Rationally-Based Structural Design of Welded Plate Panels

This study predicts the behavior of welded plate panels (unstiffened plates) with different geometrical properties (slenderness ratio and aspect ratio) in order to address a rational structural design procedure, as these parameters are of great importance from a structural design perspective. Nonlinear finite element analysis has been used to simulate the butt-welding process of plate panels, giving the three-dimensional distribution of distortion and residual stresses induced by welding through the design of a moving heat source. The numerical results are validated with published experimental measurements. The effect of geometrical properties such as slenderness ratio β and aspect ratio a/b on the creation of welding-induced imperfections (distortion and residual stresses) have been investigated in this work. These geometrical properties influence the creation of the welding-induced imperfections, which in turn affect the load-carrying capacity of the plate panels. Three different plate slenderness ratios with three different aspect ratios have been studied. It is concluded that increasing the plate aspect ratio can highly increase the out-of-plane distortion magnitude as well as the compressive residual stress. The plates with high slenderness ratio (thin thicknesses) are highly affected by increasing plate aspect ratio a/b. As the slenderness ratio β increases, the reduction in the ultimate strength due to the existence of welding-induced imperfections highly decreases. Slenderness ratio β can highly affected the ultimate strength of plates with smaller aspect ratio more than plates with higher aspect ratio.

Concurrent Lamination and Tapering Optimization of Cantilever Composite Plates under Shear

The operational performance of cantilever composite structures can benefit from both stiffness tailoring and geometric design, yet, this potential has not been fully utilized in existing studies. The present study addresses this problem by simultaneously optimizing layer and taper angles of cantilever laminates. The design objective is selected as minimizing the average deflection of the tip edge subjected to shear loads while keeping the length and total volume constant. The plate stiffness properties are described by lamination parameters to eliminate the possible solution dependency on the initial assumptions regarding laminate configuration. The responses are computed via finite element analyses, while optimal design variables are determined using genetic algorithms. The results demonstrate that the plate aspect ratio significantly influences the effectiveness of stiffness tailoring and tapering as well as the optimal layer and taper angles. In addition, concurrent exploitation of the lamination characteristics and plate geometry is shown to be essential for achieving maximum performance. Moreover, individual and simultaneous optimization of layer and taper angles produce different optimal results, indicating the possible drawback of using sequential approaches in similar composite design problems.

Nonlinear Vibrations of Embedded Nanoplates Under In-Plane Magnetic Field Based on Nonlocal Elasticity Theory

Nonlinear vibrations of the orthotropic nanoplates subjected to an influence of in-plane magnetic field are considered. The model is based on the nonlocal elasticity theory. The governing equations for geometrically nonlinear vibrations use the von Kármán plate theory. Both the stress formulation and the Airy stress function are employed. The influence of the magnetic field is taken into account due to the Lorentz force yielded by Maxwell's equations. The developed approach is based on applying the Bubnov–Galerkin method and reducing partial differential equations to an ordinary differential equation. The effect of the magnetic field, elastic foundation, nonlocal parameter, and plate aspect ratio on the linear frequencies and the nonlinear ratio is illustrated and discussed.

Using Hyperbolic Shear Deformation Theory for Study and Analysis, the Thermal Bending of Functionally Graded Sandwich Plate Properties

Background: Several studies and patents have been carried out on the realization and optimization of structures and structural elements subjected to several-weights-critical-applications. Among the structures optimized in engineering, there are sandwich structures that are mainly used to react under these conditions. Objective: In this article, we have investigated the thermal bending response of simply supported Functionally Graded Sandwich Plate (FGSP). Methods: Using simple Hyperbolic Shear Deformation Theory (HSDT). A type of FGSP with both functionally graded materiel FGM face and ceramic hard core are considered. Based on the principle of virtual work, the governing equations are derived and then these equations are solved via Navier procedure. Analytical solutions are obtained to predict the deflection, axial and shear stress of FGSP. Results: To verify the efficiency of the present method a comparison with existing literature and patents results is employed. The influence of the plate aspect ratio, the relative thickness, the gradient index, the sandwich plate schemes, and the thermal loading conditions on the bending of FGSP are investigated. Conclusion: A good agreement is obtained between present results and the existing literature solutions. It can be concluded that the proposed theory is accurate and simple in solving the thermoelastic bending behavior of functionally graded sandwich plates. Various patents have been discussed.

Stochastic Vibration Analysis of Functionally Graded Plates with Material Randomness Using Cell-Based Smoothed Discrete Shear Gap Method

A cell-based smoothed finite element method with discrete shear gap technique is used to study the stochastic free vibration behavior of functionally graded plates with material uncertainty. The plate kinematics is based on the first-order shear deformation theory and the effective material properties are estimated by simple rule of mixtures. The input random field is represented by the Karhunen–Loéve expansion and the polynomial chaos expansion is used to represent the stochastic output response. The accuracy of the proposed approach in terms of the first- and the second-order statistical moments are demonstrated by comparing the results with the Monte Carlo Simulations. A systematic parametric study is carried out to bring out the influence of the material gradient index, the plate aspect ratio and the skewness of the plate on the stochastic global response of functionally graded plates. It is inferred that all the considered parameters significantly influence the statistical moments of the first fundamental mode.

Drag force on an accelerating submerged plate

We present results on the drag on, and the flow field around, a submerged rectangular normal flat plate, which is uniformly accelerated to a constant target velocity along a straight path. The plate aspect ratio is chosen to be $AR=2$ to resemble an oar blade in (competitive) rowing, the sport which inspired this study. The plate depth, i.e. the distance from the top of the plate to the air–water interface, the plate acceleration and the plate target velocity are varied, resulting in a plate width based Reynolds number of $4\times 10^{4}\lesssim Re\lesssim 8\times 10^{4}$. In our analysis we distinguish three phases; (i) the acceleration phase during which the plate drag is enhanced, (ii) the transition phase during which the plate drag decreases to a constant steady value upon which (iii) the steady phase is reached. The plate drag force is measured as function of time which showed that the steady-phase plate drag at a depth of $1/5$ plate height (20 mm depth for a plate height of 100 mm) increased by 45 % compared to the plate top at the surface (0 mm). Also, it is shown that the drag force during acceleration of the plate increases over time and is not captured by a single added mass coefficient for prolonged accelerations. Instead, an entrainment rate is defined that captures this behaviour. The formation of starting vortices and the wake development during the time of acceleration and transition towards a steady wake are studied using hydrogen bubble flow visualisations and particle image velocimetry. The formation time, as proposed by Gharib et al. (J. Fluid Mech., vol. 360, 1998, pp. 121–140), appears to be a universal time scale for the vortex formation during the transition phase.

Buckling Stability Assessment of Plates with Various Boundary Conditions Under Normal and Shear Stresses

In the present paper, the buckling behavior of plates subjected to shear and edge compression is investigated. The effects of the thickness, slenderness ratio and plate aspect ratio are investigated numerically. Effects of boundary conditions and loadings are also studied by considering different types of supports and loading. Finally, the results of numerical methods are compared with the theoretical results. This work mainly investigates the buckling behavior of plates but also the capabilities of program of plate-buckling (PPB) and ABAQUS for performing linear and nonlinear buckling analyses. The results will be useful for engineers designing walls or plates that have to support intermediate floors/loads.

Derivation of physical and optical properties of mid-latitude cirrus ice crystals for a size-resolved cloud microphysics model

Single-crystal images collected in mid-latitude cirrus are analyzed to provide internally consistent ice physical and optical properties for a size-resolved cloud microphysics model, including single-particle mass, projected area, fall speed, capacitance, single-scattering albedo, and asymmetry parameter. Using measurements gathered during two flights through a widespread synoptic cirrus shield, bullet rosettes are found to be the dominant identifiable habit among ice crystals with maximum dimension (Dmax) greater than 100 µm. Properties are therefore first derived for bullet rosettes based on measurements of arm lengths and widths, then for aggregates of bullet rosettes and for unclassified (irregular) crystals. Derived bullet rosette masses are substantially greater than reported in existing literature, whereas measured projected areas are similar or lesser, resulting in factors of 1.5–2 greater fall speeds, and, in the limit of large Dmax, near-infrared single-scattering albedo and asymmetry parameter (g) greater by ∼ 0.2 and 0.05, respectively. A model that includes commonly imaged side plane growth on bullet rosettes exhibits relatively little difference in microphysical and optical properties aside from ∼ 0.05 increase in mid-visible g primarily attributable to plate aspect ratio. In parcel simulations, ice size distribution, and g are sensitive to assumed ice properties.

Derivation of physical and optical properties of midlatitude cirrus ice crystals for a size-resolved cloud microphysics model

Single-crystal images collected in mid-latitude cirrus are analyzed to provide internally consistent ice physical and optical properties for a size-resolved cloud microphysics model, including single-particle mass, projected area, fall speed, capacitance, single-scattering albedo, and asymmetry parameter. Using measurements gathered during two flights through a widespread synoptic cirrus shield, bullet rosettes are found to be the dominant identifiable habit among ice crystals with maximum dimension (Dmax) greater than 100 μm. Properties are therefore first derived for bullet rosettes based on measurements of arm lengths and widths, then for aggregates of bullet rosettes and for unclassified (irregular) crystals. Derived bullet rosette masses are substantially greater than reported in existing literature, whereas measured projected areas are similar or lesser, resulting in factors of 1.5–2 greater fall speeds, and, in the limit of large Dmax, near-infrared single-scattering albedo and asymmetry parameter (g) greater by ~ 0.2 and 0.05, respectively. A model that includes commonly imaged side plane growth on bullet rosettes exhibits relatively little difference in microphysical and optical properties aside from ~ 0.05 increase in mid-visible g primarily attributable to plate aspect ratio. In parcel simulations, ice size distribution and g are sensitive to assumed ice properties.