Simulation Study on Failure of Constant Force Spring (CFS) Fitted in a Counter Balancinglinkage Mechanism

A failure characteristic investigation is carried out on a constant forcespring (CFS) (also known as flat spiral spring) fitted in a counterweight balancingmechanism. A SolidWorksSimulation Softwarewas used to performed the static and fatigue test. Based on the simulation results, the maximum Von Mises stress obtained is 455.6 MPa which is less thanthe yield stress, Sy of the material which is520 MPa. The minimum life of the CFS obtained from simulation and analytical fatigue analysis are 4,991cycles and 4,185 cycles respectively. The maximum operating torque applied to the CFS is 62.672 Nmm which corresponds to the position when the CFS is fully deflected. These is much lower than maximum design torque, which is calculated to be 1,335,496.2 Nmm. This shows that the torque applied to the CFS in the counterweight balancing mechanism is acceptable.