Mechanical behaviour of saturated wood under compression Part 2: Behaviour of wood at low rates of strain some effects of compression on wood structure

Summary

The mechanical behaviour of three species of hardwoods, soaked in different liquids, had been investigated at high rates of strain using a Hopkinson pressure bar system. In order to determine the influence of the rate of strain, samples from the same species were subjected to compression-tests at low rates of strain. It was noticed that, at low rates of strain, the saturated samples were always less stiff than the dry ones, which is in agreement with the literature, but differs from the behaviour at high rates of strain. This difference is attributed to the behaviour of the liquid present in the large cavities of the material, which must depend on the rate of strain. It was also noticed that the samples could support higher stresses at high rates of strain. Although permanent sets were measured after the tests, the samples were not always visibly damaged, but some typical failures were detected by means of microscopy. The damaged zones presented similar aspects, whatever the rate of strain.