Finite element stress analysis of forging dies to improve their fatigue life

The forging dies, and in a particular case a bolt die, were stress analyzed by the finite element method. Two possible modes of die failure, due to hoop and axial stresses, were investigated. The critical zones of highly concentrated stresses have been identified. Several approaches were studied to overcome the tensile stresses that result in a premature failure of a forging die. The results of the finite element simulations show that generating the compressive or negative stresses, as produced by the techniques applied, can completely remove, or at least significantly reduce the detrimental tensile stresses generated/during forging. This can readily improve the fatigue life of dies. Numerical stress analysis was performed on critical elements lying in the transition zone of dies. Finally, advanced numerical methods, especially the finite element method, were used to determine the optimum mean stress and the optimum alternative stress as well as to analyze the compressive negative stresses generated by the applied techniques. The ABAQUS software was used for the finite element simulation. The optimum mean stress and the optimum alternative stress at the most critical finite element were determined to be 140-150 and 34-38 MPa, respectively.