汽车悬架稳定杆连杆支架的疲劳仿真分析及结构优化

针对某型车辆常规耐久性试验过程中稳定杆连杆支架出现断裂的问题,对稳定杆连杆支架进行疲劳寿命分析和结构优化.首先运用ANSYS软件建立稳定杆连杆支架的有限元模型;然后基于静态有限元疲劳分析方法对连杆支架进行强度分析计算,并依据强度分析结果对稳定杆连杆支架进行疲劳寿命预测分析;其次根据等强梁理论对稳定杆连杆支架进行结构优化,支架截面由原来的等截面改为变截面,并对优化后的结构进行疲劳寿命预测;最后通过疲劳台架试验和裂纹断口分析,验证仿真分析结果.通过台架试验和仿真结果的对比可以得出,稳定杆连杆支架优化前后其疲劳寿命预测准确,优化后结构疲劳寿命符合预期.     

火箭筒托架零件一体化成形分析及轻量化设计

目的 研究某型号火箭筒托架零件一体化成形及工况载荷下的结构轻量化设计方法。方法 提出了基于3D打印制造的铝合金一体化快速成形方法,并结合有限元分析和理论公式,得出了一体化托架在冲击载荷作用下的结构强度评估方法,进行了变形、应变及应力分析,在此基础上对托架进行了轻量化优化设计。结果 在满足强度要求的情况下,一体化托架相对传统成形整体质量减轻了153.535g,减少了41.76%,效果明显。结论 实现了托架的一体化成形,完成了托架的轻量化设计,研究结果为火箭筒零件一体化成形及冲击载荷下结构的轻量化设计提供了参考。     

汽车尾灯支架装配变形的数值模拟与验证

目的 深入研究汽车尾灯装配变形,建立可以精确预测尾灯装配变形的有限元方案。方法 通过数字图像相关法研究了尾灯紧固过程中钣金支架的变形情况,获得了支架上关键位置的变形规律。引入有限元仿真分析方法,建立了全工况有限元仿真分析模型,对尾灯装配的整个过程进行数值仿真。结果 获得了装配后钣金变形量的预测值,通过对3类尾灯的装配过程进行仿真分析,对比实际测量的钣金支架变形数据,验证了该模型能够较为精确地预测尾灯装配中的变形误差。结论 提出了尾灯装配定位基准与螺栓紧固点分离的解决方案,从设计上有效避免了新车型尾灯装配超差问题的产生。     

半固态ZL201合金本构关系研究

采用Gleeble 3800热模拟试验机对液相线铸造获得的ZL201合金半固态坯料进行了不同工艺参数下的热模拟试验,并进行了变形抗力本构方程拟合,以此为基础根据Stefan方程确定了幂律模型中的表观粘度等参数.采用商用仿真软件ANYCASTING对汽车发动机支架进行了触变压铸过程数值模拟分析,获得了ZL201合金的半固态充填流动特征响应.结果表明:半固态表观粘度随剪切速率增大而下降,在充型过程中呈现剪切变稀的触变成形特点,半固态浆料将以层流方式充填型腔,可获得充型完好的半固态压铸零件.     

基于Ansys的纸浆模塑成型设备吸浆模支架轻量化设计

目的利用有限元分析软件Ansys对纸浆模塑成型设备吸浆模支架进行轻量化设计。方法首先运用APDL建立了支架参数化有限元模型,对其进行了静力分析,结果表明,支架强度存在较大富裕,具有轻量化的优化空间;选取支架许用应力作为状态变量,支架总质量作为优化目标函数,基于Ansys Design Opt模块,采用一阶优化方法对支架进行了轻量化设计。结果优化后,支架总质量降低了33%,节约了生产成本。结论提出了纸浆模塑吸浆模支架结构轻量化的优化设计方案。     

基于试验设计与有限元仿真的辐射井水平钻机承载部件优化设计

为了提升辐射井水平钻机承载部件的安全性与稳定性，运用试验设计（design of experiment，DOE）与有限元仿真技术对承载部件进行优化设计。通过正交试验法结合ANSYS Workbench有限元静力学仿真对由回转平台、立支架及横支架组成的承载系统的加强筋板布置形式进行优化设计，获得承载系统加强筋板的最优布局类型。在此基础上，运用基于试验设计的响应面优化法对回转平台的台面厚度、筋板高度及筋板厚度进行优化设计，进一步减小回转平台的最大等效应力、最大变形及质量，提升承载系统的安全性与稳定性。结果表明承载系统加强筋板的最优布局类型为：回转平台采用纵横筋板，立支架采用X形筋板，横支架采用V形筋板；回转平台的最优参数组合为：台面厚度为11.2 mm，筋板高度为31.9 mm，筋板厚度为12.3 mm。集成运用试验设计与有限元仿真技术对水平钻机承载部件进行优化设计的方法可为水平钻机实体样机设计提供一定的参考。     

包装机械设计中计算机辅助设计软件的联合应用研究

目的研究Pro/E,Ansys与Optistruct在包装机械设计中的联合应用问题。方法在分析Pro/E,Ansys及Optistruct软件的特点基础上,结合每个软件在包装机械设计中各自的侧重点及优势,提出了在实际研发中三者联合应用的方法,并对三者间数据传送进行了说明;通过包装机械设计过程中的实例,进行了3个软件的联合应用研究。结果 Pro/E,Ansys和Optistruct等3个软件各具优势,分别侧重于三维建模绘图、有限元仿真分析和结构优化;三者可以进行数据间的相互传送,通过联合应用流程实现在包装机械设计中的联合应用;对托架结构设计的优化实例表明:最大应力减小了18.4%,最大变形减小了58%。结论 Pro/E,Ansys与Optistruct在包装机械设计中的联合应用使得设计过程高效准确,优化效果明显。     

Porous ceramic lamellae for orthodontic ceramic brackets: Part II In vitro performance testing

This study was undertaken to test a new and original orthodontic bracket base, consisting of a porous lamella, which was designed to facilitate removal of ceramic brackets from the enamel surface after treatment. In the phase of the study presented here, two types of lamella and the adhesive resin used to bond them to brackets and teeth, were evaluated in vitro. Two types of test were carried out on bracketed teeth. The tensile bond strength was measured for specimens that had been either kept in water for 24 h at 37°C or subjected to 18000 cycles in water between 6°C and 55°C. The stress required to remove brackets with debracketing pliers was measured and the mode of failure recorded for specimens that had been kept in water for 24 h at 37°C. The results indicate that bracket/lamella assemblies can be bonded to enamel sufficiently strongly for clinical application and can be safely removed without damage to enamel.     

基于真实载荷的托架瞬态分析及优化

目的 研究托架在称量传感器标定过程中的应力、变形情况。方法 采用有限元分析技术对称量传感器标定过程进行仿真模拟,研究托架在称量传感器标定过程中的应力、变形情况,并对有限元分析结果进行验证。结果 通过对仿真结果分析发现了称量传感器标定装置托架应力集中部位。结论 优化设计时对应力集中部位进行了圆角化,使得托架强度和刚度得到了较大的提高。     

复合材料加筋板低速冲击损伤及剩余压缩强度试验研究

采用落锤法对复合材料加筋板进行了低速冲击损伤（LVI）试验,根据复合材料加筋板构型,设计了冲击支持支架,研究了支持支架的间距对冲击结果的影响;用相同的冲击能量对复合材料加筋板结构中3处典型位置进行冲击,得到不同位置的损伤形貌;分别对完好件和损伤试验件进行压缩试验,将试验结果进行对比,分析不同位置的冲击损伤对结构压缩性能的影响。试验结果表明：在相同的冲击能量下,支持支架间距越小,所造成的冲击损伤越严重;在50 J冲击能量下,筋条区蒙皮处的冲击所造成的损伤不易观察,筋条间蒙皮处的冲击所造成的损伤最为明显,而筋条边缘蒙皮处的冲击可以导致筋条边缘的脱粘;冲击损伤会使加筋板屈曲载荷轻微下降,筋条间蒙皮和筋条区蒙皮冲击损伤对压缩结果影响相对较小,筋条边缘处的冲击会引起损伤处蒙皮的子层屈曲,并影响结构破坏形式,使结构压缩承载能力有较为明显的下降。     

高拱坝气幕隔震效果的三维数值模拟

对锦屏一级拱坝进行了气幕隔震效果的三维数值模拟，其中气幕单元采用拉格朗日法中的位移格式，库水单元采用欧拉法中的压力场格式，坝体与气幕的交界面自动满足位移协调条件，气幕与库水交界面满足力的平衡条件。数值仿真结果表明：气幕显著降低了上游坝面的动水压力，气幕厚度越大，隔震效果越好。与无气幕时相比，气幕厚度为1m、3m、5m时，动水压力分别降低了77.1%、83.3%、87.7%，位移反应也相应降低。因此，气幕隔震技术在水工建设中有很好的推广前景。     

Fatigue strength analysis of a welded railway vehicle structure by different methods

The endurance limit approach with maximum amplitude loading (constant loading amplitude) and the cumulative damage approach with variable amplitude loading are both established methods for the fatigue assessment of the bogie frame of a rolling stock. These methods are presented for the vertical main loading of a bogie frame for a light rail vehicle. Assessments are carried out for the normative load requirements according to the relevant standard EN 13749 [1] and also for a vertical force range spectrum deriving from a multiple body system simulation of this railway vehicle. The multiple body system simulation supplies more realistic loads depending on the actual railway application conditions. These different fatigue assessments allow a comparison of the normative load requirements with realistic load assumptions.In general the stress analysis is based on the nominal stress approach. Additionally, for the area subject to the maximum stress, a notch stress analysis is carried out. The comparison of stress analyses for some selected stress points shows the potential and the advantages of the fatigue assessment with the real loading assumptions and with different evaluation methods.     

气动控制单元支架背压成形工艺研究及数值模拟分析

目的背压成形工艺是一种能够控制材料塑性流动的流动控制技术,研究背压工艺在气动控制单元支架零件成形中的可行性。方法针对支架零件特殊结构设计工艺方案,结合有限元数值模拟技术,利用DEFORM-3D软件,模拟分析了支架零件的背压成形过程,获得了成形过程中的等效应力分布状态及成形载荷的变化情况。结果通过模拟结果及工艺试验结果显示,零件下端薄壁状支脚充填效果较好,两端高度一致,端面平整。结论验证了背压工艺在支架零件成形中的可行性。     

基于实测道路谱的纯电动轻卡电池包支架动态载荷仿真及疲劳分析

为保证纯电动轻卡电池包支架的疲劳寿命分析与实车试验场道路耐久试验的关联性,提出了一种将多体动力学、疲劳寿命分析及试验场实测道路谱数据相结合的分析方法。采用ADAMS软件建立了由七通道虚拟试验台、电池包支架及整个车架组成的刚柔耦合多体动力学模型,以试验场采集的电池包支架加速度为目标响应信号,采用Femfat.lab软件使用虚拟迭代方法,反求得到了电池包支架疲劳分析的载荷边界条件。采用Miner线性疲劳损伤理论在疲劳仿真软件nCode中分析了电池包支架的疲劳寿命,分析结果显示其寿命能够满足疲劳性能要求,并最终通过了实车试验场道路耐久试验的验证,验证了此方法的工程实用性。所提出的分析方法对于研究电动汽车电池包支架的疲劳性能具有重要的参考价值。     

Fatigue strength of steel beams with bracket plates welded to the tension flange

Fatigue tests under three-point bending were carried out on mild steel beams with bracket plates welded to the tension flange. The variables considered were the beam and bracket designs and the position of bracket connected. Particular attention was paid to the effect of configuration in the bracket-ends, which was varied in two distinct cases; in one the taper of the bracket end was straight and in the other it was rounded in three different ways. A good SN correlation was obtained by plotting the results in terms of bending stress range at the location of failure in the flange. This followed from the fact that the propagation of cracks across the flange exhausted the considerable part of fatigue life of beams. Thus the design details did not affect strongly the endurance of beams. However, the initial stage of cracking was sensitive to the types of bracket-ends. The fatigue crack associating with a straight bracket-end originated either from the weld toe on the flange at the bracket-to-flange junction or through the weldment, depending on the relative magnitude of two stresses suffering in the flange and in the bracket plate. The rounding of the bracket-ends prevented the occurrence of fracture through weld due to increase in the flexibility at the bracket-to-flange junction, but it did not improve the strength of crack initiation at the weld toe. It was suggested that the crack initiation of both fracture types in beams was possibly predicted from the results of comparative tests on plate specimens with longitudinal non-load-carrying fillet welds and with transverse load-carrying fillet welds.     

力限控制在振动试验中的应用研究

传统航天器加速度响应控制振动试验是根据特定的加速度规范,控制振动台台面加速度,这种试验方法会在试件固有频率处产生过试验现象,力限振动试验可以有效地缓解这种过试验.本文基于简单二自由度模型给出了详细计算力限条件的方法,在此方法基础上,推导出了航天器试件支架与振动台台面间力谱和加速度谱,并对试件支架进行力限正弦振动试验和力限随机振动试验,实验结果表明：与传统加速度响应控制方法相比,基于简单二自由度模型力谱条件的力限振动控制试验能够更加真实模拟动力学环境,有效缓解振动过试验,可以为航天器振动试验提供很好的试验依据。     

基于厚度和应变映射方法的成形和抗凹性能联合仿真

为提升汽车板抗凹性能仿真精度,开展了成形和抗凹性能仿真研究。首先,利用模具将HC180BD+Z板料冲压成两种应变量的试样,然后利用半球形钢制压头以10 mm/min速度对试样进行加载,获得试样初始刚度和失稳凹陷载荷;其次,利用Ls-dyna进行成形和抗凹性能仿真,不考虑成形因素的影响下,初始刚度和失稳凹陷载荷仿真误差<10%,通过采用厚度和应变映射方法后,初始刚度和失稳凹陷载荷仿真误差<5%;最后,对比分析了厚度和应变映射对初始刚度和失稳凹陷载荷仿真结果的影响。研究表明：初始刚度与材料厚度相关,而失稳凹陷载荷与材料厚度和屈服强度相关;通过采用厚度和应变映射方法,能有效提升抗凹性能仿真分析精度;各向同性硬化模型高估了失稳凹陷载荷,采用各向同性和随动混合硬化模型能获得更好的仿真结果。     

Molecular dynamics simulations on nanoindentation mechanisms of multilayered films

Molecular dynamics (MD) simulations were carried out to study the effects of indention deformation, contact, and adhesion on Al, Ni, and Al/Ni multilayered films. The results show that when the indention depth of the sample increased, the maximum load, plastic energy, and adhesion increased. Jump-contact behavior was observed at the beginning of the loading process. Force relaxation and adhesion took place at the holding depth and during the unloading process, respectively. The glide bands of the interface were on the {1 1 1} 1 1 0 slip systems and the maximum width of the glide bands was about 1 nm. The mechanical responses of the indented films are also discussed.     

基于UG的某洗碗机包装防震垫的设计

用UG NX软件的三维建模功能设计出了某洗碗机防震垫的模型,用其高级仿真模块对该防震垫进行了有限元分析,发现了应力和变形存在的不足。用UG NX软件的优化功能,以满足应力变形为优化条件,模型相关尺寸为优化目标,进行了优化计算,并对优化结果进一步验证,发现优化后的产品符合应力变形指标要求。此方法缩短了设计周期,为类似产品设计提供了一种可靠的设计方法,有参考价值。     

Investigation on the mechanical stresses in a muffler mounting bracket using Root Cause Failure Analysis (RCFA), finite element analysis and experimental validation

In the present work, experimental investigation on the failure of a muffler mounting bracket attached to commercial vehicle is done. Cracks are identified at the welded location of muffler mount which shows that weld joint has better strength than the muffler/bracket body. To understand the possible root causes of the failure, fishbone diagram was used, which helped in determining the major causes of the failure by a graphical representation. Further, the three parameter Weibull distribution was also developed to determine the Mean Time to Failure (MTTF) life which was found to be 15,172 km. In addition, tensile testing of sheet metal was performed on the sheets which was used in the manufacturing of Muffler. Furthermore, a Thermo-Mechanical coupled analysis was carried out using commercial code, ANSYS 16.0, which adapts Finite Element Analysis (FEA) formulation. The thermal loads on muffler were imported to structural analysis along with a static load of 4 g acceleration were imposed on the muffler body to simulate the effects of high impact loads. The effect of temperatures resulted in high von-misses stresses which were in agreement with practical observations. It is observed that the stresses at bracket region were at the same location both from the experimental and finite element analysis. Further, by considering different mounting design concepts, multiple analyses were carried out to determine the most suitable brackets for the muffler. The present work attempts to diagnose the cause of failure and to make the fail-safe design.