Dynamic Characteristics Of Plates Research Articles

ДОСЛІДЖЕННЯ ВПЛИВУ КОНСТРУКТИВНИХ ФАКТОРІВ НА ТЕХНІЧНУ РЕАЛІЗАЦІЮ МЕТОДУ ЕКСПРЕС-КОНТРОЛЮ ТЕПЛОТИ ЗГОРАННЯ ПРИРОДНОГО ГАЗУ

Проведено аналіз відомих нормативних методів і технічних рішень для розрахункового і експериментального методу визначення теплоти згорання природного газу. Обгрунтовано необхідність визначення теплоти згорання вологого природного газу у споживачів за місцем роботи газоспоживного обладнання. Викладено технічне рішення для реалізації запатентованого авторами способу визначення теплоти згорання природного газу прямим методом за температурою згорання газу. Кількісно оцінена зміна відносної похибки визначення теплоти згорання природного газу від вологи газу і вологи повітря для умов реалізації запропонованого способу визначення теплоти згорання для конкретних трьох проб газу з теплотою згорання 7759 ккал/м3, 8145 ккал/м3 та 8538 ккал/м3. Встановлені закономірності зміни відносної похибки визначення теплоти згорання від двох складових вологості. Здійснене моделювання відносної похибки визначення теплоти згорання природного газу одночасно від його вологості і вологості навколишнього повітря. Досліджено вплив конструктивних факторів, які впливають на технічну реалізацію методу експрес-контролю теплоти згорання природного газу. Встановлено наявність суттєвого градієнта температури вздовж поверхні тонкої пластини та набагато менше її значення для грубшої пластини. Досліджені динамічні характеристики нагрівання пластини і термопари при вимірюванні температури полум’я.

Research on dynamic characteristics of plate under pedestrian excitation based on Newmark-β

Development of micro and ultra-precision machining, precision instruments and equipment, precision assembly and testing has put forward more and more high requirements to vibration isolation on environmental elements, especially the pedestrian excitation generated by workers' normal walking. Therefore, it is very important to study the pedestrian excitation's influence on vibration characteristics of precision instruments and equipment. In this study, dynamic model including mathematical model of pedestrian excitation, interaction model between pedestrian and rectangular plate structure, the human–plate coupled dynamic equation in vertical direction of pedestrian–plate structure was established. And then we use the Newmark-β method to solve the time-domain step-by-step integration of the first four order modes' dynamic equations and study the influence of the linear notion trajectory along the central axis direction on the dynamic characteristics of the rectangular plate. By simulation, we discussed plate structure response under different conditions, including plate structure displacement and acceleration response under the single person excitation with different velocities, under normal walking velocity with different number of pedestrians and under this case of different distance between two pedestrians. The results show that the structural vibration induced by pedestrian excitation has great influence on dynamic characteristics of plate.

ИССЛЕДОВАНИЕ ДИНАМИЧЕСКИХ ХАРАКТЕРИСТИК ДИСКОВОГО ТОРМОЗА С ПЛАВАЮЩЕЙ ТОРМОЗНОЙ КОЛОДКОЙ

ИССЛЕДОВАНИЕ ДИНАМИЧЕСКИХ ХАРАКТЕРИСТИК ДИСКОВОГО ТОРМОЗА С ПЛАВАЮЩЕЙ ТОРМОЗНОЙ КОЛОДКОЙ

Free damped vibration analysis of Mindlin plates with hybrid material-foundation viscoelasticity

Suppressed vibration of shear deformable plates with hybrid viscoelastic damping of material and foundation is investigated. Viscoelasticity of foundation is established by adopting Kelvin-Voigt model while viscoelasticity of materials is expressed by Boltzmann superposition integral, which uses dynamic mechanical analysis (DMA) results in terms of Prony series. Application of Laplace transformation and Mindlin plate theory with Hamilton principle led to a system of coupled integro-PDE of motions. Weighted residual method, numerical iterative algorithm and Fourier transform are implemented to achieve complex frequencies and transient responses of plates. Assessment of accuracy is carried out in the both elastic and viscoelastic domains. In the earlier, the frequencies are compared with counterparts obtained by p-version Ritz method and in the latter, dynamic characteristics of Mindlin and classic plates are examined that represent acceptable correlation. The influences of hybrid material-foundation damping, edge conditions, foundation characteristics and geometrical parameters on dynamic characteristics of plates are studied via a set of parametric study.

Theoretical and Experimental Study for Free Vibration for Cantilever Plate Partially or Totally Submerged in Fluid

In this thesis the dynamic characteristics (natural frequency and mode shape) of cantilever plates was studied when they immersed partially or totally in the fluid. The viscosity, density and compressibility of the fluid were taken into account in the theoretical analysis by using the (ANSYS Package) which mainly depends on the (Finite Element Method) in the analysis; by execute interaction between fluid and plate in the interface surface. The (damping analysis) method was used to analyze the new fluid-plate system; this new system is different in its characteristics when compared with the characteristics of the fluid or plate individually. The results were compared with the dry plate characteristics, which were obtained by using the same analyses package, but in this case the (modal analyses) method was used.The natural frequencies and mode shapes for cantilever plates with different aspect ratios immersed in different ratios in fluid were obtained. The effects of submerging ratio and aspect ratio on the plate's dynamic characteristics theoretically and experimentally were investigated. The results showed that, the submerged of cantilever plate in fluid reduce the natural frequency, and this depends on the fluid type, submerged ratio and aspect ratio, and the density is the most influential fluid property on the dynamic characteristics of the plate.

Optimization of the static and dynamic characteristics of plates with isogrid stiffeners

In this paper, the orientation angles of stiffeners arranged in the form of isogrid configuration over a flat plate are selected to optimize the static and dynamic characteristics of these plates/stiffeners assemblies. The static characteristics are optimized by maximizing the critical buckling loads of the isogrid plate, while the dynamic characteristics are optimized by maximizing multiple natural frequencies of the stiffened plate. A finite element model is developed to describe the statics and dynamics of Mindlin plates which are stiffened with arbitrarily oriented stiffeners. The model is used as a basis for optimizing separately or simultaneously the critical buckling loads and natural frequencies of the plates per unit volume of the plates/stiffeners assemblies. Numerical examples are presented to demonstrate the utility of the developed model and optimization procedures. The presented approach can be invaluable in the design of plates with isogrid stiffeners for various vibration and noise control applications.

On the quintic nonlinear Schrödinger equation created by the vibrations of a square plate on a weakly nonlinear elastic foundation and the stability of the uniform solution

Plates are common structural elements of most engineering structures, including aerospace, automotive, and civil engineering structures. The study of plates from theoretical perspective as well as experimental viewpoint is fundamental to understanding of the behavior of such structures. The dynamic characteristics of plates, such as natural vibrations, transient responses for the external forces and so on, are especially of importance in actual environments. In this paper, we conside the envelope surface created by the vibrations of a square plate on a weakly nonliner elastic foundation and analyze the stability of the uniform solution of the governing equation for the envelope surface. We derive the two-dimensional equation that governs the spatial and temporal evolution of the envelope surface on cubic nonlinear elastic foundation. The fact that the governing equation becomes the quintic nonlinear Schrödinger equation is shown. Also we obtain the stability condition of the uniform solution of the quintic nonlinear Schrödinger equation.

Governing equations of envelope surface created by nearly bichromatic waves propagating on an elastic plate and their stability

Plates are common structural elements of most engineering structures, including aerospace, automotive, and civil engineering structures. The study of plates from theoretical perspective as well as experimental viewpoint is fundamental to understanding of the behavior of such structures. The dynamic characteristics of plates, such as natural vibrations, transient responses for the external forces and so on, are especially of importance in actual environments. In this paper, we consider natural vibrations of an elastic plate and the propagation of a wavepacket on it. We derive the two-dimensional equations that govern the spatial and temporal evolution of the amplitude of a wavepacket and discuss its features. We especially consider wavenumber-based nearly bichromatic waves and direction-based nearly bichromatic waves on an elastic plate. The former waves are defined by the waves that almost concentrate the energy in two wavenumbers, which are very closely approached each other. The latter waves are defined by the waves that almost concentrate the energy in two propagation directions and two propagation directions are very close each other. The fact that the solution of the governing equation for wavenumber-based nearly bichromatic waves is stable is also shown.

A Comment on Governing Equations of Envelope Surface Created by a Two-Dimensional Directional Wavepacket Centered around a Propagation Direction on an Elastic Plate

Plates are common structural elements of most engineering structures, including aerospace, automotive, and civil engineering structures. The study of plates from theoretical perspective as well as experimental viewpoint is fundamental to understanding of the behavior of such structures. The dynamic characteristics of plates, such as natural vibrations, transient responses for the external forces and so on, are especially of importance in actual environments. In this paper, we consider natural vibrations of an elastic plate and the propagation of a wavepacket on it. We derive the two-dimensional equations that govern the spatial and temporal evolution of the amplitude of a wavepacket and discuss its features. We especially consider a directional wavepacket on an elastic plate, which propagation direction is centered around a main direction, but which wavenumber and frequency are fixed by a certain value. The fact that its envelope becomes time-invariant and is governed by the Schrodinger–Nohara type equation is shown.

Dynamic regularities of plate motion

Abstract On the basis of an analysis of dynamic characteristics of plates (vectors of angular momenta and momenta, their components, etc.), important dynamic regularities (laws) in positions and motions of the plates were discovered.

Vibration of stepped thickness plates

The vibration characteristics of stepped thickness plates of rectangular geometry with simply supported edges are investigated through an exact analysis. To illustrate the effect of sudden variation of thickness in the step form on the dynamic characteristics of plates, numerical calculations have been made for various combinations of thickness step, step-length ratio and side ratio. Natural frequencies for the first eight to nine modes are presented in the form of tables. Nodal lines are also plotted for a few selected cases. Several interesting features such as that of the thickness step splitting the degenerate frequencies of uniform rectangular plates into distinct ones, and the “frequency crossing” of some of the modes are observed.