Strain Rate Effect and Energy Absorption Characteristics of Russian Pine

The Russian pine is widely used in packaging, transportation and penetration test.In this paper, we studied the stress-strain relationship and the failure mode of the Russian pine under quasi-static loading.The results show that the deformations of the pine in the radial and tangential directions undergo three phases:elastic deformation, plastic deformation and densification, and in the axial direction the pine undergoes small plastic deformations and damages when the yield limit is reached.The failure mode of the tangential and radial directions is mainly dissociated along the fiber direction, and the axial failure mode is dominated by the kink crack.Furthermore, we carried out high strain-rate dynamic compression tests of the Russian pine at the strain rates ranging from 500 s^-1 to 5 000 s^-1 using the split Hopkinson pressure bar system.The results show that the initial yield stress in the axial direction is more sensitive than that in the tangential and radial directions.The radial platform stress increases more rapidly with the strain rate than the tangential platform stress.The energy absorption capacity along the tangential and radial directions increases gradually as the strain rate increases, while it decreases gradually along the axial direction.The failure mode under dynamic loading is highly similar to that under the quasi-static loading.