Evaluation of the Non-Uniformity of Acoustic and Elastic Properties of Compression Coil Springs

The paper is devoted to the investigation of the acoustic and elastic properties of automotive and railway springs manufactured by cold coiling and high-temperature machining, respectively. The mirror-shadow method of multiple reflections based on measuring the velocities of longitudinal and transverse waves propagating along the rod diameter of the spring is used to evaluate the non-uniformity of the acoustic properties. Specially designed pass-through electromagnetic-acoustic transducers of transverse waves of axial polarisation and transducers of longitudinal waves on the basis of flexible piezo film of polyvinylidene fluoride provide multiple reflection of volume waves along the cross-section of the coiled coil of the spring. The elasticity, shear moduli and Poisson’s ratio are calculated from the results of wave velocity measurements. It was established that the non-uniformity of acoustic and elastic properties along the length of the bar differs for automotive and railway springs. It was found that there are differences in the non-uniformity of acoustic and elastic properties along the length of the coiled bar for automotive and railway springs.