基于FEA的手柄拉簧失效分析与流程优化设计

Failure Analysis and Optimization Design for Handle Tension Spring

拉簧是汽车座椅调角器中的重要零件。按传统查表法和公式法设计拉簧,疲劳次数增加至2万次左右,常出现疲劳失效,造成反复更改设计和浪费。通过疲劳实验分析失效形式主要为弯钩疲劳断裂,且采用理论计算和FEA(有限元)分析钩环处的应力集中最大。研究了簧丝直径d、中径D、圈数n等参数对拉簧寿命影响,得到最大应力与抗拉极限的比值是衡量疲劳寿命的参数,比值越小,零件疲劳寿命越大。提出流程优化设计,给出设计和校核过程中安全系数S和弯钩处应力值校核的范围,优先校核簧体和钩环应力,减少拉簧设计的不确定因素,极大地提高设计成功率。

Tension spring is an important part of automotive seat recliner. The tension spring designed with traditional look-up table method and formula method, often appears fatigue failure when fatigue number increases to about 20 000 times, causing repeated design change and waste. Through fatigue experiment analysis, the main failure mode of tension spring was the hook fatigue fracture, and the stress concentration in shackle was the largest by theory and FEA analysis. The influences of the diameter d, the pitch diameter D, the number of turns n of the spring were studied. It is shown that the ratio of maximum stress and tensile limit was the parameter to measure fatigue life. The smaller the ratio is, the greater the fatigue life of parts is. The optimization design process was put forward, the safety factor S and the checking range of hook stress value were given during the design and checking process. The spring body and the shackle stress were checked first, reducing the uncertainty of tension spring design, greatly increasing the success rate of design.