Interply shear

Vanclooster, K., Lomov, S. V. and VerpoesL I. (2(X)8), Investigation of interply shear in composite forming . Proceedings for the Ilth ESAFORM Conference on Material Forming. Lyon, France, pp. 957—960. 

The manufacture of hemispherical domes is well established, particularly in the field of composites, as a method of assessing the relative ability of the materials and processes to produce doubly curved shell components. In the case of knitted fabric-reinforced thermoplastics, some of the key parameters relevant to product manufacture are (i) material strain behavior (stretching V5. draw-in), (ii) surface finish, (iii) gross wrinkling and buckling of the sheet material, and (iv) interply shear in the laminate. 

When the textile fabric reinforcement is combined with the matrix to form the composite prepregs, a set of deformation modes are introduced, which may be referred to as top-level deformation modes since they involve the movements of the reinforcement (macro- and micro-level fabric deformation mechanisms) and the matrix. They are in fact the conformation modes of the composite prepreg sheet or group of sheets, as is usually the case, during the forming process. The hierarchy of the top-level deformation modes consist of transverse flow, resin percolation, interply shear and intraply shear, as summarized by Cogswell and revisited by Martin et... 

The degree of bonding analysis has been verified for both compression molding and online consolidation of thermoplastic composites. In these studies, composite test specimens were consolidated under controlled processing conditions. The most common types of tests performed to measure the interply bond strength were the interlaminar (short beam) shear test [21,25] or the lap shear test [12,21,26]. 

More recently Christie [5] has developed a finite-element simulation package, SimForm, using transversely anisotropic, hyperelastic discrete ply deformation as a first step to simulate the viscoelastic shear response discussed earlier in this section. The program employs three-dimensional continuum elements to describe deformations in each ply, while a contact procedure couples the motion of neighbouring plies to simulate the interply slip process. Interply slip is given a linear velocity-dependent... 

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