Analysis Of Flexural-Torsional Coupled Vibration Of Thin-Walled Fiber Reinforced Composite Beams With I-Shaped Sections

Fibre-reinforced plastic (FRP) is a composite material made of a polymer matrix reinforced with fibres. FRP is commonly used in the aerospace, automotive, marine, and construction industries due to the distinguished advantages of fibres, such as, high modulus, low weight, high tensile strength, high heat resistance, suit specific design and so forth. However, the FRP exist the alternative characteristics of heterogeneity and anisotropy which induce some troubles in mechanical analyzing, especially in the aspect of structural vibration. Thus, the investigation of the structural vibration of FRP has important theoretical significance.The purpose of this paper is to develop a natural frequency calculation method of FPR thin-walled beams, to study the vibration mode of the structure and to study the direction arrangement of fibers’effects on natural frequency. In order to avoid FRP structure’s resonance, the structural damage can be reduced. The resonance is owing to the transmission system’s defects or errors, the incentive of external environment, the imbalance of the rotating masses, the working load fluctuations and other factors, which cause the vibration frequency of material and the natural frequency similar.The paper is based on the composite material mechanics and dynamic mechanics, with the FPR thin-walled beams to be a studying object. It is to study FPR materials thin-walled beam’s bending, torsion and bending torsional coupled vibration problems, gaining the laminated structure of natural frequencies, and the corresponding vibration mode, and to use the finite element software ANSYS to contrast the theoretical results, analyzing the differences from theoretical analysis and finite element analysis. The analysis results show that the model of this paper have better practicability in the calculation of fiber reinforced composite thin-walled beams’inherent frequently, and mode shapes, they provide the reference values for designing and manufacturing the FPR thin-walled beams, as well as the strength and fatigue life studies.