Loss-Factor:

The next important property of a material from dynamic applications point of view is the loss-factor. You will always observe that during un-loading a material never comes back through the same path that it traced during loading. This indicates the presence of hysteresis. Of course the extent of hysteresis differs significantly from material to material. Polymers, for example show very high hysteresis in comparison to the metals or ceramics. A typical hysteresis curve is shown below. The loss factor is defined as the ratio of amount of energy dissipated during a cycle of loading and un-loading to the amount of strain-energy stored in the system. High loss-factor indicates higher material damping which is desirable in components subjected to noise and vibration.