The clamping effect in [+/-alpha](s)-angle-ply laminates

Tensile specimens made of [+/- alpha](s)-angle-ply laminate of finite width and finite length are considered with regards to their effective axial stiffness properties. Presuming an axial load introduction by rigid clamps, the inplane laminate displacements are constrained accordingly at the respective specimen edges. As a consequence, the effective tensile stiffness of the laminate deviates clearly from the predictions of the laminated plate theory. For the description of this effect, a closed-form analysis is presented. Assuming an approximation of the real displacement field, the resultant effective specimen tensile stiffness is derived as a function of the specimen length. Comparison to respective finite element analysis gives good agreement, and validates the presented closed-form analysis as very useful.