Dynamic Behaviour of Two-Layered Beam Subjected to Mechanical Load in Thermal Environment

The research investigates a composite beam composed of two layers of different materials and thicknesses subjected to thermal and mechanical loads. Two cases of thermal loading are considered here: uniformly distributed temperature along the whole beam and linearly distributed temperature along the beam thickness. A reduced model of the problem based on the first three beam normal modes is formulated. Additionally, a simplified one-mode reduction model is developed and solved analytically by the harmonic balance method (HBM). A comparison between the results of the three-mode reduction and one-mode reduction models highlights the applicability and limitations of the latter. Differences in the resonance curves produced by these models are thoroughly examined. The correctness of the reduced models is validated through comparison with the created finite element model (FEM) of the bilayer beam. The detailed bifurcation diagrams presented for the three-degrees-of-freedom (3-DOFs) model reveal phenomena such as loss of stability, mode interaction, buckling, and existence of multiple solutions. These findings provide deeper insights into the dynamic behaviour of thin composite beams subjected to mechanical and thermal loads, considering different variations of the temperature distribution.