Optimization of multi-sandwich-panel composite structures for minimum weight with strength and buckling considerations

2018 ◽  
Vol 25 (2) ◽  
pp. 229-241 ◽  
Author(s):  
Hai-Tao Fan ◽  
Hai Wang ◽  
Xiu-Hua Chen
Keyword(s):  
Composite Structures ◽  
Sandwich Panel ◽  
Maximum Stress ◽  
Design Space ◽  
Minimum Weight ◽  
Sandwich Panels ◽  
Stacking Sequence ◽  
Genetic Operators ◽  
Stress Criterion ◽  
The Core

AbstractA genetic algorithm-based method is proposed to globally optimize the stacking sequence of multi-sandwich-panel composite structures for minimum weight with strength and buckling considerations. The prerequisites for the continuity between sandwich panels are first studied. To implement the summarized continuity rules in the evolutionary optimization, three newly constructed chromosomes are developed to encode the global stacking sequence with no additional repair. Genetic operators, including specialized mutation, swapping and crossover operators, are also developed to effectively explore the design space and keep the continuity rules followed. The Hashin criterion and maximum stress criterion are used to evaluate the strength of sandwich panels. A typical multi-sandwich-panel composite structure with identical and different core thicknesses is optimized to verify the validity and efficiency of the proposed method. It is found that much lighter solutions are obtained with an acceptable efficiency in all cases. It is also found that the weight of the multi-sandwich-panel composite structures can be further reduced when the core thicknesses are not identical.

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.

Structural-Acoustic Optimization of Sandwich Panels

2005 ◽  
Author(s):  
Francesco Franco ◽  
Kenneth A. Cunefare ◽  
Massimo Ruzzene
Keyword(s):  
Numerical Optimization ◽  
Composite Structures ◽  
Gradient Methods ◽  
Sandwich Panels ◽  
Relative Importance ◽  
Structural Elements ◽  
Acoustic Response ◽  
The Core ◽  
Design Flexibility ◽  
The Face

Sandwich panels, comprising face sheets enclosing a core, are increasingly common structural elements in a variety of applications, including aircraft fuselages and flight surfaces, vehicle panels, lightweight enclosures, and bulkheads. The design flexibility associated with such composite structures provides significant opportunities for tailoring the structure to the load and dynamic response requirements for the particular application. Design flexibility encompasses the details of the face sheets and the core. This paper deals with the numerical optimization of different sandwich configurations for the purposes of achieving reduced structural acoustic response. Laminated face sheets and core geometries, comprising honeycomb and truss-like structures, are considered. The relative importance of the mass and stiffening properties of the core and face sheets are discussed. The optimization work is carried out using commercial codes. Benefits and limits of using an optimization algorithm based on gradient methods are highlighted.

Shear-Lag Effect in Sandwich Panels With Stiffeners Under Three-Point Bending

1980 ◽  
Vol 47 (2) ◽  
pp. 383-388 ◽  
Author(s):  
K. Kemmochi ◽  
T. Akasaka ◽  
R. Hayashi ◽  
K. Ishiwata
Keyword(s):  
Strain Distribution ◽  
Sandwich Panel ◽  
Sandwich Panels ◽  
Bending Rigidity ◽  
Shear Lag ◽  
Shear Lag Effect ◽  
Three Point Bending ◽  
The Core ◽  
Lag Effect ◽  
Modified Theory

In this paper, a modified theory based upon Reissner’s procedure for the shear-lag effect of the sandwich panel is presented, which includes the effects of the anisotropy of the faces and the shearing rigidity of the core. In order to verify this theory, bending experiments were performed with sandwich panels composed of a soft core, stiffeners, and orthotropic faces. It was found that the effective bending rigidity calculated from this theory was lower than that derived from the classical bending theory and that the theoretical strain distribution on the faces agreed well with the experimental results.

Evaluations of failure initiation criteria for predicting damages of composite structures under crushing loading

2018 ◽  
Vol 37 (21) ◽  
pp. 1279-1303 ◽  
Author(s):  
Hongyong Jiang ◽  
Yiru Ren ◽  
Zhihui Liu ◽  
Songjun Zhang ◽  
Xiaoqing Wang
Keyword(s):  
Composite Structures ◽  
Maximum Stress ◽  
Failure Modes ◽  
Damage Model ◽  
Axial Loading ◽  
Failure Criteria ◽  
Quantitative Relation ◽  
Stress Criterion ◽  
Failure Initiation ◽  
Numerical Predictions

The crushing behaviors of thin-walled composite structures subjected to quasi-static axial loading are comparatively evaluated using four different failure initiation criteria. Both available crushing tests of composite corrugated plate and square tube are used to validate the stiffness degradation-based damage model with the Maximum-stress criterion. Comparatively, Hashin, Maximum-stress, Stress-based Linde, and Modified criteria are respectively implemented in the damage model to predict crush behaviors of corrugated plate and square tube. To develop failure criteria, effects of shear coefficients and exponents in the Modified and Maximum-stress criteria on damage mechanisms of corrugated plate are discussed. Results show that numerical predictions successfully capture both of experimental failure modes and load–displacement responses. The Modified criterion and particularly Maximum-stress criterion are found to be more appropriate for present crush models of corrugated plate and square tube. When increasing the failure index, the crushing load is decreased, which also causes premature material failure. The shear coefficient and exponents have dramatic influence on the crushing load. Overall, an insight into the quantitative relation of failure initiation is obtained.

Optimal design of sandwich panels with hybrid core

2017 ◽  
Vol 21 (7) ◽  
pp. 2181-2193 ◽  
Author(s):  
Robert Studziński
Keyword(s):  
Sandwich Panel ◽  
Minimum Weight ◽  
Sandwich Panels ◽  
Inequality Constraints ◽  
Optimization Procedure ◽  
Geometrical Parameters ◽  
Optimal Solutions ◽  
Limit States ◽  
Mathematical Functions ◽  
Flat Steel

The main aim of the paper is to find optimal solutions of sandwich panels with flat steel facings and a hybrid core made of aerogel and polyisocyanurate (PIR) foam. The optimal solutions have to satisfy conflicting criteria, i.e. a maximum range of applications and minimum weight, while at the same time respecting both the principles of sustainable development in the construction industry and the limit states (ultimate and serviceability) conditions. The design vector consists of the geometrical parameters of the sandwich panel including its span length and the parameter which describes the proportion of aerogel thickness to the total thickness of the core. The mechanical properties of the hybrid core are described by mathematical functions which were obtained in laboratory tests. In optimization, an evolutionary algorithm was used. The Pareto results were obtained while respecting the inequality constraints introduced in the optimization procedure directly (box conditions) and by means of the external penalty function. The presented optimization of a sandwich panel extends the class of problems discussed in the literature by considering both the hybrid core and the thermal conductivity aspect.

scholarly journals Impact perforation of sandwich panels with graded hollow sphere cores: Numerical and Analytical investigations

2021 ◽  
Vol 250 ◽  
pp. 02027
Author(s):  
Ibrahim Elnasri
Keyword(s):  
Boundary Conditions ◽  
Hollow Sphere ◽  
Sandwich Panel ◽  
Peak Load ◽  
Sandwich Panels ◽  
Core Density ◽  
Plateau Stress ◽  
The Core ◽  
The Impact ◽  
Force Displacement

In this study, we numerically and analytically 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 effect of boundary conditions on the perforation resistance of the studied graded core sandwich panels was 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 un-clumping boundary conditions in the graded core sandwich panel, which is rather too hard to achieve with clumping boundary conditions. Finally, an analytical model, taken account only gradient in the quasi-static plateau stress, is developed to predict the top skin pic peak load of the graded sandwich panel.

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.

scholarly journals Numerical modelling of sandwich panels with a non-continuous soft core

2018 ◽  
Vol 157 ◽  
pp. 06007
Author(s):  
Jolanta Pozorska
Keyword(s):  
Numerical Modelling ◽  
Static Analysis ◽  
Sandwich Panel ◽  
Sandwich Panels ◽  
Soft Core ◽  
Structural Behavior ◽  
Progressive Damage ◽  
Local Instability ◽  
Unilateral Constraints ◽  
The Core

The paper presents the problem of static analysis of sandwich structures with a non-continuous soft core. In the numerical 3D FE models, the core is divided into separated parts. The contact between these parts has the form of unilateral constraints. The model also allows for local debonding of the facing and local imperfections of sandwich panel geometry. Particular attention is paid to the problem of local instability of the facing that is compressed during bending. The phenomenon of progressive damage and the influence of non-continuity of the core on the structural behavior of the sandwich panel is also discussed.

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.

scholarly journals An Investigation on Low Velocity Impact Response of Multilayer Sandwich Composite Structures

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
S. Jedari Salami ◽  
M. Sadighi ◽  
M. Shakeri ◽  
M. Moeinfar
Keyword(s):  
Composite Structures ◽  
Sandwich Panel ◽  
Testing Machine ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Core Material ◽  
Sandwich Composite ◽  
Low Velocity ◽  
Velocity Impact ◽  
The Core

The effects of adding an extra layer within a sandwich panel and two different core types in top and bottom cores on low velocity impact loadings are studied experimentally in this paper. The panel includes polymer composite laminated sheets for faces and the internal laminated sheet called extra layer sheet, and two types of crushable foams are selected as the core material. Low velocity impact tests were carried out by drop hammer testing machine to the clamped multilayer sandwich panels with expanded polypropylene (EPP) and polyurethane rigid (PUR) in the top and bottom cores. Local displacement of the top core, contact force and deflection of the sandwich panel were obtained for different locations of the internal sheet; meanwhile the EPP and PUR were used in the top and bottom cores alternatively. It was found that the core material type has made significant role in improving the sandwich panel’s behavior compared with the effect of extra layer location.

Sign in / Sign up

Export Citation Format

Share Document