|
The torsion constant is a geometrical property of a bar's cross-section which is involved in the relationship between angle of twist and applied torque along the axis of the bar, for a homogeneous linear-elastic bar. The torsion constant, together with material properties and length, describes a bar's torsional stiffness. The SI unit for torsion constant is m4. == History == In 1820, the French engineer A. Duleau derived analytically that the torsion constant of a beam is identical to the second moment of area normal to the section Jzz, which has an exact analytic equation, by assuming that a plane section before twisting remains plane after twisting, and a diameter remains a straight line. Unfortunately, that assumption is correct only in beams with circular cross-sections, and is incorrect for any other shape where warping takes place.〔 Archie Higdon et al. "Mechanics of Materials, 4th edition". 〕 For non-circular cross-sections, there are no exact analytical equations for finding the torsion constant. However approximate solutions have been found for many shapes. Non-circular cross-section always have warping deformations that require numerical methods to allow the exact calculation of the torsion constant.〔Advanced structural mechanics, 2nd Edition, David Johnson〕 The torsional stiffness of a beams with non-circular cross sections is significantly increased if the warping of the end sections is restrained by, for example, stiff end blocks.〔(The Influence and Modelling of Warping Restraint on Beams )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「torsion constant」の詳細全文を読む スポンサード リンク
|