Flexural test

A mechanical test in which a specimen is pulled along its axis until it breaks, measuring properties such as tensile strength, tensile modulus and elongation at break. For plastics and composites it is commonly performed to methods in the ISO 527 series or ASTM D638 and D3039. It is the baseline test for characterising resins, laminates and reinforcement materials.

The shear strength between the plies of a laminate, usually measured with a short beam shear test such as ISO 14130 or ASTM D2344. Low ILSS indicates poor fibre-to-matrix bonding or laminate quality, and correlates with susceptibility to delamination.

Mechanical or physical testing of small standardised specimens, known as coupons, cut from a laminate, panel or production sample rather than testing the full component. Coupon results underpin material qualification, design allowables and batch quality control in composites manufacture.