Natural Frequencies, Sensitivity and Mode Shape Details of an Euler–bernoulli Beam With One-Step Change in Cross-Section and With Ends on Classical Supports
“…Free vibration analysis of beams with continuous and discontinuous variation in cross-section has drawn attentions of researchers for many years. Particularly the free vibration problem of multiple-stepped beams has been extensively investigated theoretically, numerically, and experimentally [3][4][5][6][7][8].…”
“…Free vibration analysis of beams with continuous and discontinuous variation in cross-section has drawn attentions of researchers for many years. Particularly the free vibration problem of multiple-stepped beams has been extensively investigated theoretically, numerically, and experimentally [3][4][5][6][7][8].…”
“…Studies on stepped beam systems are usually linear.Özkaya and Tekin [4] investigated the non-linear vibrations of a clamped-clamped EulerBernoulli beam with n steps on the arbitrary points and researched the contributions of the non-linear terms on natural frequencies. Naguleswaran [5] obtained motion equations of three different Euler-Bernoulli stepped beams with all states of boundary conditions and computed three natural frequencies using the motion equation. In his other study, Naguleswaran [6] considered three different types of stepped beams and investigated the vibration of a beam with up to three step changes.…”
In this study, the vibrations of multiple stepped beams with cubic nonlinearities are considered. A three-to-one internal resonance case is investigated for the system. A general approximate solution to the problem is found using the method of multiple scales (a perturbation technique). The modulation equations of the amplitudes and the phases are derived for two modes. These equations are utilized to determine steady state solutions and their stabilities. It is assumed that the external forcing frequency is close to the lower frequency. For the numeric part of the study, the three-to-one ratio in natural frequencies is investigated. These values are observed to be between the first and second natural frequencies in the cases of the clamped-clamped and clamped-pinned supports, and between the second and third natural frequencies in the case of the pinned-pinned support. Finally, a numeric algorithm is used to solve the three-to-one internal resonance. The first mode is externally excited for the clamped-clamped and clamped-pinned supports, and the second mode is externally excited for the pinned-pinned support. Then, the amplitudes of the first and second modes are investigated when the first mode is externally excited. The amplitudes of the second and third modes are investigated when the second mode is externally excited. The force-response, damping-response, and frequencyresponse curves are plotted for the internal resonance modes of vibrations. The stability analysis is carried out for these plots.
“…Physically it is expected that the solution 1 will be continuous and have continuous derivatives. Additional continuity conditions can be determined mathematically by integrating the ODE in (10). The continuity conditions at an arbitrary point are listed in (13a), (13b), (13c), and (13d).…”
Section: Problem Formulationmentioning
confidence: 99%
“…In [9] it was demonstrated that when the area and moment of inertia of a beam structure are of a specific polynomial form, the equation of motion for the transverse bending could be transformed to that of a homogeneous beam for which an analytical solution is easily obtainable. With regard to a system with a step discontinuity in the mass per unit length and bending stiffness, [10,11] demonstrated that an analytical solution can be found for the transverse vibrations by applying continuity conditions at the location of the step. Other times, the solution to a nonuniform, Euler-Bernoulli beam structure can be expressed in terms of special functions such as Bessel functions and Chebyshev polynomials [12][13][14].…”
Section: Introductionmentioning
confidence: 99%
“…Additionally, the moment and shear in the system are investigated and compared for the cases with and without a first-order correction to the mode shapes. For the case of a stepped beam, an analytical solution can be found [10,11], which serves as an exact solution to which the perturbation theory results can be compared. Determining a solution for a system with piecewise continuous spatial properties, for which in some sections an analytical solution cannot be found, is the goal of the current work.…”
The Lindstedt-Poincaré method is applied to a nonuniform Euler-Bernoulli beam model for the free transverse vibrations of the system. The nonuniformities in the system include spatially varying and piecewise continuous bending stiffness and mass per unit length. The expression for the natural frequencies is obtained up to second-order and the expression for the mode shapes is obtained up to first-order. The explicit dependence of the natural frequencies and mode shapes on reference values for the bending stiffness and the mass per unit length of the system is determined. Multiple methods for choosing these reference values are presented and are compared using numerical examples.
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