橡胶楔体与刚性缺口接触大变形分析

利用Ｋｕｏｗｌｅｓ与Ｓｔｅｒｎｂｅｒｇ提出的非线性弹性大变形应变能函数,对橡胶楔体与刚性缺口接触问题进行大变形渐近分析,推导了楔体尖端场的渐近方程,得到楔体尖端附近的应力应变场及应力的奇异性指数与橡胶楔体角度、刚性缺口角度及材料常数有关的表达式;楔尖附近同一半径上应力分量为常数,同时,利用非线性有限元理论编制了大变形有限元程序,考虑楔体尖端与缺口接触边界条件,计算得到了与分析解一致的结论,当缺口角     

软材料接触力学问题的实验研究

针对硫化硅橡胶在刚性压头作用下的大变形接触问题,研究了橡胶类软材料接触区区域变形场的实验测量技术。为了研究硫化硅橡胶与刚性体在试件内部接触的大变形问题,本文提出了一种体内数字栅云纹实验技术,给出了该技术的原理和实现方法。然后运用数字图像处理方法得到了橡胶材料大变形位移u场、v场,并结合橡胶材料在压头作用下的理论分区模型,分析了软材料接触区域的大变形场,讨论了接触区域的变形分区规律,并初步给出了接触区域应变计算方法。     

八次对称二维准晶材料接触问题

本文通过引入位移函数和应用Fourier分析与对偶积分方程理论圆满解决了在一个刚性平头冲头作用下八次对称二维准晶材料的接触问题，得到了此材料接触问题应力与位移的解析表达式。结果表明，如果接触位移在接触区域内为一常数，则接触应力在接触边缘具有1／2阶奇异性，这为准晶材料的接触变形提供了重要的力学量。     

集中力拉伸楔体大变形理论分析及数值计算

对任意向集中力拉伸用下的橡胶类材料楔体尖端应力应变场进行了渐近分析,并利用有限元与无限元耦合作了数值计算,结果表明大应变情况下,楔体尖端场处于单向拉伸状态,应力主奇异项为ｒ＾－λ,ｒ为变形后至顶点距离,λ依赖于材料本构常数,数值计算与理论解吻合很好。     

十二次对称二维准晶中的无摩擦接触问题

利用积分变换的方法讨论了在一个刚性压头作用下十二次对称二维准晶的无摩擦接触问题. 通过引入位移势函数,将数量巨大而复杂的偏微分方程转化为两个独立的双调和方程,应用Fourier分析与对偶积分方程理论解决了十二次对称二维准晶材料的无摩擦接触问题,得到了相应的接触应力解析表达式,结果表明：如果接触位移是一常数,则接触应力在接触区域边缘具有-1/2阶奇异性;反之,如果接触应力在接触区域边缘具有-1/2阶的奇异性,则接触位移一定为一常数,这为准晶材料的接触变形提供了重要的力学参数.     

和界面接触的刚性线夹杂对SH波的散射

利用积分变换方法，得出了两相材料中单位简谐力的格林函数。根据简谐集中力的格林函数得出了和界面接触的刚性线的散射场。利用无穷积分的性质，把和界面接触刚性线的散射场分解为奇异部分和有界部分。通过分解后的散射场建立了和界面接触剐性线在SH波作用下的Cauchy型奇异积分方程。根据所得奇异积分方程和刚性线的散射场得到了刚性线端点的奇异性阶数及奇性应力。应用刚性线端点的奇性应力定义了刚性线端点的应力奇异因子。对所得Cauchy型奇异积分方程的数值求解，可得刚性线端点的应力奇异因子。     

弹塑性微凸体侧向接触相互作用能耗

传统的结合面研究多基于光滑刚性平面与等效粗糙表面接触假设,忽略了结合面上微凸体侧向接触及相邻微凸体之间的相互作用,这导致理论模型与实际结合面存在较大出入.针对承受法向静、动态力的机械结合面,从微观上研究了微凸体侧向接触及相互作用的接触能耗.将法向静、动态力分解为法向分力和切向分力,获取弹性/弹塑性/塑性阶段考虑微凸体侧接触及相互作用的加、卸载法向分力-变形和切向分力-位移的关系.通过力的合成定理,从而获取加、卸载法向合力与总变形之间的关系,由于法向分力产生的塑性变形及切向分力产生的摩擦,导致加载、卸载法向合力-总变形曲线存在迟滞回线.通过对一个加、卸载周期内的法向合力-总变形曲线积分,获得一个周期的微凸体接触能耗,包括应变能耗及摩擦能耗.仿真分析表明:微凸体在3个阶段的能耗均随变形的增大而非线性增大.微凸体侧向接触角度越大,能耗越大,且在弹性阶段最为明显.在弹性阶段,仅存在侧向的摩擦能耗,故结合面在低载荷作用下必须采用双粗糙表面假设.在塑性阶段,由于微凸体接触能耗为应变能耗,且接触角对其能耗影响甚微,故结合面在大载荷作用下可采用单平面假设对其进行研究.相对于KE和Etsion模型,本文提出的模型与Bartier的实验结果更吻合.     

载重子午线轮胎三维非线性有限元分析

建立了一个轮胎结构有限元分析模型，考虑了轮胎变形的几何非线性，轮胎与地面和轮胎与轮辋的大变形非线性接触，轮胎材料的非均匀性，橡胶材料的不可压缩性和物理非线性及橡胶基复合材料的各向异性。结果表明，该模型有效可靠。     

带裂纹三维二十面体准晶平面弹性的无摩擦接触问题

利用平面弹性复变方法,通过求解边值问题,研究了单个刚性压头作用在带任意形状裂纹的三维二十面体准晶下的无摩擦接触问题,求得了应力函数封闭解的表达式,同时得到了裂纹左右端点处应力强度因子和压头下方任意点处声子场接触应力的显式表达式。理论结果表明,声子场接触应力在压头边缘具有-1/2阶奇异性。如果忽略相位子场作用,本文得到的结果可退化为已有文献中弹性材料相应结论。数值结果用于分析带水平直裂纹三维二十面体准晶下半平面与单个平底刚性压头无摩擦接触时量纲为一的应力强度因子和量纲为一的接触应力的分布规律;量纲为一的应力强度因子在裂纹距边界垂直距离和压头半宽度之比约为0.3和1.5处取得最大值;量纲为一的接触应力呈对称分布,在压头中心处最小,在压头边缘处达到峰值且具有奇异性;相位子场弹性常数、耦合系数与Lamé常数的比值对量纲为一的声子场接触应力的大小和分布规律几乎无影响。     

橡胶复合材料结构大变形有限元分析

建立了一个橡胶复合材料结构有限元分析模型。在该模型中 ,考虑了轮胎变形的几何非线性、轮胎与地面和轮胎与轮辋的大变形非线性接触、轮胎材料的非均匀性和物理非线性及橡胶基复合材料的各向异性。此外 ,本文还利用该模型研制的有限元分析软件对全钢丝子午胎的变形轮廓进行了详细的分析。     

ANALYSIS OF AN INCOMPRESSIBLE RUBBER WEDGE CONTACTING WITH A RIGID NOTCH

I. INTRODUCTION It is well known that rubber materials are much more important in modern society. It is, therefore,not surprising that a sizable number of investigations have been concerned with the rubber materials.Considerable attention has been paid …     

Crack at the apex of a loaded notch

This paper deals with the plane elastostatic problem of an infinite wedge, subjected to arbitrary surface tractions, and cracked along the wedge angle bisector. The problem is reduced to a single Fredholm integral equation, which is solved numerically for normal loads on the crack faces and various loads on the wedge faces. It is shown that the crack tip intensity factor depends strongly on the wedge angle. An approximation to a half plane with a notch of finite angle, cracked at its apex, is also obtained.     

Higher order fields for damaged nonlinear antiplane shear notch, crack and inclusion problems

Damaged nonlinear antiplane shear problems with a variety of singularities are studied analytically. A deformation plasticity theory coupled with damage is employed in analysis. The effect of microscopic damage is considered in terms of continuum damage mechanics approach. An exact solution for the general damaged nonlinear singular antiplane shear problem is derived in the stress plane by means of a hodograph transformation, then corresponding higher order asymptotic solutions are obtained by reversing the stress plane solution to the physical plane. As example, traction free sharp notch and crack, rigid sharp wedge and flat inclusion, and mixed boundary sharp notch problems are investigated, respectively. Consequently, higher order fields are obtained, in which analytical expressions of the dominant and second order singularity exponents and angular distribution functions of the near tip fields are derived. Effects of the damage and hardening exponents of materials and the geometric angle of notch/wedge on the near tip quantities are discussed in detail. It is found that damage leads to a weaker dominant singularity of stress, but to little stronger singularities of the dominant and second order terms of strain compared to that for undamaged material. It is also seen that damage has important effect on the angular distribution functions of the near tip stress and strain fields. As special cases, higher order analytical solutions of the crack and rigid flat inclusion tip fields are obtained, respectively, by reducing the notch/wedge tip solutions. Effects of damage and hardening exponents on the dominant and second order terms in the solutions of the crack and inclusion tip fields are discussed.     

环形含内钝缺口试件在斜加载作用下弹塑性场的分布特征

运用有限元数值计算方法,对含内缺口的环形试件在受到与缺口对称面成不同角度的载荷作用下,缺口前端附近的弹塑性场分布特征进行了研究,得到了缺口前端应力和应变场以及塑性区的变化情况,此外,选取缺口弧度不同的模型,探讨了缺口顶端钝化程度对弹生场的影响,为了对计算结果的可靠性进行评价,运用高精度云纹干涉实验力学方法进行了验证性试验,试验得到的位移,应变分布情况与计算结果基本吻合。文中得到的结果为钝口试件的材     

An incompressible rubber wedge under the tension of a line load at its tip

An analysis is made of the stress distribution and the deformation pattern near the apex of an incompressible rubber wedge under the tension of a concentrated force. The asymptotic method for the tip stress field is developed. The problem is treated as a plane strain case. Finally, the FEM numerical results agree with the theoretical ones.     

Strain gage method for determining stress intensities of sharp-notched strips

An efficient and simple strain gage method for determining the stress intensities of sharp-notched strips is proposed. The bisector of the notch angle is inclined to the edge so that the mixed-mode loading is created simultaneously at the notch tip. A theory of determining the stress intensities using strain gages is described on the basis of the two-dimensional theory of elasticity. Experiments on specimens with various notch shapes are carried out to verify the theoretical results. Experimental results are in good agreement with theoretical results.     

A new version of the Neuber rule accounting for the influence of the notch opening angle for out-of-plane shear loads

The paper deals with nonlinear stress and strain distributions at the root of sharp and rounded notches with different opening angles under antiplane shear loading and small scale yielding. In order to make an easier comparison with the Neuber rule, the material is thought of as obeying the particular nonlinear law used in the past just by Neuber.By solving the linear differential equation resulting from the use of the hodograph transformation, a new relationship linking linear and nonlinear stress and strain concentrations is found. The relationship is written also in terms of the relevant notch stress intensity factors. In contrast with the Neuber rule, this relationship strictly depends on the notch opening angle. Even when the notch opening angle is zero, it does not match the Neuber Rule, but results in an additional factor 2 which is in agreement with Hult and McClintock’s solution when the notch tip radius tends to zero and the notch becomes a crack.     

含缺陷的固支梁受冲击载荷作用的实验研究

本文报导了含缺陷的固支梁受圆柱形飞射物撞击的实验过程和实验结果,分析和讨论了输入能量、切口深度、质量比等参数对非完善梁塑性动力响应特性的影响。     

Unsteady boundary layer on a circular cylinder embedded to a wedge

The boundary layer growth on a circular cylinder embedded to a wedge, when the motion is started impulsively from rest, is discussed using the method of inner and outer expansions. The equation for the time of separation involving the Reynolds number and the wedge angle is obtained. A uniformly valid solution is also found for the entire flow field. It is found that separation first occurs at the points where the cylinder meets the wedge. Also, the time of earliest separation decreases with increase in the Reynolds number and with increase in the wedge angle.