FINITE ELEMENT ANALYSIS OF OFF-AXIS UNIDIRECTIONAL LAMINATES WITH INTRALAMINAR DAMAGE

摘要

In this paper, the initiation and propagation of intralaminar damage (fiber/matrix interface debonding and matrix cracking) are predicted using a finite element micromechanical approach. For the case of off-axis loading of unidirectional laminates, a three-dimensional repeated unit cell model based on periodic fiber array is established. Appropriate periodic boundary conditions for combined shear and normal stress loads are applied. To model the separation of the fiber/matrix interface, a thin layer of interphase elements is introduced in the unit cell model. To model progressive matrix cracking, a 'smeared crack approach' is employed. As an application example, glass/epoxy unidirectional laminates with various off-axis angles are analyzed. Predictions of the damage modes are in agreement with experimental observations. Moreover it is shown that the global stress-strain curve with progressive intralaminar damage can also be well predicted.