Modelling the Ends of Compression Helical Springs for Vibration Calculations

The squared ends of compression helical springs are modelled as fixed ends with adjacent pinned supports. A theory is developed for the calculation of the natural frequencies, its predictions being compared with experiments on springs with about 2 1/2, 4 and 8 1/2 active turns, using two new designs of test rig. The discrepancy between theory and experiment is typically 1 per cent. The paper contains discussions of the application of the theory to forced vibration calculations, and the modelling of other types of end. Two methods are reviewed for the design of helical springs with the object of avoiding vibration problems.