某轻型载货车转向液壶支架断裂分析及其优化

Fracture Analysis and Optimization of A Light Truck Steering Oil Pot Bracket

针对某轻型载货车转向夜壶支架的断裂问题,首先建立其离散化模型,对其进行模态性能分析,分析结果表明其第一阶模态频率接近于发动机激励频率,从而引起共振,产生疲劳断裂风险。然后采集纵梁端的时域信号,并将其转换成频域信号,以此对其进行频率响应分析,分析结果表明其最大应力超过材料屈服强度,安全系数偏低,其应力集中点与失效位置相同。再基于功率谱密度函数对其进行振动疲劳分析,分析结果表明其疲劳寿命低于设计要求值,其薄弱点与断裂位置相符。再基于多学科多目标平台对其结构参数进行优化分析,分析结果表明其第一阶固有频率提高了18.9%,其最大应力降低了38.1%,其疲劳寿命提升了2.1倍,其总重量减轻了18.2%。在满足各项性能要求的同时,其轻量化效果也比较明显。最后对其优化方案进行实车验证,验证结果表明优化之后其振动加速度降低了46.5%,支架成功通过了整车路试验证。

Aiming at solving the fracture problem of a light truck steering oil pot bracket. Firstly, the bracket was modal analysised based on establishing discretization model, the analysis results showed that its first modes frequency was close to the engine excitation frequency, it would cause resonance and produce fatigue fracture risk. Secondly, the time domain signals of longitudinal beam ends were collected, and they were converted into frequency domain signals, so the bracket was frequency response analysis, the analysis results showed that its stress exceed the yield strength of the material, its safety factor was low, its stress concentration point was the same as the failure position. The bracket was vibration fatigue analysis based on power spectrum density function, the analysis showed that its fatigue life were below the design requirement, its weak point was the same as the breaking position. The bracket structural parameters were optimization analysised based multi-disciplinary and multi-objective platform, the analysis results showed that its first modes frequency was improved by18.9%, its stress was reduced by 38.1%, its fatigue life was improved by 2.1 times, its weight was reduced by 18.2%. While it meet the performance requirements, its lightweight effect was also obvious. Lastly, its optimal solution was vehicle certificated, the test results showed that its vibration acceleration was decreased by 46.5%, the bracket was successfully passed the vehicle test certification.