Geometrical nonlinear thermal response of sandwich panels with temperature dependent mechanical properties—Extended high-order approach

2019 ◽  
Vol 21 (5) ◽  
pp. 1700-1725 ◽  
Author(s):  
Yeoshua Frostig ◽  
George Kardomateas
Keyword(s):  
Mechanical Properties ◽  
Sandwich Panel ◽  
Mechanical Response ◽  
Numerical Study ◽  
Thermal Response ◽  
High Order ◽  
Theory Approach ◽  
Temperature Dependent ◽  
The Core ◽  
Compressive Loads

The thermal and the thermo-mechanical responses of a sandwich panel with a compliant core are investigated within the framework of the extended high-order approach where the core properties are temperature dependent or independent. Loads schemes include thermal field within temperature working range simultaneous with in-plane compressive loads applied to the core only and to the face sheets and core in the form of the uniform end—shortening of edge of panel. The mathematical formulations use the extended high-order sandwich panel theory approach that takes into account the in-plane rigidity of the core and uses the deformation patterns of the high-order sandwich panel theory. The linear and nonlinear field equations along with the appropriate boundary conditions are presented. A numerical study is conducted, and it investigates the thermal response with temperature independent and temperature dependent mechanical properties of the core as well as the thermo-mechanical response due to in-plane compressive loads. The results include displacements, stress resultants, and stress at critical locations along the panel as well as equilibria curves. They reveal that, in general, the panel with temperature independent properties response remains almost linear while with temperature dependent ones it takes a general nonlinear response. The addition of an external mechanical load changes the response from a linear/nonlinear one that may be allowable stress controlled to a case where loss of stability occurs.

Design Study of Composite Sandwich Truck Tank Using a High-Order Sandwich Theory Approach

2001 ◽  
Author(s):  
Ole T. Thomsen ◽  
Jack R. Vinson
Keyword(s):  
Sandwich Panel ◽  
Numerical Study ◽  
Structural Response ◽  
Hydraulic Head ◽  
High Order ◽  
Elastic Response ◽  
Core Material ◽  
Theory Approach ◽  
Design Study ◽  
Composite Sandwich

Abstract The paper presents a preliminary design study on the structural response of a boxy composite sandwich truck tank subjected to hydraulic head loading. The design study is approximate in that it considers a 2-D cross section of the composite sandwich truck tank. The design study is performed using a high-order sandwich theory formulation in which the elastic responses of the face laminates are accounted for individually, and in which the transverse flexibility of the sandwich core is included. Thus the model allows the sandwich panel thickness of the truck tank to change during deformation, and the model accounts for the existence of transverse normal stresses in the core material in the sandwich panel sections. The paper includes a presentation of the high-order formulation for the curved sandwich panel parts of the composite sandwich truck tank sections, as well as a brief description of the numerical solution of the complete set of system equations with corresponding boundary conditions. The paper is concluded with a numerical study, showing the characteristic features of the elastic response of a composite sandwich truck tank section subjected to hydraulic head loading.

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.

scholarly journals Evolution of Meniscal Biomechanical Properties with Growth: An Experimental and Numerical Study

2021 ◽  
Vol 8 (5) ◽  
pp. 70
Author(s):  
Marco Ferroni ◽  
Beatrice Belgio ◽  
Giuseppe M. Peretti ◽  
Alessia Di Giancamillo ◽  
Federica Boschetti
Keyword(s):  
Mechanical Properties ◽  
Stress Relaxation ◽  
Developmental Stage ◽  
Mechanical Response ◽  
Numerical Study ◽  
Numerical Models ◽  
Mechanical Stimulus ◽  
Specific Response ◽  
Mechanical Parameters ◽  
Biochemical Analyses

The menisci of the knee are complex fibro-cartilaginous tissues that play important roles in load bearing, shock absorption, joint lubrication, and stabilization. The objective of this study was to evaluate the interaction between the different meniscal tissue components (i.e., the solid matrix constituents and the fluid phase) and the mechanical response according to the developmental stage of the tissue. Menisci derived from partially and fully developed pigs were analyzed. We carried out biochemical analyses to quantify glycosaminoglycan (GAG) and DNA content according to the developmental stage. These values were related to tissue mechanical properties that were measured in vitro by performing compression and tension tests on meniscal specimens. Both compression and tension protocols consisted of multi-ramp stress–relaxation tests comprised of increasing strains followed by stress–relaxation to equilibrium. To better understand the mechanical response to different directions of mechanical stimulus and to relate it to the tissue structural composition and development, we performed numerical simulations that implemented different constitutive models (poro-elasticity, viscoelasticity, transversal isotropy, or combinations of the above) using the commercial software COMSOL Multiphysics. The numerical models also allowed us to determine several mechanical parameters that cannot be directly measured by experimental tests. The results of our investigation showed that the meniscus is a non-linear, anisotropic, non-homogeneous material: mechanical parameters increase with strain, depend on the direction of load, and vary among regions (anterior, central, and posterior). Preliminary numerical results showed the predominant role of the different tissue components depending on the mechanical stimulus. The outcomes of biochemical analyses related to mechanical properties confirmed the findings of the numerical models, suggesting a specific response of meniscal cells to the regional mechanical stimuli in the knee joint. During maturation, the increase in compressive moduli could be explained by cell differentiation from fibroblasts to metabolically active chondrocytes, as indicated by the found increase in GAG/DNA ratio. The changes of tensile mechanical response during development could be related to collagen II accumulation during growth. This study provides new information on the changes of tissue structural components during maturation and the relationship between tissue composition and mechanical response.

Geometrical Nonlinear Effects in the Dynamic Response of Sandwich Beams

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Itay Odessa ◽  
Oded Rabinovitch ◽  
Yeoshua Frostig
Keyword(s):  
Dynamic Response ◽  
Nonlinear Dynamic ◽  
High Order ◽  
Theory Approach ◽  
Nonlinear Frequency ◽  
Sandwich Beams ◽  
Nonlinear Dynamic Response ◽  
The Core ◽  
Geometrical Nonlinear ◽  
The Face

Abstract The geometrical nonlinear dynamic response of sandwich beams is studied using a dynamic high-order nonlinear model. The model is derived using the variational principle of virtual work and uses the Extended High-Order Sandwich Panel Theory approach with consideration of two interfaces between the three layers. A first-order shear deformation theory is adopted for the face sheets, while the kinematic assumption of high-order small deformations that account for out-of-plane compressibility are considered for the core layer. The nonlinearity of the dynamic model is introduced by considering geometrically nonlinear kinematic relations in the face sheets. The nonlinear kinematic relations and the dynamic modeling aim to evaluate the effects of the two features and their coupling on the response. The nonlinear dynamic response of sandwich beams is studied through two numerical cases and comparison of the nonlinear results with their linear counterparts. The first case looks into the coupling of the global geometrical nonlinear behavior with the dynamic behavior. The second case focuses on the local instability of the face sheets and its interaction with the compressibility of the core in the dynamic response of soft core sandwich beams. The comparison of linear and nonlinear dynamic response in the two cases sheds light on the coupling of the geometrical nonlinear and dynamic behaviors. Among other features, the latter is expressed by nonlinear attractors, higher modes response, nonlinear frequency response, and significant wrinkling response.

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.

Numerical Study of Deformation and Fracture of Ceramics Nanocomposite with Different Structural Parameters under Mechanical Loading

2016 ◽  
Vol 683 ◽  
pp. 601-608
Author(s):  
Igor S. Konovalenko ◽  
Egor M. Vodopjyanov ◽  
Evgenii V. Shilko
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Numerical Study ◽  
Structural Parameters ◽  
Phenomenological Approach ◽  
Sample Volume ◽  
Model Composite ◽  
Deformation And Fracture ◽  
Kinetics Of ◽  
Geometrical Dimensions

Deformation, fracture and effective mechanical properties of sintered ceramics composite under uniaxial compression were studied. To perform this investigation the plain numerical model of ceramics composites based on oxides of zirconium and aluminum with different structural parameters was developed. The model construction was carried out within the frame of particle based method, namely the movable cellular automaton method (MCA). The implementation of the phase transition in the MCA-model composite was carried out on the basis of the phenomenological approach, the main point of which was the formulation of the principle of irreversible mechanical behavior of the material. Increase the fracture toughness of ceramics after (T-M) transition in its structure was realized in the model by introducing transition kinetics of the automata pair from "bound" to an "unbound" state. The structure of model composite was generated on the basis of scanning electron microscope images of micro-sections of real composite. The influence of such structural parameters as geometrical dimensions of layers, inclusions, and their spatial distribution in the sample, volume content of the composite components and their mechanical properties, as well as the amount of zirconium dioxide undergone the phase transformation on the mechanical response were investigated

scholarly journals Geometric Nonlinearity Effects in the Response of Sandwich Wide Panels

2016 ◽  
Vol 83 (9) ◽  
Author(s):  
Zhangxian Yuan ◽  
George A. Kardomateas ◽  
Yeoshua Frostig
Keyword(s):  
Geometric Nonlinearity ◽  
Sandwich Panel ◽  
Hard Core ◽  
Order Theory ◽  
High Order ◽  
Three Point Bending ◽  
The Core ◽  
Nonlinear Version ◽  
Simplifying Assumptions ◽  
Nonlinear High Order

In the literature, there are various simplifying assumptions adopted in the kinematic relations of the faces and the core when considering a geometrically nonlinear problem in sandwich structures. Most commonly, only one nonlinear term is included in the faces and the core nonlinearities are neglected. A critical assessment of these assumptions, as well as the effects of including the other nonlinear terms in the faces and the core, is the scope of this paper. The comprehensive investigation of all the nonlinear terms is accomplished by deriving and employing an advanced nonlinear high-order theory, namely, the recently developed “extended high-order sandwich panel theory” (EHSAPT). This theory, which was derived as a linear theory, is first formulated in this paper in its full nonlinear version for the simpler one-dimensional case of sandwich wide panels/beams. Large displacements and moderate rotations are taken into account in both faces and core. In addition, a nonlinear EHSAPT-based finite element (FE) is developed. A series of simplified models with various nonlinear terms included are derived accordingly to check the validity of each of these assumptions. Two sandwich panel configurations, one with a “soft” and one with a “hard” core, loaded in three-point bending, are analyzed. The geometric nonlinearity effects and the relative merits of the corresponding simplifications are analyzed with these two numerical examples. In addition to a relative comparison among all these different assumptions, the results are also compared to the corresponding ones from a commercial FE code.

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