Measuring Shear Moduli in Wood with Small Tension and Compression Samples
Keywords:Shear modulus, modulus of rigidity, wood, tension test, compression test
AbstractShear moduli in wood were measured on tension and compression specimens by means of rosettes of specially made bonded resistance strain gages. Angle α between the load axis and the longitudinal, L, direction for matched specimens were 10, 20, and 45 degrees. Better results were achieved with the tension specimens than with the compression specimens probably because of end restraint of the compression specimens. Although there were only small differences among shear moduli measured at angles α of 10, 20, and 45 degrees, the 20-degree specimens usually had shear moduli values that were closest to those from plate specimens. The maximum strain in each test specimen was not parallel to the load axis: for most specimens it was calculated by strain gage rosette analysis to be at an angle between 20 and 30 degrees to the load axis. Although instrumentation with strain gages is time-consuming, the specimens are easier to cut accurately from wood than are the plate specimens that are sometimes used.
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