A Prevalent Error in Optimization Design of Helical Springs

This paper reveals the popular error and problem in optimization design of helical springs. Most of the engineers and researchers regard wire diameter d, mean coil diameter D and number of active coils n as design variables in the mathematical model of optimization design for helical springs. In fact, only two variables are independent variables in the three design variables. The dependent variable in the optimization design model influences the behavior of the systems to be optimized, which is also possible to calculate wrong results. This paper analyses relationship of wire diameter d, mean coil diameter D and number of active coils n. To take number of active coils n as the dependent variable is reasonable. It can lead to wrong results to take n as the independent variable. The right independent variables in optimization design of helical spring are wire diameter d and mean coil diameter D.