Mesoscale failure analysis of the hybrid structure by injection overmolding after compression process

The injection overmolding after compression (IOAC) is a promising hybrid process that manufactures the load-bearing parts by assembling the fiber-reinforced thermoplastic (FRTP) laminate with FRTP ribs. However, the size effects of interfacial mechanical interlocking on failure evolution are unclear. A mesoscale model of representative volume element, including the fibers, matrix, matrix-fiber interface as well as the IOAC interface, is established to predict its failure process and failure modes. The influence of IOAC interface waviness (height, width, and thickness) on shear and tensile strength is investigated. The results show that the increased height and thickness positively affect the shear and tensile strength, while the increased width has a negative effect. The crack originates from the wave trough of waveform interface at tensile loading, while it originates between the wave trough and the wave crest under shear loading. The primary failure modes of IOAC structure include interface fracture, matrix damage, and matrix-fiber interface debonding. The results in this work can guide the interface design by changing its waviness through the surface pretreatment and IOAC process control. Visualizing the failure process of IOAC structure can provide some information difficult to capture in tests, which is useful in predicting the failure degree and location of IOAC structure in engineering application.