Analysis of the performance of a beam made of composite materials with a glue layer

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.