Shear Testing of Composites

Unlike an isotropic metal, the shear properties of composites are highly directional and not related to the material tensile properties. Therefore, shear testing of composites presents several challenges. Our composite testing experts will help you select the best shear test method for your desired results. 

Designing a test method that provides a pure shear stress state within a gage area can be difficult with composites. We utilize different test methods to gather measure the shear properties of your composite material, including interlaminar and in-plane shear testing. 

Interlaminar shear strength ASTM D2344  

Interlaminar shear is a property of the laminating resin or resin fiber interface, measured by loading the planes of lamination so they slip past one another. Interlaminar shear testing of composites is relatively easy to perform. Thus, it is often used for quality control, screening, or environmental degradation evaluation, such as fluid exposure or thermal cycling.

Some common standards for interlaminar shear testing of composites including short beam shear test ASTM D2344, in-plane shear strength of reinforced plastics ASTM D3846, and interlaminar shear strength by short-beam method ISO 14130. 

In-plane shear stress ASTM D3518 

In-plane shear testing testing of composites measures forces acting in shear within the plane of lamination. This may be measured by loading a +/-45 laminate in tension. As testing progresses past 5% shear strain, results may deviate from shear loading because of the change in specimen geometry. The in-plane shear method is described in ASTM D3518 and ISO 14129.    

V-notch shear testing ASTM D5379

The ASTM D5379 specification for V-notch or Iosipescu shear requires a specimen with v-notches on opposite sides. ASTM D5379 provides shear strain, shear stress, and shear modulus data. The v-notched specimen can also be used for in plane and interlaminar shear tests. 

ASTM D7078 outlines a newer version of in-plane shear testing where a larger gage length is needed, such as for a fabric or braid with large unit cells.

The Element advantage

Element has tested thousands of composite specimens according to the interlaminar and in-plane shear standards previously mentioned. Our composite testing experts understand the level of detail needed for sample preparation and fixture alignment to obtain the best quality results.

For more information about our shear testing of composites services or to request a quote, contact us today.