Model of Plastic Deformation at the Front of a Circular Crack Under Nonaxisymmetric Loading

The constrained plastic deformation at the front of a circular mode I crack under nonaxisymmetric loading in the crack plane is studied. It is shown that the normal stresses in the plastic zone depend on the polar angle and external stresses. The constraint is maximum at those points on the crack front along tangents to which the maximum external tensile stresses act     

金属塑性变形极限判据

研究出金属材料塑性变形极限判据，它为断裂力学和失效分析提供理论依据。利用这判据，裂纹尖端的临界应变和相应的临界应力可以确定。在板料成形中，拉应力下颈缩失稳的临界应变值可以定出。节省大量试验工作。     

钨塑性变形与断裂行为及其辐照效应的研究综述

金属钨具有独特的力学特性和物理化学特性,是核能、航空航天、微机电系统等领域广泛应用的结构材料.钨在服役条件下的变形和断裂行为是影响其服役状态的关键因素之一.但是,钨的塑性变形和断裂表现出异于其它金属材料的力学行为,比如,屈服强度表现出非施密特效应和拉压不对称性,断裂韧性低且具有各向异性、尺寸效应和温度效应,等等.这些特性与钨的位错特性、晶界特性、晶粒尺寸、晶粒取向等微结构紧密相关.辐照条件下高能粒子与钨原子的相互作用会引起其微观组织结构的变化,形成的位错、位错环等辐照缺陷导致钨的辐照硬化和辐照脆化,揭示钨微结构与力学行为之间的物理关系、研究辐照对钨力学行为的影响机制成为近年来关注的热点.论文围绕钨的塑性变形和断裂行为及其辐照效应,从实验、理论、模拟三个方面综述研究者们在原子尺度、位错尺度、单晶尺度、多晶宏观尺度取得的研究成果;最后,对钨力学行为研究方面的重要问题做出展望.     

拉压性能不同材料全量型本构关系及厚壁筒的应力分析

将经典全量理论作了推广，考虑了应力状态及塑性体积变形对拉压性能不同材料的塑性行为的影响。应用该本构模型分别计算了厚壁筒在内压和外压作用下的应力分布。给出了径向应力、环向应力和轴向应力沿壁厚的分布图。将本文的计算解与拉压性能相同(不考虑体积变形、强化曲线唯一)的幂函数强化材料的厚壁筒的理论解进行了比较。结果表明，材料的拉压性能不同对厚壁筒的环向应力和轴向应力影响较大。因此，对于拉压性能不同材料，考虑到其对应力状态及塑性体积变形敏感时，是不能将其简化成拉压性能相同、体积不可压缩、强化曲线唯一的理想材料。     

氧化铝陶瓷在高温磨损过程中的塑性变形与再结晶

Ａｌ２Ｏ３陶瓷在８００℃以上高温下的摩擦明显减小，在摩擦表面形成了由极细结晶构成的表面层。为了探讨这种表面层的形成机理，研究了Ａｌ２Ｏ３／Ａｌ２Ｏ３摩擦副在８００－１２００℃下于干摩擦时的塑性变形与再结晶，且用表面层厚度和晶粒大小来表征。表面层厚度和再结晶粒子尺寸均取决于试验温度、表观接触压力和滑动速度。根据对应变速率和摩擦表面温度的测算，发现再结晶粒了尺寸与Ｚｅｎｅｒ－Ｈｏｌｌｏｍｏｎ常数Ｚ的对     

Plastic macrodeformation of polycrystalline and submicrocrystalline titanium for biomedical applications

The deformation behavior of commercially pure submicrocrystalline and coarse-grained titanium was studied at the macroscopic level. Stress-strain curves of the materials were analyzed. Time-space distributions of local strains were studied at all stages of strain hardening using speckle interferometry. The life time of test specimens of the materials and the coordinates of the fracture region were calculated theoretically and confirmed experimentally. The motion of the zones of localized plasticity was studied. The prefracture stage was shown to involve “condensation” of the zones of localized plasticity and migration of deformation to the fracture neck. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 3, pp. 164–172, May–June, 2008.     

有限宽板孔边弹塑性变形测试

测量应变集中区域的弹塑性变形，对于研究材料损伤或微裂纹的产生，以预防宏观裂纹的产生及扩展具有重要的意义。为给航空发动机轮盘的损伤容限设计研究提供相关材料的力学实验参数，做了两个有限宽中心带孔试件的拉伸试验。试验中，采用单调逐级加、卸栽的循环加栽方式，并应用自动网格法和数字图像相关技术测量了孔用的全场位移分布。再应用最小二乘法将离散的位移分量拟合成二元多项式函数，求解出拉伸方向的应变分布，并给出孔边应力σ与孔边应变εy的关系曲线。     

爆炸与冲击载荷下结构和材料动态响应研究的新进展

对激波与高应变率现象的基础问题及应用国际学术会议 (EXPLOMET 2 0 0 0 )和第 2 0届国际理论与应用力学大会 (ICTAM 2 0 0 0 )上有关爆炸冲击载荷下结构和材料动态响应的研究论文进行了回顾和综合分析。分别从应力波、结构的高应变率响应和材料的高应变率响应三个方面就其新进展和新动向作了述评。     

Elastoplastic Deformation of a Compound Disk under Impulsive Loading

The small elastoplastic deformation theory and the finite-element method are used to analyze the behavior of a compound disk under axisymmetric impulsive loading. Numerical results are presented, which describe the development of plastic deformation, the effect of hardening and the duration of the loading impulse on the oscillatory elastoplastic deformation of the disk__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 4, pp. 94–99, April 2005.     

On the Macroscopic Description of Stored Energy and Self Heating During Plastic Deformation

In order to describe the complex cyclic hardening and softening properties of austenitic steels, we developed a simple phenomenological plasticity model during previous work. Now, we embed the model in a thermomechanical framework such that the second law in terms of the Clausius–Duhem inequality is fulfilled. Since the thermomechanical generalisation of the model is a rather formal and in some sense an arbitrary procedure, we check the implications of the generalised phenomenological model in context of two thermomechanical investigations. First, we study the fraction of the plastic work, which is not dissipated as heat and consequently stored in the material. Second, based on some simplifying assumptions, we present a semi-analytical solution of the thermomechanical problem of a cylindrical rod heated by plastic dissipation under uniaxial tension–compression loading. In both cases, the model response is in accordance with experimental observations.     

材料生长与变形的连续介质模型:平衡方程与边界条件

本文探讨了生长变形体连续介质模型的平衡理论框架。文中首先证明了广义输运定理，根据这个定理，推导了生长变形体广义平衡方程的一般形式及其生长边界条件，并导出反映生长边界面对平衡影响的生长耦合函数。在此基础上，具体讨论了质量、动量、动量矩以及能量平衡方程，并对其中相伴出现的一些新的物理量进行了评述；此外，还根据非平衡热力学理论的局域平衡假设建立了描述生长变形体热力学过程的熵不等式。这些方程唯象反映了生长变形体在运动、变形与生长过程中各物理量之间的耦合关系与平衡规律。     

Nonaxisymmetric Deformation of Solids of Revolution Made of Elastic Orthotropic Materials with Different Tensile and Compressive Moduli

A method is proposed to allow for the difference of the tensile and compressive moduli of compound orthotropic bodies of revolution subject to nonaxisymmetric loading and heating. The compliance matrix is symmetrized by introducing weighting coefficients that take into account the influence of the sign of stresses in two mutually perpendicular directions on the corresponding coefficients of this matrix __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 7, pp. 47–57, July 2005.     

PLASTIC POST－BUCKLING OF A SIMPLY SUPPORTED COLUMN WITH A SOLID RECTANGULAR CROSS－SECTION

ＰＬＡＳＴＩＣＰＯＳＴ－ＢＵＣＫＬＩＮＧＯＦＡＳＩＭＰＬＹＳＵＰＰＯＲＴＥＤＣＯＬＵＭＮＷＩＴＨＡＳＯＬＩＤＲＥＣＴＡＮＧＵＬＡＲＣＲＯＳＳ－ＳＥＣＴＩＯＮＣｈｅｎｇＹａｏｓｈｕｎ（程尧舜）（ＣｏｌｌｅｇｅｏｆＳｔｒｕｃｔｕｒａｌＥｎｇｉｎｅｅｒｉｎ...     

用数字圆栅技术研究橡胶类材料I型断裂问题

采用数字云纹技术对橡胶类材料的大变形断裂力学问题进行了实验分析。提出了数字圆环栅和射线栅技术，给出了该技术的测量原理和方法。应用此技术对橡胶薄板材料的I型断裂的裂尖变形场进行了测量，给出了极坐标系下的实验径向位移场ur，和环向位移场uθ。的分布图，对实验结果进行了详细的分析，并结合大变形断裂的分区理论模型进行了比较与讨论。     

具有Homologous变形约束立体桁架的形态分析

本文研究了具有Homologous位移约束的结构形状分析问题。文中第一部分把结点分成三类:表示Homologous变形点(自由度=h),形状可变点(自由度=f)和边界点。然后对于任意的桁架结构给出Homologous参数,n=h+f和m=1+f,引入具有n×m的系数矩阵的基础方程。在第二部分,利用广义逆矩阵导出基础方程的解存在条件。然后建立包含未知结点坐标的非线性方程组,并由Newton-Raphson法进行数值分析,以找出最终形状。最后一部分举了一个三维桁架的例子,以说明该方法的有效性,实用性。     

Effect of Temperature Sensitivity and Inelastic Behavior of Phase Materials on the Bearing Capacity of Plane Structures with Uniformly Stressed Reinforcement

An inelastic problem of uniformly stressed reinforcement of plane temperature-sensitive composite structures is formulated. Analytical solutions are obtained for the thermoelastic and inelastic cases. On the basis of these solutions, it is shown that the bearing capacity for inelastic projects can be increased severalfold as compared to thermoelastic projects, and reinforcement can be substantially saved in the inelastic case under fixed loading. Despite the worsening of strength characteristics of the composition phases, the bearing capacity of the structure remains almost unchanged upon heating in the inelastic case and can even increase in the thermoelastic case.     

Deformation of Particulate Composite with Physically Nonlinear Inclusions and Microdamageable Matrix

The structural theory of short-term damage is generalized to the case where the matrix of a particulate composite has microdamages and the inclusions deform nonlinearly. The basis for this generalization is the stochastic elasticity equations of a porous-matrix particle-reinforced composite. Microvolumes of the matrix meet the Huber-Mises failure criterion. A balance equation for damaged microvolumes is derived. The balance equation and the equations relating macrostresses and macrostrains of a particulate composite with porous matrix and physically nonlinear inclusions constitute a closed-form system. The system describes the coupled processes of physically nonlinear deformation and microdamage. Algorithms for calculating the microdamage-macrostrain relationship and plotting deformation diagrams are proposed. Uniaxial tension curves are plotted for the case where the material of inclusions is linearly hardening__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 2, pp. 3–11, February 2005.     

Deformation of a fibrous composite with physically nonlinear fibers and microdamageable matrix

The structural theory of short-term microdamage is generalized to a fibrous composite with a microdamageable matrix and physically nonlinear fibers. The basis for the generalization is the stochastic elasticity equations of a fibrous composite with a porous matrix. Microvolumes in the matrix material meet the Huber-Mises failure criterion. The damaged-microvolume balance equation for the matrix is derived. This equation and the equations relating macrostresses and macrostrains of a fibrous composite with porous matrix and physically nonlinear fibers constitute a closed-form system of equations. This system describes the coupled processes of physically nonlinear deformation and microdamage occurring in different components of the composite. Algorithms for computing the microdamage-macrostrain and macrostress-macrostrain relationships are developed. Uniaxial tension curves are plotted for a fibrous composite with linearly hardening fibers __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 1, pp. 38–47, January 2006.     

Deformation of a laminated composite with a physically nonlinear reinforcement and microdamageable matrix

The structural theory of short-term microdamage is generalized to a laminated composite with a microdamageable matrix and physically nonlinear reinforcement. The basis for the generalization is the stochastic elasticity equations of a laminated composite with a porous matrix. Microvolumes in the matrix material meet the Huber-Mises failure criterion. The damaged-microvolume balance equation for the matrix is derived. This equation and the equations relating macrostresses and macrostrains of a laminated composite with porous matrix and physically nonlinear reinforcement constitute a closed-form system of equations. This system describes the coupled processes of physically nonlinear deformation and microdamage occurring in different composite components. Algorithms for computing the microdamage-macrostrain relationships and deformation diagrams are developed. Uniaxial tension curves are plotted for a laminated composite with linearly hardening reinforcement __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 11, pp. 47–56, November 2005.     

基于高阶变形理论的夹层板的弯曲与振动

考虑面板和夹芯的面内刚度和横向剪切刚度以及抗弯刚度,考虑了高阶剪切变形,根据横向剪应变分布情况给出横向剪切转角的位移函数,基于哈密尔顿原理,推导了基于高阶变形理论、适用于软、硬夹芯情况夹层板的基本方程.作为算例,以四边简支条件下的夹层板的弯曲与振动,在不同的面板与芯层的弹性模量比和厚度比下进行了计算,并与Reissner理论、Hoff理论以及邓宗白基于Reissner理论的修正模型的计算结果进行了对比.与前述理论与方法相比,论文方法考虑因素更为全面,对夹层板的适用范围更为广泛,计算结果更为精确.针对Nastran软件计算夹层板的振动问题,对其适用范围作了简要分析.