【作者】 李春；

【导师】 董桂田； 王国强；

【作者基本信息】 吉林大学 ， 机械工程， 2005， 硕士

【摘要】 落物保护装置(FOPS)的功能是当车辆遇到落物时保障司机生命安全,最大限度地降低事故造成的财产损失。随着国际上对工程车辆安全生产性能要求的提高,FOPS 已成为许多国家强制性的安全要求。本文对FOPS 的落物冲击过程进行了研究。本文的主要工作和创新点包括: 1、采用结构塑性动力学的方法对薄板受低速冲击的非线性塑性动力响应进行了讨论。应用Calder—Goldsmith 能量理论,在薄板理论的基础上简化FOPS 的顶板为刚塑性模型,建立了其最大位移数学模型,并研究讨论了影响塑性动力响应的一些因素,包括应变率效应、应变强化效应、几何大变形、横向剪力和转动惯量、材料的弹性效应以及材料和结构中的缺陷对响应特征的影响。2、本文以CLG856 型轮式装载机为例,采用适合解决冲击碰撞问题的软件ANSYS/LS-DYNA 建立了FOPS—落锤的冲击体系有限元模型,对落物过程进行了动力学仿真,计算了冲击后FOPS 相对于DLV 的最大相对位移量和等效应力的大小及分布,得到了落物过程落锤的位移、速度和加速度随时间的变化曲线;研究了冲击过程中能量的转化过程与转化形式;讨论了影响最大相对变形量及其出现时刻的主要因素—落锤冲击速度、顶板厚度和横梁尺寸的影响。3、以CLG856 的FOPS 为例,对其FOPS 进行了落物试验,整个试验过程遵守ISO—3449:1992 和ISO3164:1995 的规定,测量了顶板中心点的加速度和应变,对该FOPS 的抗冲击性能作出评判,对仿真结果和试验结果进行了一致性分析。更多还原

【Abstract】 The function of the Falling Object Protective Structures(FOPS) is to protect driver from the accident caused by the impact .Because of the flexibility as well as rigidity of the FOPS, it can not only stand the crash but also absorb the energy through its deformations, as a result it can evidently reduce the damage to the passengers. With the advanced request for the security of engineering vehicle in the world, FOPS is becoming the forced demand in more and more country. At the same time, in our country, there are more and more project about the security capability verification of FOPS is under developing. On the bases of systematic summarization on the critical problems, research methodologies and research outcomes in the area of impact research home and abroad, the dissertation,on the one hand, analysises the more important problems in the mathematic modeling as well as the simulation and has given the relative methods to solve these problems.On the other hand ,it has determined its main research targets as the most relatively displacement of FOPS relative to DLV and the research objects are also broadened to the research of energy absorption characteristics for FOPS during the process of falling object impact. To verify CLG856 wheel loader’s FOPS, the laboratory tests have been performed according to ISO3449:1992 (Earth-moving machinery-Falling -object-protective structures-Laboratory tests and performancerequirements) and ISO3164:1995(Earth-moving machinery-Laboratory evaluations of protective structures–Specifications for deflection-limiting volume). By tests results, the crashworthiness of FOPS have researched and evaluated. The falling object impact FOPS is a problem with three-dimension nonlinear large deformation and structual dynamics. The author has made detailed analysis to the large plastic deformation dynamic characteristics for the top cover of the FOPS under low impact speed, which explicitly present the essence of the inherent plastic dynamic features of the FOPS. Computer simulation is one of the most important ways to research the modern impact problem. In this article, the dynamic character of FOPS is mainly focused, as well as the performance of the FOPS energy-absorbing under low speed impact更多还原