【作者】 李艳；

【导师】 赵万忠；

【作者基本信息】 南京航空航天大学 ， 车辆工程， 2019， 硕士

【摘要】 汽车发生正面碰撞时,吸能盒是保险杠系统关键的吸能部件,因而如何通过优化设计提高其耐撞性能,以保证整车被动安全性和人身财产安全,是一项非常重要的研究任务。本文以汽车前置吸能盒为研究对象,引入结构仿生学概念于其结构设计中,基于负泊松比单胞结构提出一种新型仿生吸能盒,并对其结构进行多目标优化设计。本文的主要研究工作为:首先,以人体胫骨为仿生对象设计了新型仿生吸能盒结构。吸能盒外壳结构仿照胫骨的骨密质结构形态设计为内凹形结构。同时,参考胫骨内部的疏松多孔的骨松质结构,并借鉴于现有泡沫铝等正泊松比材料结构的成形缺陷,提出了将负泊松比结构材料应用于吸能盒的内部填充结构。在此基础上,建立了刚性墙-吸能盒正面碰撞仿真模型,并基于RCAR法规对模型进行了验证。其次,基于吸能特性、缓冲能力和压缩变形等几个方面的评价指标,对比分析了新型吸能盒、传统吸能盒、以及填充负泊松比内芯的传统吸能盒的碰撞性能,最终得出正功能梯度负泊松比内芯结构的吸能盒变形模式最理想。在此基础上,分析了新型吸能盒外壳厚度及内芯厚度梯度对吸能盒耐撞性能的影响,为后续的近似模型建立及多目标优化设计奠定了基础。最后,确定了新型仿生吸能盒优化设计的设计变量、优化目标和约束条件,结合最优拉丁超立方试验设计方法和改进的响应面法,建立了新型仿生吸能盒各性能指标与设计变量之间的近似模型,并采用基于存档的微型遗传算法和改进的非支配排序遗传算法分别进行了寻优搜索,寻求优化设计的最优解集。本文的研究结果可以为汽车吸能盒的开发与设计提供一定的理论基础与技术支持。更多还原

【Abstract】 The crash box is a main energy-absorption part in frontal impact,therefore,it is a very important research topic that how to improve its crashworthiness through optimization design,so as to ensure the vehicle passive safety and personal property safety.In this paper,the front-end crash box is taken as the research object,and the bionic structure concept is introduced into its structural design.Based on the negative Poisson’s ratio(NPR)cell structure,a novel bionic crash box is proposed,and its structure is optimized by multi-objective design method.The central content of this dissertation is focused on these points:Firstly,taking the human tibia as a bionic object,this article proposes a novel structure of the crash box.The outer shell structure of the crash box is modeled as a concave structure according to the compact bone of tibia.Meanwhile,considering the internal spongy part of tibia and structural defects of the existing positive Poisson’s ratio material such as foam aluminum,the negative Poisson’s ratio structure is applied to the inner filling structure of the crash box.On this basis,the simulation model of frontal impact between the rigid wall and crash box is established,and the model is validated based on RCAR regulation.Secondly,in view of the evaluation indexes of energy absorption index,cushioning capacity and compression displacement,this work fills the original quadrilateral crash box with the NPR inner core(O-F-G crash box for short),and compares the novel bionic crash box with the original quadrilateral crash box and the O-F-G crash box.The comparison results show that the crash box with positive functional gradient NPR inner core has the ideal deformation mode.On this foundation,the effects of shell thickness and thickness gradient on the crashworthiness of the novel bionic crash box are analyzed,and these lay the foundation for the subsequent research.Finally,the design variables,optimization objectives and constraints of the optimal design of the novel bionic crash box are determined.Based on this,by combining the optimal Latin hypercube design(Opt LHD)and improved response surface methodology,an approximate model between the performance indexes and design variables of the novel bionic crash box is established.In addition,archive-based micro genetic algorithm(AMGA)and improved non-dominated sorting genetic algorithm(NSGA-II)is used to search for the optimal solution set of optimization design.The findings of this study can provide theoretical basis and technical support for the development and design of crash box.更多还原