Anelastic deformation and the friction stress of bone

Abstract

The elastic and non-elastic tensile deformation characteristics of longitudinal bovine and rabbit compact bone specimens have been measured with a microstrain technique. For both types of specimen, limited elastic deformation was observed, with a microscopic yield stress (MYS) (the stress to produce a non-elastic strain of 2×10⁻⁶) of 12±8MNm⁻². Measurements of stress—strain behaviour during loading, unloading and recovery of residual non-elastic strain with time at zero stress, which were made for stress increments from the MYS to fracture, revealed a series of closed hysteresis loops. From these results, the non-elastic strain is attributed entirely to anelastic deformation and the concept of a friction stress (σ_F), which defines the onset of anelastic deformation, is introduced.