The Young’s modulus and shear modulus of extruded polystyrene foam were obtained by measurements using the longitudinal and flexural vibration methods on specimens with various lengths and performing a subsequent numerical analysis on the test data. In addition to the vibration tests, ISO 844 compression and ASTM C273/C273M-11 shear tests were conducted, and the results were compared with those obtained from the vibration tests. The Young’s modulus values could be measured accurately by the longitudinal and flexural vibration tests while reducing the effects of the specimen configuration. In contrast, the shear modulus value was often dependent on the specimen configuration. The Young’s modulus and shear modulus values obtained from the vibration tests were often higher than those obtained from the standardised tests because the bending of cell wall is not induced in the vibration test. Although a provisional method for reducing the influence of the specimen configuration was proposed based on the numerical results, further research is required to measure the elastic modulus of extruded polystyrene foam accurately.
Open-hole compression tests on Sitka spruce (Picea sitchensis Carr.) were conducted, and the effect of the hole notch on the compressive strength has been investigated. A circular hole was cut at the centre of the longitudinal (R)-radial (R) plane. A compression load was applied to the specimen along the L or R direction, and the nominal stress at the onset of nonlinearity and the nominal compressive strength were obtained. In the test, the diameter of the hole was varied, and the effect of the diameter was analysed based on point stress criterion (PSC). It was revealed that the notch sensitivity of Sitka spruce was not so significant, and this tendency was more pronounced for the compressive strength in the R direction than in the L direction. Despite the notch insensitivity, however, the open-hole compressive strength could be predicted appropriately by the PSC.
The four-point bending strength of key-hole side-edge-notched (4KHSENB) western hemlock (Tsuga heterophylla Sarg.) has been determined with a focus on the effects of the notch length and hole size on the results. A hole notch with various lengths and hole diameters was cut at the mid-length in the longitudinal-radial plane. Bending loads were applied to the specimen along the depth direction at the two trisectional points of the span, and the nominal bending stress in general and at the onset of non-linearity was determined. The effects of the input parameters were analysed based on the elementary beam theory (EBT), the point stress criterion (PSC), and linear-elastic fracture mechanics (LEFM). It was found that the PSC and LEFM methods are effective for fitting the relationships between the side-edge-notched strength and notch length in the longitudinal and radial directions, respectively.
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