Improvement of cutting simulation using the octree method

This paper develops an octree-based algorithm for machining simulation. Most commercial machining simulators are based on the Z-map model, which has several limitations in terms of achieving a high level of precision in five-axis machining simulation. Octree representation being a three-dimensional (3D) decomposition method, an octree-based algorithm is expected to be able to overcome such limitations. With the octree model, the storage requirement is reduced. Moreover, recursive subdivision is processed in the boundaries, which reduces useless computations. The supersampling method is the most common form of antialiasing and is typically used with polygon mesh rendering in computer graphics. The supersampling technique is being used to advance the efficiency of the octree algorithm.     

Improvement of the representative volume element method for 3-D scaffold simulation

Predicting the mechanical properties of the 3-D scaffold using finite element method (FEM) simulation is important to the practical application of tissue engineering. However, the porous structure of the scaffold complicates computer simulations, and calculating scaffold models at the pore level is time-consuming. In some cases, the demands of the procedure are too high for a computer to run the standard code. To address this problem, the representative volume element (RVE) theory was introduced, but studies on RVE modeling applied to the 3-D scaffold model have not been focused. In this paper, we propose an improved FEM-based RVE modeling strategy to better predict the mechanical properties of the scaffold prior to fabrication. To improve the precision of RVE modeling, we evaluated various RVE models of newly designed 3-D scaffolds using FEM simulation. The scaffolds were then constructed using microstereolithography technology, and their mechanical properties were measured for comparison.     

工程机械液压系统动态仿真设计方法研究

工程机械的液压系统原理图只对液压系统做静止描述，不能表达出诸如油液的流向、各油路压强的变化、各液压元件的动作顺序及其工作机理等重要内容。针对以上问题，这里介绍了一种综合利用Autocad、3DSMAX、UG以及Authorware等软件，进行液压系统动态仿真设计的新型方法，利用这种方法可以形象地描述工程机械的液压工作原理、液压元件的动作过程，验证设计思想，同时便于用户快速查找和排除液压系统故障。     

工程车辆ADAMS建模与平顺性仿真

利用动力学分析软件ADAMS,建立了钢板弹簧车辆和油气弹簧车辆的动力学模型,开展了整车在随机路面上的平顺性仿真,分析了两种悬架对车辆平顺性的影响,并通过仿真数据与试验数据的对比,验证了动力学模型的正确性.     

求解机械多体系统的循环中点求积改进算法及其仿真

通过实际计算比较,论文从实际应用的角度详细总结了解非线性方程组的Newton型方法具有的优点和缺陷。随后提出了循环中点求积法改进算法：即在离散Newton法与同伦方法结合的基础上修改了原算法中关于偏导矩阵奇异的判断标准和迭代终止的判断标准。通过实际运算检验,这一改进明显改善了原算法的可靠性和稳定性。     

机床误差对加工精度的影响及改善措施

分析了机床加工存在误差的主要原因,着重分析因机床误差及工艺系统受力和热变形引起的常见加工缺陷及改善措施。