开槽轴的扭转应力

开槽轴的扭转应力浙江机械工业学校何西泠在轴上沿轴线方向开圆形槽，这在工程实际中是常见的。当轴传递扭矩时，开槽处出现局部“应力集中”，在“应力集中”区内可能发生疲劳破坏。因此，在开槽轴的设计中，应当考虑轴的有效应力。一根半径为ａ的圆截面轴，开有半径为ｂ...     

断路器操作机构用轴销的可靠性设计

根据断路器操作机构中轴销零件出现故障的原因，对轴销进行了应力分析，并对轴销所受的应力集中进行了可靠性设计。     

台阶轴校直工艺计算方法及实验研究

在研究热处理后台阶轴轴肩处发生弯曲变形的基础上，根据弹塑性力学理论，探讨应力集中对校直过程的影响，提出台阶轴校直工艺计算方法。实验研究表明该方法能有效应用于台阶轴的校直过程，对制定齿轮轴等台阶轴零件校直工艺有一定的指导意义。     

轴肩过渡同线形状设计研究

将有限元结构分析技术与教学规划方法相结合，对轴肩过渡曲线进行形状优化设计，提出用圆弧蜕变曲线作为轴肩和秒轮越程槽的过渡曲线，以降低轴肩应力集中。给出样条过渡曲线、椭圆过渡曲线、圆弧蜕变过渡曲线设计的设计实例，结果表明：圆弧蜕变曲线设计不仅有效地降低了轴肩应力集中，而且易于加工制造。     

轴肩过渡曲线形状设计研究

将有限元结构分析技术与数学规划方法相结合,对轴肩过渡曲线进行形状优化设计,提出用圆弧蜕变曲线作为轴肩和砂轮越程槽的过渡曲线,以降低轴肩应力集中。给出样条过渡曲线、椭圆过渡曲线、圆弧蜕变过渡曲线设计的设计实例,结果表明：圆弧蜕变曲线设计不仅有效地降低了轴肩应力集中,而且易于加工制造。     

轴毂过盈联接的应力分析和接触边缘效应

用弹性力学和有限元方法对轴毂过盈联接进行了详细的分析，据此指出了弹性力学方法的弊端和有限元方法的优势。有限元方法不仅可以获得与弹性力学完全一致的理想模型下过盈联接的应力等，还能够分析弹性力学所不能求解的接触边缘效应——由接触引起的边缘应力集中。由于考虑了应力集中的存在，用有限元分析方法对轴毂过盈联接进行设计和校核，更符合实际情况，从而更合理。     

MARC有限元分析在轴结构设计中的应用

在利用有限元方法对轴易产生应力集中的部位进行了细致地建模，通过计算得到了轴的结构应力分布规律、变形量；通过对危险截面的强度校核验证了原设计方案的可靠性，从而为该轴方案的最终确定提供了理论依据，同时也为轴的结构设计提供了一种有效的方法。     

清障车销轴断裂分析

托叉是清障车连接事故车的主要受力件,通过对断裂托叉销轴件的成分、结构等分析,表明断裂源于疲劳断裂,其结构设计不当造成应力集中是销轴断裂的主要原因。     

空心轴与实心轴过盈配合结构微动磨损与疲劳的仿真分析

为了分析空心轴与实心轴过盈配合结构微动磨损与疲劳行为的差异,建立了两种过盈配合结构的微动磨损-微动疲劳联合仿真模型。该联合仿真模型基于Archard磨损方程和有限元软件ABAQUS的自适应网格技术实现了循环微动磨损的仿真,基于线性累积损伤理论和修正的SWT临界平面法实现了微动疲劳寿命预测。分析结果表明：空心轴的微动磨损比实心轴严重,微动磨损显著降低了过盈配合边缘附近的应力集中,同时在配合内部引起了新的应力集中,并导致微动裂纹萌生位置出现在配合内部。受到微动磨损的影响,空心轴的微动疲劳寿命仅约为实心轴的40%,但两种结构的微动裂纹萌生位置几乎一致。     

销轴设计方法的比较研究

销轴几何尺寸设计时通常以静剪切强度为准则,忽略了销轴的弯曲变形和润滑油孔应力集中,此种方法设计的销轴往往出现早期失效。分别对销轴的静剪力、惯性矩、考虑应力集中时的设计准则进行了建模,并通过三种设计方法之间的对比,发现不同设计方法所设计的销轴直径不同,并且直径的差异程度与销轴的作用载荷及材料的屈服强度有关;分析了三种假设应力分布模型的最大应力,发现采用不同假设应力分布模型所计算的最大接触应力不同,并且接触应力的差异程度与销轴的作用载荷有关。同时发现最大接触应力随着配合间隙的增大而增大。     

A theoretical comparison of two possible shape memory processes in shape memory alloy reinforced metal matrix composite

Two possible shape memory processes, austenite to detwinned martensite transformation and twinned martensite to detwinned martensite transformation of a shape memory alloy have been modeled and examined. Eshelby’s equivalent inclusion method with Mori-Tanaka’s mean field theory is used for modeling of the shape memory processes of TiNi shape memory alloy reinforced aluminum matrix composite. The shape memory amount of shape memory alloy, plastic strain and residual stress in the matrix are computed and compared for the two processes. It is shown that the shape memory amount shows differences in a small prestrain region, but the plastic strain and the residual stress in the matrix show differences in the whole prestrain region. The shape memory process with initially martensitic state of the shape memory alloy would be favorable to the increase in the yield stress of the composite owing to the targe compressive residual stress and plastic strain in the matrix.     

On plastic design of complex machine parts

The technique of statically admissible plastic discontinuous stress fields is used in the plastic design of machine parts of complex shape. If the shape of the part is given the stress field is used to find a lower bound on the bearing capacity. In the case of plastic design an appropriate stress field gives a safe estimate of the shape of the designed part. Complex three-dimensional stress fields are composed of elementary sub-fields, all geometrical and statical parameters of which are tabulated in order to simplify the design procedure. Thus the procedure consists in appropriate arrangement of sub-fields into a complex system of stresses.     

振动时效的应用

矿用防爆电气开关中的焊接件,焊后存在残余应力,经退火处理后,常发生变形问题,通过调研、试验和应用证明：振动时效是消除和均化残余应力,防止变形的有效方法.此方法成本低,效率高,操作方便,产品质量稳定.     

Effect of residual stress on femoral arterial stress-strain behavior

It is well established that arteries are subjected to residual stress. Due to the effect of residual stress, the arteries open to a horse-shoe shape when a longitudinal cut is made on an excised arterial segment. Previously, the residual stress has been quantified by the opening angle of the horse-shoe shape. We have employed a finite element analysis of the open arterial segment to restore the same to the original cylindrical shape and computed the circumferential strain as well as the stress distribution in the wall. In this study, the stress and strain distribution in the femoral arteries of miniswine was computed with and without the residual stress for a range of transmural pressures. Our analysis showed that the residual stress has the effect of redistribution of the circumferential stresses between the intima and the adventitia under physiological loading. The redistribution of the stress with the inclusion of residual stress may be important in the studies on effect of wall stresses on the endothelial and vascular smooth muscle cells.     

沟槽结构对水润滑超高分子量聚乙烯轴承力学性能的影响

通过pore/mechanic模版,建立不同沟槽形式下高分子量聚乙烯水润滑轴承的模型,应用有限元分析方法,分析沟槽形式对轴承应力应变及位移的影响。结果表明:沟槽形状的变化对轴承位移影响不大,但影响轴承应力及应变的分布;当沟槽的形状为圆弧形时,轴承的应力应变的变化趋势比较平缓,容易保持轴承的稳定性。     

A study of stresses in alumina universal heads of femoral prostheses

Three-dimensional, frozen-stress photoelasticity was used to study the best shape for a proposed alumina universal head loaded on to a Vitallium cone taper spigot with a 30 degrees inclined force, as in vivo. Typical cone taper friction values were reproduced in the photoelastic models. The location of the highest tensile stresses in the Mark I shape with a flat crown was found to be on the inner surface of the crown. Changing to a torispherical surface in the Mark II shape reduced this magnitude. However, the Mark III shape with a hemispherical inner crown surface gave even lower stress there, equal to the maximum value of the hoop stress at the taper, which was measured to be fairly uniform both around and along the taper except at the ends where contact pressure concentrations were found to occur and it became reduced. Lamé axisymmetric cylinder stress predictions were found to be useful approximations to measured values and were generally overestimates of the tensile hoop stress at the head taper surface.     

基于形状优化的机械零件设计

任何机械零件都是由几何尺寸和形状构成 ,传统的机械设计方法仅考虑了零件的几何尺寸 ,而对其形状 ,特别是局部形状的设计却考虑不够 ,这些部位往往都会产生应力集中。本文就是将基于有限元分析技术的形状优化方法应用于传统的机械设计过程。使得设计出来的零件既满足常规设计的要求 ,又得到了优化的形状 ,结构的特性与受力状况得到改善     

受剪切应力作用的表面裂纹应力强度因子研究

应用改进的三维虚拟裂纹闭合方法研究了受远端剪切应力作用的有限大体半椭圆表面裂纹复合型应力强度因子分布,并讨论了整个裂纹前缘复合型应力强度因子分布随裂纹形状变化和结构参数变化的规律。研究发现在自由表面附近,Ⅲ型应力强度因子分布受角点应力奇异性影响较大,在自由表面附近出现转折,但转折现象与裂纹形状参数有关,当裂纹形状比a/c≤0.6时,应力强度因子分布曲线光滑,表现为经典的角点奇异性。     

冷轧带钢残余应力的实验研究

使用四辊可逆冷轧机,调整初始压下量为15%,将材质为08Al的冷轧带钢在4种不同的轧制工艺条件下进行轧制,并在剪切机上剪成长方形板带作为残余应力测试件,利用小孔应力释放法(即不同张力条件下对板带残余应力分布影响的实验)初步揭示了带钢残余应力与板形的关系,为改善残余应力分布进而改善板形做了有益的工作。其研究成果不仅为实际生产提供了理论依据,而且也为目前普遍受到关注的板形研究提供了新参考。     

超硬镀膜轴承滚动体的内应力及膜厚对其影响的有限元分析

本文应用三维有限元方法，分析计算了沉积超硬涂层的轴承滚动体的内应力及膜厚对内应力分布规律的影响；揭示了在接触区附近，涂层内应力呈局部凹凸面分布，界面附近的底材内应力呈＂礼帽＂型分布；并且当涂层厚度增大时，膜内最大应力减小，底材内最大应力却增大。涂层厚度一般不宜超过８μｍ．计算结果为超硬涂层轴承设计提供了理论参考．