2 Viscoelastic behaviour and failure of bovine cancellous bone under constant strain rate R.M. Guedes 1 , J.A. Simões 2 , J.L. Morais 3 1 Departamento de Engenharia Mecânica e Gestão Industrial, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto, Portugal 2 Departamento de Engenharia Mecânica, Universidade de Aveiro, 3810-193 Aveiro, Portugal 3 Departamento de Engenharias, Universidade de Trás-os-Montes, Quinta de Prados, 5000-911 Vila Real, Portugal ABSTRACT A programme has been established to characterize the long-term behaviour of cancellous bone. Fresh bovine cancellous specimens of dimensions 10x10x10 mm 3 and 10x40x3.6 mm 3 were manufactured and used within the testing programme. Results published in the literature indicate that the long-term behaviour of cancellous bone is well described by a power law, which is a very similar response of typical polymers. So far, dynamic mechanical tests (DMA) in three-point bending, under frequencies between 0.01Hz and 100Hz at room temperature, confirmed the published results in a qualitative way. Nevertheless, the measured dimensionless damping, tan , was slightly higher than the values reported in the literature for compact bone. The relaxation curves