Papers by Keyword: Fracture Design

Abstract: The eigen-values problem of matrix cracks is studied in this paper. The stress field and displacement field of plane matrix crack is setup at first. The eigen-equation of matrix cracks is founded on the basis of the stress field and displacement field. The factors to affect the eigen-values are discussed. The effect of shearing modulus and Poisson ratio of matrix material and attaching material on eigen-values are analyzed. The results show that the bigger shearing modulus of material should be selected for attaching material and the shearing modulus of attaching material should bigger than that of matrix material in fracture design.

Abstract: Artificial neural network (ANN) back-propagation model was developed to predict the fracture design parameters in reinforced ceramic matrix composites (CMCS).Training ANN model was introduced at first. And then the Training data for the development of the neural network model was obtained from the experiments. The input parameters, the presetting deflection and tip radius of the notch, and the output, the cycle times of fracture were used during the network training. The neural network architecture is designed. The ANN model was developed using back propagation architecture with three layers jump connections, where every layer was connected or linked to every previous layer. The number of hidden neurons was determined according to special formula. The performance of system is summarized at last. The ANN model exhibited excellent comparison with the experimental results. It was concluded that predicted fracture design parameters by the trained neural network model seem more reasonable compared to approximate methods. It is possible to claim that, ANN is fairly promising prediction technique if properly used.

Abstract: The fracture problems of ecomaterial (aluminum alloyed cast iron) under extra-low cycle rotating bending fatigue loading were studied using artificial neural networks (ANN) in this paper. The training data were used in the formation of training set of ANN. The ANN model exhibited excellent in results comparison with the experimental results. It was concluded that predicted fracture design parameters by the trained neural network model seem more reasonable compared to approximate methods. It is possible to claim that, ANN is fairly promising prediction technique if properly used. Training ANN model was introduced at first. And then the Training data for the development of the neural network model was obtained from the experiments. The input parameters, notch depth, the presetting deflection and tip radius of the notch, and the output parameters, the cycle times of fracture were used during the network training. The neural network architecture is designed. The ANN model was developed using back propagation architecture with three layers jump connections, where every layer was connected or linked to every previous layer. The number of hidden neurons was determined according to special formula. The performance of system is summarized at last. In order to facilitate the comparisons of predicted values, the error evaluation and mean relative error are obtained. The result show that the training model has good performance, and the experimental data and predicted data from ANN are in good coherence.

Abstract: The notch is not only one of the primary reasons of component fracture, but also the key factor in life assessment of shaft. The stress and displacement field near the tip of annular notch should be obtained at first for safe design and life assessment. A quadric coordinate system suited for annular notch is proposed and the stress and displacement component of cylindrical shaft with annular notch are derived by using the modified Galerkin displacement function. This method can be used to solve various problems of cylindrical shaft with annular notch by selecting an appropriate displacement function and provides the basis for safe design and life assessment of this kind of components. A solution of torsional problems of cylindrical shaft with annular notch is calculated as a demonstration of the method presented.

Abstract: The applied investigation of regular fracture for low carbon steel under extra-low cycle inverse rotating bending fatigue was studied in this paper. The principle of inverse rotating bending fatigue was explained at first. The effect of experimental parameters on cycle times of fracture, such as the relations of presetting deflection to quality of blanking and cycle times of fracture were discussed through the experiments. The effects of geometrical parameters of notch, such as tip radius, depth and open angle, on cycle times of fracture were studied. The results show that low carbon steel can be regular fractured through inverse rotating bending fatigue. The quality of blanking is depended on presetting deflection of inverse rotating bending.

Abstract: The eigen-equation of bi-materials cracks was founded on the basis of the stress field and displacement field. The influence of shearing modulus and Poisson’s ratio of matrix material and additive material to eigen-values were analyzed through the results of calculating. The stress intensity factors at the tip of matrix crack were calculated. The suitable parameters of bi-steel materials crack in fracture design were obtained. The results show that the effect of Poisson’s ratio on eigen-values is not obviously and the effect of shearing modulus is obviously. The shearing modulus of additive material should bigger than that of matrix material.

Abstract: The application of fracture in three-points bending to blanking of tool steel was studied. Several mechanical models of stress blanking were discussed at first. And then the experiments were made in special equipment of three points bending designed by us. Several problems, such as the effect of wedge on fracture, the effect of support condition on the quality of blanking, the effect of the geometrical parameters of notch on blanking were studied with the help of experiment. The suitable parameters of three-point bending for blanking, depth and tip radius of notch, the ratio of blanking length to the diameter of the bar and suitable support in asymmetrical geometry have been proposed.

Abstract: Rotating bending and inverse rotating bending are the two different forms of fatigue. The application of regular blanking for brass under extra-low cycle inverse rotating bending fatigue was investigated. The principle of inverse rotating bending fatigue was explained at first. And then the experiment of inverse rotating bending fatigue was made in special equipment designed by the authors. Several problems, i.e. the relations of the quantities such as cycle times of fracture, the strain amplitude near the notch tip and fracture toughness of fatigue to the presetting deflection, the effects of depth and tip radius of notch on the cycle times of fracture, were discussed with the helps of experiment. Finally, The relation of depth of crack propagation to cycle times were discussed also. The suitable parameters of inverse rotating bending fatigue for blanking of brass were obtained.

Abstract: Safety designs and fracture designs are the two important fields of crack theory. The fracture problems of middle carbon steel under extra-low cycle rotating bending fatigue loading are studied in this paper. The experiments have been made in special rotating bending fatigue fracture machine designed by us. Several problems, the relations of the cycle times of fracture and the strain amplitude near notch tip to the deflection, the effects of depth and tip radius of notch to the cycle times of fracture, are discussed through the experiments. The mathematical expression of fracture toughness to the cycle times of fracture is obtained. The suitable parameters of rotating bending fatigue fracture model for middle-carbon steel in extra-low cycle times has been proposed.