一种预测界面裂纹形成的新方法

本文提出了一种预测界面裂纹形成的新方法，称为“β=0法”．这是一种变换方法，通过调整有关材料弹性常数，把振荡应力场变换为非振荡应力场．界面韧性曲线将随调整后新的材料性质而改变．本文方法预测的临界荷载与界面断裂力学预测的临界荷载严格一致．最后通过几个实例说明了保持能量释放率不变的情况下，怎样实施β=0法．

带裂纹层合板能量释放率分析

为了进一步了解裂纹尖端应力场的特性，本文对复合材料层合板的界面裂纹作了分析。文中强调了能量释放率分量存在的条件，并给出能量释放率分量和应力强度因子间的关系式。结合经典板理论的分析结果，根据外荷作用及某些几何参数和材料多数，导出了一般复合材料层合板的应力强度因子的封闭形式解。为了得到在一般荷载条件下能量释放率的分量，必须分别确定模型混合参数Ω，文中讨论了确定参数Ω的方法，最后，应用本文方法于几种不同种类的复合材料层合板，证明其结果可应用于工程实践。

圆柱壳孔边裂纹应力强度因子的计算和分析

从Reissner壳体理论出发,将“局部-整体分析法”应用于圆柱壳孔边裂纹问题,比较精确地计算了圆柱壳孔边轴向裂纹和环向裂纹的应力强度因子,获得了应力强度因子随壳体几何尺寸、开孔大小及剪切刚度变化的规律。以作者在文[7,8]中的有限元分析结果为基础,推广Petroski-Achenbach方法,建立圆柱壳孔边裂纹问题的权函数,分析计算了圆柱壳孔边裂纹问题,获得了较好的结果,最后给出了便于工程应用的较精确的计算鼓胀系数的近似公式。

带裂纹层合板复应力强度分析

本文用经典板理论求得了复合材料层合板的界面应力强度因子．利用裂纹尖端能量释放率和复应力强度因子间的关系，给出最一般的复合材料层合板，在相应外荷载和模型混合参数下的复应力强度因子的一个封闭形式的解．然后提出确定这一模型混合参数的步骤，给出某些层合板的数值结果．并给出在相应外荷载下的小范围接触条件．特别证明了界面韧度曲线的对称性质．最后讨论振荡指数消失后，预计的断裂荷载的精确性．还通过一个实例表明β＝０法的有效性和局限性．

ANALYSIS OF ENERGY RELEASE RATE FOR CRACKED LAMINATES

An interface crack analysis is presented for further understanding the characteristics of the crack-tip field. The conditions under which the energy release rate components would exist are emphasized and the relations between energy release rate components and the stress intensity factors are given. Combining with the results of chasical plate theory analysis. a closed-form solution for stress intensity factors in terms of external loading as well as some geometric and material parameters for fairly general composite laminates is derived Then. an analytical solution for energy release rate components is deduced. In order to get energy release rate components under general loading condition. a mode mix parameter, Ω, must be determined separately. A methodology for determining Ω is discussed. Finally. several different kinds of laminates are examined and the results obtained could be used in engineering applications.

用一种新型材料制成的涡轮盘的高温蠕变特性

对一种新型高温镍基合金材料作了蠕变试验,分析整理了试验资料,用最小二乘法拟合了高温蠕变物理方程。用自编的有限元计算程序,对喷气发动机高压Ⅰ级涡轮盘作了热弹塑性蠕变分析,所得结果可供工程设计参考。

关于材料不可压缩性的一个注记

本文从连续介质力学基本原理出发,探讨了材料不可压缩的问题,提出了大变形条件下不可压缩性的表示方法,指出了量级上的误差范围。这些表示方法为有限元法的应用提供了一个基础。

ANALYSIS OF COMPLEX STRESS INTENSITIES FOR CRACKED LAMINATES

Classical plate theory has been used to find out interfacial stress intensity factors in composite laminates. By using a well-known relation between the crack-tip energy release rate and the complex stress intensity factor. a closed-form solution for complex. Stress intensity in terms of external loading and a mode mix parameter for fairly. general composite laminates is given. Then a procedure for determining this mode mix. parameter is presented. followed by numerical results for some laminates. Small scale contact condition is expressed in terms of external loading In particular, a symmetric property of interfacial toughness curye is proven. Finally. the accuracy of failure load predicled by elininating oscllation index is discussed. and an example is presented to show the validity and limitation of β=0 approximation.