Determination of stress concentration factor in the section of the composite plate weakened by the hole, upon contact of the hole with the cylinder

Abstract

Problematic. When designing bolted joints (BJ), it is necessary, to carry out verification strength calculations. In this case, it is advisable to use express analysis: calculations using simple formulas of sufficient accuracy. One of the main strength calculations of BJ is the calculation of the gap section weakened by the hole. For BJ plates made of layered fibre-reinforced polymers (FRP), the problem has not yet been solved.Research objective. To verify the accuracy of two well-known express analysis formulas for stress concentration factors (SCF) at the contact of the hole with the bolt, using contrasting examples of materials and schemes for reinforcing FRP plates.Realization technique. Numerical calculations were carried out using the finite element method (contact problem) for a BJ plate made of layered FRP. A 3D orthotropy of each monolayer was assumed. Two simple express analysis formulas were tested. The results are tabulated. The illustrations are provided.The results of research. Numerical estimates are obtained that characterize the degree of influence of material characteristics and reinforcement patterns in a layered FRP plate and the accuracy of the formulas considered.Conclusions. A change in the material and the reinforcement scheme of the layered FRP leads to a significant change in the SCF values of the bolt-loaded hole in the section of the plate weakened by the hole, and the considered express analysis formulas have insufficient accuracy for contrast cases of materials and plate reinforcement schemes. More research is needed.