Analytical review of design aspects of helical spring

Abstract

The curvature correction factor is an important parameter for evaluating the stress of helical springs. A novel modelled curvature correction factor (KG) was proposed in terms of the shear correction factor (KS) and spring index (C). This factor (KC) falls between the Wahl and Bergstrasser correction factors, considering the stresses due to shear, torsional, and curvature effects. The ratio of the actual deflection to estimated deflection and the ratio of the actual stiffness to estimated stiffness are mirror images of each other. In addition, when C continued to decrease, the curvature correction factor increased sharply. In practical design, the actual deviation is greater than the evaluated deflection, and the evaluated deflection may need to be increased by a certain percentage to obtain the actual deflection. Therefore, a general equation was developed for this purpose. The ratios of the actual and evaluated deflections and the actual and evaluated stiffnesses were mirror images of each other. For suitable assumed data, the torsional shear stress, maximum shear stress, and modelled curvature stress were almost straight and parallel to each other.