白车身接附点的动刚度对整车NVH(noise、vibration、harshness)性能有非常大的影响,通过对车身与副车架的关键接附点进行动刚度分析,可以为车辆正向开发中NVH性能的提升提供理论参考,另一方面又能够缩短开发周期和降低开发成本.以一款日产SUV车型为研究对象,面向开发设计阶段白车身关键接附点动刚度不足的问题,提出了基于灵敏度分析的白车身结构接附点动刚度优化分析方法,将接附点平均动刚度提升至8 000 N/mm以上.首先通过建立白车身的有限元模型,利用仿真软件中Optistruct结构求解器进行模态分析、动刚度分析,计算得到车身接附点IPI(input point inertance)曲线;其次绘制出目标值的动刚度曲线并与计算得到的IPI曲线进行对比,计算各个安装点X、Y、Z3个方向的平均动刚度值;然后根据对比结果利用直接频响分析找出左后减震器接附点Y向IPI曲线峰值过高的原因;最后结合板厚灵敏度分析对相对薄弱区域提出车身结构尺寸优化和形貌优化的优化方案.通过验证,左后减震器接附点Y向动刚度平均值达到设计目标值.优化后的左后减震器接附点Y向动刚度得到较大提升,为白车身后续设计提供了重要的理论依据,使其达到工程设计的目标要求.
Body in White Structure Bonding Points Based on Sensitivity Analysis Dynamic Stiffness Optimization Method
The dynamic stiffness of body-in-white joints has a great influence on NVH(noise,vibration and harshness)perform-ance of the vehicle.The analysis of the dynamic stiffness of the key joints of the body and subframe can provide a theoretical reference for the improvement of NVH performance in forward development of vehicles.On the other hand,it can shorten the development cycle and reduce the development cost.Taking an SUV model as the research object,an optimization analysis method was proposed for the dynamic stiffness of the body-in-white structure at the key attachment points in the development and design stage,which was based on sensitivity analysis,and raised the average dynamic stiffness of the installation points to more than 8 000 N/mm.Firstly,the finite ele-ment model of the body in white was established,and the modal analysis and dynamic stiffness analysis were carried out by using the Optistruct structure solver in the simulation software to calculate the IPI(input point inertance)curve of the body attachment point.Secondly,the dynamic stiffness curve of the target value was drawn and compared with the calculated IPI curve,and the average dy-namic stiffness value of each installation point in X,Y and Z directions was calculated.Then,according to the comparison results,the reason of the high peak value of the left rear shock absorber connection point Y direction IPI curve was found by direct frequency re-sponse analysis.Finally,an optimization scheme for the size optimization and morphology optimization of the body structure in the rela-tively weak area was proposed based on the sensitivity analysis of plate thickness.Through verification,the average Y dynamic stiffness of the left rear shock absorber installation point reaches the design target value.After optimization,the dynamic stiffness of the left rear shock absorber installation point Y is greatly improved,which provides an important theoretical basis for the subsequent design of the body in white,so that it can meet the target requirements of engineering design.
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