采用基于超单元的方法对轿车的白车身进行了建模和动态仿真设计. 该方法不仅可以提高计算速度，同时可以对轿车车身中的各个子结构进行独立的动态优化设计. 针对轿车设计中平顺性问题，还提出了车底板上2点垂直方向位移响应的均方值为最小的车身优化方法，对车身结构进行动态优化设计，获得了令人满意的优化结果.

数控车床丝杠进给系统刚度对系统的失动量和定位精度影响较大。基于进给系统质量和弹簧力学模型，给出了进给系统轴向刚度和扭转刚度对失动量的影响与定位误差的解析表达式，为进给系统结构设计、降低系统的失动量和提高系统的定位精度提供了理论依据；结合实例进行了应用分析计算，取得了明显效果。

在分析龙门式加工中心C轴系统内部热源的种类、传热途径以及确定边界条件的基础上，建立了瞬态传热学模型和有限元模型，并推导出节点温度的矩阵方程. 用有限元法计算了三维瞬态温度场分布，得出系统达到热平衡所需的时间约118h，同时计算了各部件达到热平衡时的温度场分布和温升，最高温度发生在热源处，最高温升为221402℃，这些为散热结构优化设计提供了理论依据.

Afiniteelementmodelispresentedforfree-dampedbeam-stiffenedplates. Thenodesof theplateelementsaretreatedasmaster-nodes, andthecorrespondingnodesofthebeamelementsare consideredasslave-nodes. Thestiffnessandmassmatricesoftheelementsaredeveloped. Basedon theanalysisofthedynamicpropertiesofthestructures, modallossfactorsarepredictedbythemodal strainenergymethod. Finally, anexampleisgiventocomparetheresultsobtainedfromtheproposed methodwiththeresultsoftheANSYSsoftware. Theresultsshowthatthemethodinthispaperis computationallyefficient, simpleandfeasiblewithhighprecisionandengineeringpracticability.

A mathematical model of the computer numerical control (CNC) heavy cutting servo system including chatter in cutting courseswas constructed for the chatter in CNC heavy cutting. The theoretical analysis, computer simulation and orthogonal tests on thismodel show that increasing the gain of position Kpp can improve the rapid tracking performance of machine tools, and decreasing the delay time of speed loop τs can quickly eliminate the static error in the system, but the limited cutting width blim will descend correspondingly; excessively large or excessively small gain of speed loop Kps can result in decreasing blim; optimizing Kpp, τs and Kps can improve the dynamic and static performance of the system and increase blim. It is easy and feasible to op timize the servo parameters by the orthogonal test. This method can effectively improve the systemps stability and limited cutting width and it is suitable for the CNC heavy cutting of heavy-duty machine tools.