BlueScope Steel (Port Kembla, New South Wales, Australia)
BlueScope Steel required stress analysis and design modification of a strip rolling mill screw down nut which had been subjected to excessive wear in the top section of the nut and hence reducing the number of load carrying threads. Strength and fatigue analysis of the current screw down nut was performed to determine the overall load distribution profile along the nut threads and to verify the tendency of failure when subjected to cyclic loading in accordance with best engineering practices (i.e. first principles-based stress/fatigue analysis).
What we did:
- Performed detailed root cause failure analysis of current screw down nut thread via strength (structural FEA) and fatigue analysis considering permanent and imposed (motor torque, screw thread reaction) loads and current lubrication level/distribution.
- Performed screw down nut design modifications including variable lubrication levels/ distributions and higher tensile strength materials to achieve required design life.
Outcome:
Avesta Consulting successfully determined the cause of premature failure of the screw and nut. performed subsequent fatigue failure analysis and provided suitable recommendations to reduce wear rates and increase fatigue life.
