Structural optimization–based fatigue durability analysis of electric multiple units cowcatcher

• Main Authors: Yonghua Li, Yuhan Li, Yuedong Wang, Jian Wang
• Format: Article
• Language: English
• Published: SAGE Publishing 2017-08-01
• Series: Advances in Mechanical Engineering
• Online Access: https://doi.org/10.1177/1687814017726294

This study aims to evaluate the fatigue durability of a cowcatcher and optimize its structure. The cowcatcher, which serves as the crucial component of electric multiple units, generally influences the electric multiple units operating security and stability. A finite element model considering material properties and geometry sizes of the cowcatcher is established for structural strength analysis. Based on the P-S-N curve, the nominal stress method is introduced to analyze the fatigue durability of the cowcatcher. Considering influences of input variables such as elastic modulus, Poisson ratio, loads, and plate thickness on the fatigue durability, the parametric model of cowcatcher is built. In addition, three-level fractional factorial design is chosen to ascertain the location of sampling points in the above variables’ sampling space. The response surface of the cowcatcher is fitted using Kriging model. Then, a non-linear programming by quadratic Lagrangian algorithm is proposed for optimizing the cowcatcher structure. With a comparison of fatigue durability pre-optimization and post-optimization, conclusions on cowcatcher design and application are made. The proposed method not only prolongs the fatigue life of the cowcatcher but also improves its structure reliability.