某ABS阀支架振动疲劳分析及其优化设计

Vibration Fatigue Analysis and Optimization Design of A ABS Valve Bracket

为了解决某ABS阀支架断裂失效问题,首先基于有限元方法对其进行模态分析,分析结果表明其前两阶固有模态频率与发动机的激励频率相一致,将产生共振,不满足模态性能要求。然后采集横梁左、右端的载荷谱,将其转换为功率谱密度载荷,并通过单位激励的频率响应分析,建立单位激励与应力之间的传递函数,以此对其进行振动疲劳分析,分析结果表明该支架的疲劳循环次数低于目标值,不满足疲劳性能要求,并且其危险点与断裂位置相同。再采用霍克-吉维斯直接搜索算法对该支架进行参数优化,并新增一条加强筋,得到最终对优化方案。优化之后该支架的第一阶频率能够避开发动机激励频率,其疲劳循环次数高于目标值,其重量也降低了16%,能够同时满足模态性能、疲劳性能和轻量化的要求。最后对优化方案进行道路验证和测试,测试结果表明该支架的振动激励降低了39.3%,优化效果比较明显,并且没有出现开裂现象。

Aiming at solving the fracture failure problem of a ABS valve bracket. Firstly, the bracket was modal analysised based on finite element method, the analysis results show that its first two natural modes frequency were consistent with the engine excitation frequency, it would produce resonance, it didn' t meet the modal performance requirements. Secondly, the load spectrum of left and right crossbeam ends were collected, and they were converted into power density load. The transfer function between unit excitation and stress was established by frequency response analysis of unit excitation, the vibration fatigue analysis show that its fatigue cycles were below the target values, it didn't meet the fatigue performance requirements, its danger point was the same as the breaking point. The bracket was parameter optimizated by hooke- jeeves direct search method, the final optimal solution was obtained by adding a new reinforcement. Its first frequency could avoid the engine excitation frequency, its fatigue cycles were exceeding target value, its height was also reduced by 16%, it could meet modal performance requirements, fatigue performance requirements and lightweight requirements. Lastly, its optimal solution was certificated and tested by road test, the test results show that its vibration excitation was decreased by 39. 3%, the optimization effect was obvious, and the cracking didn't occurrs.