To assess the interlaminar shear stress failure of a laminate subjected to out-of-plane shear loading, Qx and Qy, HyperSizer must determine the ply-by-ply interlaminar shear stresses resulting from this loading. However, Classical Lamination Theory (CLT) or even higher order theories (such as first order shear deformable) do not provide the correct interlaminar stress distribution through the laminate thickness. In fact, CLT provides identically zero interlaminar shear stresses, whereas the higher-order plate theories provide piece-wise profiles that are discontinuous at ply interfaces.
HyperSizer resolves these out-of-plane shear forces, Qx and Qy into ply-by-ply shear stresses τxz and τyz using a newly developed technique called the “Simplified Shear Solution” (SSS), based on composite beam theory. The SSS assumes that the force, moment, and shear resultants are known at a particular location in a panel and is independent of the source of these known resultant quantities. This makes the solution ideal for HyperSizer where force resultants can be either typed in by the user or extracted from a finite element solution.
The SSS is extremely efficient as it provides a closed form rather than a numerical solution which can run thousands of times per second. The method works in concert with CLT, which provides the in-plane ply-by-ply stresses, to provide a better approximation of the true multi-axial stress state within laminates and panels. The details of the SSS are presented in this document. The generality of SSS allows it to be applied to any of HyperSizer’s panel concepts including unstiffened laminates, sandwiches, uniaxial and grid stiffened concepts.
See the HME document for more detailed information.
