Dynamic crushing characteristics of spruce wood under large deformations
An extensive series of large deformation crushing tests with spruce wood specimens was conducted. Material orientation, lateral constraint and loading rate were varied. Regarding material orientation, a reduction in the softening effect and the general force level was observed with a higher fiber-load angle. A comparison with characteristics gained by application of Hankinson’s formula showed discrepancies in compression strength and the beginning of the hardening effect. Lateral constraint of the specimens caused a multiaxial stress state in the specimens, which was quantified with the applied measuring method. Further, a higher force level compared to specimens without lateral constraint and significant hardening effect at large deformations resulted. Thus, the influence of a multiaxial stress state on the force level could be determined. An increase in the loading rate led to higher force levels at any displacement value and material orientation.
Strain rate effects on the compressive response of wood and energy absorption capabilities – Part A: Experimental investigations
Abstract Strain rate effect on wood material is of major interest when dealing with applications dedicated to energy absorption or wood machining. To understand and evaluate the strain rate influence on the wood responses, three experimental apparatus are used in order to cover a large range of strain rates, between 0.001 and 600  s - 1 , and to allow observing densification regime for strains until 70%. The influence of strain rate on mechanical properties, in particular, initial crushing stress, plateau stress and specific absorbed energies is investigated in the three orthotropic directions for two wood species (spruce and beech) really different in terms of relative density and microstructure. It is noticed that wood properties are strain rate sensitive and this sensitivity depends on the loading direction.
Chromatographic analysis of elastomer antidegradants and accelerators
Summary The use of various chromatographic methods in the analysis of all classes of elastomer antidegradants and accelerators is reviewed. The review of extraction methods is also included.