某货车疲劳载荷谱测量方法的分析

车身疲劳开裂问题的分析与优化须以准确的受力输入为前提,针对用户目标路面进行的实际道路试验,是获取有效载荷谱最有效直接的方法。结合整车构造的受力状况和CAE车身分析输入需求,选择合适的测试安装硬点并对其进行加速度响应测量,同时对车身关键开裂点进行应变信号测量,以对CAE分析结果进行有效性验证。将测量得到的信号,通过Labview/Matlab联合处理,为车身结构的CAE分析与优化提供数据输入和结论验证。     

基于模态分析的某客车车身NVH性能优化

针对某客车存在的车身共振问题,对白车身进行模态分析、获取其模态参数,分析出产生共振的原因为车身一阶模态频率与轮胎不平衡产生的激励频率相近;建立白车身有限元模型,进行模态仿真分析;通过对比试验及仿真的白车身模态参数,验证模型的准确性;针对其一阶模态频率,对白车身模型进行模态应变能分析,选取车身一阶模态振型下刚度不足位置,对白车身进行加强,提高白车身一阶模态频率,使之避免与轮胎激励频率相近而造成的车身共振,实现白车身NVH性能的改善.     

某轿车自车身模态分析

以有限元模态分析和试验模态分析的相关理论为基础,对某轿车白车身的模态进行了研究。首先,在HyperMesh建立了白车身有限元模型,并用梁单元模拟焊点。在Nastran软件中用Lanczos方法对白车身进行了模态分析,得到白车身的固有频率及各阶振型。其次,采用随机信号对白车身进行两点激励,用多点拾振方法采集响应信号,将信号处理后,得到白车身的固有频率及对应的振型。通过对比有限元模态分析结果和试验结果,验证了所建有限元模型的有效性。     

某纯电动汽车白车身弯曲刚度分析与优化设计

在某款纯电动汽车的设计开发过程中,为满足操纵性、安全性、可靠性、NVH、碰撞安全等性能要求,同时由于布置电池后下车体骨架的结构变更,需要对白车身弯曲刚度进行CAE分析。利用HyperMesh、Nastran、HyperView等仿真软件建立纯电动汽车白车身有限元模型,并进行弯曲刚度分析。根据CAE分析结果提出优化方案,再对优化方案进行弯曲刚度分析,最终保证优化后的白车身弯曲刚度满足目标值要求,为该车型白车身结构改进和优化设计提供参考。     

白车身结构弯曲静刚度有限元与试验分析

为了确保轿车满足安全性和舒适性方面的要求,通常会为新研发的车型提出一个车身刚度设计目标。文中对测试白车身弯曲静刚度时,白车身约束关系与模拟真实环境施加外载荷进行了一些理论上的探讨,并进行了试验与CAE分析验证。     

浅述轿车车身刚度

车身刚度影响到轿车的可靠性、安全性、操纵稳定性、NVH性能、燃油经济性、工艺性等方面,对于车身设计来讲有着举足轻重的作用,现代车身设计越来越广泛地采用CAE及试验手段来分析验证车身的刚度。分析刚度对车身的影响并说明一些常规的试验以及结构设计过程中需要考虑的内容,简述了车身的刚度问题。     

某车型座椅安全带安装固定点强度分析

车型项目开发前期,利用CAE仿真对汽车车身钣金上的座椅安全带安装固定点进行分析,验证车身钣金上的固定点是否满足国家法规要求,降低后期实车安全性能试验风险。     

碰撞安全性能驱动的车身前端结构优化设计

为了提高概念设计阶段车身结构设计对后续详细设计阶段的指导意义,通过车身零部件的隐式参数化建模方法实现CAE驱动的概念设计。以车身正碰主要吸能结构的前防撞梁、吸能盒以及前纵梁为例,建立了包含对车身结构碰撞性能具有较大影响的细部结构的参数化模型,并对模型的网格质量进行控制,可以实现参数化CAD与CAE模型间的快速响应。概念设计阶段该参数化模型可以通过形状、尺寸、材料的协同优化,提高后续工程设计的可靠性和效率,缩短开发周期。     

某SRV白车身动态性能研究及工程治理

以某SRV车为研究对象,针对其整车振动过大问题,利用CAE技术对其白车身动态性能进行研究,以期改善该sRV整车NVH性能.研究探明了其动态性能较为薄弱的环节,并据此对白车身提出改进设计方案.测试结果表明,将改进后的白车身搭载到整车上以后,整车噪声可降低5 dB,显著提高了整车NVH性能.     

基于平台模块化的汽车车身前期优化技术研究

针对CAE分析常滞后于产品开发,无法有效支持平台模块化搭建前期车身刚度模态性能保持在目标值内的问题,对广汽自主某B级平台某款乘用车进行了研究,利用网格变形技术,完成了详细工程数据发布前,跨平台B级车向C级车的快速变形,利用灵敏度分析和多目标优化分析,对变形后的目标车型进行了车身弯扭刚度和弯扭模态的性能优化。基于灵敏度分析结果和性能优化结果进行了车身轻量化分析,通过刚度模态试验台对车身详细工程数据进行了测试,对比分析了试验结果与CAE分析结果。研究结果表明,采用该技术后,传统多人力且超过两周的车身建模时间可以缩短至单人力1 h以内,车身刚度模态性能提升超过6%的同时减重8.9 kg,为产品进入后续详细设计阶段的性能保证提供了帮助,提高了CAE分析技术在平台模块化开发中的重要性。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.