Response of the beam-base system to a sudden change in the modulus of elasticity of the beam material

A mathematical model of the dynamic process excited in a statically loaded beam-base system by a sudden change in the beam's bending rigidity is constructed. It is assumed that either the beam material's elastic modulus or the beam's cross-sectional axial moment of inertia changes when it is rotated by 90 degrees relative to the beam's longitudinal axis while maintaining the load direction. Forced vibrations are investigated by decomposing the load and static deflection of the initial beam into rows according to the beam's natural vibration modes with changed parameters. Natural frequencies and corresponding displacement and bending moment modes are determined by the initial parameter method using a vector-matrix representation of the states of arbitrary beam sections. Numerical results are provided to demonstrate the capabilities of the approach.