摘要
悬臂整梁弯曲凸起时,凸起的梁段上表面会受到拉应力、下表面会受到压应力,这已成为材料力学教材中的常识。但是,自由端被螺栓或销钉连接的悬臂叠层梁,在外载荷作用下弯曲凸起时会发生一个反常现象,即在弯矩大的凸起梁段上表面受到拉应力、下表面受到压应力,而在弯矩小的凸起梁段有可能是上表面受到压应力、下表面受到拉应力。计算分析表明,产生反常现象是悬臂叠层梁的上层叠梁轴向拉力,与悬臂叠层梁的下层叠梁轴向压力形成力偶矩造成的。所以,有关教材把销钉连接的悬臂叠层梁作为整梁来考查梁应力的试验是不成功的。
When the whole cantilever beam bends and bulges,the upper surface of the bulged beam section will be under tension stress,and the lower surface of the bulged beam section will be under compressive stress,which has become a common knowledge in materials mechanics textbooks.However,when the free end of a cantilever laminated beam is connected by a bolt or a pin,an abnormal phenomenon will occur when the convex beam is bent under external load,that is,the upper surface of the convex beam section with large bending moment is subject to tensile stress and the lower surface is subject to compressive stress,while the upper surface of the convex beam section with small bending moment may be subject to compressive stress and the lower surface is subject to tensile stress.The calculation and analysis show that the abnormal phenomenon is caused by the couple moment formed by the axial tension of the upper layer of the cantilever laminated beam and the axial pressure of the lower layer of the cantilever laminated beam.Therefore,it is not appropriate to use the cantilever laminated beam connected the pin as the whole beam to investigate the beam stress in relevant textbooks.
作者
吴晓
Wu Xiao(College of Mechanical Engineering,Hunan University of Arts and Science,Changde 415000,Hunan,China)
出处
《工程与试验》
2020年第2期1-2,10,共3页
Engineering and Test
关键词
材料力学
悬臂
叠层梁
应力
轴向
mechanics of materials
cantilever
laminated beam
stress
axial direction
