刚体

The basic approach of protecting people from being hurt or killed in an accident is to improve crashworthiness of vehicles. This paper starts with discussing theories and methods for vehicle passive safety design, which included experiential methods, analytic methods, multi-body dynamics methods, crash test methods and the finite element method. Emphasis will be paid to the basic FEM theories and algorithms of impact problems. Topics discussed include the governing equation, element discretization, hourglass control, time integration, material model, shell element algorithms and contact-impact algorithms. For more reliable simulation results, this paper then conducts study on how to accurately get material model parameters by combining the FEM method with experimental method, and develops relevant material test machine and parameter calculating software. Based on that, basic typical impact simulation and test validation study are conducted. On the basis of the above work, the paper studies the thin-shell structures'crashworthiness, which was affected by the following factors: spot-weld features, shell thickness, cross-section and pre-deformation. As to vehicle parts'crashworthiness, the paper conducts simulation study of designing energy-absorbing steering system and adaptive airbag system. A practical energy-absorbing steering wheel is designed as an example. In further depth research, the paper suggests several inverse quantificational methods for vehicle crashworthiness design based on the ideal crash characteristics. The above theories and methods are applied with good results through several practical vehicles' crashworthiness design and improvement.

文中对汽车碰撞安全性的设计理论和方法进行了归类和总结，其中包括经验法、解析法、多刚体动力学法、试验法以及有限元方法等；重点介绍了碰撞有限元法的基本理论和有关算法，涉及到有限元求解控制方程、单元离散、沙漏模态控制、时间积分、材料模型和应力修正、薄壳单元算法以及接触碰撞界面算法等，探讨了有限元计算中的材料模型参数获取技术，开发了相应的材料试验装置及材料模型参数反求软件，在此基础上进行了基本的碰撞仿真算例和试验对比研究；文中通过应用有限元方法研究了薄壁构件的碰撞吸能特性，指出了设计薄壁吸能构件时需要考虑的几个主要影响因素，即焊点、壁厚、横截面和预变形等；在关于车辆部件的碰撞安全性能设计中进行了吸能转向机构和自适应安全气囊的仿真研究，提出了吸能转向机构和自适应安全气囊的仿真研究方法；文中最后探讨了整车碰撞性能的设计与改进方法，提出了以理想碰撞特性为目标，采用分段加速度或者根据碰撞时间进行设计的反推设计法、部件吸能仿真优化设计法等量化设计方法，并通过综合应用文中所讨论的相关技术进行了整车碰撞性能的设计与改进实例研究，所选定的车型是大众化的普通轿车和碰撞安全性基础较差的微型面包车，研究结果表明，本文所提出的设计与改进方法是适用而有效的，具有重要的工程实用意义和价值。

For a rigid body rotating about a principal axis , the angular acceleration is related to torque by T =Ia.

对于绕主轴转动的刚体来说，角加速度与转矩的关系是T＝Ia。

The latter employs the suspected angular acceleration model, so that the uncertain vehicle dynamic model is avoided being utilized.

基于EKF的姿态求解算法，通过假定机体角加速度模型，避免了一般基于滤波方式的姿态算法中需要复杂刚体运动方程的缺点。

Week 5 Angular momentum of particle and conservation law of angular momentum, angular momentum of rigid body, theorem of angular momentum, conservation law of angular momentum.

第5周 质点的角动量和角动量守恒定律，刚体的角动量、角动量定理、角动量守恒定律。

To use respectively that rigid body plane differential equations of motion, theorem of angular momentum, conservation law of mechanical energy , and the law of conservation of energy.

分别采用刚体平面运动微分方程、动量矩定理、机械能守恒定律以及能量法，对拟定的半圆柱体微振问题进行分析求解，并作以比较，明确了从不同角度入手分析解决微振动问题所需基础知识和基本理论以及相对难易程

Newton's laws, concepts of momentum, energy, angular momentum, rigid body motion, and non-inertial systems.

牛顿定律，动量的概念，能量，角动量，刚体运动，以及非惯性系。

It is well known that the angular velocity of a rigid body is no relative to the basic points .

刚体的角速度与基点无关，这是一个熟知的事实。

No-spherical rigid body that has anisotropic inertia is called no-spherical sphere of inertia.

具有"各向同性"的转动惯量的非球形刚体称为非球形惯量球。

To study the regular human gaits,the test system based on string displacement sensor and human joint angle measurement instrument are used to measure the motion trajectory of anklebone and the joint angles of lower limb under walking in different road conditions,and the measurement data is analyzed and treated based on human rigidbody model and with data fusion method.Then the gaittrajectories and standphases are gotten under the condition of upstairs,normal walking and downstairs.The result shows that the longest standphase is in upstairs condition,the middle is normal walking and the shortest is downstairs.

为研究人体的步态运动规律，采用基于拉线传感器检测系统和人体关节角度测量装置，对人在不同路况下行走时踝关节运动轨迹和下肢关节角度进行了测量，根据人体下肢刚体模型和数据融合方法对测量结果进行了分析和处理，得到了人在上楼梯、平地行走和下楼梯时的步态轨迹和3种路况下的支撑相；上楼梯时的支撑相最大，平地行走次之，下楼梯最小。

The result indicates that this new method has such advantages as antinoise performance, high precision, and high success rate of registration and it is a universal and automatic registration method for rigid images. These virtues endow it with promising applications.

实验表明，该方法是一种具有抗噪声、精度高、配准成功率高等特点的通用的刚体图像全自动配准方法，具有良好的应用前景。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。