Determination of in-plane and out-of-plane shear moduli of composite materials

The aim of this work is to compare from an experimental point of view the determination of in-plane shear strength of unidirectional composite materials by means of two off-axis tests: three-point flexure and tensile. In the case of the off-axis three-point flexure test, the condition of small displacements and the condition of lift-off between the specimen and the fixture supports have been taken into account. Some considerations regarding stress and displacement fields are presented. The in-plane shear characterization has been performed on a carbon fiber reinforced unidirectional laminate with several fiber orientation angles: 10°, 20°, 30°, and 45°. Test conditions for both off-axis experimental methods, in order to ensure their applicability, are presented. Off-axis flexure test is considered more suitable than off-axis tensile test for the determination of in-plane shear strength.

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Determination of in-plane shear characteristics of composite materials with [±45°] layup

Mechanics of Composite Materials ◽

10.1007/bf02254785 ◽

1996 ◽

Vol 32 (2) ◽

pp. 176-182 ◽

Cited By ~ 1

Author(s):

A. Arnautov ◽

T. Bach

Keyword(s):

Composite Materials ◽

Plane Shear ◽

Shear Characteristics

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Controlling Out-of-Plane Shear Wave Propagation With Broadband Cloaking

Volume 4: Dynamics, Vibration, and Control ◽

10.1115/imece2019-12156 ◽

2019 ◽

Author(s):

Mao Liu ◽

W. D. Zhu

Keyword(s):

Linear Transformation ◽

Elastic Waves ◽

Shear Waves ◽

Nonlinear Transformation ◽

Plane Shear ◽

Shear Moduli ◽

Transformation Medium ◽

Invisibility Cloak ◽

Independent Functions ◽

Out Of Plane

Abstract A major challenge in designing a perfect invisibility cloak for elastic waves is that density and elasticity tensors need to be independent functions of its radius with a linear transformation medium. The traditional cloak for out-of-plane shear waves in membranes exhibits material properties with inhomogeneous and anisotropic shear moduli and densities, which yields a poor or even negative cloaking efficiency. This paper presents design of a cylindrical cloak for shear waves based on a nonlinear transformation. This excellent broadband nonlinear cloak only requires variation of its shear modulus, while the density in the cloak region remains unchanged. The nonlinear ray trajectory equation for out-of-plane shear waves is derived and a parameter to adjust the efficiency of the cylindrical cloak is introduced. Qualities of the nonlinear invisibility cloak are discussed by comparison with those of a cloak with the linear transformation. Numerical examples show that the nonlinear cloak is more effective for shielding out-of-plane shear waves from outside the cloak than the linear cloak and illustrate that the nonlinear cloak for shear waves remains highly efficient in a broad frequency range. The proposed nonlinear transformation in conjunction with ray trajectory equations can also be used to design nonlinear cloaks for other elastic waves.

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Comparison of Theoretical and Laboratory Out-of-Plane Shear Stiffness Values of Cross Laminated Timber Panels

Buildings ◽

10.3390/buildings8100146 ◽

2018 ◽

Vol 8 (10) ◽

pp. 146 ◽

Cited By ~ 3

Author(s):

Jan Niederwestberg ◽

Jianhui Zhou ◽

Ying-Hei Chui

Keyword(s):

Shear Modulus ◽

Cross Section ◽

Single Layer ◽

Beam Theory ◽

Shear Stiffness ◽

Plane Shear ◽

Shear Moduli ◽

Cross Laminated Timber ◽

Highly Sensitive ◽

Out Of Plane

The lay-up of cross laminated timber (CLT) leads to significant differences in properties over its cross-section. Particularly the out-of-plane shear behavior of CLT is affected by the changes in shear moduli over the cross-section. Results from laboratory shear tests are used to evaluate the shear stiffness of 3- and 5-layer CLT panels in their major and minor strength direction. The results are compared to calculated shear stiffness values on evaluated single-layer properties as well as commonly used property ratios using the Timoshenko beam theory and the shear analogy method. Differences between the two calculation approaches are pointed out. The shear stiffness is highly sensitive to the ratio of the shear modulus parallel to the grain to the shear modulus perpendicular to the grain. The stiffness values determined from two test measurements are compared with the calculated results. The level of agreement is dependent on the number of layers in CLT and the property axis of the CLT panels.

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A Test Method for Experimental Determination of Shear Moduli of Fibre Reinforced Composite Materials

Advanced Composites Letters ◽

10.1177/096369359400300101 ◽

1994 ◽

Vol 3 (1) ◽

pp. 096369359400300

Author(s):

B. Laleh ◽

P. Myler

Keyword(s):

Composite Materials ◽

Carbon Fibre ◽

Transverse Shear ◽

Test Method ◽

Reinforced Composites ◽

Simple Test ◽

Shear Moduli ◽

Reinforced Composite ◽

Fibre Reinforced Composites

This paper describes a simple test method for determining the in-plane and transverse shear moduli of unidirectional carbon fibre reinforced composites. The method employs photoelastic coating techniques in conjunction with four point offset bend loading conditions.

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Comparison of Theoretical and Laboratory Out-of-Plane Shear Stiffness Values of Cross Laminated Timber Panels

10.20944/preprints201809.0443.v1 ◽

2018 ◽

Author(s):

Jan Niederwestberg ◽

Jianhui Zhou ◽

Ying-Hei Chui

Keyword(s):

Shear Modulus ◽

Cross Section ◽

Single Layer ◽

Beam Theory ◽

Shear Stiffness ◽

Plane Shear ◽

Shear Moduli ◽

Cross Laminated Timber ◽

Highly Sensitive ◽

Out Of Plane

The lay-up of cross laminated timber (CLT) leads to significant differences in properties over its cross-section. Particularly the out-of-plane shear behavior of CLT is effected by the changes in shear moduli over the cross-section. Results from laboratory shear tests are used to evaluate the shear stiffness of 3- and 5-layer CLT panels in their major and minor strength direction. The results are compared to calculated shear stiffness values on evaluated single-layer properties as well as commonly used property ratios using the Timoshenko beam theory and the shear analogy method. Differences between the two calculation approaches are pointed out. The shear stiffness is highly sensitive to the ratio of the shear modulus parallel to the grain to the shear modulus perpendicular to the grain. The stiffness values determined from two test measurements are compared with the calculated results. The level of agreement is dependent on the number of layers in CLT and the property axis of the CLT panels.

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In-Plane Shear Strength Determination of Composite Materials in Laminated and Sandwich Panels

Applied Mechanics Reviews ◽

10.1115/1.3101842 ◽

1997 ◽

Vol 50 (11S) ◽

pp. S237-S240 ◽

Cited By ~ 6

Author(s):

J. R. Vinson

Keyword(s):

Shear Strength ◽

Composite Materials ◽

Test Procedure ◽

Sandwich Panels ◽

Laminated Composite ◽

Adhesive Bond ◽

Shear Stresses ◽

Plane Shear ◽

Laminated Composite Materials

A simple test procedure is available to determine the in-plane shear strength of laminated composite materials, as well as other orthotropic and isotropic advanced material systems. The test apparatus is simple, inexpensive, and the flat rectangular plate test specimen is not restricted in size or aspect ratio. In addition to its use for laminated composite materials, the test can also be used for foam core sandwich panels. In sandwich panels, the tests can be used to determine the in-plane shear strength of the faces, the core and/or the adhesive bond between face and core. The shear stresses developed vary linearly in the thickness direction and are constant over the entire planform area.

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