STRESS-STRAIN DIAGRAMS AND SELECTED MECHANICAL CHARACTERISTICS OF ELM AND ASH WOOD AT COMPRESION LOADING IN LONGITUDINAL DIRECTION.

This article deals with new possibility of the PC recording and evaluation of the stress-strain diagrams at compression loading in longitudinal direction of elm Whims scabra) and ash (Fraxinus excelsior el.) wood. We compared the chosen mechanical characteristics (ultimate limit sigma(u), proportional limit sigma(p)), and evaluated their relations to density. We confirmed presumption that sigma(u) and sigma(p) compression loading in longitudinal direction rise with the density of the tested kinds of wood. Ultimate limit for elm wood has average value 50,1 MPa, for ash wood 51.7 MPa. Proportional limit for elm wood has average value 33.5 MPa, for ash wood 35.3 MPa. Kind of wood factor have not significant influence to proportional limit sigma(p) and ultimate limit sigma(u), for elm and ash wood. Densities of elm and ash woods are significantly different.