一种用于金属薄板轴向拉压疲劳试验的防弯夹具

在金属薄板的轴向疲劳S-N曲线测试中,研究将一种侧向防弯曲夹具应用于存在压向载荷的试验。通过粘贴应变片方法测量试样的表面应力,对试样的受力情况做了定量的分析。测量结果表明试样安装防弯曲夹具后,基本消除了由压缩失稳产生的弯曲应力。且通过对不同拧紧方式的测量,表明一定的夹紧力下不对试验力产生影响。试验夹具设计成对试样中心轴线的支撑而让边缘疲劳敏感部位处在非接触状态,试样断口表明疲劳起源在这些并没有与试样接解的部位。用钛和铝两种材料的薄板在不同试验机上进行了不同寿命和频率的试验,试验结果与正应力比试验同时给出以对比,各种研究表明本试验有效解决了薄板疲劳受压时的失稳问题。     

自紧身管临界裂纹尺寸的概率断裂力学研究

基于概率断裂力学理论和Mome Caflo模拟方法，本文进行了自紧身管临界裂纹尺寸的可靠性研究。自紧身管内表面的疲劳裂纹考虑为半椭圆形式。裂纹尖端处的应力强度因子由内压和自紧残余应力共同产生。自紧残余应力采用了符合身管材料具有强化和包辛格效应性能推导的公式计算，它产生的应力强度因子通过权函数方法得到。根据断裂准则，可计算出自紧身管的临界裂纹尺寸。实例分析表明，对数正态分布为临界裂纹尺寸的最佳分布，同时给出了在各种置信度和可靠度下自紧身管的临界裂纹尺寸。     

Refinement of the plastic-zone boundary in the vicinity of a crack tip for the quasiviscous and viscous types of fracture

A refined solution of the elastoplastic problem of an insulated mode I crack in a thin plate of reasonably large dimensions is obtained. Estimates of the plastic zone in the vicinity of the crack tip are given for quasiviscous and viscous types of fracture.Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 1, pp. 126–132, January–February, 2005     

The scattering of harmonic elastic anti-plane shear waves by two collinear cracks in the piezoelectric plate by using the non-local theory

In this paper, the dynamic interaction between two collinear cracks in a piezoelectric material plate under anti-plane shear waves is investigated by using the non-local theory for impermeable crack surface conditions. By using the Fourier transform, the problem can be solved with the help of two pairs of triple integral equations. These equations are solved using the Schmidt method. This method is more reasonable and more appropriate. Unlike the classical elasticity solution, it is found that no stress and electric displacement singularity is present at the crack tip. The non-local dynamic elastic solutions yield a finite hoop stress at the crack tip, thus allowing for a fracture criterion based on the maximum dynamic stress hypothesis. The project supported by the Natural Science Foundation of Heilongjiang Province and the National Natural Science Foundation of China(10172030, 50232030)     

多功能Hopkinson压杆型试验装置的研制与应用

对传统的Hopkinson压杆试验装置进行了改进和完善，除了用于材料的动态压缩以外，还能进行动态拉伸、绝热剪切、裂纹扩展速度测定、动态断裂韧性测试等．本文介绍了几种试验方法的基本原理，并给出了试验结果．     

摩托车传动用滚子链磨损特性的研究

道路行驶磨损试验结果表明，摩托车传动用滚子链套筒和销轴零件的主要磨损形式是磨粒磨损，并伴随有疲劳磨损的特征．由微观分析和链条的磨损伸长量可知：套筒和销轴的初始表面硬度较高，有利于改善其磨损表面形貌状态和耐磨性；在磨粒磨损机制下，套筒和销轴零件的表面硬度较低，容易产生“犁切”，表面层的循环硬化现象比较明显，磨损严重；在油池润滑条件下，套筒和销轴零件的表面硬度较高，裂纹的扩展速率较快，循环软化现象也较明显，当表面硬度较低时发生循环硬化．循环软化与循环硬化是导致磨损严重的原因之一．     

Integral formulation for a circular cylindrical cavity in infinite solid and a finite length coaxial cylindrical crack compressed axially

A method for solving problems of fracture of an infinite solid with a circular cylindrical cavity and a coaxial cylindrical crack near the surface under an uniform axial compression is proposed using a non-classical criterial approach associated with a mechanism of a local stability loss near the defect. The theory of integral Fourier transforms and series expansions are used to reduce these problems to a system of paired integral equations and then to a system of linear algebraic equations with respect to the contraction parameter.     

裂纹扩展速度对焦散线的影响和动态应力光学常数的测定

本文从焦散线形成原理的数学描述出发,用扩展裂纹尖端附近的应力分量表达式,在前人工作的基础上,作了详细的数值计算。特别分析了裂纹扩展速度对焦散斑和初始曲线的形状、大小的影响,为测量扩展裂纹尖端的动态应力强度因子K_1~d提供了依据,并通过拟合得到了以裂纹扩展速度为参量的修正因子表达式。本文还提出了一种测定透明材料动态应力光学常数的方法,并用这一方法测定了有机玻璃的动态应力光学常数。     

临界空穴扩张比准则的适用性

用新研制成的DE36平台钢制的轴对称和平面应变试样,进一步考察了临界空穴扩张比V_(Gi)准则[1]、[2]、[3]的适用性。实验和大应变有限元理论计算结果表明,V_(Gi)准则适用于所研究材料。文中指出,按V_(Gi)准则可根据试样或构件材料中V_G的发展变化来预起裂位置。     

三维有限体中平片裂纹的超奇异积分方程方法—Ⅱ.数值方法

超奇异积分方程方法的理论分析已在本文的第Ｉ部分中给出，这一部分是经的数值方法，及用此方法求解的若干典型的平片裂纹问题。