Comparison of the shear behavior in graphite-epoxy composites evaluated by means of biaxial test and off-axis tension test

Characterization of shear behavior in composite materials remains a not fully solved problem. In the last fifty years, many different approaches have been proposed to solve this problem (rail shear, thin-walled tube torsion, off-axis tensile, ±45° tensile, Arcan, Iosipescu, asymmetric four-point ben...

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Autores principales:	Marín Juan Carlos, Barroso Alberto
Formato:	article
Lenguaje:	EN
Publicado:	De Gruyter 2021
Materias:	composite materials testing off axis cruciform samples mechanical characterization Materials of engineering and construction. Mechanics of materials TA401-492
Acceso en línea:	https://doaj.org/article/a0b842f3da2245409810145df9d6537d
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spelling	oai:doaj.org-article:a0b842f3da2245409810145df9d6537d2021-12-05T14:11:03ZComparison of the shear behavior in graphite-epoxy composites evaluated by means of biaxial test and off-axis tension test2191-035910.1515/secm-2021-0022https://doaj.org/article/a0b842f3da2245409810145df9d6537d2021-05-01T00:00:00Zhttps://doi.org/10.1515/secm-2021-0022https://doaj.org/toc/2191-0359Characterization of shear behavior in composite materials remains a not fully solved problem. In the last fifty years, many different approaches have been proposed to solve this problem (rail shear, thin-walled tube torsion, off-axis tensile, ±45° tensile, Arcan, Iosipescu, asymmetric four-point bend, plate twist, v-notched rail shear, off-axis flexural, and shear frame), although none of these approaches have achieved an unquestionable solution. For this reason, proposals of alternative methods and comparison between different experimental techniques are of interest. In the present work, the use of cruciform samples with the fiber oriented at 45° with respect to the load directions, and subjected to tension-compression (creating a pure shear stress state at the central part of the samples), is studied. The experimental results of the cruciform samples have been compared with the off-axis tests (with the fiber at 10°) for the same material (AS4/8552), finding a good agreement between the shear experimental curves, especially at the initial part of the curve, where the shear modulus is calculated. Nevertheless, the shear strength value obtained by means of the cruciform specimen has shown to be significantly lower than that obtained using the off-axis test. A Finite Element numerical model of the cruciform specimen has been developed to analyze the stress field of the samples. Numerical results have shown that there is a central area of the cruciform specimens where a pure and uniform shear stress state is developed, which is suitable for the evaluation of the shear constitutive law of the material. It has been observed that there is a (σ 22) stress concentration in the transition between the straight and curved parts of the boundary geometry of the samples, which explain some premature failures of the samples. This premature failure could be avoided with tabs extended up to the beginning of the central part of the sample.Marín Juan CarlosBarroso AlbertoDe Gruyterarticlecomposite materialstestingoff axiscruciform samplesmechanical characterizationMaterials of engineering and construction. Mechanics of materialsTA401-492ENScience and Engineering of Composite Materials, Vol 28, Iss 1, Pp 215-222 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	composite materials testing off axis cruciform samples mechanical characterization Materials of engineering and construction. Mechanics of materials TA401-492
spellingShingle	composite materials testing off axis cruciform samples mechanical characterization Materials of engineering and construction. Mechanics of materials TA401-492 Marín Juan Carlos Barroso Alberto Comparison of the shear behavior in graphite-epoxy composites evaluated by means of biaxial test and off-axis tension test
description	Characterization of shear behavior in composite materials remains a not fully solved problem. In the last fifty years, many different approaches have been proposed to solve this problem (rail shear, thin-walled tube torsion, off-axis tensile, ±45° tensile, Arcan, Iosipescu, asymmetric four-point bend, plate twist, v-notched rail shear, off-axis flexural, and shear frame), although none of these approaches have achieved an unquestionable solution. For this reason, proposals of alternative methods and comparison between different experimental techniques are of interest. In the present work, the use of cruciform samples with the fiber oriented at 45° with respect to the load directions, and subjected to tension-compression (creating a pure shear stress state at the central part of the samples), is studied. The experimental results of the cruciform samples have been compared with the off-axis tests (with the fiber at 10°) for the same material (AS4/8552), finding a good agreement between the shear experimental curves, especially at the initial part of the curve, where the shear modulus is calculated. Nevertheless, the shear strength value obtained by means of the cruciform specimen has shown to be significantly lower than that obtained using the off-axis test. A Finite Element numerical model of the cruciform specimen has been developed to analyze the stress field of the samples. Numerical results have shown that there is a central area of the cruciform specimens where a pure and uniform shear stress state is developed, which is suitable for the evaluation of the shear constitutive law of the material. It has been observed that there is a (σ 22) stress concentration in the transition between the straight and curved parts of the boundary geometry of the samples, which explain some premature failures of the samples. This premature failure could be avoided with tabs extended up to the beginning of the central part of the sample.
format	article
author	Marín Juan Carlos Barroso Alberto
author_facet	Marín Juan Carlos Barroso Alberto
author_sort	Marín Juan Carlos
title	Comparison of the shear behavior in graphite-epoxy composites evaluated by means of biaxial test and off-axis tension test
title_short	Comparison of the shear behavior in graphite-epoxy composites evaluated by means of biaxial test and off-axis tension test
title_full	Comparison of the shear behavior in graphite-epoxy composites evaluated by means of biaxial test and off-axis tension test
title_fullStr	Comparison of the shear behavior in graphite-epoxy composites evaluated by means of biaxial test and off-axis tension test
title_full_unstemmed	Comparison of the shear behavior in graphite-epoxy composites evaluated by means of biaxial test and off-axis tension test
title_sort	comparison of the shear behavior in graphite-epoxy composites evaluated by means of biaxial test and off-axis tension test
publisher	De Gruyter
publishDate	2021
url	https://doaj.org/article/a0b842f3da2245409810145df9d6537d
work_keys_str_mv	AT marinjuancarlos comparisonoftheshearbehavioringraphiteepoxycompositesevaluatedbymeansofbiaxialtestandoffaxistensiontest AT barrosoalberto comparisonoftheshearbehavioringraphiteepoxycompositesevaluatedbymeansofbiaxialtestandoffaxistensiontest
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Comparison of the shear behavior in graphite-epoxy composites evaluated by means of biaxial test and off-axis tension test

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