X-ray characterization of glass fiber reinforced thermoplastic orientation and fatigue damage evolution for automotive technical part

The current work presents a new contribution to the phenomenological modeling of mechanical fatigue damage in short glass fiber reinforced thermoplastic matrix composites for PA66-GF35. The majority of Injection Simulation Softwares are not able to predict a realistic orientation and repartition of fibers in the corner or flange of complex component such as in the automotive parts. The first part of this work is to implement the experimental distribution of short glass fiber in order to simulate realistic fatigue damage for GFRP. For this reason, Micro X-ray tomography is used to characterize the repartition and the orientation of glass fiber in critical area of the automotive part (flange, corner⋯). The fatigue damage model used in this work is developed by Nouri et al [1]. (NML) in order to simulate the fatigue damage in glass fiber reinforced plastics GFRP. This model is able to predict the three damage stages observed during cycling loading of thermoplastics composite reinforced by glass fiber: i) onset of the damage, ii) coalescence of microcracks and propagation, iii) macroscopic cracks propagation and material failure. Glass fiber orientation and repartition obtained by X-ray tomography is used to create Abaqus cae file for automotive part. The model is implemented via Umat into Abaqus. The model parameters are identified using an inverse strategy with one single specimen based on heterogeneous fatigue tests. It consists on the use of optical whole-field displacement/strain measurements (digital image correlation) coupled to an inverse method from one single coupon. It is worth noting that the mechanical test must give rise to heterogeneous stress/strain fields. Indeed, in this case, the constitutive parameters are expected to be all involved in the response of the specimen.