This paper presents a method to calculate elastodynamic fracture parameters of surface crack by using the elastic line - spring model combined with perfect ansys software . the main content includes : the traditional line - spring model which is used in the static analysis of surface crack is extended to the dynamic case , the corresponding constitutive relations are derived and combined with the software ansys , and then the corresponding computational technique is formulated 本文将线弹簧模型与有限元软件ansys相结合，对弹性表面裂纹的动态断裂参量进行了研究，所进行的工作主要有：将传统的用于静态表面裂纹分析的线弹簧模型推广用于动态断裂分析，导出了相应的线弹簧本构关系，并与有限元( ansys )相结合，建立了相应的求解技术。
Analyzing the propagation behaviors for open and close crack , the author gain that normal fault is more dangerous to earthquake than reverse fault and glide fault . 3 . appling fracture mechanics to discuss reservoir - induce earthquake mechanism , the author observes the characteristic of surface crack and gains the stress intensity factor induced by the pressure of rock , water and osmosis 针对库区断层为表面裂纹这一特点，研究水库地震的断裂特点，得出地应力作用下的应力强度因子、库水作用下的应力强度因子和渗压作用下的应力强度因子以及它们的应力强度因子之合，并且合理的解释了构造型水库地震的诱发机理。
This segregation behavior of sn accords with the mechanism of non - equilibrium segregation . it can be obtained through the theoretical calculations that the critical time of sn non - equilibrium segregation is 124 seconds at 750 and the critical cooling rate is 8 / s when cooling from 1320 . it is suggested that controlling the cooling rate during continuous casting to avoid the critical cooling rate ( 8 / s ) and avoiding high stress near the trough temperature ( 750 ) may control the form 通过研究残留元素sn的偏聚机制及其对o . 15wt . % c钢热塑性的影响，对试验钢进行脆性预测:建议在该钢的连铸过程中弯道矫直温度尽量避开塑性谷底温度750 ，二冷区的冷速尽量避开临界冷却速率8 / s ，从而可以减少该低碳钢连铸坯表面裂纹和横向裂纹，提高其成材率。
This thesis calculates the sifs of circular cracks in a circular bar , writes a computer program to calculate the initial crack ' s growth life in everywhere of the bar , simulates the evolution course of crack from sub - surface to surface and calculates the growth life of sub - surface crack 计算了圆形试棒中任意位置存在圆形裂纹时的应力强度因子，编写了计算程序，可对任意位置处初始裂纹的扩展寿命进行计算。计算了圆形试棒亚表面裂纹扩展到表面的过程和亚表面夹杂的裂纹扩展寿命。
" second , jhe failure process of lpg vessel usually includes two phasest the crack formation and the crack propagation . after the temperatat field distribution and the iil . stress field distribution of lpg vessel without cracks are calculated , the stress intensity factor of lpg vessel with initial radial crack as well as surface crack are calculated and analyzed 其次，液化气容器的失效过程通常分为裂纹形成和裂纹扩展两个阶段，本文在对无裂纹液化气容器的瞬态温度场和应力场进行了计算后，对含有初始表面裂纹的液化气容器的瞬态应力强度因子进行了计算和分析。
A new line - spring element is established and combined into ansys , which is used to analysis of surface crack . and static case and dynamic case are solved respectively , the results are consistent well with the accepted numerical solutions . it is shown that established element is successful , and the effects of the factors on the transient response are examined in detail 在ansys中提出了一种新的线弹簧单元用于表面裂纹分析，并分别用于表面裂纹静态与动态的分析，所得结果与已有解吻合良好，说明此单元模型的建立是成功的，最后对影响表面裂纹动态应力强度因子的因素做了分析。
Furthermore , according to results , the resistance of steel can reflect the damage exactly . ( 2 ) depending on the analysis of flaw size of the experimental samples , a theoretical model has been reached . the model is more close to the experiment result 在观察得到的试样表面裂纹的萌生和扩展规律的基础上，通过对损伤后的实验数据进行拟合，得到了钢的疲劳损伤累积的一般理论模型，该模型更好的反映了钢在疲劳循环的中早期的破坏，在疲劳测量精度上有了较好的改进。
With the experiment of surface crack growth of bhw - 35 weld metal , the law of the surface crack shape variation when it grows was obtained , and the law of surface crack growth rate was also gotten . these direct the evaluation of the surface crack fatigue growth life and the critical value of its length 对bhw - 35钢焊缝材料进行表面裂纹扩展试验研究，得到裂纹的扩展形貌变化规律，并对其疲劳扩展寿命进行预测研究，为汽包下降管角焊缝部位的表面裂纹扩展寿命预测提供依据，同时也确定了其表面裂纹扩展的临界值。
The cumulative damage modes and their distribution regions on 7t / 4 quasi - isotropic laminates were reasonably simulated and the predicted fatigue lives agree well with the test results . residual strength evaluation is playing a significant role in damage tolerance analysis of structures . chapter 4 describes a simple procedure for the evaluation of residual strength of metallic structures with cracks developed b 提出按剩余西北工业大学博士学位论文:飞机结构疲劳和断裂分析中若干问题的研究强度等效和按疲劳寿命等效两种途径将撞击损伤当量化为表面裂纹，并根据有限的试验结果进行了尝试，得到了一些初步结果。
The main results and academic contributions of the dissertation can be summarized as following : 1 ) for the difficulty to obtain the accurate analytical solution of the stress constraints around 3d cracks , detailed 3d fe analyses have been conducted to study the out - of - plane constraint factor tz around a straight through - thickness crack , a quarter - elliptical corner crack and a semi - elliptical crack embedded in an isotropic elastic plate subjected to uniform remote tension loading . the distributions of tz are minutely studied in the forward section of the cracks . strong 3d zones ( tz > 0 ) along the crack front were investigated despite the far field stress - free boundary conditions 全文主要研究内容和学术贡献如下: 1 .针对一般三维裂纹端部场应力约束准确解析的困难,对均匀拉伸载荷作用下各向同性弹性板中穿透厚度中心直裂纹、半椭圆表面裂纹和1 / 4椭圆角裂纹进行了大量详细的全场应力三维有限元分析,首次全面分析了非穿透裂纹端部场三维影响区范围,给出了不同形状三维裂纹前沿离面应力约束因子tz的数值解,并结合k场平面解给出了非穿透裂纹端部应力场k - tz双参数描述。
