This dissertation presents astrain life analysis involving various prediction methods of the thermal fatigue toollife for the direct tooling which are produced using laser additive material. Different tool life prediction methods eornposed of computational, theoretical and experimental are given. The assumptions and possible solutions that are especially viable for the predictions of toollife and cracking in the direct tooling models are presented. The mechanism of the thermal fatigue toollife and the fracture mechanics differ depending upon its geometrical designs, structural materials, process parameters and fatigue behaviors. It is thus important to understand the inherent architecture and the process of the toollife model, the fracture prediction which is associated with the various laser additive material in the structural model design, and the applied research applications of industrial case studies.
A systematic methodology form vital links in the thermal fatigue tool life predicton and craek length analysis. Instead of performing experiments, it is possible to predict the thermal cyclic behavior using the heat transfer analysis. Various boundary conditions for the thermal cyclic model simulation are compared with the experimental test in order to select the optimum parameters. The systematic process to obtain a thermal fatigue behavior parameters vvith the stress concentration location are described. Various geometry models and materials are simulated. A comparison of various prediction methods are made and the most accurate methods are identified.
Toollife prediction and crack length of the direct tooling in thermal fatigue analysis can be made using various methods. The utility of such models for the predictions of direct tooling in the case of laser additive material in the die casting and fatigue tool parameters. An emerging field of applied research in the industry shows that the predicted results are practically feasible. From the fracture mechanics analysis, strain life mcthod with stress conccntration loeation in thc Coffin Mansan calculations is presented. The stress concentration is analyzed using the computational simulation. The thermal strain and stress concentration factor are considered in the thermal fatigue toollife analysis.
The process for analyzing the stress distribution at the stress concentration location through stress intensity factar and J integral are performed using the Griffith theory. Thermal fatigue crack accounting for the conditions of critical crack length is demonstrated. Hence, the Paris law calculations are made and the stress intensity results of ANSYS Workbench simulation and many publications data are analyzed. The fracture model parameters are assumed to be representative of typical practical situations as shown by the experimental test results. Based on the fracture mechanics, the stress intensity factor and the J integral values are predicted.
The parametrie study models of the critical geometrical design, the laser additive material, the initial temperature and the fatigue loading parameters are developed to enhance the toollife prediction results which are presented in the later parts of this dissertation. A future prospective and potential developments in this area are also presented. The future is likely to bring about an integration of development methods with ANSYS APDL concurrent to CAD tools and ANSYS Workbench for the advanced laser additive material that could predict the thermal fatigue toollife and crack length accurately in the early design stage.