira ◽

Rita CM Sales ◽

José E Baldo

Keyword(s):

Fracture Toughness ◽

Carbon Fiber ◽

Fracture Mechanics ◽

Image Correlation ◽

Fiber Reinforced ◽

Fused Filament Fabrication ◽

Critical Energy Release Rate ◽

Linear Elastic ◽

Continuous Carbon Fiber ◽

Carbon Fiber Reinforced

This work presents the experimental determination of fracture mechanics parameters of composite specimens manufactured by fused filament fabrication (FFF) with continuous carbon fiber reinforced thermoplastic filaments, based on Linear Elastic Fracture Mechanics (LEFM). The critical mode I translaminar fracture toughness (KIc) and the critical energy release rate (GIc) are found for unidirectional and cross-ply laminates. The specimens were submitted to quasi-static tensile testing. Digital Image Correlation (DIC) is used to find the stress field. The stress fields around the crack tip are compared to linear elastic finite element simulations. The results demonstrate the magnitude of fracture toughness is in the same range as for polymers and some metals, depending on lay-up configuration. Besides, fractographic analyses show some typical features as river lines, fiber impression, fiber pulls-out and porosity aspects.

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