Composite Sandwich Panels Research Articles

Experimental analysis of corrugated core sandwich panel with smart composite face-sheets under high-velocity impact

The present research work investigated on the behavior of corrugated core composite sandwich panel (CCCS) with composite face-sheets reinforced by pseudo-elastic NiTi shape memory alloy (SMA) wires subjected to high-velocity impact experimentally. The number of SMA wires, their location, and their pre-strain percentage are the parameters studied in this investigation. The sandwich specimens were made by woven glass fibers/epoxy composite face-sheets strengthened by the SMA wires and Aluminum corrugated core and prepared using the wet hand lay-up method. Their behavior is evaluated under high-velocity impact test by a gas gun impactor testing machine. According to the results obtained, a significant change in the amount of energy absorption of the specimens containing SMA wires is observed. By increasing the number of the SMA wires, the energy absorption by the specimen is increased, but by pre-straining the SMA wires, the effect in energy absorption is significant. Also, when the projectile hits the SMA wire in CCCS, better properties in energy absorption can be observed. The results show that the energy absorption increased from 117.247 J for the specimen without the SMA wire to 128.749 J for the six SMA wires specimen. On the other hand, by applying the pre-strain to the SMA wires, the residual stresses in the specimens and hence the energy absorption in the specimen with six SMA wires with 3% pre-strain increased to 142.57 J.

Parametric study on dynamic responses of stiffened sandwich composite bridge deck panel

Recently, the use of sandwich composites in different fields of engineering such as aerospace, marine, automobile, pipelines, bridge structure, industrial work, has attracted significant attention. Sensitivity analysis of structures made of sandwich composites is necessary to design them properly and maintain their longevity. The present study analyzes stiffened sandwich composite bridge deck panels and focuses on its sensitivity analysis. The lack of control in the manufacturing of the sandwich composites may lead to non-uniform material properties, and thus variation in its behavior. The variation in the dynamic responses obtained through the free vibration analysis of the bridge deck panel models of stiffened composites due to is studied. The free vibration analysis is implemented using a finite element method. The analysis is carried out with the stiffeners located in different positions and alignments. The glass fiber-reinforced plastic (GFRP) and polyvinyl semi-rigid foam are considered in the face and core layer for modeling the deck panels, respectively. The sensitivity of the bridge deck panels is also observed with the presence of holes of different diameters in the core layer of the sandwich composite plate without stiffeners and with a transverse stiffener. It has been noticed that dynamic response, i.e. the eigenvalue, is sensitive concerning the in-plane parameters of the face layers compared to other parameters. Moreover, an increase in the size of the hole in the core layer results in a decrease in the dynamic response of the stiffened sandwich composite bridge deck panel. The knowledge of the sensitivity of the sandwich composites will be helpful to update the model and also to design the bridge deck for better performance and improved longevity.

Dynamic response of polypropylene honeycomb/polystyrene foam core sandwich composite panels: Experimental and numerical analysis

In this study, dynamically loaded sandwich panels with two different core materials and face sheets made of aluminum alloys (6061-T6) were investigated experimentally and numerically under low-velocity impact. Polypropylene, PP (C3H6)n honeycomb and extruded polystyrene foam, XPS (C8H8)n were preferred as core material. By using the contact force and kinetic energy changes, which were the impact test results of the sandwich panels, the contact and impact resistance was examined. As a result of the tests, damaged regions and permanent central displacement were determined and energy absorption capabilities were demonstrated for two different structures. The results obtained were compared with the results obtained by the open finite element method. In this study, it was shown that the face-sheet thickness of sandwich panels was an important parameter affecting the impact behavior. The behavior of the core material when the face-sheet loses its rigidity was investigated and it was found that polystyrene foam was more effective in preventing impact damage. However, it was found that using the PP honeycomb or XPS was affected the impact behavior in different points.

A Numerical and Experimental Investigation into the Impact Response of Sandwich Composites under Different Boundary Conditions

The paper reports the results of an experimental and numerical investigation into the effect of the support conditions on the low velocity impact behaviour of sandwich composite panels. Significant differences are observed experimentally between the structural and damage responses to impact of small-span and large-span sandwich panels. In particular, impact events on large-span panels generate lower peak forces, larger displacements and smaller damage sizes in comparison to small-span panels subjected to the same impact energy. The experimental results are employed to validate the capability of a finite element (FE) tool to simulate the impact behaviour of the sandwich panels for the different boundary conditions. The comparison of FE and experimental results shows that the model provides a good prediction of the structural response as well as of the extent and mechanisms of impact damage for both small-span and large-span lengths, thus demonstrating the potential of the FE tool for verification and design of sandwich components in real engineering applications.

Transient response analysis of sandwich composite panel

In order to introduce a novel way relied on enhancing structural design as well as utilizing advanced material for protecting nonmetallic structures from detrimental impacts of transient thermal shock, this research analyzes the transient coupled thermo-elasticity response of the sandwich cylindrical panel with nanocomposite face-sheets strengthened with the functionally graded distributions of graphene-platelets affected by thermal shock loading. To determine the performance of the simply-supported system in the content of the time-altering stresses and deflections, the analytical solving approach, according to the broadly-known Navier technique, is applied to the governing equations developed on the bases of the exact theory of elasticity. It is considered that the internal surface of the panel is thermally isolated, while the outer surface is affected by thermal shock. The energy balance relation specified for this thermal boundary condition is solved to acquire the temperature gradient. Inverting the Laplace transform would be done with the aid of Dubner and Abates’ technique to designate time-history of displacements, shear stresses, and temperature distribution. The Halpin-Tsai micromechanics adjusted for nanocomposites is utilized to calculate thermoelastic properties of the nanocomposite face-sheets. The obtained numerical outcomes revealed the growth of the geometrical factor called mid-radius to thickness ratio leads to higher ultimate temperature and lower transverse shear stress.

Vibration of a Satellite Structure with Composite Lattice Truss Core Sandwich Panels

Composite materials are widely employed in spacecraft, aiming at increasing mass savings and load bearing capacities. Due to the excellent static and dynamic performance, lattice truss core sandwich structures have become one alternative of satellite structure materials. In addition, the dramatic potentials of multifunctional integration accelerate development of new spacecraft technology. In this investigation, a novel satellite structure concept with composite lattice truss core sandwich panels is proposed. A series of vibration tests and a finite element analysis campaign are conducted to determine the dynamic responses of the satellite structure. The developed finite element models provide a feasible numerical analytical scheme to address the vibration performance and structural integrity inspection. And the current satellite structure prototype demonstrates outstanding prospects of significant mass reduction and rapid assembly process.

Experimental and numerical study of transverse shear modulus for bioinspired glass fiber‐reinforced polymer sandwich core

AbstractSandwich panels with cellular material cores are widely used in the aerospace, automotive, and marine industries. Although honeycombs with hexagonal cells are the most frequent shapes for cores, new possibilities in lightweight structures have lately emerged. The present work evaluates the transverse shear modulus of the glass‐reinforced polymer honeycomb core (GFRP ‐ HC) and glass‐reinforced polymer corrugated bioinspired model (GFRP ‐ CBIM) core. The experimental results from the alternative dynamic technique agreed well with the numerical simulation. In the GFRP sandwich beam with corrugated HC and CBIM's core, numerical free vibration analysis was performed. The CBIM core has a higher natural frequency than the HC core, according to the numerical data. Further, numerical analysis has been performed on the bioinspired cores by varying the side length and edge radius. Modified bioinspired model ‐ 03 core design (MBIM03) appears to be a good option for regular honeycombs used in sandwich composite panels for industrial applications that demand low weight, high rigidity, and a large amount of energy‐absorbing capacity.

Core Configuration Effect On The Flexural Behaviour Of Sandwich Panel Made Of Aluminium Skin And Sengon Wood Core

Among the many choices of composite sandwich panel cores, Balsa wood is one of the main alternatives of cores made of wood. However, the availability and price of Balsa wood are quite expensive, so it needs alternatives from other types of wood such as Sengon wood. The purpose of this study was to evaluate the feasibility of Sengon wood as a core of composite sandwich panels. Three variations of the Sengon wood layout had been prepared as the core of the sandwich panels with a skin made of aluminum. All specimens, including the control specimens made of whole Sengon wood, were prepared with a size of 550 x 50 x 24 mm for length, width, and depth, respectively. Each variation and also the control specimens were made of 3 pieces. Tests were carried out based on the ASTM C 393-94 standard under the three-point bending test scheme. The results showed that the sandwich panel with plain Sengon wood core has the highest capacity to carry a flexural load, which is approximately 177.391 MPa, followed by a sandwich panel with long and end grain Sengon board that possess flexural strength of 153.913 MPa and 79.101 MPa, respectively. The flexural strength of these sandwich panels is superior to solid Sengon wood. The sandwich panels showed a typical ductile material indicated by a non-linear curve without a distinct yielded point before reach the maximum failure load. Three sandwich panels with various Sengon wood cores collapsed under three types of failure mechanisms; face wrinkling, shearing of the core, and delamination between the interface of skin and core. In conclusion, Sengon wood has a great potential to be used as the core material for a composite sandwich panel.

Influence of Temperature and Moisture on Free Vibration Behavior of Skew Laminated Composite Sandwich Panels with CNTRC Core

This paper presents the influence of temperature and moisture on the free vibration characteristics of skew laminated composite sandwich (SLCS) panels. The face sheets of the panels are made of graphite–epoxy composite, while the core consists of carbon nanotube-reinforced composite. The coupled hygro-elastic and thermo-elastic relations for the SLCS shells/panels are formulated using first-order shear deformation theory. The nonmechanical stiffness matrices are represented by the initial stress stiffness matrix developed using nonlinear strain–displacement relations. The temperature and moisture-dependent material properties are considered to analyze the laminated composite sandwich spherical, hyperbolic, ellipsoid, cylindrical Shells, and flat plates. Several numerical examples are comprehensively studied to establish the influence of temperature, moisture, the volume fraction of carbon nanotubes in the core material, functional gradation types, skew angle, and edge constraints on the vibration responses of SLCS shells. Further exploration is devoted to studying the combined effect of moisture, temperature, and the geometrical parameters such as length to width ratio, length to thickness ratio, radius-to-length ratio, and the core thickness to face sheet thickness ratios on the natural frequency of the skew laminated composite sandwich panels.

An experimental and numerical study on the vibration characteristics of glass fiber composite sandwich panel with lattice cores

This research aims to design, manufacture, and determine the vibration characteristics of a composite sandwich panel with lattice cores. For this purpose, first, a glass fiber sandwich panel with lattice truss core has been fabricated in the laboratory. In this part, the vacuum-assisted resin transfer molding method has been used to achieve laminates without any porosity. Afterward, the modal tests have been performed to obtain the natural frequencies, shape modes, damping ratio, and frequency responses of the sandwich panel. In addition, a finite element analysis has been developed to calculate the natural frequencies, damping ratio, and mode shapes of the composite sandwich panel. Then the experimental data have been compared to numerical simulation, and good agreement has been found.

Comparing Testing Methods of Partially Composite Sandwich Wall Panel Glass Fiber–Reinforced Polymer Connectors

Precast concrete insulated sandwich wall panels have been commonly used as exterior load bearing or cladding wall panels on building structures. These panels are usually designed as composite, partially composite, or noncomposite, depending on the strength of the shear connectors connecting the two exterior concrete wythes. Various proprietary available shear connectors are used to achieve the required degree of composite action. The design information of the shear connectors is provided by the connector supplier based on testing results. Currently, there is no universally accepted method of testing composite shear connectors in practice or in the literature, however, connector suppliers usually use one of two testing methodologies recommended by the International Code Council–Evaluation Service, namely, AC320 or AC422, respectively. It is not known which test provides a better measurement of design values such as strength and stiffness, and there is no such comparison in the literature. In this study, 68 pushoff experiments were presented to evaluate the difference between these two testing methodologies. The testing program consisted of 20 single shear specimens and 48 double shear specimens. Three different commercially available shear connectors were used as well as variable insulation wythe thicknesses. The results were statistically analyzed. Large differences in the measured connectors’ shear strengths and stiffness were observed between the two testing methods, with AC422 providing consistently larger ultimate shear and secant stiffness, but considerably more variability. Large-scale flexural specimens from the literature were modeled using AC320 and AC422 as-measured results, and AC422 tests were found to predict deflections, cracking, and strength more accurately. It was concluded that AC422 produces a more accurate measure of connector properties, but suffers from large variability, resulting in a recommendation that further investigation into changing testing parameters and/or methods is warranted to reduce this variability.

Impact Damage Characteristics of Quartz Fiber and NOMEX Paper Honeycomb Sandwich Panel composite materials

To provide a reference for practical engineering application of fiber composite materials, this work researches on the impact resistance of type-B quartz fiber/modified cyanate ester composite material laminates and NOMEX paper honeycomb sandwich panels. Firstly, low-speed impact tests are carried out on the quartz fiber laminates and the NOMEX paper honeycomb sandwich panels by setting different parameters to analyze the impact energy and punch mass on impact damage; secondly, based on the experimental results, impact responses are analyzed; and the damage morphology of the two composite materials is observed through visual inspection and with the aid of the CT scanning technology. The results show that according to time-load curves, the NOMEX paper honeycomb sandwich panels have two peak load moments, respectively corresponding to the moments when the upper and lower panels are penetrated; the quartz fiber laminates show three different types of failures, namely substrate cracking, fiber fracture and delamination. As for the NOMEX paper honeycomb sandwich panels, two types of damage are found: fiber fracture and honeycomb core extrusion fracture. When the punch mass is constant, the greater the impact energy is, the more serious the damage is; and when the impact energy is constant, the greater the punch mass is, the more serious the damage is.

Mechanical and damping property evaluation of jute fiber reinforced composite periodic core sandwich panels

ABSTRACT The present article investigates the dynamic characteristics of jute fiber-reinforced sandwich composite panels with periodic cores. The sandwich panel contains the jute fibers-reinforced polymer (JFRP) composites as face layers and the silicone rubber as the core layer. The tensile and flexural properties of JFRP composite material were examined using ASTM D3039 and ASTM D7264 standards. The finite element model was developed to obtain the dynamic properties of the composite sandwich panel with conventional and periodic cores. Furthermore, the influence of end condition, core to face layer thickness ratio, and face layer to core thickness ratio on the dynamic properties of the sandwich panels are presented. The numerical results indicate that the periodic core composite sandwich panel greatly influences the structural stiffness compared with a conventional composite sandwich panel.

Fatigue of composite honeycomb sandwich panels under random vibration load

The fatigue test of composite honeycomb sandwich panels has been carried out under random vibration load in this investigation. The test results show that, the failure mode of the honeycomb sandwich structure under random vibration load is the same as that under constant-amplitude load, both of which are core shear failure and the resulting face-core delamination. Based on the test results and the S-N curve of honeycomb sandwich panel under constant-amplitude load, a method has been proposed to predict the fatigue life of composite honeycomb sandwich structures under random vibration load. The core shear stress is taken as the fatigue damage parameter. The validity of the proposed method has been verified by comparing the predicted results with the test results.

Laser Welding of Metal-Polymer-Metal Sandwich Panels

In the production of metal-polymer multilayer composite parts, e.g., for automotive applications, the possibilities of thermal joining are limited due to the instability of the polymer core at elevated temperatures. Accordingly, such materials require a special approach to their welding. The three-layered metal-polymer-metal samples were made of DPK 30/50+ZE dual-phase steel as cover sheets that were electrolytic galvanized, and a polypropylene-polyethylene foil as core material, with thicknesses of 0.48/0.3/0.48 mm. The samples were welded on both sides using a 1.06 µm Nd:YAG ROFIN StarWeld Manual Performance laser. Significant improvements of the welding conditions are achieved by machining the edges of materials to be welded. The parameters of laser welding were chosen in such a way that the polymer structure remained almost unchanged. The weld thickness was about 40% of the thickness of each steel layer. It was established that within the selected laser processing parameters the melting occurred uniformly, while the polymer layer practically did not change its structure. Therefore, it can be stated that two-sided joint welding of metal-polymer-metal composite sandwich panels, without significant degradation of the polymer core layer, is feasible.

Bending response of sandwich panels with steel skins and aluminium foam core

AbstractNominated for Eurosteel 2021 Best Paper AwardThe introduction to the market of metal foams represents a significant opportunity to increase the use of metal in the construction market. In fact, the development of new products made of metal foams and steel could improve the performance of conventional buildings in terms of stiffness and resistance. The first structural applications of these materials have already shown the potential of composites made of foam and steel, and demonstrated the feasibility of producing mono‐dimensional and bi‐dimensional elements with a high resistance‐to‐weight ratio. Reducing the structural weight can be a significant advantage in many cases, such as infrastructures or buildings in seismic zones. Within this framework, the work presented in this paper aims to assess the response of composite sandwich panels made of steel and aluminium foam using a set of tests that will serve as the basis for developing a new system of dry‐assembled composite floors. The tests were carried out at the Strength laboratory (Structural Engineering Test Hall) at the University of Salerno, Italy and were designed to verify the mechanical properties of metal foam panels and double‐skin glued sandwich panels. The tests have shed light on the basic mechanical properties of both foams and sandwich panels.

Compressive Strength Experiment of Honeycomb Sandwich Composite Panel

The experimental investigation on the compressive properties of honeycomb sandwich composite panels was carried out in this paper. The local compressive specimens and global compressive specimens were manufactured for compressive experiment. The test fixture has been designed and manufactured to examine the compressive behavior of honeycomb sandwich panel. The results indicate that there is no buckling occurred in local compressive specimen skin during the whole compressive experiment. The average failure load of local compressive specimens is 106884 N. The local buckling increases with the loading until the global compressive specimens are unstable. The fracture positions locate along the horizontal line at the middle height of global compressive specimen, which is different from local compressive specimens. The average buckling load and failure load of global compressive specimen are 31850 N and 82282 N respectively.

Comparative experimental study into the explosive blast response of sandwich structures used in naval ships

Naval ships can be constructed using sandwich composite structures with the core material being polymer foam or balsa wood. Naval ships are at risk from explosive blasts from underwater and airborne munitions, and therefore the sandwich structures used must be resistant to extreme deformation and damage caused by blast loads. An experimental study is presented comparing the explosive blast response of sandwich composite panels with a polymer foam (PVC) core or balsa core with polymer laminate facesheets reinforced carbon or glass fibres. These materials studied are representative of sandwich structures used on naval ships. Sandwich panels were subjected to small-scale explosive air blasts of increasing shock wave impulse loads. The out-of-plane deformation and damage was influenced by both the facesheet laminate material and the core material. The fibreglass laminate facesheets were more resistant to blast-induced damage than the carbon fibre facesheets. The blast damage to the facesheet-core interfaces and within the core was more extensive using balsa compared to polymer foam. The study provides new insights into the relative blast performance of different types of sandwich structures used in naval ships.

An exact solution for vibro-acoustic response of smart sandwich panels with MEE composite Layer

To the best of our knowledge, this is the first endeavor to provide an exact solution for a vibro-acoustic response of Magneto-electro-elastic (MEE) composite plate and sandwich panels with MEE facings. The governing equation of motion is developed using Hamilton’s principle considering the third-order shear deformation theory to account for transverse shear. Based on boundary conditions and the Maxwell equation, the variation of electric and magnetic potentials are adopted along the thickness of the MEE composite layer. Analysis of the vibro-acoustic response of sandwich panels which are extensively used in aerospace structures such as cellular, trapezoidal, triangular, and honeycomb are presented. Influences of electric and magnetic potential on the vibro-acoustic response are also presented for the different types of truss core and honeycomb core sandwich panels.

Sound Insulation Performance of Composite Double Sandwich Panels with Periodic Arrays of Shunted Piezoelectric Patches.

The existing sandwich structure of the aircraft cabin demonstrates a good sound insulation effect in medium and high frequency bands, but poor in the low frequency band. Therefore, we propose an infinite new lightweight broadband noise control structure and study its sound transmission loss (STL). The structure is an orthogonally rib-stiffened honeycomb double sandwich structure with periodic arrays of shunted piezoelectric patches, and demonstrates lighter mass and better strength than the existing sandwich structure. The structure is equivalent according to Hoff’s equal stiffness theory and the effective medium (EM) method. Using the virtual work principle for a periodic element, two infinite sets of coupled equations are obtained. They are solved by truncating them in a finite range until the solution converges. The correctness and validity of the model are verified by using simulation results and theoretical predictions. Eventually, a further study is performed on the factors influencing the STL. All the results demonstrate that the STL in low-frequency can be improved by the structure, and the sound insulation bandwidth is significantly broadened by adding shunted piezoelectric patches. The structure can provide a new idea for the design of broadband sound insulation.