Using complex variable methods in elasticity, this paper deals with the plane problems ot a finite disc containing an internal linear crack at any position under general loads, obtains the general forms of Complex str...Using complex variable methods in elasticity, this paper deals with the plane problems ot a finite disc containing an internal linear crack at any position under general loads, obtains the general forms of Complex stress functions and stress-intensity tactors expressed in terms of series, and to these problems disiusses three sposial cases,i.e.the cases of the crack under a uniform pressure, a uniform shear stress and the use of the dise rotating uniformly. In these cases the approximate formulas calcidating the stress-intensity factors are also presented. The calculated results shun that for the middle and.small orachs situated inside the disc and not near the external boundary,these approximate formulas give good or better approximation.展开更多
The unpredictable structure failures of carbon steel and low alloy steel leading to accidents may be caused by the propagation of a flaw or crack already present in the structure.Fracture toughness which describes the...The unpredictable structure failures of carbon steel and low alloy steel leading to accidents may be caused by the propagation of a flaw or crack already present in the structure.Fracture toughness which describes the ability of a material containing a crack to resist fracture is one of the most important material properties for design applications of metallic structures.Since this material property is influenced by several parameters,namely material chemistry,heat treatment,morphology of structure,it requires millions of experiments to be conducted to understand and predict it.So,mathematical modeling is one of the solutions to find the effect of these parameters and design future alloys.Stress–intensity factor(KIC)is a quantitative parameter of fracture toughness determining a maximum value of stress which may be applied to a specimen containing a crack(notch)of a certain length.An artificial neural network(ANN)model was developed using over 100 sets of data to study the effect of alloying elements on fracture toughness,KIC for the low alloy steel.20%of data was used for training,60%to develop predictive model and rest of the 20%for validation.The model can predict the fracture toughness of unknown new data close to 80%accuracy which is good enough for statistical modeling.The details of program code with ANN modeling steps have been explained.Prediction of fracture toughness by the model with variation of alloy composition as well as yield stress gives interesting and important information which may help in designing alloy which will resist crack propagation in a structure and hence enhance the life of structure to fail.展开更多
The main task of fracture mechanics of rock masses is the study on the propagating mechanism of fractures in rock masses , which can be efficiently conducted by discontinuty displacement (DD) numerical evaluation . Fi...The main task of fracture mechanics of rock masses is the study on the propagating mechanism of fractures in rock masses , which can be efficiently conducted by discontinuty displacement (DD) numerical evaluation . Firstly ,the element stress and displacement are analysed and the principle and steps of the numerical calculation of stress intensity factor and fracture extension force are introduced .The numerical results of parallel and echelon fracture systems ,which are compared with real field fractures .are presented. Finally . a simple engineering application example is presented .展开更多
文摘Using complex variable methods in elasticity, this paper deals with the plane problems ot a finite disc containing an internal linear crack at any position under general loads, obtains the general forms of Complex stress functions and stress-intensity tactors expressed in terms of series, and to these problems disiusses three sposial cases,i.e.the cases of the crack under a uniform pressure, a uniform shear stress and the use of the dise rotating uniformly. In these cases the approximate formulas calcidating the stress-intensity factors are also presented. The calculated results shun that for the middle and.small orachs situated inside the disc and not near the external boundary,these approximate formulas give good or better approximation.
文摘The unpredictable structure failures of carbon steel and low alloy steel leading to accidents may be caused by the propagation of a flaw or crack already present in the structure.Fracture toughness which describes the ability of a material containing a crack to resist fracture is one of the most important material properties for design applications of metallic structures.Since this material property is influenced by several parameters,namely material chemistry,heat treatment,morphology of structure,it requires millions of experiments to be conducted to understand and predict it.So,mathematical modeling is one of the solutions to find the effect of these parameters and design future alloys.Stress–intensity factor(KIC)is a quantitative parameter of fracture toughness determining a maximum value of stress which may be applied to a specimen containing a crack(notch)of a certain length.An artificial neural network(ANN)model was developed using over 100 sets of data to study the effect of alloying elements on fracture toughness,KIC for the low alloy steel.20%of data was used for training,60%to develop predictive model and rest of the 20%for validation.The model can predict the fracture toughness of unknown new data close to 80%accuracy which is good enough for statistical modeling.The details of program code with ANN modeling steps have been explained.Prediction of fracture toughness by the model with variation of alloy composition as well as yield stress gives interesting and important information which may help in designing alloy which will resist crack propagation in a structure and hence enhance the life of structure to fail.
基金The research is supported by the National Nature Science Foundation of China
文摘The main task of fracture mechanics of rock masses is the study on the propagating mechanism of fractures in rock masses , which can be efficiently conducted by discontinuty displacement (DD) numerical evaluation . Firstly ,the element stress and displacement are analysed and the principle and steps of the numerical calculation of stress intensity factor and fracture extension force are introduced .The numerical results of parallel and echelon fracture systems ,which are compared with real field fractures .are presented. Finally . a simple engineering application example is presented .
