Abstract
This paper investigates the effect of ground end coils on axial stiffness, as well as the magnitude and direction of transverse reactions occurring during axial compression of a coil spring. As shown, conventional relationships for calculating axial stiffness can significantly overestimate its value, especially for springs with a small number of active coils. Transverse reaction forces during axial compression of a spring can reach high values. The paper shows that these forces can exceed more than 30% of the axial force caused by the compression of the spring. There are no relations in the available literature to estimate the effect of spring geometry on the value and direction of the transverse reaction generated during axial compression of the spring. On the basis of experimental studies of axial compression of springs, a numerical model with high accuracy was developed - the average difference between the experimental results and the results of the numerical model was 2.7%. The model took into account friction between coils, large deformations and carefully studied material parameters. Using the developed numerical model, a total of 245 numerical analyses were carried out, based on which new relationships were developed to accurately calculate axial stiffness, lateral reaction force and its angle. The new relationship for calculating axial stiffness shows better agreement with the results of numerical analyses than all the relationships found in the literature to date. The average difference between the results of this relation and the results of the numerical analyses carried out did not exceed 2%. A new relation has been proposed for determining the value of the transverse reaction occurring in axial compression of springs. This relation also shows high agreement with the results of numerical analyses. In addition, a new relation has been proposed to determine the direction of the transverse reaction force.