Because the shear modulus of a composite material is usually far less than its elastic modulus, shear response plays a great role in the performance of a beam made of composite materials, especially in the case of a beam with large section height. When a square pipe beam made of composite materials supports a structure member such as a glass-glue-glass structure, there is a weaker glue layer in the middle of the beam flange. In this case, complex warping will be produced in the beam cross section because of shearing. Based on the piecewise linear displacement field theory, calculation models of static analysis and self-vibration frequency are set up for a square pipe beam made of composite materials and deformed within the symmetry plane, and the results are compared with those from classic theory. The calculation results in this paper prove that the geometry parameters of the beam and the mechanical parameters of the glue layer have great effect on the performance of the beam; in particular, when the glue is by far weaker than the composite material, the glue plays a dominant role, and in this situation the classic beam theory is not applicable.%摘 要:复合材料剪切模量通常比弹性模量低1个数量级,这就导致复合材料梁结构剪切效应比普通梁结构显著得多,尤其是梁截面高度较大的情况.作为夹胶玻璃等结构的复合材料支撑框架,复合材料方管梁翼缘通常存在较弱的胶层,此时复合材料梁横截面包含不同剪切模量的材料层,这就导致梁横截面在剪切作用下发生复杂的翘曲.剪切翘曲效应对梁结构的性能有着极大的影响,本文在分段线性位移场假设基础上,推导了对称面内变形的方管梁结构静力以及自振周期计算模型,并同经典梁理论计算结果进行对比,分析了梁几何参数、胶层力学参数等因素对两个模型计算误差的影响.计算结果表明,当胶层较弱时,弱层带来的层间剪切效应对梁的性能有着决定性的影响,此时经典梁理论不再适用.
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