INFLUENCE OF SUPPORT COMPLIANCES ON STABILITY AND LIMITING SLENDERNESS RATIO OF COMPRESSION HELICAL SPRINGS

In the paper, the influence of support compliances on the stability and the limiting slen-derness ratio of compression helical springs was investigated. To analyze the stability of helical springs, the concept of an equivalent column was applied and a general system of supports described by three independent compliances was utilized. In the general case, the solution obtained, which describes the critical force, depends on two rotational compliances and a lateral compliance of a transverse shift of the support. The influence of the individual compliances on the critical load and on the limiting slenderness ratio was studied. Simple approximation formulas were proposed to describe these relationships. Key words: helical spring, stability, support compliance, slenderness ratio 1. Introductory remarks Helical springs, specially compression ones, fulfil different functions in the technique: do the work, store energy, alleviate the impact, raise or take vibration and many others. Moreover, they may be subjected to loss of stability. A helical spring should be treated as a spatially curved bar. Such an approach, based on Kirchhoff-Clebsh equations and geometrically non-linear theory, was developed by Nikolai (1955). It was applied to the problems of stability of helical springs, among others, by Cherny