Two-plate Structure Research Articles

An effective model for bolted flange joints and its application in vibrations of bolted flange joint multiple-plate structures: Theory with experiment verification

Bolted flange joints are widely used in various engineering structures to combine two or more substructures together. However, the understanding of mechanical mechanism of bolted flange joints is still insufficient due to the lack of efficient mathematical models. This paper proposes an effective mathematical model for bolted flange joints, which is then employed to conduct vibration analysis on bolted flange joint multiple-plate structures. During the modeling process, the flange is modeled by the Kirchhoff plate theory, and the bolted joints are modeled by the two-dimensional face constraint in bolted joint affected region (BJAR). The artificial spring technique is adopted to simulate the face constraint. The friction contact model and equivalent linearization technique are adopted to analyze the stick and slip states of bolted joints. By adopting the Chebyshev orthogonal polynomials as admissible functions, governing equations are derived. Then, the Rayleigh-Ritz method is applied to study the free vibration characteristics, and the Newmark-beta method is employed to study the vibration response under base excitation. The experimental studies are performed on the bolted flange joint two-plate structure (BFJTPS) to illustrate the effectiveness of the proposed theoretical model. The results indicate that the proposed mathematical model can well predict the vibration characteristics of multiple-plate structures under both bolt looseness and no-looseness conditions. The soft nonlinearity phenomenon under bolt looseness condition can be successfully revealed by the model.

Scattering of Oblique Water Waves by Two Unequal Surface-Piercing Vertical Thin Plates with Stepped Bottom Topography

Based on linear water-wave theory, this study investigated the scattering of oblique incident water waves by two unequal surface-piercing thin vertical rigid plates with stepped bottom topography. By using the matched eigenfunction expansion method and a least square approach, the analytical solutions are sought for the established boundary value problem. The effects of the incidence angle, location of step, depth ratio of deep to shallow waters, and column width between two plates, on the reflection coefficients, the horizontal wave forces acting on the two plates, and the mean surface elevation between the two plates, are numerically examined under a variety of wave conditions. The results show that the existence of the stepped bottom between two plates considerably impacts the hydrodynamic performances of the present system. It is found that the effect of stepped bottom on the reflection coefficient of the present two-plate structure is evident only with waves of the low dimensionless frequency. Moreover, the influence of the step location on the hydrodynamic performance of the present two-plate structure is slight if the step is placed in between the two plates.

Power flow analysis of built-up plate structures using the dynamic stiffness method

The dynamic stiffness method (DSM) in our recent paper, which can consider both in-plane and out-of-plane vibrations simultaneously, is formulated to investigate the power flow characteristics of built-up plate structures. Prior to power flow analysis, comprehensive validation works on our DSM are performed so as to better exhibit its numerical capabilities. Power input and power transmission within a two-plate structure are then analyzed by following the context of in-plane and out-of-plane vibrations. In addition, three vibration transmission paths within a multiple plate structure are characterized in terms of power flow densities, which can provide better physical insights in vibration transmission within complex plate structures. Compared to power flow analysis based on the well-known reception/mobility method, our approach is strongly recommended for the dynamics of built-up structures since it can assemble the overall stiffness matrix in a straightforward manner like that in the conventional finite element technique.

Vibration Transmission within Beam-stiffened Plate Structures Using Dynamic Stiffness Method

The dynamic stiffness method (DSM), which considers both in-plane and out-of-plane vibrations, is employed to investigate the vibration transmission of built-up plate structures. Two numerical examples are designated to demonstrate the capabilities of this method. First, representative transmission modes for a flat plate stiffened a single stiffener are presented, which would help us in composing physical images on wave propagation phenomenon. In addition, power input and power transmission within a two-plate structure are analyzed by following the context of in-plane and out-of-plane vibrations. This work is recommended to address in-depth the understanding of vibration transmission using the dynamic stiffness method, such as wave reflection, refraction, wave type conversion, and etc.

A Miniature Two-Plate Electrical Capacitance Tomography Sensor

As one of tomographic imaging techniques, electrical capacitance tomography (ECT) has been successfully applied to many industrial applications. While ECT sensors are normally circular, some other shapes, such as square and parallel, are demanded for some specific applications. This paper introduces an ECT sensor with a two-plate structure, providing incomplete measurement data only. It is flexible to place the two electrode plates, for fitting a sensing space. Four aspects of the sensor are discussed based on the software simulation: 1) the effective sensing area; 2) the distance between the two plates; 3) the angle between the two plates; and 4) the number of electrodes. A two-plate ECT sensor with 2 × 3 electrodes on each plate is fabricated. Capacitance is measured by an ECT system based on impedance analyzer. Images of different permittivity distributions are generated by linear-back projection and Landweber iteration algorithms. The experimental results show that the two-plate ECT sensor can produce good images similar to a conventional ECT sensor.

A two-plate lateral photonic crystal with controllable negative refraction

We propose a two-plate lateral photonic crystal (LPC) with controllable negative refraction. Our experiment and analysis demonstrate that the electromagnetic wave can be negatively refracted between two parallel periodic metal plates. The negative refraction is provided by lateral periodicity of the two-plate structure. The lateral mechanism reduces the interaction between the wave and the periodic medium as compared with bulk photonic crystals. The simplicity of the LPC allows for easy control of its parameters. Variation of spacing between the plates controls negative refraction by varying the focal length of a proposed lateral photonic crystal.