The influence of constructional damping of mounting on the Mecynorrhina Torquata beetle wing-based frame vibrations

This paper presents the experimental study and numerical simulation on the influence of the constructional damping of mounting on the beetle wing-based frame vibrations. The physical model consist of four parts arranged horizontally and is based on the main structure of wing venation. The damping vibration was modelled by placing individual hyper viscous rotary dampers supports. The numerical modelling results and the experimental data were compared

Constructional damping mounting influence on T type frame vibrations

The study presents a formulation and solution for the problem of damped vibration in T-type frame. The physical model took into consideration the energy dissipation in a vibrating frame as a result of constructional damping in the points of the frame mounting and the supports. As the solution of the problem an influence of constructional damping and system geometry changes on first three eigenvalues of the frame are shown (damped frequencies and vibration amplitude decay rates)

Transverse and longitudinal damped vibration of the GAMMA type frame

In this paper, the problem of transverse and longitudinal damped vibration of the Γ type frame was formulated and solved. The effect of constructional damping of the column support and fixing bolt frame support on degree of vibration amplitude decay was presented. The vibration energy dissipation in the model (modelled by the rotational viscous dampers) is a result of the movement resistance taken into account in the frame supports. The eigenvalues of the system with respect to changes in system geometry and for a selected and variable damping coefficient values were calculated

Damped vibrations of the Γ type frame with open cracks

This paper discusses the formulation and solution for the problem of damped transverse vibrations of the Γ type frame with open cracks. Dissipation of vibration energy in the frame results from the movement constraint in the column and bolt support (constructional damping) and internal damping of viscoelastic material of the frame (rheological model by Kelvin-Voigt). Presence of a crack impacts local flexibility that has an effect on frame vibration response. The boundary problem for the above system was formulated based on the Hamilton’s principle and solved numerically for the complex eigenvalues ω*. The effect of the crack depth and its location on damped vibration was presented. The effect of both types of damping on the degree of amplitude decay was also presented

The influence of constructional damping of mounting on the Mecynorrhina Torquata beetle wing-based frame vibrations

This paper presents the experimental study and numerical simulation on the influence of the constructional damping of mounting on the beetle wing-based frame vibrations. The physical model consist of four parts arranged horizontally and is based on the main structure of wing venation. The damping vibration was modelled by placing individual hyper viscous rotary dampers supports. The numerical modelling results and the experimental data were compared

Influence of material distribution and damping on the dynamic stability of Bernoulli-Euler beams

The study analyzed the influence of materials and different types of damping on the dynamic stability of the Bernoulli-Euler beam. Using the mode summation method and applying an orthogonal condition of eigenfunctions and describing the analyzed system with the Mathieu equation, the problem of dynamic stability was solved. By examining the influence of internal and external damping and damping in the beam supports, their influence on the regions of stability and instability of the solution to the Mathieu equation was determined

Influence of spatial distribution and the type of material on the occurrence of bandgaps in phononic crystals

The study investigated the effect of the fill factor, lattice constant, and the shape and type of meta-atom material on the reduction of mechanical wave transmission in quasi-two-dimensional phononic structures. A finite difference algorithm in the time domain was used for the analysis, and the obtained time series were converted into the frequency domain using the discrete Fourier transform. The use of materials with large differences in acoustic impedance allowed to determine the influence of the meta-atom material on the propagation of the mechanical wave

Designing of quasi one-dimensional acoustic filters using genetic algorithm

In phononic quasi one-dimensional structures, there is a phenomenon of a phononic bandgap (PhBG), which means that waves of a given frequency do not propagate in the structure. The location and size of PhBG depend on the thickness of the layers, the type of materials used and their distribution in space. The theoretical study examined the transmission properties of quasi one-dimensional structures designed using a genetic algorithm (GA). The objective function minimized the transmission integral and integral of the absolute value of the transmission functions derivative (to eliminate high transmission peaks with a small half width) in a given frequency range. The paper shows the minimization of transmission in various frequency bands for a 40-layer structure. The distribution of multilayer structure transmission was obtained through the Transfer Matrix Method (TMM) algorithm. Structures surrounded by water were analyzed and built of layers of glass and epoxy resin

One dimensional phononic FDTD algorithm and transfer matrix method implementation for Severin aperiodic multilayer

In this paper, the power spectrum and phononic properties of the quasi one-dimensional Severin aperiodic multilayer was investigated. Multilayer phononic structures with their phononic band gap properties can be used as filters of mechanical waves. In the paper, the implementation of the Finite Difference Time Domain (FDTD) algorithm with discrete Fourier transform and the Transfer Matrix Method algorithm in the Wolfram Language in Mathematica was made

The Effect of Layer Thickness on the Reflectance of a Quasi One-Dimensional Composite Built with Zr55Cu30Ni5Al10 Amorphous Alloy and Epoxy Resin

The study examined the impact of the angle of incidence of mechanical waves on various types of quasi one-dimensional superlattice. Binary periodic structure, quasi-periodic distribution of Thue-Morse layers and Severin’s aperiodic multilayer were used. Using the concatenation and recursive rules, the distribution of layers was determined for individual structure types for generation numbers equal to 3, 4 and 5. The structures were selected so that the thickness of the composite was the same for each type of distribution for a given generation number value. Transfer Matrix Method algorithm was used to determine reflectance. The band structure of reflectance has been demonstrated for incidence angles up to 90 degrees at mechanical wave frequencies up to 50 kHz. The existence of wide bands of high reflectance above the acoustic frequencies was demonstrated for the analyzed structures. Increasing the layer thickness caused an inhomogeneous shifts of transmission peaks towards lower frequencies