Effect of elliptic or circular holes on the stress distribution in plates of wood or plywood considered as orthotropic materials
Effect of elliptic or circular holes on the stress distribution in plates of wood or plywood considered as orthotropic materials
复制标题
椭圆形或圆形孔对被视为正交各向异性材料的木板或胶合板应力分布的影响
DOI：
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发表时间：
1944
期刊：
影响因子：
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通讯作者：
C. B. Smith
中科院分区：
文献类型：
--
作者：
C. B. Smith
This is a mathematical analysis of the stress distribution existing near a hole in a wood or plywood plate subjected to tension, as, for example, near holes in the tension flanges of wood box beams. It is assumed that the strains are small and remain within the proportional limit. In this analysis a large, rectangular, orthotropic plate with a small elliptic hole at the center is subjected to a uniform tension along two opposite edges. By taking equal axes for the elliptic hole, the theoretical stress distribution in the neighborhood of a circular hole is obtained. The analysis shows that for a circular hole in a plain-sawn plate of Sitka spruce a maximum tensile stress of 5.84S is attained, S being the uniform tension applied in the direction of the grain. This maximum stress occurs on the edge of the circular hole at the ends of the diameter perpendicular to the direction of the uniform tension. Although this stress concentration may be greater than that found in isotropic materials, it is much more sharply localized and is relieved by plastic flow when the stress exceeds the proportional limit. For the reader who does not wish to follow the mathematical details of this report, the formula for computing this maximum stress for wood or plywood and an explanation of the constants involved is given in the appendix. The formula has not 1 —This progress report was originally prepared by the Forest Products Laboratory in 1944. 2 Maintained at Madison, Wis. , in cooperation with the University of Wisconsin. Report No. 1510 -1Agriculture -Madison been confirmed by an extensive series of tests, but it was found to be in reasonably satisfactory agreement with the only test made. It is also demonstrated that for the Sitka spruce plate mentioned the maximum shear stress attained is 0.71S (fig. 5). The stress function from which these formulas for the orthotropic case are obtained is shown to reduce to the well-known stress function for the isotropic case.
