中文摘要：

针对全地形车车体结构动态特性分析时，有限元建模过程中发动机这一复杂形体三维模型建立及网格划分难度较大的情况。从有限元基本原理出发，找出了复杂形体简化模拟时对结果影响较大的质量、质心、转动惯量等参数。通过模拟仿真分析发现将复杂形体简化为相同质量、质心、转动惯量的简化形体仿真结果与实际最为吻合。在对全地形车车体分析时，采用该方法将发动机简化为相同质量、质心、转动惯量的长方体，实验结果和有限元仿真结果对比表明，该发动机简化模拟方法实用且可行，从而能达到在全地形车设计或改进阶段预测各种性能的目的，节约了大量的时间和成本。

英文摘要：

In the finite element modeling on dynamic characteristics analysis of ATV＇s body, to create 3D models of a complicated object, e.g. the engines, is usually very difficult, and high quality meshes for such models can be hardly acquired also. However, it is found through the basic principles of the finite element analysis that parameters such as mass, barycenter and moment of inertia of the finite element model affect the results significantly in such analysis. Based on simulation, a simplified finite element model was created, which has the same mass, barycenter and moment of inertia parameters as the original complicated objects. The analysis results show that these simplified models can simulate the complicated objects very well. The engine was simplified as a meshed cuboid structure with same cen- troid, weight and rotary inertia of the engine while the dynamic characteristics of ATV body is analyzing. The results of test and simulation show that the simple modeling method of the engine is practical and feasible, then the performances of ATV can be known durning the stage of developing and design, and a lot of time and costs can be saved.