叠梁的变形与弯曲切应力影响的关系讨论

梁的弯曲切应力分析是材料力学中的一个重要内容，但是通过叠梁与整体梁不同弯曲变形形式的演示实验来说明梁层间存在切应力容易造成概念上的混淆。本文仍然采用材料力学方法分析了层间粘接后两层之间的相互作用，指出其本质是约束两层的拉伸与压缩变形而非约束层间剪切变形。正是这种约束作用使得横截面弯曲正应力重新分布，造成两种梁弯曲变形的明显差异。这一分析过程能够启发学生思考实验现象背后的力学本质，理解相关力学概念。

DISCUSSION ON THE CORRELATION BETWEEN THE DEFORMATION IN STACKED BEAM AND THE EFFECT OF SHEARING STRESS IN BENDING

The analysis of the shearing stress in bending is an important content in mechanics of materials. However, it is easy to cause the conceptual confusion in demonstrating the existence of shearing stress on adhesive interface of stacked beam by comparing the deformation of the stacked beam and that of the integrated beam. The method based on mechanics of materials is adopted in this study to investigate the effect of the interaction between the two bonded layers, and in essence the constraint to the tension and compression deformation of the two layers is provided by bonding rather than constraint to the shearing deformation between two layers. This constraint to the tension and compression makes a redistribution of the normal stress on the cross section, and results in a significant difference between the bending deformations of the two types of beams. The analysis process can inspire students to explore the mechanical essence behind the experimental phenomena and understand the related mechanical concepts.