A structural curve with reduced stress concentration and its elastic-plastic failure analysis

Stress concentration represents a significant concern in engineering failure analysis, influencing various failure mechanisms. Mitigating stress concentration requires the implementation of an efficient transition curve. However, traditional transition curve designs, including single-curvature, multi-curvature, elliptical, and streamlined types, prove to be suboptimal solutions. This study proposes an innovative transition curve scheme inspired by biological structures to mitigate inherent stress concentration at transition regions. Tensile tests are performed on specimens featuring various transition curve schemes to assess their mechanical performance and validate the superiority of the proposed scheme. Finite element simulation is employed to analyze stress distribution under tension and bending for the various schemes. Digital Image Correlation experiments were performed to validate the numerical simulations. Results demonstrate that the proposed scheme enhances load-bearing capacity, narrows the range of high-stress and yield regions, and optimizes force flow. By incorporating critical position and limit values of the transition curve, the proposed scheme effectively disperses stress, reducing the stress concentration factor to below 1.03. This design methodology can be applied to develop transition curves for shaft shoulders and variable section parts, thereby enhancing safety, structural stability, and durability. Ultimately, this scheme extends the lifespan of the structure.