Investigation into precision engineering design and development of the next-generation brake discs using Al/SiC metal matrix composites

Substantially lightweight brake discs with high wear resistance are highly desirable in the automotive industry.This paper presents an investigation of the precision-engineering design and development of automotive brake discs using nonhomogeneous Al/SiC metal-matrixcomposite materials.The design and development are based on modeling and analysis following stringent precision-engineering principles,i.e.,brake-disc systems that operate repeatably and stably over time as enabled by precision-engineering design.The design and development are further supported by tribological experimental testing and finite-element simulations.The results show the industrial feasibility of the innovative design approach and the application merits of using advanced metal-matrix-composite materials for next-generation automotive and electric vehicles.

Three-dimensional finite element analysis on effects of tunnel construction on nearby pile foundation

A three-dimensional finite element simulation was carried out to investigate the effects of tunnel construction on nearby pile foundation.The displacement controlled model (DCM) was used to simulate the tunneling-induced volume loss effects.The numerical model was verified based on the results of a centrifuge test and a set of parametric studies was implemented based on this model.There is good agreement between the trend of the results of the centrifuge test and the present model.The results of parametric studies show that the tunnelling-induced pile internal force and deformation depend mainly on the pile?tunnel distance,the pile length to tunnel depth ratio and the volume loss.Two different zones are separated by a 45° line projected from the tunnel springline.Within the zone of influence,the pile is subjected to tensile force and large settlement;whereas outside the zone of influence,dragload and small settlement are induced.It is also established that the impact of tunnelling on a pile group is substantially smaller as compared with a single pile in the same location with the rear pile in a group,demonstrating a positive pile group effect.

Experimental and finite element analysis for fracture of coating layer of galvannealed steel sheet

Mechanical properties of galvannealed (GA) steel sheet used for automotive exposed panel and predicted failure phenomenon of its coating layer were evaluated using finite element method. V-bending test was performed to understand better the fracture of coating layer of GA steel sheet during plastic deformation. Yield strength of the coating layer was calculated by using a relative difference between hardness of coating layer measured from the nano-indentation test and that of substrate. To measure shearing strength at the interface between substrate and coating layer, shearing test with two specimens attached by an adhesive was carried out. Using the mechanical properties measured, a series of finite element analyses coupled with a failure model was performed. Results reveal that the fracture of coating layer occurs in an irregular manner at the region where compressive deformation is dominant. Meanwhile, a series of vertical cracks perpendicular to material surface are observed at the tensile stressed-region. It is found that 0.26-0.28 of local equivalent plastic strain exists at the coating and substrate at the beginning of failure. The fracture of coating layer depends on ductility of the coating layer considerably as well.

Rock-soil slope stability analysis by two-phase random media and finite elements

To investigate the strong random nature of the geometric interfaces between soil and rock, a rock-soil slope is considered as a two-phase random medium. A nonlinear translation of a Gaussian field is utilized to simulate the two-phase random media, such that the soil(or rock) volume fraction and the inclination of the soil layer can be examined. The finite element method with random media incorporated as the material properties is used to determine the factor of safety of the rock-soil slope. Monte-Carlo simulations are used to estimate the statistical characteristics of the factor of safety. The failure mode of the rock-soil slope is examined by observing the maximum principal plastic strain at incipient slope failure. It is found that the critical surface of a rock-soil slope is fairly irregular, and it significantly differs from that of a pure soil slope. The factor of safety is sensitive to the soil volume faction, but it is predictable. The average factor of safety could be well predicted by the weighted harmonic average between the strength of soil and rock; the prediction model is practical and simple. Parametric studies on the inclination of the soil layer demonstrate that the most instable scenario occurs when the slope angle is consistent with the inclination of the soil layer.

Probabilistic stability analyses of undrained slopes by 3D random fields and finite element methods

A long slope consisting of spatially random soils is a common geographical feature. This paper examined the necessity of three-dimensional(3 D) analysis when dealing with slope with full randomness in soil properties. Although 3 D random finite element analysis can well reflect the spatial variability of soil properties, it is often time-consuming for probabilistic stability analysis. For this reason, we also examined the least advantageous(or most pessimistic) cross-section of the studied slope. The concept of"most pessimistic" refers to the minimal cross-sectional average of undrained shear strength. The selection of the most pessimistic section is achievable by simulating the undrained shear strength as a 3 D random field. Random finite element analysis results suggest that two-dimensional(2 D) plane strain analysis based the most pessimistic cross-section generally provides a more conservative result than the corresponding full 3 D analysis. The level of conservativeness is around 15% on average. This result may have engineering implications for slope design where computationally tractable 2 D analyses based on the procedure proposed in this study could ensure conservative results.

胫骨内侧应力在跑步运动过程中的计算机仿真分析

背景:内侧胫骨应力综合征是困扰跑步者的一种常见的下肢慢性损伤,其损伤机制可能与“肌肉牵引”假说有关,然而这种假说还没有得到完全的证实。目的:使用肌骨仿真系统和有限元分析等方法,考察比目鱼肌、胫骨后肌、趾长屈肌在跑步过程中的收缩特征是否与跑步时胫骨内侧缘的应力水平存在相关性,从而影响内侧胫骨应力综合征的发生与发展。方法:将6名受试者不同速度跑步时的动作捕捉数据输入Anybody Modeling System骨肌仿真系统,对2.5,3.5,4.5 m/s三种跑步速度情况下的步态支撑期进行逆动力学仿真,将仿真得到的边界条件与有限元模型结合,考察胫骨内侧的应力分布情况。使用偏最小二乘回归方法分析自变量(肌力、弹性势能)与因变量(胫骨应力)之间的相关性。结果与结论:①胫骨应力水平在支撑期(1%-50%)存在速度间的统计学差异(P=0.044,F=3.834,η_(p)^(2)=0.040);②3种速度下,比目鱼肌的肌力与胫骨应力之间的平均相关性最高(r=12.999),其次胫骨后肌肌力与胫骨应力的平均相关性排名第二(r=-10.735),然后依次是趾长屈肌肌力(r=-9.751),胫骨后肌弹性势能(r=8.012),比目鱼肌弹性势能(r=9.076),趾长屈肌弹性势能(r=-4.782);③结果表明,跑步速度的增加,胫骨应力水平随之上升;比目鱼肌的收缩及吸收的弹性势能在跑步过程中的释放对于内侧胫骨应力综合征的发展将产生不可忽略的影响,而胫骨后肌和趾长屈肌的作用被高估了;综合来看,研究支持了“肌肉牵引”假说中比目鱼肌的收缩对内侧胫骨应力综合征发展发挥作用的推论。

基于SolidWorks Simulation的重叠盾构隧道穿行式全自动液压支护台车设计研究

为解决传统盾构重叠隧道施工中临时支护方案普遍存在的拆装不便、结构笨重、效率低下等问题,通过与既有支护方案的技术经济指标进行比较、分析,设计一种在无卸载支护条件下具备下部不间断穿行施工车辆功能的全自动新型液压支护台车,并利用有限元分析软件SolidWorks Simulation进行强度校核。新型液压支护台车较多地引入了电气控制和液压控制技术,在一定程度上实现了盾构隧道支护的机械化,降低了作业人员劳动强度。同时,通过对支护台车结构优化设计,有效解决了传统盾构重叠隧道支护方案中施工工序间的作业干扰问题,并减轻了台车质量,降低了施工成本。通过深圳市轨道交通7号线华新站—黄木岗站区间等工程实践表明,新型液压支护台车在保证既有隧道的结构安全、提高支护效率方面效果明显。

Development of Jacket Platform Tsunami Risk Rating System in Waters Offshore North Borneo

This work details the simulation of tsunami waves generated by seaquakes in the Manila Trench and their effect on fixed oil and gas jacket platforms in waters offshore North Borneo. For this study, a four-leg living quarter jacket platform located in a water depth of 63 m is modelled in SACS v5.3. Malaysia has traditionally been perceived to be safe from the hazards of earthquakes and tsunamis. Local design practices tend to neglect tsunami waves and include no such provisions. In 2004, a 9.3Mw seaquake occurred off the northwest coast of Aceh, which generated tsunami waves that caused destruction in Malaysia totalling US$ 25 million and 68 deaths. This event prompted an awareness of the need to study the reliability of fixed offshore platforms scattered throughout Malaysian waters. In this paper, we present a review of research on the seismicity of the Manila Trench, which is perceived to be high risk for Southeast Asia. From the tsunami numerical model TUNA-M2, we extract computer-simulated tsunami waves at prescribed grid points in the vicinity of the platforms in the region. Using wave heights as input, we simulate the tsunami using SACS v5.3 structural analysis software of offshore platforms, which is widely accepted by the industry. We employ the nonlinear solitary wave theory in our tsunami loading calculations for the platforms, and formulate a platform-specific risk quantification system. We then perform an intensive structural sensitivity analysis and derive a corresponding platform-specific risk rating model.

Non-isothermal Mold Filling and Curing Simulation for Resin Transfer Molding

A numerical model of 2.5D non-isothermal resin transfer molding simulation is developed for thin part based on the control volume/finite element method. The non-uniform temperature distribution and the heat generation during the filling stage are modeled with the lumped temperature system and the species balance. Numerical algorithm of the simulation are studied. The molding simulation for a part is performed to show the effectiveness of simulating filling time, temperature distribution and curing degree.

轮辐式索承网格屋盖钢结构单道胎架施工技术

泰安体育场作为山东省泰安市的新地标,其钢结构屋盖采用轮辐式索承网格结构,通过68榀径向索和1道中央环索形成张拉结构体系,最大悬挑跨度为45 m。通过数值分析对施工过程进行了精细化稳定性分析,针对不规则构件吊装的工程技术难点,进行了吊装方案的设计与优化;考虑到成本控制与施工周期,极具创新性地采用了径向单道胎架作为屋盖施工过程中的临时支撑,结合工程实际情况设计了胎架转换结构,并对单道胎架整体在多种可能的荷载组合作用下进行验算与校核。通过对体育场屋盖施工全过程的模拟以及对安装过程中的重难点进行优化分析,为现场施工的安全顺利开展提供了技术保障,可为其他类似采用单道胎架施工方法的工程提供施工方案设计的新思路。

自移式临时支护结构设计及液压系统研究

针对现有临时支护设备造成巷道顶板破坏和采掘失调问题,提出了一种履带式自移式临时支护结构,利用SolidWorks软件建立了履带自移式临时支护设备模型,介绍了临时支护设备的相关结构以及设备对特殊工况的适应性。借助ANSYS Workbench软件对自移式支护设备的零部件进行静力学与模态分析,校验设备的安全性。采用AMESim软件对临时支护设备的支护功能进行建模仿真,验证液压系统工作的可靠性。

基于IDA方法的柱承式筒仓结构地震易损性分析

易损性分析是柱承式筒仓结构开展基于性能设计研究的重要基础。为此,选用某钢筋混凝土柱承式筒仓为研究对象,通过有限元软件ABAQUS,分别采用混凝土损伤塑性模型和理想弹塑性模型(Dracker-Prager)模拟筒仓结构及仓内粮食颗粒,建立考虑粮食-仓体相互作用的柱承式筒仓非线性有限元模型。根据增量动力分析法(IDA),按照谱相容性原则选取10条地震动记录,分别以最大层间位移角和地面峰值加速度作为筒仓结构工程需求参数和地震动强度参数,进行空仓、半仓、满仓三种储粮工况的柱承式筒仓结构地震易损性分析以及地震损伤风险评估。结果表明:(1)三种储粮工况下柱承式筒仓结构最大层间位移角均发生在柱顶位置,支承柱进入塑性状态的层间位移角分别为0.015、0.013、0.011 rad;(2)储粮质量大小是决定柱承式筒仓结构损伤刚度退化的重要因素;(3)三种储粮工况下的柱承式筒仓结构均满足“小震不坏、中震可修、大震不倒”的抗震设防目标;(4)满仓工况筒仓50年超越倒塌极限状态的概率为0.45%,小于FEMA P750中定义的50年倒塌风险的限值1%。研究成果可为筒仓结构基于性能的设计研究及抗震性能评估提供依据。

An instrument for methodological quality assessment of single-subject finite element analysis used in computational orthopaedics

The methodological quality of subject-specific finite element analysis papers depends on the rigor of the study design and detailed description of key elements,while assessment instruments are often confined to clinical trials or quasi-experiments.This study aims to present an instrument for methodological quality assessment of singlesubject finite element analysis used in computational orthopaedics(MQSSFE).Based upon existing instruments and relevant review papers,a pilot version was developed consisting of 37 items with 6 domains,including study design and presentation of findings,subject recruitment,model reconstruction and configuration,boundary and loading conditions(simulation),model verification and validation,and model assumption and validity.We interviewed four experts in the field to assess the face validity and refined the instrument.The instrument was tested for interrater reliability among two assessors on nine finite element study papers.Also,the criterion validity was evaluated by comparing the similarity of the MQSSFE and the modified Down and Black instrument.The intraclass correlation coefficient was 0.965,while the MQSSFE was significantly moderately correlated with the modified Down and Black instruments(r=0.61).We believed that MQSSFE was adequately appropriate,reliable,and valid for assessing the methodological quality for finite element studies used in computational orthopaedics.The instrument could facilitate quality assessment in the systematic reviews of finite element models and checklists for fidelity.

基于ANSYS的膨胀管膨胀过程力学研究

为了研究膨胀管在均布挤压载荷作用下的应力、应变情况,采用有限元软件ANSYS Workbench对膨胀管膨胀过程进行显示动力学仿真模拟。膨胀锥在不同载荷作用下对膨胀管挤压,使其发生弹塑性变形。膨胀管受到膨胀锥的挤压力作用与套管密切接触,达到了对套管的修补和密封作用。通过分析膨胀管的膨胀过程获得了膨胀套管装配体不同零件的应力、应变云图结果和对应的应力、应变曲线变化情况,从而为实际工程应用提供有价值的理论参考。

紧凑新型高温超导可控电抗器的仿真研究

为解决电网配网侧无功就地消纳的需求,文章提出了一种紧凑新型高温超导可控电抗器,介绍了该紧凑新型高温超导可控电抗器工作原理与基本结构,搭建了有限元分析模型并得到其电感调节特性,以期为相关人员提供参考。

冲击响应谱在卫星运输冲击响应分析中的应用

卫星运输过程中的动力学环境存在一定的随机性与不确定性,给卫星的安全运输带来隐患。目前工程上尚未形成通用化的卫星运输仿真方法,也未制定指导性的运输分析力学环境条件。文章提取卫星运输过程中经常出现的2种典型斜坡形式的冲击信号,基于ABAQUS软件建立卫星与运输支撑工装的有限元模型,分别开展了瞬态响应与冲击响应谱分析。结果表明,相比于瞬态响应分析,冲击响应谱分析节约了95%的运算量,且分析偏差在17%以内,并能够实现对响应最大情况的包络,可更好地满足工程上对仿真分析快速且准确的需求。

超导储能电感用于重接型电磁推进电源的研究

为了验证高温超导储能电感作为重接型电磁推进脉冲电源的可行性,采用Ansoft Maxwell 3D建立了重接型电磁推进器瞬态仿真模型,脉冲电源的设计结合了多模块储能电感串联充电和并联放电的模式,电路中采用转换电容器限制断路开关工作过程中的高电压。电感和电容参数都对最佳触发放电位置有一定的影响,即对驱动线圈电流脉冲的上升沿时间有影响。因为驱动线圈建立磁场的速度决定抛体感应出的涡流大小,抛体受到的驱动力与驱动线圈磁场大小和磁场建立的速度都有关。在多级推进系统的参数设计时,除了减小触发放电位置外,还需适当地减小驱动线圈的电感和减小转换电容的参数。

钛合金抽芯铆钉铆接过程分析及规律探索

钛合金抽芯铆钉为航空航天用高端紧固件,针对铆接过程中钛合金抽芯铆钉强度匹配关系不明晰的问题,研究了基于deform软件的铆接过程分析方法。在结构尺寸、材料参数标定基础上,建立了抽芯铆钉铆接过程仿真模型;通过分析铆接过程中铆接力变化规律,将铆接力变化区间划分为四个变化区域:钉套影响区、驱动环断裂区、锁环锁紧区以及钉杆断裂区,四个区域的合理分布是保证钛合金抽芯铆钉高成功率研制的重要基础。通过改变各零件材料变量属性,进一步确定了钛合金抽芯铆钉各组件强度/强度分布对四区域峰值的影响规律。相关研究为提高钛合金抽芯铆钉铆接成功率提供了技术基础。

多胞子弹冲击泡沫夹芯梁的动力学响应分析

为了研究均匀/梯度多胞子弹冲击泡沫夹芯梁的耦合响应过程和多胞子弹对夹芯梁的加载效果,对该冲击过程开展了理论分析、数值模拟和试验研究:通过将泡沫夹芯梁等效为单梁以简化分析,基于多胞子弹的冲击波模型和泡沫夹芯梁的等效单梁响应模型,构建了多胞子弹冲击泡沫夹芯梁的耦合分析模型,给出了冲击过程中各响应阶段的控制方程,并结合龙格-库塔方法对方程进行了数值求解;基于三维Voronoi技术,开展了均匀/梯度多胞子弹冲击泡沫夹芯梁的细观有限元模拟;在多胞子弹的冲击测试平台上进行了试验研究,结合高速摄影技术获取了多胞子弹和泡沫夹芯梁的速度响应。结果表明:耦合分析模型可以准确地预测多胞子弹和泡沫夹芯梁的速度历程曲线以及多胞子弹产生的冲击压强;在初始动量相同但密度分布或初速度不同的多胞子弹冲击下,同一构型的泡沫夹芯梁展现出不同的力学响应,这说明多胞子弹的加载不能简单地等效为脉冲加载,多胞子弹与夹芯梁之间的耦合效应不可忽略;相较于均匀多胞子弹,梯度多胞子弹的冲击压力波形更加尖锐,在其衰减过程中展现出更强的非线性特征。

基于ABAQUS的平纹织物同面对向弯曲有限元模拟

为明晰织物结构对其弯曲性能的影响机制,对织物弯曲过程进行了有限元模拟和实验验证。以涤纶织物为例,通过VHX-5000型超景深数码显微镜观测织物,得到纱线几何参数;根据纱线实际尺寸,利用SolidWorks专业建模软件构建涤纶平纹织物的三维几何模型;基于有限元分析软件ABAQUS研究织物同面对向弯曲性能,分析纱线弹性模量、摩擦因数、泊松比等参数对弯曲实验的影响,并将有限元仿真结果与实验结果进行对比。结果表明:模拟所得抗弯力-位移曲线与实验曲线在0.01水平上呈显著相关,模拟结果与实验结果一致,证明用有限元模拟弯曲织物模型的有效性。