Dynamic stresses in helical springs locally coated with highly-damping material in resonant longitudinal vibration conditions

This paper analyzes the effectiveness of damping resonance vibrations of a spring using a new method of local coatings made of highly-damping material covering its last coils, as well as the influence of these coatings on the maximum values of dynamic stresses and the values of natural vibration frequencies of springs. It is shown that while an elastomeric coating applied on the whole length of spring wire always causes a decrease in the first natural frequency of the spring, application of the same amount of damping material only on its end-coils may lead to an increase in this frequency. The mathematical model derived in the paper allows users to calculate the effectiveness of dynamic stress reduction both in the spring and the coating itself, for arbitrary geometrical and material properties of coatings. The numerical examples presented to illustrate the derived model confirm the advantageous properties of local elastomeric coatings. (C) 2014 Elsevier Ltd. All rights reserved.