Stress distribution in polymeric film laminated leather under biaxial loading

摘要

The needle and stitch parameters on pigment-coated and polymeric film laminated leather behaviour under biaxial loading have been investigated.Simulation by finite element analyses (FEA)was used to determine the influence of the stitch number upon the distribution of principal stresses under the membrane deformation,while by experiments punching of the investigated materials was performed using a special punching unit.Investigations by FEA show that the stress in the middle of a stitch is four to five times higher than stresses at the beginning or at the end of the stitch.Besides,the increase of the stitch density increases stress values.Leather and polyurethane film break up straight below the specimen and punch contact zone.On the other hand,crack formation and propagation depend on the stitch density and shape of the needle.