Foam Core Sandwich Panels Research Articles

Recycled PET foam core sandwich panels with reinforced hybrid composite facesheets: A sustainable approach for enhanced impact resistance

This research explores the Low-Velocity Impact behavior of thermoplastic composite sandwich panels with 100% recycled Polyethylene Terephthalate (PET) foam sourced from post-consumer plastic water bottles. Being recognized as a reliable technique, hybridization using stainless-steel mesh layers was employed to reinforce the panels’ composite facesheets of sandwich panels accessible for modular housing, cold storage rooms and cargo trucks. Adequate impregnation of the reinforcement metallic mesh layer alongside proper skin-to-core adhesion was accomplished by optimizing a two-phase compression molding method. The effect of hybridization on impact response of sandwich panels with two different PET foam core thicknesses, and stacking sequence were evaluated. It was revealed that reinforcing the impacted surface of the composite sandwich panels significantly increased the perforation threshold. Moreover, analyzing the post-impact section view of the samples indicated that hybridization modified the damage propagation response of the PET foam core sandwich composites, through which the energy absorption capacity was improved.

Evaluation of mechanical properties and energy absorption of polyurethane foam core sandwich panels with kevlar/basalt-epoxy laminates as face sheets

Evaluation of mechanical properties and energy absorption of polyurethane foam core sandwich panels with kevlar/basalt-epoxy laminates as face sheets

Mechanical Properties of Eco-Friendly, Lightweight Flax and Hybrid Basalt/Flax Foam Core Sandwich Panels.

Greener materials, particularly in sandwich panels, are in increasing demand in the transportation and building sectors to reduce environmental impacts. This shift is driven by strict environmental legislation and the need to reduce material costs and fuel consumption, necessitating the utilisation of more sustainable components in the transportation and construction sectors, with improved load-bearing capabilities and diminished ecological footprints. Therefore, this study aims to analyse and evaluate the structural performance of polyethylene terephthalate (PET) core and flax or basalt/flax FRP sandwich panels as an alternative to conventional synthetic materials. The novel eco-friendly sandwich panels were manufactured using the co-curing technique. Four-point bending, edgewise compression and core shear tests were performed and insights into how the skin properties affect the strength, stiffness and failure mode of specimens were provided. The stress-strain behaviour, facing modulus and strength, flexural rigidity, core shear strength and failure modes were evaluated. The flexural facing modulus of the flax and flax/basalt sandwich skins were found to be 5.1 GPa and 9.8 GPa, respectively. The flexural rigidity of the eco-friendly sandwich panel was compared with published results and demonstrated a promising structural performance. The environmental benefits and challenges were outlined and critically evaluated focusing on transportation and construction applications.

Effect of Kevlar and Carbon Fiber Face Sheet on the Deformation Behavior of Aluminum Hybrid Composite Foam Core Sandwich Panel under Flexural Loading

Effect of Kevlar and Carbon Fiber Face Sheet on the Deformation Behavior of Aluminum Hybrid Composite Foam Core Sandwich Panel under Flexural Loading

Low-velocity impact response optimization of the foam-cored sandwich panels with CFRP skins for electric aircraft fuselage skin application

Abstract Composite sandwich structures are widely used in the aerospace field due to their advantages of high strength, lightweight, and fatigue resistance. However, these structures are prone to damage with very-low-energy impacts. In order to improve the impact resistance of aircraft skin structure, a low-velocity impact resistance of sandwich structure specimens was tested by means of drop hammer impact, and the impact damage area was scanned by ultrasonic C-scan, and obtains the impact damage of specimens with different impact energies and different ply sequences. Combined with the Hashin failure criterion, the finite element equivalent model of composite sandwich structure under low-velocity impact was established. The errors between the simulation results and the C-scan results of the test piece were less than 10%, in which the experimental measurements and numerical predictions were in close agreement. Finally, the finite element equivalent model was applied to optimize the application of model sandwich, which was used for fuselage skin of a certain electric aircraft. The total thickness of the laminate structure remains unchanged before and after optimization, but the impact resistance was significantly enhanced. The ±45° lay-up was beneficial for the structure to absorb the impact energy.

Addressing the Orbital Debris Threat Directionality for Enhanced Protection of Low-Earth-Orbit Robotic Spacecraft

This study conducts a detailed investigation into addressing the directionality of micrometeoroid and orbital debris (MMOD) threats, emphasizing the strategic placement of protective resources on a spacecraft. The research considers the conversion of the structural sandwich panel and the multilayer thermal blanket into multifunctional elements that provide MMOD protection without causing substantial weight gain or affecting operational parameters. The effectiveness of the reconfigured components, such as the foam core sandwich panel and multilayer insulation blanket toughened by Nextel fabrics, is evaluated using developed and validated numerical models and experimental methods. Their performance is demonstrated by meeting the protection needs of the Canadian robotic Radarsat Constellation Mission spacecraft.

Understanding Damage Initiation and Propagation Mechanisms in Polyurethane Foam Core Sandwich Panels Using Acoustic Emission Monitoring

Understanding Damage Initiation and Propagation Mechanisms in Polyurethane Foam Core Sandwich Panels Using Acoustic Emission Monitoring

Analytical model of low-velocity impact penetration of sandwich panels with metal foam core and nanocomposite face sheets

This paper investigates the low-velocity penetration dynamic response of metal foam core sandwich panels with composite face sheets reinforced by nanoparticles. Based on the experimental results, an energy model is developed to predict contact force, impactor displacement, energy absorption, mechanisms of impact damage, and failure modes. An elastic–plastic–rigid (E–P–R) model is used to derive the energy absorbed by the metal foam. A stress function in terms of density ratio and strain is considered to predict the compression behavior of metal foam. The effect of nanoparticles investigated by the Halpin Tsai model. The analytical prediction is compared with the results of the experimental test and a reasonable agreement has been observed. The tested sandwich panel consisted of an aluminum foam core and an epoxy/carbon fiber face sheet reinforced with reduced graphene oxide (RGO). This model is useful for improving the design of sandwich panels with carbon fiber composite face sheet reinforced with nanoparticles and aluminum foam core. The results of impact test showed the addition of reduced oxide graphene increased the value of the first peak load by about 15%, the second peak load by about 36% and the amount of energy absorption in sandwich panel by about 18%. The radios of delamination and debonding reduced by 47% and 17.5%, respectively, compared to the sample without nanoparticles.

Augmenting foam-core sandwich panel with toughened blanket for enhanced orbital debris protection

Experimental and numerical analyses have demonstrated that foam-core sandwich panels (FCSP) can serve as a practical substitute for conventional sandwich structures, offering both structural support and effective protection against micrometeoroid and orbital debris (MMOD) in space applications. This research aims to enhance further the MMOD protection level beyond the inherent capability of FCSP by augmenting the panel with the toughened thermal blanket. The study employs a numerical simulation approach validated with physical test data and investigates the effect of integrating Nextel fabrics into multilayer insulation blankets on the overall shielding performance of the system.

Experimental characterization of impact damage in foam-core sandwich structures using acoustic emission, optical scanning and X-ray computed tomography techniques

Sandwich structures used in transportation and energy industries are commonly subjected to low-velocity impact in the course of manufacturing, service and maintenance, which can lead to the premature degradation of structural stiffness and strength. A single non-destructive evaluation technique is often difficult to provide a comprehensive assessment on impact damage from online to offline and from visible to invisible. In the present study, acoustic emission (AE), three-dimensional (3D) optical scanning and X-ray computed tomography (CT) techniques are combined to provide a systematic approach for damage characterization of thick foam-core sandwich panels under low-velocity impact. In the tests, the mechanical responses such as force-time and force-displacement curves are obtained from the testing system. The AE technique is adopted to monitor damage initiation and evolution in situ; optical scanning and X-ray computed tomography techniques are used for off-line damage identification and quantification. The results show that the AE signal waveform stream, cumulative counts and cumulative energy correlate well with the mechanical responses of the sandwich panel under the low-velocity impact, enabling capture of valuable information for online damage monitoring. Unlike general cases, the AE signals generated from low-velocity impact are found to be presented in strong bursts of nearly coincident events in the short duration. Therefore, the distributions of AE amplitude and peak frequency between adjacent AE counts are extracted to study the different damage modes and damage mechanisms. The X-ray computed tomography images enable to precisely visualize the fracture behaviors of the PET foam-core inside the sandwich panel in a nondestructive fashion, which evidently supports the AE and optical scanning results. The study is anticipated to demonstrate effectiveness and capability of the proposed experimental methodology for damage detection and characterization on sandwiched composite structures subjected to impact loading.

The effect of nanoclay on the performance of basalt-epoxy facesheet and foam core sandwich panels

It has been reported that the properties of a foam-based sandwich panel can be enhanced by incorporating nanoclay into the facesheet or foam core. In this study, an attempt was made to disperse nanoclay into the epoxy adhesive so as to bond the facesheet with the core. The sandwich panel in this study was fabricated using a basalt/epoxy laminate as the facesheet and polyvinyl chloride foam as the core material. The characterisation results through flexural and quasi-static indentation tests revealed that the infusion of nanoclay led to an increase of up to 34% in the bending strength, 51% in the core shear strength, and 72% in energy absorption. In addition, the nanoclay-reinforced sandwich panel showed a slightly higher sound absorption coefficient than the control specimen without nanoclay. Another interesting observation from the flexural and quasi-static indentation tests was that the addition of nanoclay also influenced the failure behaviour and the size of the damaged area. The superior energy and sound absorption characteristics make the foam-based sandwich panel a potential material for structural applications requiring acoustic insulation.

Numerical and Experimental Study on Loading Behavior of Facade Sandwich Panels

This paper focuses on the study of the strength of facade sandwich panels used in building construction. The paper describes the results of experimental and numerical research on the behavior of sandwich panels made of polyisocyanurate core (PIR) and their structural connections when exposed to tensile and compressive loads. In the initial phase of this study, laboratory tests were performed to determine the physical and mechanical characteristics of the material from which the sandwich panels are made. Laboratory tensile and compression tests were performed on small samples of sandwich facade panels. In order to verify the obtained results, they were compared with the numerical analysis performed in the ANSYS software. The numerical model was found to accurately predict the results of the laboratory tests, suggesting that the model can be used to predict the behavior of these panels under different loads in service. The study showed that the foam core sandwich panel exhibits excellent mechanical properties. The results indicate the suitability of foam-based composite structures in the construction industry for various applications, such as roof and wall structures. The findings of this study may help in the development of lightweight and durable construction materials for the industry.

Evaluating UHMWPE-stuffed aluminium foam sandwich panels for protecting spacecraft against micrometeoroid and orbital debris impact

Robotic spacecraft shielding for protection against micrometeoroid impact is typically provided by existing structural panels, thermal insulation blankets, or reinforced component containers. Here the performance of an open cell aluminium foam core sandwich panel with intermediate ultra-high molecular weight polyethylene (UHMWPE) stuffing under hypervelocity impact of spherical aluminium projectiles was evaluated. Providing comparable structural and thermal performance as honeycomb sandwich panels, foam core sandwich panels have demonstrated improved impact shielding behaviour in existing studies. The inclusion of UHMWPE stuffing is found, through experimental testing and a comprehensive numerical study, to increase the shielding capability of foam core sandwich panels (40–80% increase in critical projectile diameter) for a modest weight penalty (25%). Compared to conventional aluminium honeycomb sandwich panels with equivalent weight, the improvement in shielding performance is >100%.

Enhancing the foam-core sandwich panel for protection against near-centimeter-size MMOD and beyond

Foam-core sandwich panels (FCSP) have been shown in experimental and numerical studies to be a viable alternative to conventional sandwich structures such as honeycomb sandwich panels. The inherent morphological design of the foam core, in addition to its structural role, makes it an excellent choice for spacecraft protection against micrometeoroid and orbital debris (MMOD). If the maximum acceptable risk level requires MMOD protection against larger particles beyond the FCSP's protective capability, it will have to be improved. This paper discusses and evaluates concepts for enhancing the foam-core sandwich panel for protection against larger MMOD particles. The study employs a numerical simulation approach with adequate validation based on physical test results.

Flexural Characterisation of Sandwich Panel with Corrugated Glass Reinforced Polymer

The corrugated foam core sandwich construction is used in variety of structural applications. These structures are subjected to flexural, impact, edgewise compression and shear loads. Traditional process for manufacturing of sandwich panel is not suitable for making corrugated core sandwich panel. In this work a novel methodology has been developed for construction of corrugated foam core sandwich panel. The present study focuses on the flexural behaviour of sandwich panel by varying the foam densities and corrugated cell. Two types of densities with one cell and two cells are used. The sandwich employs a Glass Reinforced Polymer (GRP) orthotropic material for both the two outer skins and the inner core web. In particular, the core is designed to have uneven topology to cooperate with GRP skins in membrane and flexural properties by adding a corrugated foam core. At first, a comparison has been performed between different density foams. Initially, 40 kg/m3 with 1 unit cell and 32 kg/m3 with 1 unit cell are compared, and then the same densities are compared with 2 cells. Among all, 40 kg/m3 with two cells shows highest flexural strength compared to the other specimens. Also, the sandwich panel with an empty core has been tested to understand the strength of the face sheet and corrugated core.

Crushable polymer foam behavior at cold temperatures

Experiments were conducted to characterize and develop predictive constitutive equations for the elastic-plastic, post-yield hysteresis behavior of Divinycell H100 foam at temperatures as low as −40°C. The initial elastic modulus and yield strength of the foam increased almost linearly by about 50% as temperatures decreased from 23 to−40°C. Post-yield hysteresis, which was described by strain hardening, viscoelasticity and damage also increased as the temperature fell to −40°C, but this behavior was curtailed by a sharp reduction in tensile and shear ductility as the foam approached its ductile-to-brittle transition temperature near −50°C. An anisotropic elastic-plastic, viscoelastic damage constitutive model was extended to predict cold temperature behavior. Good agreement was found between analytical predictions and the experimental results. The temperature-dependent constitutive equation can be used in conjunction with appropriate failure criteria to predict foam-core sandwich panel behavior in cold regions.

Optimization of Pin Position and Angle for Z-Pin-Reinforced Foam Core Sandwich Structures

Sandwich panels (SP) are very promising components for structures as they ally high levels of specific stiffness and strength. Civil, marine and automotive industries are some examples of the sectors that use SPs frequently. This work demonstrates the potential of manufacturing Z-pin-reinforced foam core SPs, using a design strategy that indicated optimal values for both pin position and angle, keeping the same pin diameter as determined in a previous study. A simple search algorithm was applied to optimize each design, ensuring maximum flexural stiffness. Designs using optimal pin position, optimal pin angle and optimal values for both parameters are herein investigated using numerical and experimental approaches. The optimal pin position yielded an increase in flexural stiffness of around 8.0% when compared to the non-optimized design. In this same comparison, the optimal pin angle by itself increased the flexural stiffness by about 63.0%. Besides, the highest increase in the maximum load was found for those composites, molded with optimized levels of pin position and pin angle, which synergistically contributed to this result. All results were demonstrated with numerical and experimental results and there was a good agreement between them.

Low velocity impact penetration response of foam core sandwich panels with face sheets

Foam aluminum sandwich panels have potential applications in many fields because of their excellent performance. This study aims to explore the low velocity penetration dynamic response of foam sandwich panels. Based on the experimental results, a three-stage penetration model is established. Based on the principle of energy conservation, minimum potential energy and accumulating damage theory, the load and displacement time history, energy absorption and initial failure mode of the sandwich panel during penetration are predicted theoretically. The theoretical prediction results are compared with the experimental results, showing that the predicted failure load and deformation are within 10% of the experimental data. This paper provides an analytical method for studying the deformation failure mode and energy absorption mechanism of metal foam sandwich panels, which is helpful to improve the efficiency of metal foam sandwich panels in design.

Dynamic fluid-structure interaction of graded foam core sandwich plates to underwater blast

• Performing fluid-structure interaction analysis on fully clamped graded foam core sandwich. • Introducing cavitation evolution under the planar underwater impulsive loading. • Showing nonuniformed distribution of the cavitated bubbles during its extension and collapse. • Proposing the determining factors of cavitation evolution for the graded sandwich. • Showing superiority of the core gradient design for eliminating cavitation. The aim of this paper is to address characteristics of cavitation evolution caused by the one-dimensional fluid-structure interaction as the graded foam core sandwich panels are subjected to underwater impulsive loadings. A transparent underwater shock tube is adopted to generate controllable and planar blast impulses exerted on the fully clamped sandwich panels. The effects of the impulsive intensity, core strength, core density gradient, and boundary condition are carried out to examine the cavitation evolution during the dynamic fluid-structure interaction. The results show that the initiation, extension, and collapse of the cavitation are significantly determined by the propagations of the breaking front and the closing front, which have different correlations with the considering effects. Due to the dynamic core compression and unloading, the distinct elevating speed of the closing front is firstly found in the fluid-structure interaction under the impulsive loadings. During the cavitation evolution, the non-uniformed distribution of the cavitated bubbles indicates that the cavitation region closer to the fluid-solid interface experiences more considerable pressure drops. The dynamic response of the weakest layer of the core shows predominant influences on the propagation trajectories of wave fronts and reducing of the cavitation ratio, indicating that the core gradient design can efficiently decrease the transmitted impulse and has superiority to the uniform cores with the identical areal mass.

Study on Flexural Behavior of Glass Fiber Reinforced Plastic Sandwich Composites Using Liquid Thermoplastic Resin.

Experimental and numerical studies of composite sandwich structures are warranted to reap the benefits of these materials when they are well designed. In the current research, new liquid thermoplastic and epoxy resins were used to fabricate four composite sandwich panels with two additional foam types and different densities in the wind turbine industry. A comprehensive comparison of three-point bending test results was made. Finite-element-based simulations using the ABAQUS program with Hashin’s damage criterion were conducted to examine the failure behavior of the GFRP sandwich composites. The flexural behavior of the glass-fiber-reinforced plastic (GFRP) sandwich panels was investigated and compared with the experiments. The results show that the GF/PVC/Elium composite panel gives the highest load absorption, flexural strength, flexural modulus, core shear ultimate strength, and facing stress due to effect of the core foam and resin types. For the PVC foam core sandwich panel, using thermoplastic resin increased the flexural strength by 18% compared to that of the epoxy resin. The simulation results show excellent agreement between the finite-element-predicted failure loads and the experimental results.