Steel Sandwich Plate Research Articles

Experiment on different T-joint characteristics for laser-welded I-core galvanized steel sandwich plates

The sandwich plate is one of the lightweight structures that have been utilized in lightweight applications. One of the topologies, such as I-core, was designed to evaluate the mechanical behavior when subjected to 3-point bending test. A theoretical formula for an I-core sandwich plates was discussed on the bending stiffness. In this project, galvanized steel elements (faceplate and core) were fabricated through welding. The manufacturing process for both galvanised steel and PVC foam was mentioned in detail, and the laser weld geometry parameters were summarized. Significantly, T-joint were made into different weld dimension characteristic. Hence, special equipment was used to assemble the elements. Overall, the study shows a positive outcome. It can be seen that with and without rootgap divide the centric and eccentric characteristic curve. The sequence from higher to lower stiffness is as follows: centric + no rootgap > eccentric + no rootgap > centric + rootgap > eccentric + rootgap. An ideal characteristic generates higher stiffness than other failures by inserting PVC foam: for instance, eccentric + no rootgap presented 5.2% difference from ideal. Furthermore, faceplate failure mode is a noticeable deformation displayed during the experiment, such as face wrinkling and face yielding. Meanwhile, debonding is also a notable failure mode, demonstrated at the T-joint and PVC foam. Therefore, this study provides a useful understanding of strength and stiffness via different T-joint weld dimension characteristics and failure mode of I-core sandwich plates.

Investigation of rolling shear properties of cross-laminated timber (CLT) and comparison of experimental approaches

The structural behaviour of a cross laminated timber (CLT) system is dictated in-part by the rolling shear properties (both strength fr and modulus Gr) of its laminates. To investigate the rolling shear properties of CLT, short-span four-point bending tests, modified planar shear (MPS) tests with timber sandwich plates, and MPS tests with steel sandwich plates were conducted on Australian grown Eucalyptus nitens and radiata pine, as well as European grown Norway spruce. A strong positive relationship between aspect ratio and strength was found, which agrees with previous research. However, the annual ring orientation distribution rather than the aspect ratio was shown to have the most pronounced effect on the shear modulus. The load direction, which has not been accounted for by researchers, was shown to have a substantial effect on the measured rolling shear strength. When the applied load direction was parallel to the annual rings, the Eucalyptus nitens, radiata pine and Norway spruce specimens exhibited rolling shear strengths of 4.1, 2.7 and 1.7 MPa respectively. These average recorded strengths were found to decrease by 16%, 40% and 52% respectively when the load direction was changed to run perpendicular to the rings instead. By directly measuring the shear deformations of two specimens tested under different MPS approaches using Digital Image Correlation (DIC), the impact of the plate material on the recorded shear modulus was isolated. This revealed that the MPS tests with steel plates recorded average rolling shear modulus values which were as much as 42% higher than their counterparts with timber plates, as well as identifying substantial errors in laser and LVDT-like measurement tools. It is recommended that a DIC approach is employed to complement or replace a UTM or laser sensor deformation measurement approach to mitigate these potential errors.

Numerical simulation on the anti-penetration performance of polyurea-core Weldox 460 E steel sandwich plates

Polyurea has the characteristic of strong energy absorption capacity, and thus it is considered to be an excellent material for structural protection. Therefore, research on the anti-penetration performance of polyurea-core sandwich plates is of great significance for understanding the mechanism of protection and extending its application. In this paper, the anti-penetration performance of polyurea-core sandwich plates is investigated by using the AUTODYN-2D axisymmetric algorithm. Firstly, the accuracy of the numerical algorithm and the polyurea material model are both validated against the experimental data. On the basis, four different thicknesses (from 8 mm to 20 mm) of the interlayer and seven different initial impact velocities (from 300 m/s to 1100 m/s) are selected to study the anti-penetration performance of the polyurea-core sandwich plates under different conditions. Meanwhile, the comparative numerical cases are also performed using rubber-core sandwich plates. The results show that during the penetration, the polyurea presents obvious self-closing behavior, which increases the ballistic resistance. With respect to the rubber-core sandwich plate, the velocity drop per unit areal density of the polyurea-core sandwich plate, as well as the energy absorption ratio, is always greater. As a result, the polyurea interlayer can significantly improve the anti-penetration performance of the sandwich plate.

Study and analysis of heat transfer performance of colored steel sandwich plate

Abstract The experimental research and theoretical analysis of the thermal performance of 4 kinds of colored steel polystyrene sandwich plates and 4 kinds of colored steel rock wool sandwich plates were carried out in this thesis, and the thickness of colored steel polystyrene sandwich plates and colored steel rock wool sandwich plates was 50 mm, 75 mm, 100 mm and 125 mm, respectively. The steady-state heat transfer test device was adopted to test the test specimens, and then the heat transfer coefficient of each test specimen was calculated through the test principle and test results. Later, the heat transfer coefficient values of 8 test specimens were compared and analyzed, and the regression equation that the heat transfer coefficient changed with the thickness of sandwich insulation materials was acquired. The research and analysis indicated that the thermal insulation performance of colored steel sandwich plates changed with the thickness of sandwich plates. When the thickness was less than 75 mm, it showed a linear trend. When the thickness was greater than 75 mm, it changed in the form of a curve, and the slope of the curve decreased with the increase of the thickness. That is, the impact of increasing the thickness of insulation materials on heat transfer performance decreased gradually. The regression curve equation calculated on the basis of the test data could provide reference for the engineering design and application of colored steel sandwich plate.

DYNAMIC BEHAVIOUR OF SANDWICH PLATE WITH DIFFERENT CORE CONFIGURATION UNDER ACTION OF IMPULSIVE LOADING

Steel sandwich structures with honeycomb and corrugated cellular cores have demonstrated the capability of supporting significant static bending loads while also enabling effective mitigation of impulse loads, the main objectives to use these structures is weight reduction and isolate or reduce the deflection and stress. This research aims to study the effect of dynamic load on the dynamic properties of various types of sandwich cores then find the best model that withstand high stresses and dissipate loads with less mass was possible. The studied model of sandwich is of dimensions (500x500x100) mm with five cells. Four types of steel sandwich plate (SSP) finite element models of various core types have been created: (1) triangle corrugated core, (2) trapezoid corrugated core, (3) square honeycomb and (4) out-of plane hexagonal honeycomb, the mass of various types was constant with value of 13.75 kg. The SSP types were compared by using ANSYS (15.0) APDL software.The finite element models are examined under the effect of transient concentrated stepped load of (350N) during 10ms. The time history response showed that the minimum von-Mises stress and minimum deflection occur at triangle corrugated SSP with values of stress (12.5Mpa) and deflection (3.8 ), but in energy absorption the square honeycomb is the best type with reduction of stress (99.65%) and reduction of deflection of (98.95%).

Numerical study of steel sandwich plates with RPF and VR cores materials under free air blast loads

One of the most important design criteria in military tunnels and armoured doors is to resist the blast loads with minimum structural weight. This can be achieved by using steel sandwich panels. In this paper, the nonlinear behaviour of steel sandwich panels, with different core materials: (1) Hollow (no core material); (2) Rigid Polyurethane Foam (RPF); and (3) Vulcanized Rubber (VR) under free air blast loads, was investigated using detailed 3D nonlinear finite element models in Ansys Autodyn. The accuracy of the finite element model proposed was verified using available experimental test data of a similar steel sandwich panel tested. The results show the developed finite element model can be reliably used to simulate the nonlinear behaviour of the steel sandwich panels under free air blast loads. The verified finite element model was used to examine the different parameters of the steel sandwich panel with different core materials. The result shows that the sandwich panel with RPF core material is more efficient than the VR sandwich panel followed by the Hollow sandwich panels. The average maximum displacement of RPF sandwich panel under different ranges of TNT charge (1 kg to 10 kg at a standoff distance of 1 m) is 49% and 53% less than the VR and Hollow sandwich panels, respectively. Detailed empirical design equations were provided to quantify the maximum deformation of the steel sandwich panels with different core materials and core thickness under a different range of blast loads. The developed equations can be used as a guide for engineer to design steel sandwich panels with RPF and VR core material under a different range of free air blast loads.

Geometrical parameters influence on the stiffness of steel sandwich plates with web-core

Laser welded sandwich plates with web-core have found their position in the marine and land vehicles. To implement such design accurately, knowledge about the influence of geometrical parameters on the stiffness is necessary. In this paper, the over-hanging three points bending tests were performed on the laser welded web-core steel sandwich plate under quasi-static conditions, together with the finite element (FE) simulations. The following parameters were analysed: the thickness of the face plate, the spacing of the two core plates and the height of the core plates. The agreement between experimental measurements and FE results was considered to be good. It is shown that changes of these parameters can contribute to increase or decrease of the stiffness of web-core sandwich plate, but the height of the core plate has no effect on the shear stiffness as the spacing of the two core plates is known. There are linear, exponential and polynomial fitted relationships between the geometrical and the stiffness of the web-core sandwich plates.

Design and behavior of steel–concrete–steel sandwich plates subject to concentrated loads

This paper investigates, experimentally and analytically, the ultimate strength behavior of steel–concrete–steel (SCS) sandwich plates under concentrated loads. The proposed SCS sandwich plate consists of two external steel plates and a sandwiched concrete core. 17 quasi-static were carried out to evaluate their structural performances under concentrated loads. 20 test data in the literature were used to analyze the failure mode and load-transferring mechanisms of the SCS sandwich plate under concentrated loads. The influences of sandwich plates with different plate geometry, diameter of connectors and their spacing, and concrete core strengths were analyzed and discussed. Theoretical models were developed to predict the resistances of the connectors, flexural resistance of the SCS sandwich plate, punching resistances of the concrete core and punching resistance of the top steel plate. Design methods were then developed to predict the maximum resistance of SCS sandwich plate subject to concentrated load based on the minimum the design resistance calculated for each individual components. The accuracy of the design methods were validated against the test results. Finally, the ultimate load resistance of the SCS sandwich plate was compared with the ice-contact pressure in ISO code to check its applicability for use as ice-resisting wall in the arctic region.

Ultimate strength behaviour of steel–concrete–steel sandwich plate under concentrated loads

This paper studied ultimate strength behaviour of Steel–Concrete–Steel (SCS) sandwich plate under concentrated loads. Eight square SCS sandwich plates were simply supported and tested to failure under concentrated loads. The investigated parameters included strength of the core material, thickness of the steel skin plate, content of the steel fibre in the core, size of the loading area, and different type of the fibre. Test results showed that SCS sandwich plate exhibited two peak resistances that benefited from the tension membrane action of the top steel skin, which behaved differently from reinforced concrete structures. The influences of different parameters on ultimate strength behaviours of SCS sandwich plate have been analysed and discussed. On the basis of the experimental studies, analysis and discussions, theoretical models were developed to predict the ultimate resistances of the SCS sandwich plate under concentrated loads. The developed models considered the punching shear resistance of the top steel skin plate, modified the resistance contributed by the headed studs, adopting proper critical perimeter for the punching cone, and developing formulae for the second peak resistance. The analytical models were observed predicting well the ultimate resistances of the SCS sandwich plates.

Damping strategies for steel lattice sandwich constructions

A square steel sandwich plate with lattice corrugated core is explored for damping improvement. A range of damping materials are filled inside the openings provided by the corrugated core, or are applied on the surfaces of the facesheets. The dynamic properties such as natural frequency and damping factor are experimentally measured for the sandwich plate with each filling solution. The relative performance of each insertion is compared in terms of damping capacity and added mass.

Bending Properties of Laser Welded Web-Core Steel Sandwich Plates

This paper presents a detailed discussion of the bending properties of laser welded web-core steel sandwich plates and the influence of weld width on stiffness and strength. The over-hanging three point bending test was conducted on the laser welded web-core steel sandwich plates with various welds width by self-designed device, together with the finite element simulations. A good agreement is obtained between the 2D FE analyses and experiment results. The stiffness and strength of the sandwich plates increased with the increasing of weld width, especially for the weld width lower than 60% thickness of the core plate. It is necessary to consider the weld width in the design and evaluation of the stiffness and strength of the laser welded web-core sandwich plate. Base on the results, the FEM is the priority to analysis bending properties of laser welded web-core steel sandwich plates.

Influence of general corrosion on buckling strength of laser-welded web-core sandwich plates

The strength of a web-core steel sandwich plate is potentially reduced in a corrosive environment. This study is dedicated to the influence of a reduction in the thickness of the plates as a result of general corrosion on sandwich plate buckling strength and first-fibre failure. Two scenarios are investigated in which corrosion reduces the thickness of (a) the outer sides of the face plates and (b) all surfaces, including the core. The laser weld between the face sheets and the core is assumed to be intact. The assumptions are made on the basis of earlier experimental findings. Critical buckling and geometric non-linear analysis are carried out with the finite element method, with the kinematics being represented using two approaches: (1) equivalent single-layer with first-order shear deformation theory, and (2) a three-dimensional model of the actual geometry of the structure, modelled using shell and connector elements. The former is used to identify the effect of corrosion on the stiffness coefficients and, consequently, the buckling strength. The latter is used for verification and for stress prediction during post-buckling. A rapid decrease in the buckling strength was found for corrosion affecting the outer sides of the sandwich plate. The decrease in the buckling strength doubled in the case of the diffusion of moisture (water) into the core. The shear-induced secondary bending of the faces was found to affect the first-fibre yield.

The Strength of Laser Welded Web-Core Steel Sandwich Plates

All steel laser welded sandwich plates have found their position in the marine and land vehicles. To implement such design accurately, knowledge about its strength properties and the influence of laser weld dimensions on strength is necessary. In this paper, the over-hanging three point bending tests were conducted on the laser welded web-core steel sandwich plate with various weld dimensions by self-designed device, together with the finite element simulations. The results show that the joint is formed on the first plastic hinge when the load is no longer a linear relationship with the deflection, and the joint cracking when the load reaches the maximum bearing capacity of sandwich plate. The joint yield load and the maximum bearing capacity of the sandwich plates increased with the increasing of weld width. Meanwhile, the mode of failure of sandwich plates also changed: When the weld width is smaller, the mode of failure is joint yield, When the weld width is greater than 3mm, the mode of failure is the combination of partial joint yield, face plate and core plate local yield, while the face plate and core plate yield exists in the whole weld joint. It is necessary to consider the weld width in the design and evaluation of the strength of the laser welded web-core sandwich plate.

The Effect of Weld Geometry on the Stiffness of I-Core Steel Sandwich Plate

This paper presents the influence of the weld widthroot gapand weld offset of the T-joint to the overall stiffness of sandwich plate with finite element simulations. From the results of finite element calculation and some of experimental verification we can see:(1) For this structure, welding joint damage occurs before the face plate buckling.(2) Among the factors weld widthgap and weld offset of the T-joint, the weld width affect the overall stiffness the most. (3) When root gap and weld offset lower 0.1mm and 0.12 mm, respectively, they have a little influence on the resistance of deformation ability for the sandwich plate, they can be ignore.

The Crashworthiness Properties of Rectangular Column Steel Sandwich Protection Devices for the Bridges

In the paper, the protective equipments of the bridges were studied. The new type of protective devices, which was the rectangular column sandwich plate protective devices, and they were suggested. The ANSYS/LS-DYNA, which is non-linear dynamics finite element software, was applied to simulate the crashworthiness performance of the rectangular column steel sandwich plate, and analyzed the crashworthiness performance factors of the sandwich plate from the different structure parameters to optimize the overall crashworthiness sandwich plate. After structural optimization, it can be gotten that the rectangular column sandwich plates were better than traditional steel plates in crashworthiness performance. Then, the sandwich plate was used to replace the outside steel plates of the traditional box-protective device, from that obtained the overall crashworthiness performance of the rectangular column steel sandwich protective devices were better than the traditional box-protective device.

Fatigue Tests and Numerical Analyses of a Connection of Steel Sandwich Plates

In shipbuilding, steel sandwich plates are applied in several areas. Particularly the connections between the sandwich plates may be prone to fatigue in the case of cyclic loads. Therefore, the fatigue strength of a fillet-welded connection of a steel sandwich plate under in-plane loading has been investigated experimentally and numerically. Numerical calculations are performed using the crack propagation and the effective notch stress approach. In the notch stress approach, the modelling of the weld root may create problems as the relatively thin face plates are affected by the notch rounding of 1 mm. Two different shapes are considered. Furthermore, the small size notch approach with a reference radius of 0.05 mm is applied. From the comparison of the results with the fatigue strength found in the tests, conclusions are drawn for appropriate modelling.

Effect of plastic deformation on diffusion-rolling bonding of steel sandwich plates

Diffusion bonding is one of the most important techniques for composite materials, while bonding temperature, holding time, and rolling reduction are the key parameters that affect the bonding strength of sandwich plates. To study the effect of plastic deformation on the bonding strength, laboratory experiments were carried on a Gleeble Thermal Simulator to imitate the diffusion-rolling bonding under different reductions for steel sandwich plates. The bonding strength and interlayer film thickness were measured, and the element diffusion was analyzed using line scanning. The relationship between the bonding strength and “diffused interlayer” thickness was investigated. It has been found that the bonding strength increases with reduction, whereas the interlayer film thickness decreases gradually as the reduction increases. The diffusion under plastic deformation is obviously enhanced in comparison with that of nil reduction. The mechanism of plastic deformation effect on the diffusion bonding and related models have been discussed.

Modelling of constrained thin rubber layer with emphasis on damping

An interface finite element for the rubber layer in a steel–rubber–steel sandwich plate is developed. The novel element is based on a series expansion of the displacement field in the thickness direction. This technique makes it possible to achieve a high resolution of the displacement field in the thickness direction without adding more degrees-of-freedom in this direction. A fractional order viscoelastic model is used to describe the constitutive behavior of rubber. In particular, we consider a “Nitrile” type rubber and fit the model parameters to experiments. The purpose and the predictive capability of the interface element are investigated by calculating the harmonic response of sandwich plates. The results are then compared with measured responses as well as with responses obtained by a commercial general purpose finite element code and an analytical solution for a sandwich beam equation. Finally, we conclude that the interface element is accurate and efficient in the modelling of constrained rubber layers.