Experimental and numerical studies of the open hole tensile strength of drilled‐ and molded‐hole unidirectional laminates

Abstract In this paper, we created a new molded‐hole process to manufacture holes instead of drilling in unidirectional (UD) carbon fiber reinforced plastics avoid fiber discontinuity. Several open hole tensile (OHT) tests were carried out on specimens with Cross ply (CP) and Quasi‐isotropic (QI) stacking sequence with drilled holes and molded holes. At the same time, we established finite element analysis (FEA) models of drilled‐hole laminate and molded‐hole laminate to characterize the stress field around the hole. The numerical analysis results reveals that the max principal strain distribution around the molded hole has much higher coincidence with fiber axial direction than that in drilled‐hole laminate. Moreover, the OHT strength results of QI specimens indicate that the plates with molded holes were more 50% higher than those with drilled holes. This process will provide reference for molded UD CFRP structure holes. And the numerical model can help engineering designer make OHT strength prediction. Highlights A new molded‐hole process for unidirectional prepreg was created. Molded‐hole specimens have higher open hole tensile strength than drilled‐hole pieces. The simulation results were close to the experimental results.