Numerical analysis of the stress intensity factor (SIF) induced by indentations was proposed based on the conservation integral. Simulation of the intensification of the stress fields by software of finite element method. The stress intensity factor for such stress fields was calculated. The SIF with different elastic modulus and poisson ratio was compared, focused on the relation between SIF and fracture toughness, and investigated the change law. Use the numerical result to researching damage behavior of material and testing the mechanical properties in engineering.

When aperiodic array and cylindrical flat ended rigid indenter is pressed on the cylindrical substrate,a mixed mode I-II singular stress field will induced at the edge of the indentation,which shares the same singularity with the same mode cracks and well lead contact boundary to fracture.Based on the equivalent crack method,the stress intensity factors for indentation with periodic array and cylindrical flat ended rigid indenter had been found.

The indentation fracture can be used widely in the areas including rock breakage and test of fracture toughness of materials．When an elastic half － plane substrate is subject to indentations by a rigid，flat － ended punch，a singular stress field and K － dominant region should arise adjacent to the punch edges．When the intensification of such singular stress fields reaches its critical value，fracture will take place on the surface of the contact boundary．The cracking of indentation is a new type of fracture problem．By using the energy release rate of boundary translation the fracture of indentation has been formulized and
critical load and critical cracking angle of the indentation have been found in the present paper．

The earthquake wave broadcasting through the ground leads a ground dissemination when the earthquake happen， then the ground moves along the pipe axial displacement makes the axial tensile stress．Neglect inertial force，but considering dynamic water pressure．Adoption the statical analysis method to analysis ascending pipe stress，and incorporation a calculation
example using Ansys software to analyze submarine pipeline axial stress．The example was analysis and got the conclusion was that the submarine pipeline could not be broke where ９ degrees earthquake intensity happened.

Periodic－arrayed indentation is one of the powerful tools in investigating the near surface properties of materials in the micro－/nano－scale．When an elastic substrate in half－plane was subject to indentations by a rigid ，flat － ended punch ，a singular stress field and K－dominant region should arise adjacent to the punch edges．When the intensification of such singular stress fields reaches its critical value， fracture will take place on the surface of the contact boundary． The cracking of indentation was a new type of fracture problem．By using the energy release rate of boundary translation the fracture of indentation has been formulized and critical load and critical cracking angle of the indentation have been found.

The probability assessment method for pressure piping system containing defects in petrochemical industrial piping was put forward based on GB/T 19624-2004，considering random factors. Safety assessment program for pressure piping system containing defects was worked out. The program not only can assuredly assess pressure piping system containing defects, but also the failure risk caused by each individual defects is got in pipeline containing defects, thus the failure risk of the whole pipeline system is gained.