The background to the Second World-Wide Failure Exercise

Kaddour, A.S.; Hinton, M.J.; Smith, PA; Li, S

doi:10.1177/0021998312449885

Cited by 81 publications

(39 citation statements)

References 17 publications

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“…Cuntze's theory [1,2] assumes that the longitudinal strain or stress at failure under multiaxial loading is a constant as determined from a uniaxial test. However, the FE longitudinal stresses or strains at failure for all of the 16 load cases considered here do not show them to be constant.…”

Section: Fe Results and Failure Criterionmentioning

confidence: 99%

“…Multiaxial stress problems in composites have gained attention through efforts such as the Worldwide Failure Exercises (WWFE-I and II) [1,2]. However there is still a paucity of reliable experimental data for biaxial or multiaxial load cases, especially for those involving through-thickness compression and in-plane tension, due to the cost and complexity of multiaxial testing.…”

Section: Introductionmentioning

confidence: 99%

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Effect of high through-thickness compressive stress on fibre direction tensile strength of carbon/epoxy composite laminates

Gan

Wisnom

Hallett

2014

Composites Science and Technology

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The fibre-direction tensile strength of carbon/epoxy laminates under the influence of throughthickness compressive stresses has been experimentally investigated. In a unidirectional (UD) laminate, the through-thickness compressive stresses will cause premature longitudinal fibresplitting, masking the effect of transverse stresses on the fibre-direction strength. Here a cross-ply laminate has been used. With the addition of 90° plies preventing the 0° fibres from splitting, it effectively allows the dependence of fibre-direction tensile strength on high through-thickness stresses to be studied. The severity of the through-thickness loads has been varied using cylindrical indenters of different radii, up to the loads near the through-thickness compressive failure stress of the cross-ply laminate. The results show that there is a linear decrease in fibre-direction strength with the mean through-thickness stress. In all the test cases, the specimens failed in a catastrophic brittle manner, with scanning electron micrography showing primarily a fibre tensile fracture mode. The detailed stress state in the specimens has been calculated via finite element analysis. Two failure criteria are proposed, which can be used as conservative design criteria concerning fibre-dominated failures in multiaxial load scenarios. IntroductionWith the increasing use of composite materials replacing metals in aerospace applications, the need to consider complex load conditions is also increasing. Highly localised throughthickness stresses can often be seen in components where localised contact conditions exist, such as in bolted joints. These stresses may interact with co-existing primary in-plane tensile loading in the fibre-direction, leading to earlier failure. when he studied through-thickness compressive loading on unidirectional and cross-plied carbon/epoxy AS4/8552 laminates. The through-thickness stresses that interact with the unidirectional composite fibre direction strength found in the literature are mostly in the form of hydrostatic pressure, at most up to moderate values of ~700 MPa. The current study is a detailed expansion of initial results presented in [12]. In this work, a biaxial test method is developed to apply highly localised through-thickness compressive stress (locally as high as -1700 MPa, as calculated by linear elastic finite element analysis) on a simple cross-plied carbon/epoxy tensile test specimen.The high through-thickness compressive strength of a cross-plied laminate allows the interaction between a broad range of through-thickness compression and in-plane tensile strength to be examined. Multiple experimental load cases are presented and finite element models have been used to study the stresses within the specimens so that a simple failure criterion can be proposed for engineering design purposes. Experimental Specimen preparation and rig setupThe material under consideration is Hexcel's carbon epoxy pre-preg system, IM7/8552 with a nominal ply thickness of 0.125 mm. Four identical panels wi...

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Section: Fe Results and Failure Criterionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of high through-thickness compressive stress on fibre direction tensile strength of carbon/epoxy composite laminates

Gan

Wisnom

Hallett

2014

Composites Science and Technology

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“…This 'Part B' introductory paper, taken together with the introductory paper to 'Part A', 44 has been written to provide a commentary on the process adopted for carrying out WWFE-II. The organisers believe that the process provides an effective, objective and dispassionate means of examining the robustness of the leading 3-D failure theories, whilst at the same time ensuring that the current state of knowledge in this field has been captured in a clear set of publications.…”

Section: Discussionmentioning

confidence: 99%

“…[44], a thorough understanding of the triaxial failure behaviour of composites is important in many applications, including:…”

Section: The Second World-wide Failure Exercisementioning

confidence: 99%

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The background to Part B of the Second World-Wide Failure Exercise: Evaluation of theories for predicting failure in polymer composite laminates under three-dimensional states of stress

Hinton

Kaddour

2013

Journal of Composite Materials

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The Second World-Wide Failure Exercise was launched and organised by the authors to determine the accuracy of current theories for predicting failure in polymer composite laminates under three-dimensional states of stress. This paper provides an introduction to the second stage ('Part B') of Second World-Wide Failure Exercise within which the level of maturity and accuracy of the leading three-dimensional failure theories for composites are assessed against experimental data, their strengths and weaknesses are identified and conclusions are drawn. The Second World-Wide Failure Exercise builds upon the process and philosophy developed during the First World-Wide Failure Exercise with the clear aims of ensuring that the assessment is objective, transparent and an effective, accessible benchmark for use by the composites community.

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Structural Health Monitoring for Carbon Fiber Resin Composite Car Body Structures

Herrmann

Wellnitz

Jähn

et al. 2013

Sustainable Automotive Technologies 2013

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The background to the Second World-Wide Failure Exercise

Cited by 81 publications

References 17 publications

Effect of high through-thickness compressive stress on fibre direction tensile strength of carbon/epoxy composite laminates

Effect of high through-thickness compressive stress on fibre direction tensile strength of carbon/epoxy composite laminates

The background to Part B of the Second World-Wide Failure Exercise: Evaluation of theories for predicting failure in polymer composite laminates under three-dimensional states of stress

Structural Health Monitoring for Carbon Fiber Resin Composite Car Body Structures

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