Papers by Keyword: Sandwich Plate

Abstract: The influence of linear and non-linear temperature and moisture concentration distribution on the stress distribution was studied for metal/ceramic sandwich plate with transverse cracks. An interlaminar adhesive layer between two different layers is taken into account which transferring the normal stress and the interlaminar shear stress. The validation of the used model was done with the comparison of the stiffness reduction as a function of crack density and the experimental data. A comparison showed that a satisfactory qualitative and quantitative agreement was obtained. The temperature and moisture concentration variation are studied using the linear and non-linear distribution around the cracks to predict the stress distributions along the axis x. Finally, it observed through this study that the variations of the thermal and moisture concentration distribution largely impact the stress distribution for a sandwich plate with transverse cracks in the central layer and also with different mechanical properties of each layers.

Abstract: An 8-noded quadratic isoparametric plate bending finite element that incorporates first-order transverse shear deformation and rotary inertia is used to predict the free vibration response of sandwich plate structures. A programme has been developed using MATLAB. The finite element results presented here show good agreement with the available semi-analytical solutions and finite element results. Parametric studies have been conducted by incorporating variation in support conditions, fibre angles of the skins and overall thickness and detail interpretations are provided.

Abstract: Sandwich plates are one of the important components in construction of engineering and especially aerospace structures. In this paper, buckling analysis of sandwich plates was investigated experimentally and analytically using layerwise theory. The sandwich plate was rectangular and made of two composite laminates as skins and a viscoelastic core. The formulation was based on the first order shear deformation theory and the Rayleigh-Ritz method was used for approximating and determining the displacement field. The behavior of viscoelastic material modeled using Zener three-element model. The results obtained from layerwise theory compared with experimental results and showed good agreement. This study demonstrated that, layerwise theory could describe buckling behavior of sandwich plates with high accuracy and represents more realistic and acceptable description of behavior of the plates with much less computational cost.

Abstract: This paper investigated the damage degree and damage mechanism of aluminum sandwich plate subjected to blast loading by using numerical simulation method. Finite elements models of aluminum foam sandwich plates were established. The distortion and damage pattern of the sandwich plate under different masses of detonator were got by using LS-DYNA to simulate the destructive effect of shock wave and detonation product against sandwich plate. The results showed that the maximal deflection and overloading of the sandwich plates were different because of the changing of mass of detonator. This paper could provide some reference for the designing of sandwich structures.

Abstract: The cores have to be spliced in the manufacturing process of sandwich plate due to the processing technology, the influence of core splice, compared with integrated core, on mechanical behavior of sandwich plate were investigated through two experiments. Two styles of specimens (B-style and C-style) were taken into experiments in sequence which included two kinds of plate with different cores.Firstly, it was found in stiffness experiment that stiffness and strength of sandwich plate with splicing core were obviously weaker than that with integrated core, which mean the former performed larger deformation under the same predetermined load with higher strain and behaved lower ultimate bearing capacity. Meanwhile the failure modes were mainly sheet crushing collapse and there was no evident difference in the failure mode of the two styles specimens with different cores. It concluded that the cores splice reduced the stiffness in location of two core splicing but the effect on the failure mode was slight.Secondly, it was found in stability experiment that the mechanical behaviour was approximately linear under the predetermined axial load and the predetermined out-of-plane load and similarly bulking strength of the sandwich plate with splicing core was about 10%~15% lower than that with integrated core. Basically, delamination between sheet and core kept accompany with bulking of the plate each time and two styles specimens with different cores didn’t show evident differences in failure mode as well. It demonstrated the conclusion and that core splice accounted to make the specimens produced geometric imperfections which resulted in stiffness reduction.Thirdly, based on experiments it was clear that the mechanical behaviour of sandwich plates with splicing cores suffered from more obvious discreteness compared with that with integrated cores, which indicated that manufacturing technology had greater influence on the former and core splice should be avoided in some important location of structure.Lastly, numerical simulation method based on progressive damage analysis was also studied and good correlation with experimental results was obtained, which could well predict the mechanical behaviour of the sandwich plates with splicing core and integrated core.

Abstract: This paper investigated the anti-penetration performance of different sandwich structures plate using numerical simulation method. Finite elements models of the bullet and sandwich plate were established. The penetration performance of sandwich plate by bullet was simulated by software of LS-DYNA and dynamic response of the bullet during the penetration process was got. The results show that the anti-penetration performance is different because of the different cores in the plate. Besides, the density of the aluminum foam core has a direct effect on the performance. This paper could provide some reference for the designing of sandwich structures.

Abstract: In order to obtain the side walls section structures of high speed train applicable to different running speeds and conditions, a multi-objective optimization design is made based on the structure of topology optimization. In this optimization formulation, the weight of sandwich plate, static compliance and maximum deformation are used as the objective functions; the thickness of face panels and cores in five parts of the side wall are variables; and the air pressure gradient in compartments is the constraint function. Surrogate model techniques are adopted for constructing the response surfaces based on the optimization. Finally, a multi-objective optimization is performed using the NSGA-II algorithm and the optimization generates a Pareto solution set. The structure performance in Pareto set is greatly improved by 8.21% -33.58% than that of topology structure. In addition, the Pareto solution set provides engineers with many alternative Pareto-optimal solutions for optimization design of the sandwich plate section applied in the high-speed train.

Abstract: Based on LS-DYNA, this paper compares four modeling methods for sandwich plates, e.g. the layered shell element, the solid and shell mixing element, the shared-node shell element and the thick shell element. Four modeling methods are used to simulate sandwich plates with different thickness-to-span ratios and different mesh sizes. The comparative analysis of the relationships between the mesh size, the CPU time and the convergence rate of the accuracy of four methods shows that the layered shell element and the shared-node shell element can accurately simulate sandwich plates with high efficiency.

Abstract: 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.

Abstract: In 3-point bending fatigue experiments of sandwich plate with visoelastic core and steel faceplates, it is found that response loading of specimen is very sensitive to cycling frequency. From fatigue test, different loading response of sandwich beam obtained in various cycling frequencies. Based on viscoelastic theory, responses of deformation of sandwich plate in cyclic square load wave are calculated. And an explanation of influences of cycling frequency is elaborated.