Experimental Study on Tensile-Shear Fatigue of Bolts

Le résumé fourni par la source

In practical engineering structures， bolts often operate under tensile-shear combined stress states， whereas current design codes only provide calculation methods for bolt fatigue life under pure tension or pure shear loads. Therefore， this study conducted tensile-shear fatigue tests on bolts using a specially designed testing device. Fatigue tests were performed at five different loading angles （0° pure tension， 30° tensile-shear， 45° tensile-shear， 60° tensile-shear， and 90° pure shear） to analyze the influence of tensile-shear angles on bolt fatigue life. The S-N curves under different angles were unified based on Mises stress， and the effects of bolt material and diameter on fatigue life were discussed. The results showed that under the same loading force， bolts in tensile-shear combined states were more prone to fatigue failure compared to pure tension or shear load. At different tensile-shear angles， the fatigue life of bolts increased with the increase of material strength. Material influence coefficients for different angles were proposed： compared with 8.8-grade high-strength bolts， the fatigue strength of 4.8-grade and 6.8-grade bolts decreased by approximately 5% and 2%， respectively， while that of 10.9-grade high-strength bolts increased by approximately 21%. Under the same stress， the fatigue life of bolts first increased and then decreased with the increase of bolt diameter. Compared with M8 bolts， the diameter amplification factors for M16， M30， and M42 bolts were approximately 1.24， 1.37， and 1.07， respectively.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.