Dynamic pulse buckling and failure analysis of the single curved composite sandwich panel using the core high-order theory

2020 ◽  
Vol 234 (10) ◽  
pp. 1990-2011
Author(s):  
Seyed Ali Ahmadi ◽  
Mohammad Hadi Pashaei ◽  
Ramazan-Ali Jafari-Talookolaei
Keyword(s):  
Sandwich Panel ◽  
Failure Modes ◽  
Viscoelastic Model ◽  
Sandwich Panels ◽  
High Order ◽  
Foam Core ◽  
Composite Sandwich ◽  
The Core ◽  
Pulse Buckling ◽  
Dynamic Pulse

The current study aims to investigate the facesheet dynamic pulse buckling of simply supported, cylindrical composite sandwich panels using the Budiansky–Roth buckling criterion. The foam core has been modeled with isotropic elastic-perfectly plastic properties and various failure modes of the sandwich panel like facesheet fracture, foam shear fracture, and foam yield are investigated. The extended high-order sandwich panel core theory was used to model the compressibility of the core. To study the mechanical properties of the viscoelastic foam core, the Kelvin–Voigt linear viscoelastic model was applied. The transient responses and stress components obtained from the present method are compared with finite element solutions using commercial software ANSYS and those reported in the literature. Accordingly, reasonable agreement is observed. It was shown that the pulse local buckling strength of the panel increases with a decrease in the panel radius or an increase in the thickness of the panel, and facesheet fracture is considered more a likely failure mode of these sandwich panels.

Numerical Study on the Response of Functionally Graded PVC Foam Core Sandwich Panels Subjected to Non-Contact Underwater Explosion

2018 ◽  
Author(s):  
Tianyu Zhou ◽  
Pan Zhang ◽  
Yuansheng Cheng ◽  
Manxia Liu ◽  
Jun Liu
Keyword(s):  
Sandwich Panel ◽  
Blast Resistance ◽  
Sandwich Panels ◽  
Underwater Explosion ◽  
Functionally Graded ◽  
Front Face ◽  
Foam Core ◽  
Compression Phase ◽  
The Core ◽  
Back Face

In this paper, the numerical model was developed by using the commercial code LS/DYNA to investigate the dynamic response of sandwich panels with three PVC foam core layers subjected to non-contact underwater explosion. The simulation results showed that the structural response of the sandwich panel could be divided into four sequential regimes: (1) interaction between the shock wave and structure, (2) compression phase of sandwich core, (3) collapse of cavitation bubbles and (4) overall bending and stretching of sandwich panel under its own inertia. Main attention of present study was placed at the blast resistance improvement by tailoring the core layer gradation under the condition of same weight expense and same blast load. Using the minimization of back face deflection as the criteria for evaluating the blast resistant of panel, the panels with core gradation of high/middle/low or middle/low/high (relative densities) from the front face to back face demonstrated the optimal resistance. Moreover, the comparative studies on the blast resistance of the functionally graded sandwich panels and equivalent ungraded ones were carried out. The optimum functionally graded sandwich panel outperformed the equivalent ungraded one for relatively small charge masses. The energy absorption characteristics as well as the core compression were also discussed. It is found that the core gradation has a negligible effect on the whole energy dissipation of panel, but would significantly affect the energy distribution among sandwich panel components and the compression value of core.

The buckling of truncated conical sandwich panels under axial compression and external pressure

2014 ◽  
Vol 229 (11) ◽  
pp. 1965-1978 ◽  
Author(s):  
Keramat M Fard ◽  
Mostafa Livani
Keyword(s):  
Boundary Conditions ◽  
Axial Compression ◽  
Sandwich Panel ◽  
Sandwich Panels ◽  
Shear Deformation Theory ◽  
External Pressure ◽  
Thickness Ratio ◽  
Composite Sandwich ◽  
The Core ◽  
Panel Thickness

Based on a new improved higher-order sandwich panel theory, the buckling analysis of a truncated conical composite sandwich panel with simply supported and fully clamped boundary conditions was performed for the first time. This panel was subjected to axial compression and external pressures. The governing equations were derived by using the principle of minimum potential energy. The first-order shear deformation theory was used for the composite face sheets, and for the core, a polynomial description of the displacement fields was assumed. Geometry was used for the consideration of different radii curvatures of the face sheets and the core was unique. The effects of types of boundary conditions, conical angles, length to smaller radius of core ratio, core to panel thickness ratio, and smaller radius of core to panel thickness ratio on the buckling response of truncated conical composite sandwich panels were also studied. The results were validated by the results published in the literature and the presented FE results were obtained by ABAQUS software.

Finite Element Study on the Influence of Shear Key Diameter on the Shear Performance of Composite Sandwich Panel with PU Foam Core

2013 ◽  
Vol 376 ◽  
pp. 103-107
Author(s):  
A. Mostafa ◽  
K. Shankar
Keyword(s):  
Finite Element ◽  
Failure Mode ◽  
Sandwich Panel ◽  
Mechanical Response ◽  
Shear Loading ◽  
Foam Core ◽  
Element Analysis ◽  
Composite Sandwich ◽  
The Core ◽  
Pu Foam

The present study deals with the shear behavior of the composite sandwich panels comprised of Polyvinylchloride (PVC) and Polyurethane (PU) foam core sandwiched between Glass Fiber Reinforced Polymer (GFRP) skins using epoxy resin. Experiments have been carried out to characterize the mechanical response of the constituent materials under tension, compression and shear loading. In-plane shear tests for the sandwich panel reveal that the main failure mode is the delamination between the skin and the core rather than shearing the core itself since the skin-core interaction is the weakest link in such structure. The Finite Element Analysis (FEA) of the sandwich structure, based on the non-linear behavior of the foam core and skin-core cohesive interaction, shows that shear response and failure mode can be predicted with high accuracy.

In-Plane Shear Damage Prediction of Composite Sandwich Panel with Foam Core

2013 ◽  
Vol 376 ◽  
pp. 69-73
Author(s):  
A. Mostafa ◽  
K. Shankar
Keyword(s):  
Failure Mode ◽  
Sandwich Panel ◽  
Mechanical Response ◽  
Shear Loading ◽  
Foam Core ◽  
Element Analysis ◽  
Plane Shear ◽  
Damage Prediction ◽  
Composite Sandwich ◽  
The Core

The present study deals with the shear behavior of the composite sandwich panels comprised of Polyvinylchloride (PVC) and Polyurethane (PU) foam core sandwiched between Glass Fiber Reinforced Polymer (GFRP) skins using epoxy resin. Experiments have been carried out to characterize the mechanical response of the constituent materials under tension, compression and shear loading. In-plane shear tests for the sandwich panel reveal that the main failure mode is the delamination between the skin and the core rather than shearing the core itself since the skin-core interaction is the weakest link in such structure. The Finite Element Analysis (FEA) of the sandwich structure, based on the non-linear behavior of the foam core and skin-core cohesive interaction, shows that shear response and failure mode can be predicted with high accuracy.

Impact/Debonding Tolerant Sandwich Panel With Aluminum Tube Reinforced Foam Core

2011 ◽  
Author(s):  
Gefu Ji ◽  
Zhenyu Ouyang ◽  
Guoqiang Li ◽  
Su-Seng Pang
Keyword(s):  
Sandwich Panel ◽  
Load Capacity ◽  
Sandwich Panels ◽  
Interface Debonding ◽  
Type I ◽  
Foam Core ◽  
Type Ii ◽  
Polymer Resin ◽  
The Core ◽  
Structural Applications

Sandwich construction has been extensively used in various fields. However, sandwich panels have not been fully exploited in critical structural applications due to damage tolerance and safety concern. A major problem of sandwich panels is the debonding at or near the core/face sheet interface, especially under impact loading, which can lead to a sudden loss of structural integrity and cause catastrophic consequences. In order to improve the debonding resistance and energy absorption of sandwich panel under impact loadings, a new foam core is proposed which is a hybrid core consisting of hollow metallic microtubes reinforced polymer matrix. The objective of this study was to characterize its static and dynamic performances. Two types of new hybrid cores were investigated in this work. One consisted of polymer resin reinforced by transversely aligned continuous metallic militubes, denoted as type-I sandwich panel. The other was made of polymer resin reinforced by aligned continuous in-plane metallic militubes, denoted as type-II sandwich panel. Additionally, the traditional sandwich panels with polymeric syntactic foam core were also prepared for comparisons. Static and impact tests demonstrated that interface debonding and subsequent shear failure in the core could be largely excluded from the type-II panel. Meanwhile, a significant transition to ductile failure was observed in type-II sandwich panel with dramatically enhanced load capacity and impact energy dissipation. The results indicated that type-II panel may be considered a promising option for critical structural applications featured by debonding and impact tolerance.

Novel Impact/Debonding Tolerant Sandwich Panel With Millitubes Grid Stiffened Foam Core

2012 ◽  
Author(s):  
Guoqiang Li ◽  
Gefu Ji ◽  
Su-Seng Pang
Keyword(s):  
Sandwich Panel ◽  
Structural Integrity ◽  
Safety Concern ◽  
Sandwich Panels ◽  
Low Velocity Impact ◽  
Foam Core ◽  
Low Velocity ◽  
The Core ◽  
Sandwich Construction ◽  
Structural Applications

Sandwich construction has been extensively used in various fields. However, sandwich panels have not been fully exploited in critical structural applications due to damage tolerance and safety concern. A major problem of sandwich panels is the debonding at or near the core/face sheet interface, especially under impact loading, which can lead to a sudden loss of structural integrity and cause catastrophic consequences. In order to improve the debonding resistance and energy absorption of sandwich panel under impact loadings, a new foam core is proposed which is a hybrid core consisting of grid stiffened hollow metallic millitubes reinforced polymer matrix. The objective of this study was to characterize its dynamic performances. The core consisted of polymer resin reinforced by grid stiffened continuous metallic millitubes. Low velocity impact test demonstrated that new core panel may be considered a promising option for critical structural applications featured by debonding and multiple impact tolerance.

Static mechanical response of sandwich panels with bilinear core

2018 ◽  
Vol 22 (7) ◽  
pp. 2421-2444
Author(s):  
Guangtao Wei ◽  
Lijia Feng ◽  
Linzhi Wu
Keyword(s):  
Theoretical Model ◽  
Sandwich Structure ◽  
Sandwich Panel ◽  
Mechanical Response ◽  
Constitutive Relations ◽  
Plastic Region ◽  
Sandwich Panels ◽  
High Order ◽  
Isotropic Hardening ◽  
The Core

A new theoretical model based on the extended high order sandwich panel theory is established to predict the mechanical response of sandwich panels under static loads with the bilinear constitutive stress–strain relation in the core. The constitutive relations of normal stresses related to the longitudinal and vertical normal strains in the bilinear isotropic hardening core are first formulated. The influence of the in-plane rigidity on the elastoplastic response of sandwich structures is analyzed. An in-plane loaded sandwich structure with the bilinear core is first studied based on extended high order sandwich panel theory, and the effect of the bilinear ratio on the mechanical response is evaluated. The governing equations are derived from the principle of minimum potential energy, and a Ritz-based half-analytical method is applied to get the solutions. The plastic response is acquired by an iterative procedure along with the convergence criteria. The results reveal that the local effect can be captured when the axial rigidity of the core is considered. The bilinear characteristic of the core decreases the maximum normal stress with an increase of the average value. The equivalent plastic region extends with the increase of the bilinear ratio when the sandwich structure is loaded in plane. By comparison with open literatures and finite element results, the present theoretical model is proved to be effective and efficient.

An Extended Higher-Order Free Vibration Analysis of Composite Sandwich Beam With Viscoelastic Core

2012 ◽  
Author(s):  
Soroush Sadeghnejad ◽  
Mojtaba Sadighi ◽  
Abdolreza Ohadi Hamedani
Keyword(s):  
Free Vibration ◽  
Vibration Analysis ◽  
Sandwich Panel ◽  
Sandwich Beam ◽  
Free Vibration Analysis ◽  
High Order ◽  
Theory Approach ◽  
Composite Sandwich ◽  
The Core ◽  
Viscoelastic Core

Free vibration analysis of sandwich beam with a viscoelastic core based on the extended high-order sandwich panel theory approach is presented. The effects of transverse shear and core compressibility are of high importance in sandwich structures, having an influence on the entire structural behavior especially in vibrations. For applications involving stiffer cores, the high-order sandwich panel theory (HSAPT) cannot accurately predict the shear and axial stress distributions in the core. Thus, by using the “Extended High-Order Sandwich Panel Theory” (EHSAPT), the in-plane rigidity of the core is considered in addition to the compressibility of the core in the transverse direction. The novelty of this theory is that it allows for three generalized coordinates in the core (the axial and transverse displacements at the centroid of the core, and the rotation at the centroid of the core) instead of just one (mid-point transverse displacement) commonly adopted in other available theories. The mathematical formulation uses the Hamilton principle and includes derivation of the governing equations along with the appropriate boundary conditions. The formulation uses the classical thin plate theory for the face sheets and a two-dimensional elasticity theory or equivalent one for the core. In addition, Young modulus, rotational inertia, and kinetic energy of the core are considered and core is assumed as an orthotropic viscoelastic material. The analysis is applicable for any types of loading scheme, localized as well as distributed, and distinguish between loads applied at the upper or the lower face. The obtained results are compared with recent research published by the present authors which was done numerically by using FEM on viscoelastic sandwich beam and the corresponding results of other previous researches. The influence of material properties, face layup and geometry effect on natural frequencies of composite sandwich beams are investigated.

scholarly journals A numerical study of the impact perforation of sandwich panels with graded hollow sphere cores

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110094
Author(s):  
Ibrahim Elnasri ◽  
Han Zhao
Keyword(s):  
Boundary Conditions ◽  
Hollow Sphere ◽  
Sandwich Panel ◽  
Numerical Study ◽  
Sandwich Panels ◽  
Hopkinson Bar ◽  
Core Density ◽  
The Core ◽  
The Impact ◽  
Force Displacement

In this study, we numerically investigate the impact perforation of sandwich panels made of 0.8 mm 2024-T3 aluminum alloy skin sheets and graded polymeric hollow sphere cores with four different gradient profiles. A suitable numerical model was conducted using the LS-DYNA code, calibrated with an inverse perforation test, instrumented with a Hopkinson bar, and validated using experimental data from the literature. Moreover, the effects of quasi-static loading, landing rates, and boundary conditions on the perforation resistance of the studied graded core sandwich panels were discussed. The simulation results showed that the piercing force–displacement response of the graded core sandwich panels is affected by the core density gradient profiles. Besides, the energy absorption capability can be effectively enhanced by modifying the arrangement of the core layers with unclumping boundary conditions in the graded core sandwich panel, which is rather too hard to achieve with clumping boundary conditions.

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