Dynamic Stress Analysis of a Cracked Rolling Mill Housing

Synopsis

Knowledge of the dynamic loading and stressing of a component or assembly is essential to the design engineer to ensure satisfactory performance in a safe and economic manner. Dynamic stress/strain information can be calculated if the loading and restraining conditions are known, but these are only useful if a simple model is available to mirror these factors. In practice these simple solutions are seldom available. The alternative approach is to test an existing design, a modified design or a prototype. Such testing necessitates the use of sophisticated equipment which can monitor strains continually under dynamic conditions.

This paper describes the equipment and techniques used to monitor strain and load in the region of a crack in a rolling mill housing. The crack was discovered during routine maintenance. Production continued but urgent action was initiated to assess the effect of the crack on the continued safe operation of the mill. The crack size was measured and strain and load were recorded. Fatigue crack growth rate studies and stress analysis indicated the cause of the crack and identified areas where mill practice and design could be improved. Remedial action was recommended and undertaken.