汽车缓冲吸能式保险杠碰撞能量衰变特性研究

针对汽车缓冲吸能式保险杠在瞬间将汽车撞击产生的动能转化成多向撞击状态,实现多点同步或异步衰减吸收的目的。基于Hypermesh软件建立汽车缓冲吸能式保险杠正面碰撞有限元模型,采用ANSYS/Ls-Dyna求解器对汽车正面撞击速度分别为10 km/h、20 km/h、30 km/h、40 km/h、50 km/h时保险杠的最大应力及缓冲吸能装置的吸能特性进行数值仿真,得到不同撞击速度下的碰撞能量衰变特性曲线,仿真结果表明：碰撞时吸能盒的凹槽处和横梁所受的应力最大,横梁所受的应力有向中心集中分布的规律,当其应力集中到某一程度时,横梁开始从中心处发生折弯;随着撞击动能的增加,吸能比呈先增大后减小的趋势;碰撞过程中,碰撞能量近似线性衰减,随着撞击速度的增加,碰撞能量衰减曲线的斜率急剧增大。     

卸船机拉杆应力监测及分析

抓斗卸船机是港口装卸不可或缺的主要设备,其失效的主要模式是在随机交变载荷的作用下,结构或者部件发生机械疲劳破坏。本文针对抓斗卸船机的主要受力构件拉杆进行研究,通过研究其失效模式、受力工况,并进行有限元分析,得出其在随机交变载荷下拉杆的应力状态及变形量;通过无线应力监测系统,监测抓斗卸船机拉杆在载荷工况下的应力图谱,并与有限元分析结果作对比,系统地分析了抓斗卸船机部件的失效模式,对科学地制定抓斗卸船机维护保养方案起到积极作用。     

鲁布革水轮发电机转子有限元分析及可靠性研究

转子是发电机组的重要部件,其可靠性会直接影响发电机组的整体性能。但是转子自身高速旋转的结构特点会使转子在运行过程中出现很多问题和事故,如转子支架焊缝开裂、磁机T断裂、磁极线圈翻出、开匝、转子引线熔断和阻尼环拉杆断裂等。鉴于此,该文以鲁布革电厂投运29年的发电机转子为例,通过建立有限元模型,对转子的主要部件进行了应力和疲劳计算,根据计算结果分析转子的运行状态。分析结果表明,鲁布革电厂投运的水轮发电机转子的应力、抗疲劳性能满足运行要求,能够保障机组的安全运行。     

304不锈钢线材椭圆孔型冷连轧过程有限元模拟

借助有限元模拟软件ANSYS/LS-DYNA对304不锈钢线材椭圆孔型两道次冷连轧过程进行三维弹塑性有限元模拟,得出轧件在轧制过程中的等效应力、应变、金属流动、宽展等结果。模拟所得轧件的宽展与实验值的对比证实了利用有限元软件ANSYS/LS-DYNA进行模拟的可靠性。     

涡旋真空泵应力与变形的ANSYS模拟与研究

在对涡旋真空泵运行温度场采用大型有限元分析软件ANSYS进行模拟与研究的基础上，对其工作过程的应力与变形进行了模拟分析。相关结果表明，软件分析基本上可以反应涡旋真空泵运行过程中应力与变形分布及变化情况，并为其设计参数及相关因素的确定提供有效的分析手段。     

新型冲击沉桩机-桩-土全系统动力学特性分析

对冲击碰撞现象进行充分的理解和科学分析是对冲击沉桩机进行结构设计的前提.冲击沉桩机动力学特性分析是一个涉及几何大变形、材料非线性和接触非线性的复杂动力学问题,采用应力波法难以对冲击系统结构的动态响应和桩土的相互作用进行描述.基于ANSYS/LS-DYNA分析软件,针对新型冲击沉桩机,考虑土体大变形,利用ALE流固耦合算法,建立冲击沉桩机-桩-土相互作用的全系统有限元模型.搭建冲击沉桩机实验测试平台,获得关键测点的应力波时程曲线,验证了有限元模型的正确性.依据冲击体、传力箱和拉杆的应力分布图,分析了各关键部件受力情况并提出结构设计建议.改变土体体积模量,获得了不同土体下的预制桩桩底端面承载力.研究结果为新型冲击沉桩机的结构设计和适用环境的选择提供了理论依据.     

3044 t/h超超临界锅炉磨煤机拉杆断裂原因

某电厂3044 t/h超超临界锅炉磨煤机拉杆发生断裂,通过化学成分分析、断口分析、力学性能测试和金相检验等方法对拉杆断裂原因进行了分析.结果表明:该拉杆供货态热处理质量较差,导致强度和冲击韧性指标不合格,且磨损补焊处因热处理不到位而产生冷裂纹,长期在往复拉应力及弯曲应力的作用下,裂纹疲劳扩展,最终导致拉杆疲劳断裂.     

制动电阻器结构瞬态动力分析

采用通用有限元软件 ANSYS6.1对高速行驶列车上使用的制动电阻器结构进行瞬态动力分析,得到电阻器在各个方向冲击栽荷作用下的应力分布、关键部位的内力响应时程曲线,从而保证其运行的抗冲击性和结构的安全性。     

往复式活塞压缩机连杆有限元分析

利用Solidworks 2004软件建立了往复式活塞压缩机连杆的实体模型,然后导入ANSYS软件进行了静力分析,得到了其应力分布云图,满足强度的要求。介绍连杆力学模型和有限元分析在连杆设计中的应用情况,阐述利用有限元分析得到的连杆应力和应变的计算结果,以及对连杆设计的指导意义。     

高速列车风阻制动风翼抗鸟撞分析

对研制的复合材料高速列车风阻制动风翼建立有限元模型。据接触-碰撞基本理论利用非线性动力分析软件LS-DYNA对鸟撞制动风翼过程数值仿真,将计算结果与实验数据对比验证仿真过程的合理性。结果显示,该制动风翼能承受500 km/h鸟体撞击,极限能达625 km/h,满足要求设计。鸟撞过程中制动风翼变形具有冲击波传递特征,应力峰值主要出现在被撞击区域,与底座相连部分及摇臂附近也会出现应力集中。     

SiC/Ti-6Al-4V复合材料在横向拉伸载荷下界面失效行为的数值模拟

采用有限元模拟了SiC/Ti-6Al-4V复合材料冷却过程和横向拉伸试验过程, 横向拉伸试样采用十字形试样。分别建立了平面应力和轴对称有限元模型, 采用平面应力有限元模型计算环绕纤维圆周的界面微区应力分布, 预测界面失效机制。采用轴对称有限元模型分析复合材料界面脱粘过程以及残余应力对界面径向应力分布的影响。结果表明: 对于SiC/Ti-6Al-4V复合材料十字形试样,在横向拉伸载荷下的界面失效由径向应力导致,界面失效模式为法向失效, 剪切失效模式未发生; 十字形试样在横向拉伸载荷下界面初始脱粘位置处于界面中间; 随横向拉伸应力增加, 十字形试样的界面脱粘对称向两边扩展; 界面径向应力随残余应力降低而升高。     

大幅面高速重载模切机动平台传动肘杆分析及设计

目的 利用Ansys有限元软件，对模切机肘杆进行分析及优化设计，实现高速重载模切机动平台高精度、高可靠性、高速平稳运行。方法 采用Adams动力学分析方法，对传动肘杆运动的位移、速度和加速度进行分析，得到其曲线，分析其是否满足重载高速运动工况下模切机的运动规律；利用牛顿-欧拉方法求解复杂多刚体运动系统动力学问题，求出下肘杆受力的数值解，利用有限元分析软件对动平台传动肘杆进行有限元分析，得到在加载一定压力下的应力、应变的云图，并与数值解进行对比分析，判断下肘杆机构是否满足重载的需求。结果 得到了肘杆部件的应力云图和变形云图，及其各个零件的最大应力，应力最大值为469.1 MPa。结论 利用有限元分析的手段，从理论上指导模切压力试验平台的结构优化设计，提高了设计的准确性，缩短了产品的试制周期。     

复合材料先进网格结构共固化工艺的温度场模拟

基于ANSYS软件开发了用于模拟复合材料固化过程中温度-固化度耦合场变化程序, 并分别采用二维和三维有限元模型对复合材料先进正交网格结构的软模辅助共固化工艺过程进行了数值仿真。计算结果分析表明: 二维有限元模型不考虑网格结构肋骨交叉点的影响, 能以较大时间步长进行共固化工艺的数值模拟, 且分析结果具有较高的精度; 三维精细有限元模型可考虑肋骨交叉点在共固化工艺中对复合材料先进网格结构内温度-固化度耦合场的影响; 肋骨交叉点附近的温度场明显高于结构的其他部位。      

Research on Welding Structure with Transition Changing Faces at Cylinder Block on Boom of Medium Excavator by Means of Hot Spot Stress Approach

To investigate the cracking reason in welding structure with transition changing faces at cylinder block on boom of medium excavator during fatigue test, the finite element model of boom was established by using ANSYS finite element software. The stress distribution of the boom was obtained under fatigue loading spectrum of medium excavator. In addition, the fine model of welding structure with solid element length 2 mm was set up with the help of sub-model technology in ANSYS software to get the accurate hot spot stresses around welding toes. Finally, the fatigue life of this welding structure was calculated according to IIW fatigue class. The results show that the stress gradient along with the thickness direction can be acquired by fine three-dimensional finite element sub-model of welding structure. Therefore, the weakest point in thick plate was located, which was in accordance with the experiment result.     

Deformation behavior and mechanical properties of braided rectangular pipes

The purpose of this study is to clarify the deformation behavior and the relationship between the braiding angle and mechanical properties for the braided rectangular pipe. Three-point bending test was performed for each specimen. Furthermore, the effect of the solid-core bar on the deformation state of the rectangular pipe was studied by finite element method (FEM). Moreover, the effect of the braiding angle on the deformation behavior in detail was investigated. The bending modulus and the bending strength for each specimen were decreased with an increase in the braiding angle. The local deformations occurred at the compression side under loading nose and decreased with an increase in stiffness properties in circumferential direction. From FEM analysis, using the aluminum solid-core bar was effective to restrain the local deformation. The difference between the bending moduli of experiments and FEM was decreased with an increase in the modulus in transverse direction.     

并列式三卷筒船用绞车冲击特性

为提高船用绞车抗冲击性能及为今后船用绞车设计提供参考,参照标准GJB1060制定船用绞车冲击环境,并利用ANSYS有限元软件对绞车冲击特性进行研究,对绞车在垂向、横向和纵向三个方向冲击载荷作用下加速度与应力响应进行分析,得到船用绞车整体在垂向、横向和纵向的最大应力响应比值以及最大应力值出现位置,概括绞车上六个电机在不同载荷作用下加速度响应特性,并对提升绞车抗冲击特性进行简单优化。     

Effects of transverse rumble strips on safety of pedestrian crosswalks on rural roads in China

The primary objective of this study is to evaluate the impacts of transverse rumble strips in reducing crashes and vehicle speeds at pedestrian crosswalks on rural roads in China. Using crash data reported at 366 sites, the research team conducted an observational before-after study using a comparison group and the Empirical Bayesian (EB) method to evaluate the effectiveness of transverse rumble strips in reducing crashes at pedestrian crosswalks. It was found that transverse rumble strips may reduce expected crash frequency at pedestrian crosswalks by 25%. The research team collected more than 15,000 speed observations at 12 sites. The speed data analysis results show that transverse rumble strips significantly reduce vehicle speeds in vicinity of pedestrian crosswalks on rural roads with posted speed limits of 60 km/h and 80 km/h. On average, the mean speed at pedestrian crosswalks declined 9.2 km/h on roads with a speed limit of 60 km/h; and 11.9 km/h on roads with a speed limit of 80 km/h. The 85th percentile speed declined 9.1 km/h on roads with a speed limit of 60 km/h; and 12.0 km/h on roads with a speed limit of 80 km/h. However, the speed reduction impacts were not found to be statistically significant for the pedestrian crosswalk on the road with a speed limit of 40 km/h. The study also looked extensively at the influence area of transverse rumble strips on rural roads. Speed profiles developed in this study show that the influence area of transverse rumble strips is generally less than 0.3 km.     

Effects of Boundary Conditions in Laminated Composite Plates Using Higher Order Shear Deformation Theory

This paper extends the applicability of a modified higher order shear deformation theory to accurately determine the in-plane and transverse shear stress distributions in an orthotropic laminated composite plate subjected to different boundary conditions. A simpler, two-dimensional, shear deformable, plate theory accompanied with an appropriate set of through-thickness variations, is used to accurately predict transverse shear stresses. A finite element code was developed based on a higher order shear deformation theory to study the effects of boundary conditions on the behavior of thin-to-thick anisotropic laminated composite plates. The code was verified against three dimensional elasticity results. The study also compared the stresses and deformation results of higher order theory with those obtained using commercial software such as LUSAS, ANSYS and ALGOR. The commercial software are heavily used by designers to design various components/products made of composites. Various combinations of fixed, clamped and simply supported boundary conditions were used to verify a large class of anticipated applications. Results obtained from software are in good agreement for some cases and significantly differ for others. It was found that LUSAS and ANSYS yield better results for transverse deflection and in-plane stresses. But for transverse shear stresses, it is highly dependent on boundary conditions.     

The effect of pressing direction on the 5-axis CNC incremental forming quality

The effect of pressing direction on forming quality in the 5-axis CNC incremental forming was studied by using the digital simulation technology based on the finite element analysis method. Four kinds of finite element analysis models were created according to the different pressing directions, and were simulated by using ANSYS/LS-DYNA software. Through comparing with the simulation results of the four kinds of finite element analysis models, the relationships between the pressing direction and sheet thickness distribution, sheet thickness thinning rate, outline of the middle surface and the equivalent strain of middle surface were presented.