Influence of Contact Area of Additional Elements on Frequency Spectrum Splitting in Cylindrical Shells

Thin circular cylindrical shells are widely applied in various industries. Sometimes, due to structural, operational, and strength requirements, special patches are attached to the shell construction in designs of aviation, rocket, and space technology. The article examines the influence of flush contact area of the added mass on basic frequencies and flexural modes of a thin circular cylindrical shell. The spectrum when the mass added to a shell could be considered lumped mass is identified. It is demonstrated that resizing additional element contact area significantly influences base frequencies. The reduction of a contact area of the added mass results in a noticeable drop of the lower splitting basic frequencies of shell oscillation. A drop in high frequency, possibly substantial, is associated with the extended contact area. A nonlinear relationship between a contact area of the added mass and basic frequency of shell–weight system is defined. Oscillation modes bear a resemblance to conjugate flexural sinusoidal and cosinusoidal forms; however, more complex (ambiguous) oscillatory modes are distinguished at supreme oscillation frequencies. A fundamental dependence of shell geometric characteristics bearing the added lumped mass on lower splitting basic frequencies is calculated.