基于模态试验的排气歧管参数修正研究

Study on parameter modification of exhaust manifold based on modal test

对某12V柴油机单侧排气歧管进行模态试验得到试验模态参数,使用ABAQUS软件计算排气歧管的自由模态并与试验结果进行对比。首先,分析了排气管在膨胀连接处干涉偏移量设置和接触刚度对固有频率的影响,结果表明膨胀连接处接触刚度对固有频率的影响较为显著;其次,采用局部到整体的策略,通过调整材料属性和接触设置修正排气歧管有限元模型,修正后的有限元模型振型与试验振型一致,固有频率相差小于10%,得到了满足工程计算需求的有限元模型;最后,开展温度和接触刚度双因素下的排气歧管模态分析,确定了排气歧管连接刚度随温度的修正策略。

The modal parameters of a single exhaust manifold of 12V diesel engine were obtained by modal test.The free modal parameters of the exhaust manifold were calculated by using ABAQUS software and compared with the experimental results.The effects of interference fit and contact stiffness on natural frequency were analyzed.The results show that the contact stiffness at expansion connection has a significant effect on natural frequency.The finite element model of exhaust manifold was modified by adjusting material properties and contact settings.The modified finite element model vibration mode was consistent with the test vibration mode,and the difference of natural frequency is less than 10%.The finite element model that meets the requirements of engineering calculation was obtained.Finally,the exhaust manifold modal analysis was carried out under the dual factors of temperature and contact stiffness,and the modification strategy of exhaust manifold connection stiffness with temperature was determined.