APPLICATION OF SHORT AND LONG FATIGUE-CRACK GROWTH-BEHAVIOR IN LIFETIME PREDICTION OF MINE AUXILIARY VENTILATION FANS

Growth behaviour of short and physical small cracks in a C-Mn steel he at treated to two microstructural conditions has been investigated exp erimentally on hour-glass shape specimens subjected to push-pull loadi ng at room temperature and using the replica technique for crack lengt h measurements. A crack growth equation which considers the microstruc tural effect on fatigue crack growth was used to explain the experimen tal behaviour obtained from constant amplitude tests. Long crack growt h behaviour was studied using three point bend and cruciform specimens . The experimental data was analysed using fracture mechanics and pres ented in the form of a Paris law. The theoretical and empirical deriva tions were applied to predict the inspection intervals and fatigue lif e time of mine auxiliary ventilation fans.