Express estimation of stress concentration factor near the hole loaded with a bolt in a plate from a layered polymeric composite material. Impact of monolayers stacking sequence

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Problematic. Among the various options for joining parts from layered polymer composite materials (PCM), a significant percentage is bolted joints (BJ). For their proper design, it is necessary, in particular, to carry out strength calculations. In this case, it is desirable to replace complex finite element calculations with express analysis: calculations using simple formulas of sufficient accuracy. One of the main strength calculations of BJ is the calculation of tensile strength of the section weakened by the hole. For BJ plates made from PCM, this question has not been worked out enough.Research objective. Establish of the impact degree of the monolayers stacking sequence of a PCM plate on the value of the stress concentration factor (SCF) near the hole loaded with a bolt.Realization technique. Numerical calculations were carried out using the finite element method (contact problem) for a BJ plate made of layered PCM. A 3D-orthotropy of each monolayer was assumed. Two simple express analysis formulas were tested. Diagrams were built, the presence and impact degree of the monolayers stacking sequence in a laminated PCM plate on the change of the SCF values were established.The results of research. Based on the calculation results, numerical estimates are obtained that characterize the impact degree of the monolayers stacking sequence in a laminated PCM plate and the accuracy of the considered formulas.Conclusions. The calculations showed that change of the monolayers stacking sequence of the layered PCM leads to a significant change of the SCF values near the bolt-loaded hole in the plate section weakened by the hole; that the proposed approximation (17) has insufficient accuracy for the considered materials and monolayers stacking sequences. It is necessary to continue the search for the correction function for (15) on a wider calculation and experimental base of PCM properties.