Behaviour of woven-ply PPS thermoplastic laminates with interacting circular holes under tensile loading: An experimental and numerical study

Components of aircraft structures suffer from various intrinsic stress concentrations due to holes located at mechanical joints. Critical situations arise where two or more holes are placed in proximity in the structure such that their associated stress fields interact. In this study, the failure behaviour of loaded perforated carbon/PPS plates with stress concentrations due to different configurations of interacting holes was examined experimentally and numerically. The evolution of the strain fields was quantified experimentally using Stereo Digital Image Correlation (Stereo-DIC) technique. The onset of the damage and its advancement in the tested samples were visualized via coupled charge device cameras. Microscopic studies were performed to characterize the failure behaviour of the composite samples. The numerical simulations used a finite element model with a three-dimensional Hashin damage initiation criterion and progressive damage model to simulate intra-ply and inter-ply damage, respectively. The criterion was modeled using a VUMAT subroutine and cohesive zone technique. A reasonable similarity between experimental and numerical results was achieved. The stress concentration factor (SCF) of perforated specimens was found to depend on the relative position of the interacting holes and the orientation of the composite laminates. The maximum SCF was observed for the specimens with fibre orientations of 22.5 degrees and 67.5 degrees, whereas the lowest was attained with that of 45 degrees.

Automated summary

This study examined the failure behavior of loaded perforated carbon/PPS plates with stress concentrations due to different configurations of interacting holes. Experimental and numerical results showed that the stress concentration factor of perforated specimens depends on the relative position of interacting holes and the orientation of composite laminates, with different orientations affecting the maximum and minimum values of this factor.