A Method for Improving Dynamic Characteristics of Car Body Structure

Aiming at the existing deviation between the low- order elastic natural frequency and desired prototype value of a certain car body,adopting the method of structural performance sensitivity analysis and combining with the experience of previous works,we screened and determined the sections which have important influences on the torsional stiffness of vehicle body,the first- order torsional frequency and the first- order bending frequency. On this basis,adopting the treatment methods of prolonging overlap edges, increasing or flanging the thickness of plates and stiffeners,improving the components' and relative components' structures,we modified the characteristics parameters of model surface. The result shows that( 1) because of increasing the vehicle body mass by 7. 6%,its low- order natural frequency is improved obviously,i. e., the first- order torsional frequency is increased by 10%,and the first- order bending frequency is increased by 2%;( 2) the vehicle body structure's stiffness is also improved,i. e.,the bending rigidity is increased by 1. 5%,and the torsional rigidity is increased by 8. 6%,so the comprehensive mechanical performance is perfected effectively. From this,we reached the relative technology aims about prototype vehicle and provided a reliable basis for vehicle body CAE analysis and structural design.