Bending response of laser-welded web-core sandwich plates

Ultimate strength behavior of laser-welded web-core sandwich plates under in-plane compression

Analysis And Design Of Steel Plate Shear Walls Using Orthotropic Membrane Model

This paper uses a quasi-3D refined shear deformation plate theory to investigate the buckling response of supported functionally graded (FG) porous sandwich (SW) plates. The material properties of FG sandwich porous plates (SWPPs) are defined by a modified mixing rule, supplemented by an additional term representing the porosity in the thickness of the FG layer. By incorporating indefinite integral variables, the number of unknowns and governing equations of the current theory is reduced, making it easier to use. Three common types of sandwich porous plates are considered in the analysis: an isotropic FG porous plate, an FG face plate with a homogeneous core, and a homogeneous face plate with an FG core. The current method considers both normal and shear deformations and satisfies the transverse shear stress-free boundary conditions at the top and bottom surfaces of the plate. The equilibrium equations are derived using the principle of virtual displacements. These equations are then solved using the Navier-type method. The influence of thickness strain and several parameters, including mechanical loads, porosity coefficients, layer thickness ratios, geometric parameters, and gradient indices, are studied. The numerical results of the present theory are similar to the predictions of quasi-3D theories with more unknowns, in addition to being more accurate than those obtained by higher-order shear deformation theories. The findings support the idea that the suggested theory offers an easy and effective method for predicting the buckling behavior of FG porous sandwich plates. The results show that, without taking into account transverse normal deformations, the plate is softer and the critical buckling load decreases. On the other hand, with transverse normal deformations, the plate is stiffer, which increases the critical buckling load.

Cellular plates consist of two face plates and a stiffener grid welded between them. One of their advantageous properties is that they can be calculated as isotropic ones. This property is utilized in the present study for a simply supported square plate loaded by a uniformly distributed normal load. Design constraints on normal stresses and on maximum deflection are formulated. The unknown variables are the two face plate thicknesses, the height of the welded T-section stiffeners and the number of stiffener spacing, The cost function contents the cost of material, assembly and welding. The optimum is determined by a systematic search using a Mathcad program. Welded T-stiffeners are more economic than the halved rolled I-section ones.

The effect of processing parameters, assembly parameters, and plate thickness on the weld bead geometry was examined, and the microstructure and microhardness of the typical joints were investigated in this paper. There are two kinds of welds, these are the Y-type and V-type welds in different heat input. Heat input has a small effect on bead width at the interface when the thickness of face plate is more than 3 mm. The variation of bead geometry is little when gap and offset size is small, while porosity or depression forms with increasing gap and offset. Plate thickness exerts a remarkable effect on the bead width at interface, and a big bead width at interface can be achieved by adopting thin face plate. The centricity of the laser beam is a big problem in laser lap welding T-joints with thin core plate, while bead width at interface is small in laser lap welding T-joints with thick face plate. Microstructure of heat-affected zone and fusion zone is composed of lath martensite and bainitic ferrite. Microhardness of fusion zone is lowest due to the coarse lath martensite. The desired bead geometry of laser lap welded T-joints can be produced by adopting low welding speed, thin face plate, and small gap.

Global bending response of composite sandwich plates with corrugated core. Part II: Effect of laminate construction

In this paper, a spectral finite element method for a rectangular sandwich plate with viscoelastic core having the Levy-type boundary conditions has been plated. The sandwich plate consists of two isotropic and elastic face plates with a surfaced-bonded viscoelastic core. For the analysis, the in-plane and transverse energy in the face plates and only shear energy in the core are considered, respectively. To account for the frequency dependent complex shear modulus of the viscoelastic core, the Golla-Hughes-McTavish model is adopted. To evaluate the validity and accuracy of the proposed method, the frequency response function and dynamic responses of the sandwich plate with all edges simply supported subject to an impact load are calculated and compared with those calculated by a finite element method. Though these calculations, it is confirmed that the proposed method is very reliable and efficient one for vibration analysis of a rectangular sandwich plate with viscoelastic core having the Levy-type boundary conditions.

This study aims to investigate the effect of changing skins material on the strength of sandwich plates with circular hole when subjected to mechanical loads. Theoretical, numerical and experimental analyses are done for sandwich plates with hole and with two face sheet materials. Theoretical analysis is performed by using sandwich plate theory which depends on the first order shear deformation theory for plates subjected to tension and bending separately. Finite element method was used to analyse numerically all cases by ANSYS program.
 The sandwich plates were investigated experimentally under bending and buckling load separately. The relationship between stresses and the ratio of hole diameter to plate width (d/b) are built, by studying the effect of hole size on strength of sandwich plates. The maximum stress were developed at the hole region in sandwich plates clarified the dropped in their strength. So, the experimental maximum stress was found by means of multiplying the experimental nominal stress obtained from Stress-strain curve by the stress concentration factor.
 All results which obtained, theoretically, numerically and experimentally are compared to find that the hole weaken the strength of sandwich plates because of the stress concentration and that weakness is depending on the hole size and the face sheets materials.

Thermal buckling of angle-ply laminated composite and sandwich plates according to a global higher-order deformation theory

Based on Reissner’s sandwich plate theory, the critical globlal buckling equation of sandwich plate with ribs is deduced by energy method under simple support boundary conditions. And the critical buckling solution is obtained and discussed here. Afterwards a rectangular sandwich plate with steel faceplate and polyurthane core is taken as an example. The influence on critical global buckling stress with different inertia moments in rectangular sandwich plates are discussed. simularly the effect of the lengh ratio of two sides and the thickness of rectangular sandwich plate are also studied.

C0 triangular elements based on the Refined Zigzag Theory for multilayer composite and sandwich plates

Flexural analysis of functionally graded sandwich plate with piezoelectric face sheet based on Lagrangian mechanics

In a sequence of three recent papers a new flexural theory of elastic sandwich plates has been developed, 2 and, on the basis of the theory, the flexural vibration of sandwich plates has been analyzed. The theory is good for a very wide frequency range that is of practical interest, but vibration analysis on the basis of the theory will in general be complicated due to the high order of the equations. For low frequency ranges and for ordinary sandwich plates that have very thin face layers simplified treatment of the vibration problem becomes possible and is discussed in this paper. Simpler equations of motion of sandwich plates are introduced, and their accuracy is determined by comparing with the previous more complete equations.

One of the insufficiently resolved problems related to the use of steel I-beams with sinusoidally corrugated webs that are becoming more popular in modern building practice is a behavior of its webs under patch loadings.According to modern design codes corrugated webs of welded beams under patch loading action via on of the flanges in the web plane should be checked for strength under the condition of elastic behavior of steel. But nowadays standard scientific justified technique for such analyses is absent.This paper proposes numerically analytic method for corrugated web limit state determination under patch loading, which is based on stress-strain state analysis via FEM of physico-mathematical models created according to standard corrugated profiles range of company Zeman.In the strength analysis the beams were modeled by finite elements of thin shell under the condition of elastic behavior of steel. It’s established that the web height practically don’t have an effect on the values of normal stresses at the level of its connection with the flange. The web thickness and the distribution length of the patch loading exert the main impact on the value of local stresses.A generic table that allows finding all necessary data to determine the maximum value of local patch loading under the condition of steel elastic behavior was developed. In the cases when flange thickness or distribution length of the patch loading is different to the table values it is necessary to use the linear interpolation method.Considering that in the area of local stresses the tangential stresses act simultaneously with the normal stresses, the web strength is proposed to be checked by the Huber-Mises-Hencky criterion.The application of the developed technique makes it possible to determine with a given accuracy the value of local stresses in the web and, if necessary, to correct its thickness or the flange thickness. This procedure allows refining the required web thickness when patch local loading affects it and, thus, reduces consumption of steel.

The article describes a way to increase the stability of the transversely corrugated thin web plate of an I-beam due to the use of a double corrugation profile (multi-corrugation). The results of a numerical experiment (performed at LIRA-CAD software) of a large-scale models of beams with transversely corrugated web plates of various profiles (including double corrugation profile), with identical spans, cross sections, boundary conditions, loads, and material characteristics are presented. Distribution diagram of normal and shear stresses in cross sections, deflections, and the forms of buckling of corrugated web plates with safety factors for various models are presented. Based on the calculation results, a comparative analysis of the stress-strain state of the beam models was completed.