轿车保险杠的研究现状及发展趋势

介绍了保险杠的各种结构形式与功能，从结构耐撞性、轻量化、成型工艺、行人保护4个方面对保险杠的研究现状进行了总结，并提出了未来的研究方向。     

热流道顺序控制技术在大型注塑模中的应用

以汽车保险杠为例,分别采用普通热流道和热流道顺序控制技术对充填过程进行了流动模拟,将其结果进行了比较,结果表明:采用热流道顺序控制技术能有效消除熔接痕和气穴,提高产品的表观质量,同时降低了锁模力.采用顺序阀控制技术对大型复杂制品注射成型有着实际意义.     

Development of a lightweight space debris shield using high strength fibers

In order to protect space structure against space debris impacts, it is indispensable to develop a shield with high strength materials. A high strength fiber is one of potential materials from a viewpoint of strength, lightweight, and flexibility. The purpose of this study was to develop a new lightweight shield composed of high strength fibers against medium size debris impacts. We developed four kinds of shields using Vectran fibers, and hypervelocity impact tests were carried out by a railgun accelerator. The experimental results showed that the developed shield could stop the polycarbonate projectile with 13 mm in diameter, 1 gram in weight, and 6.9 km/sec in velocity. Adoption of the high strength fiber in the bumper materials may reinforce the protection capability and reduce the weight drastically.     

Simulation of hollow shaped charge jet impacts onto aluminium whipple bumpers at 11 km/s

The computational technique of Smoothed Particle Hydrodynamics (as implemented in the hydrocodes AUTODYN-2D and AUTODYN-3D) has been used to simulate the impact of hollow shaped charge jet projectiles onto stuffed Whipple bumper shielding. Due to limited availability of material models, the interim Nextel/Kevlar-Epoxy bumper was modelled as an equivalent thickness of aluminium. Stuffed Whipple bumper shields are used for meteoroid and debris impact protection of the European module of the International Space Station (the Columbus APM). A total of 56 simulations were carried out to investigate the impact processes occurring for shaped charge jet impact. Sensitivity studies were carried out on the influence of projectile shape, pitch, yaw and strength at 11 km/s to determine the range of debris cloud morphologies. The debris cloud structure was shown to be highly dispersed, and no projectile remnant was observed at the centre of the cloud. The mass of an aluminium sphere producing equivalent damage to a shaped charge jet projectile was in the range 1.5 to 1.75 times greater than the mass of the shaped charge jet projectile. Upon loading by the dispersed debris cloud, the interim bumper failed by spallation, producing fragments moving at 2 km/s or less. The fragments distorted the rear wall (pressure wall) of the shield but did not perforate it. The experimental data show rear wall deformation but to a lesser degree. Perforation of the rear wall, observed for one test, was not reproduced by the simulation. Nextel/Kevlar-epoxy material models are required to reproduce correctly the interim bumper failure under debris cloud loading.     

Development of bumper shield using low density materials

In order to avoid critical accidents due to space debris, this paper proposes an extra bumper shield called an inflatable bumper. It consists of aluminum (Al2024-T3), high strength fiber Vectran and inflatable polyurethane. Because of this inflatability, it is compactly stored during its transportation. And after the installation outside of the space structures, this bumper is then inflated by the effect of expandable polyurethane. This method saves the amount of the transportation and the involved cost. In this paper the experiments, using several polyurethane's with different areal density, have been conducted, compared and evaluated from the viewpoints of the penetrated areal density, the total thickness penetrated, and mass distribution of the fragments captured inside the shield. As the results of the experiments, it is found that the protection ability of the proposed structure depends on the areal density of polyurethane layers and the optimum areal density is 0.525kg/m². And by using polyurethane between Vectran layers, this expandable structure captures the fragments of the secondary debris, which might cause a secondary impact on the space structure.     

基于Moldflow的汽车大型覆盖件注塑成型工艺研究

以汽车后保险杠塑件为例,利用Moldflow软件模拟了注塑过程中的熔体流动行为。针对塑件的结构特点及质量要求,提出了一种针阀控制顺序进料延时保压的热流道浇注系统,分析了填充时间、填充/保压转换点压力锁、模力、翘曲变形、熔接痕分布等情况。并将分析结果应用于注塑生产,取得了较好的实际效果。     

汽车防撞梁大型塑件注射模设计

以某汽车防撞梁塑件注射模设计为例,介绍应用Moldflow和UG进行大型塑件模具设计的流程,着重叙述了利用Moldflow/MPI对熔料的充型、冷却、塑件翘曲进行模拟分析,从而确定优化后的模具浇注系统、冷却系统等主要参数与结构。设计的模具结构紧凑,取件方便,成型的塑件符合质量要求。     

过山车液压锁紧器介绍

本文对过山车液压锁紧器的原理及特点进行了阐述,结合实际应用,对一些实际应用中产生的问题作了详尽的介绍,对新产品的开发做了展望。     

基于Moldflow的汽车大型覆盖件注射成型工艺研究

以汽车后保险杠为例,利用Moldflow软件直观地模拟出注射过程中的熔体流动过程.针对后保险杠的结构特点及品质要求,提出了一种针阀控制顺序进料延时保压的热流道浇注系统,分析了填充时间、填充/保压转换点压力、锁模力、翘曲变形、熔接痕分布等情况,消除了该类塑件易存在的熔接痕、翘曲变形大等缺陷,为实际生产提供了理论指导.     

基于响应面法的汽车前防撞梁轻量化分析

将原来的汽车前防撞横梁材料替换成超高强度钢后,在确保低速碰撞性能基础上,利用响应面法进行轻量化分析.建立前防撞梁有限元模型,用LS-DYNA进行低速碰撞仿真.在此基础上以横梁和吸能盒的厚度作为变量进行试验设计.构建各项碰撞性能的2阶多项式响应面模型,并验证模型的有效性.以质量和吸能作为优化目标,建立多目标优化模型.与原设计相比,求出的优化方案在保证低速碰撞性能的基础上实现前防撞梁减重36%.