Injection-molded short-fiber reinforced plastics (SFRPs) exhibit residual stress, which is caused by their internal fiber orientation distribution. However, measuring the internal fiber orientation distribution of SFRPs is challenging, thus resulting in no investigations into their residual stress. In this study, first, the fiber orientation distribution tensor in the thickness direction of an injection-molded SFRP flat plate was obtained using X-ray micro-computed tomography (micro-CT). Second, the anisotropic material properties arising from the fiber orientation tensor were calculated using Digimat. Third, residual stress analysis was performed by applying the material properties that correspond to the fiber orientation tensor, to a multi-layer meshed finite element model. Finally, to verify the results of the residual stress analysis, they were compared with the released strain obtained using the hole drilling method. Based on these results, released strain was thus qualitative agreement with that calculated via residual stress analysis.
