基于HyperWorks的汽车挡泥板结构拓扑优化设计

挡泥板作为汽车覆盖件的一种,其刚性要求不可忽视。基于有限元模态分析方法,得到了挡泥板的前六阶固有频率及模态振型。依据挡泥板的刚度设计要求,以第一阶固有频率最大化为目标函数,体积分数（质量）为约束条件,建立了结构优化的数学模型;利用HyperWorks对其进行了结构拓扑优化求解;根据优化结果在初始结构上布置了加强肋。挡泥板的第一阶固有频率从优化前的43.6Hz变为84.9Hz,提高了94.7%,体现了拓扑优化方法在汽车零件初始设计中具有重要的理论意义和实际应用价值。     

螺旋孔型斜轧变形的有限元分析

目的　用有限元法探索斜轧变形的规律 .方法　在分析和合理简化的基础上 ,提出斜轧变形的有限元法模型 ,以 ANSYS软件为工具 ,对该模型进行计算分析 .结果　获得轧件横断面内的应力和应变分布 .结论　结果与其他方法的结果相吻合 ,曼内斯曼 (Manesmann)效应是循环应力下疲劳的结果     

三峡水电站过机水流指标检测下的水轮机磨蚀机理浅析

对三峡水电站左岸过水轮机水流的各项物理指标以及水轮机的磨蚀状况进行了监测,并以测得的各项物理指标与水轮机的真实磨蚀状况为基础对水轮机的磨蚀机理进行了浅析。分析得出了通过现场观察,数值模拟等手段可以较为准确的预测水轮机未来的磨蚀情况,也可为检修机制的转变提供依据。     

在线测量刀具图像调焦特性的镜头对比研究

光学系统是在线高精度视觉测量系统的重要模块,其中远心镜头的引入导致对焦不准、系统复杂度和成本大大提高等问题。文章以实验室搭建的视觉测量系统为平台,采用平行背光源,分别用远心镜头和普通镜头对数控铣刀进行了直径测量。根据清晰度比率、灵敏度、局部极值因子等评价指标对两类镜头环境下的Tenengrad函数特性进行对比分析。结果显示,非远心镜头在灵敏度、分辨率和鲁棒性更占优势,高达35%左右,而远心镜头具有更好的曲线性,超出30%左右。考虑到该在线测量系统应用于复杂工业环境中,应选择分辨率、灵敏度和鲁棒性均占优势,且成本更低的非远心镜头。     

基于归一化8点算法的相机径向畸变中心校正方法

针对相机径向畸变中心定位误差的问题,提出一种方法对相机径向畸变中心校正,以实现相机径向畸变中心高精度定位。首先介绍了针孔相机和镜头畸变结合模型,其次提出了基于归一化8点算法和最小二乘法的相机径向畸变中心校正方法,得到校正精度为0.2915个像素(32.2562μm),最后通过实验验证了该校正方法的可行性。     

铝合金X射线应力测量定峰方法评估

将X射线法(XRD)的绝对应力测量评定转化为相对应力测量评定,以测量精确度和重复性为评价指标,对各种定峰方法的优劣性进行研究。实验证明,交相关法通过逐差法利用全部衍射峰信息,直接获取XRD法所需的布拉格角差值,有最好的测量精度和重复性。最大值法和抛物线法利用峰顶信息,具有较高的应力测量精度,但由于信息利用区间较窄,测量重复性较差,半高宽法(FWHM)测量精度和重复性很差,不适于对铝合金定峰。远离布拉格角处信息对重心法影响很大,对衍射峰的预处理要求也高,力臂的存在使得测量精度变差;力臂和波谱边缘随机性使测量重复性很差。交相关法对铝合金X射线应力测量有最好的定峰效果。     

防爆胶轮车动态特性研究

为掌握防爆胶轮车的动态特性,了解其动态应力、应变情况,应用多体系统动力学以及有限元法对其动态特性进行了研究．基于ADAMS建立了胶轮车的虚拟样机模型, 利用多体动力学仿真得到胶轮车在矩形坑路谱下各部件与车架铰接点的动态载荷曲线;基于ANSYS建立了胶轮车车架的有限元模型,并将动力学仿真得到的随机激励峰值加载到典型工况约束下的有限元分析模型,从而计算得到车架的动态应力分布, 并找出了应力集中的位置．动态分析结果可用于评价车架的动载峰值应力、应变,并对车架的轻量化改进设计具有一定的指导意义．     

Preparation of Ni60-WC coating by plasma spraying, plasma re-melting and plasma spray welding on surface of hot forging die

In order to produce the hear-resistant inner layer of hot-forging die, the plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2, including 10%, 20%, 30% tungsten carbide (WC) ceramic powder used as coating material to obtain different Nickel-based WC alloys coating. Micro-structure and micro-hardness analysis of the coating layer are conducted, as well as thermophysical properties for the coating layer were measured. The experimental results show that the coating prepared with 70%Ni60, 30%WC powder has the best properties with plasma spray welding, in which the micro-hardness can achieve 900HV, meanwhile it can improve the thermal property of hot-forging die dramatically.     

Relationship between the corrosion and Cr-Ni content of stainless steel in borax bath

The corrosion of stainless steel was experimentally investigated and analyzed to improve the service-life of the crucible and fixture clamps. Through the experiment, stainless steel was found to satisfy the crucible and fixture clamps materials. As the chromium element mass percentage of the stainless steel increased, the corrosion decreased rapidly at first and then slowly increased. With the corrosion time prolonging, the corrosion growth rate is generally a downward trend. With Chromium 20%, the corrosive were the least. With Nickel element mass percentage increased, the corrosion increased rapidly at first and then decreased rapidly, flatten at the last. It was special that the corrosion had little relationship with the Chromium and Nickel mass percentage when the Nickel percentage is more than 35%. The most remarkable corrosion is corresponding with the Nickel element 12%, the least corrosion with Nickel element 80%. So Nickel element 35% is the most optional.     

矿用防爆胶轮车动态应力数值模拟研究

针对矿用防爆胶轮车井下作业时受力复杂的特点,分别建立了车体多体动力学模型和车架有限元模型。应用虚拟样机技术模拟真实的工况,提取搓板路面工况下随机激励的峰值,进而通过有限元法对车架进行动态应力分析。有限元分析结果表明整个车架的最大动应力满足强度要求。