关键词: 上车踏板；开裂失效；结构优化；可靠性提升

Abstract: In response to the batch cracking issues of the boarding steps in a specific heavy-duty commercial vehicle during post-sales service, this work develops a comprehensive methodology for systematic problem localization and verification by integrating multiple quality engineering and modern design analysis tools, including post-sales big data analysis, fishbone diagrams, hypothesis testing, regression analysis, physical bench tests, and computer aided engineering (CAE) simulation. The critical causes are confirmed to be insufficient glass fiber content in the fiberglass of the boarding steps, suboptimal structural design at key locations of the step body, and inadequate strength of the connecting bracket structure. To address these issues, this work proposes an integrated improvement strategy involving material performance enhancement, topological optimization of the step body structure, and strengthening of the bracket's integrated casting. CAE simulations and loading effect tracking validation both demonstrated that the maximum stress at critical locations is reduced by an average of 48.07%, while the post-sales parts per million (PPM) failure rate decreased by 61.88%, thereby effectively improving product reliability and customer satisfaction.

Key words: boarding steps; cracking failure; structural optimization; reliability improvement