Abstract:

ESDU 08015 is the second in a series that deals with the dynamic characteristics of tension/compression springs of cylindrical helical form. The Data Item presents spring axial vibration, both free and forced, in terms of the vibration behaviour of a straight elastic rod, the so-called 'equivalent rod' representation. This portrays a spring as an elastic rod possessing the same elastic properties, specifically mass and stiffness, as the helical spring it represents.

For free vibration, cases when both ends of the rod are free, one end of the rod is clamped and the other end is free and both ends of the rod are clamped, are considered. For forced vibration, the case when one end of the spring is forced to follow a cyclic motion and the other end is clamped, together with the stresses induced on the spring by the cyclic motion, is discussed.

The free and forced vibrations of a spring-mass system are described and deal with cases when the system mass is both large compared to the mass of the spring and also of comparable size. The influence of various kinds of damping, Coulomb and viscous friction, material hysteresis, etc. are also discussed. In conjunction with forced vibration, the resonance phenomenon is also dealt with in a number of sections.