Papers by Keyword: Sandwich Panel

Abstract: In current days, sandwich structures have become popular due to their flexibility with design requirements and excellent performance under extreme loads, such as blast. There are different strategies for enhancing the blast resistance of such sandwich structures. Including an additional layer of polyurea and stiffeners are widely used techniques that may enhance the performance of the panels under high-rate loadings. In this study, the effects of polyurea and stiffeners on the protection of a steel and aluminum foam sandwich panels is studied. Effective configuration of the panels with both polyurea and stiffeners are investigated. Here, different configuration cases of the sandwich panels: (a) panel without polyurea and stiffeners, (b) with polyurea applied on the rear face, (c) with stiffeners applied on the rear face, and (d) with stiffeners and polyurea on the rear face are investigated and compared. The finite element models of sandwich panels are developed, where steel facesheets, steel stiffeners, and polyurea are modeled with shell elements, and aluminum foam core is modeled with solid elements. Elastic-plastic, crushing foam, and hyperelastic material behaviors are implemented for steel, aluminum, and polyurea layers of the sandwich panels, respectively. The performance of the different configurations of the panels are compared in terms of the response quantities, i.e., deformation, equivalent von-Mises stresses, and energy absorption. Moreover, the damage patterns with fragmentation effect are depicted for all the considered sandwich panels. The results of the study show that both polyurea and stiffeners are the most effective configurations in protecting the sandwich structures; however, with the same thickness of polyurea and stiffener, the stiffeners show better performance than polyurea against blast load. Furthermore, it is observed that the deflection values across the configurations follow a logarithmic decay pattern.

Abstract: Sandwich panels are widely used in engineering applications due to their advantageous combination of lightweight and high strength. However, their long-term mechanical performance under repeated loading highly depends on the internal lattice structure. This study experimentally investigates the behavior of SLA-manufactured sandwich panels with different lattice geometries under cyclic loading conditions. Various lattice configurations were designed and subjected to repeated compressive loads while monitoring stress relaxation and mechanical deformation over time. The results demonstrate that lattice geometry significantly affects load-bearing capacity and energy dissipation. Notably, structures incorporating vertical support members exhibited higher energy absorption, whereas those without vertical supports, such as M4 and M5, showed improved resistance to stress relaxation over multiple cycles. Furthermore, while all specimens experienced load reductions after 25 cycles, the magnitude of these reductions varied based on the lattice configuration, with M3 exhibiting the highest load decay. These findings contribute to optimizing lattice-based sandwich structures for enhanced durability and mechanical efficiency in engineering applications.

Abstract: The problem of protecting people and increasing the safety of technical equipment in situations of combat, emergency and other unforeseen extreme situations caused by a mechanical blow has always been, is and will be relevant. In the material-related aspect, the problem of developing shock-resistant materials is now transformed into the requirements of the present to create multifunctional composite panels and protective structures on their basis. Due to the fact that the experimental achievement of the required durability and reliability of products is a complex technical task (the solution of which requires large energy and financial resources), an important role is obtained by simulating the processes occurring during their operation, which gives recommendations on the correct choice of materials developed composites. In this work, the behavior of composite materials that are in a closed space under the influence of high-speed dynamic load is studied. The purpose of the work is to develop composite materials for light shockproof protective structures and to determine the nature of the packaging, the features of the structure and the level of their physical and mechanical properties. Conducted calculations of economic effect on the results of research.

Abstract: Although rigid foam core structures have gotten a lot of attention, there have only been a few researches on foam reinforced sandwich panels with aluminum alloy A6061 sheets as face-sheets. In this research, the sandwich concept was applied to develop lightweight panels for roofing system. Analysis on the influences of core thickness, density, and foam layer arrangement on energy absorption, bending strength and displacement of sandwich panel under the quasi-static three-point bending test were investigated. Sandwich panel core is made of closed-cell polyurethane foam with densities of 40 kg/m³, 60 kg/m³, and 80 kg/m³. The quasi-static three-point bending tests were conducted in accordance to ASTM C-393 Standard and the polyurethane foam cores are design accordingly to the guideline of National Institutes of Standards and Technology (NIST). Load–displacement curves and mechanical properties are shown using data from experimental works. Results demonstrate that increased in thickness of the sandwich panel, also increased the bending strength, energy absorption and displacement. Furthermore, the sandwich panel with 50 mm thickness and 60 kg/m³ density foam core has the maximum bending strength.

Abstract: The aim of the present paper is to study the vibration behavior of a sandwich structure with honeycomb core experimentally and numerically with different design parameters. The natural frequency and damping ratio were obtained. Core height, cell angle and face thickness were considered as design parameters. Finite element models for the honeycomb sandwich were developed and analyzed via ANSYS finite element analysis (FEA) software. Response Surface Method (RSM) is used to establish numerical methodology to simulate the effect of the design parameters on natural frequency and damping ration. The employment of (RSM) provides a study of the effect of design parameters on natural frequency and damping ratio, numerical modeling of them in term of design parameters and specifying optimization condition. The experimental tests were conducted on sandwich specimens for the validity goal of the previous models created via the finite element analysis. The obtained results show that the natural frequency is directly proportional to the core height and face thickness, while it is inversely proportional to cell angle, Vice versa for damping ratio. Moreover, the optimum value of natural frequency (209.031 Hz) as minimum and damping ratio (0.0320) as maximum were found at 4.8855 mm of core height, 26.770 cell angle and 0.0614 mm face thickness.

Abstract: Corrugated core panels contain a formed, corrugated core bonded between two skin sheets. These panels are typically used in applications, where a low weight is required with integrity in stiffness. This paper demonstrates the mechanical properties of a simple panel structure (SPS), constructed using strips of work-hardened, austenitic stainless steel (ASS) grade 1.4310 (type 301) with the yield strength (YS) of ~1200 MPa. The 0.5 mm thick strips were formed into a C-shape and subsequently laser welded together by lap joints to form a SPS. The thickness of the SPS was 50 mm. The bending tests for the SPS were carried out transverse and 45-degrees related to the orientation of the web sheet. The results showed that the SPS, as loaded in the transverse direction, has about the same bending stiffness prior yielding as that of the previously tested 6 mm thick, low carbon S355 plain steel sheets, but the SPS is three times lighter than 6mm thick plain steel sheet. Compared with a corrugated core panel made of an annealed ferritic stainless steel (SS-panel) with the YS ~ 250 MPa, the weight of the both panels are roughly the same, but the bending resistance of the SPS is 45% higher. Experimental tests also verified that the benefit in the stiffness is quickly reduced if the load direction differs from transverse. In the 45-degrees loading direction, the SPS and the SS-panel had almost the same bending strength. On the other hand, the SPS and the SS-panel stiffnesses are much better than that of the carbon steel (the YS ~ 300 MPa) panel (CS-panel) in the both loading directions – the SPS being twice as stiff as the CS-panel.

Abstract: This study was employed to investigate the buckling effect for a single Vf corrugated core. Brief and simple designing method is developed for UHS sandwich structure. This method is based on simplified calculation of slenderness ratio integrated with FEM simulation. Method is developed for studying the local buckling resistance of sandwich structures to optimize the panel dimensions for maximal stiffness. Five different core dimensions were tested (angles of 110-135 ° and height of 35 - 55 mm). Buckling tests were made using two different steel grades; ultra-high-strength (UHS) ARS400 and DC01 mild steel. For comparison, FEM simulations were carried out for the ARS400. The results showed that even 600% higher bending resistance can be achieved for the panel structure using the ultra-high strength steel instead of the low strength counterpart. The comparison showed that the FEM-simulations can be used reliably estimating the buckling effects in UHS panel structures. The difference between the empirical and simulation results was 5.3% in average (S.D. 4.1). In practical tests, best angle and height for the ARS400 was 110 ° and 35 mm respectively. For the DC01, the best dimensions were 125 ° and 35 mm.

Abstract: Sandwich face sheets are very important roles in composite materials. It was simulated that the quasi-static compressive crush performances of three types of sandwich sheets by ANSYS/LS-DYNA software. The aluminum top panels (“half hard”) had the higher plateau stress and its absorption energy reached 20.483J/mm³, were superior to the steel top panel (“hard”); the bottom face sheet rarely affects the energy absorption properties in cases.

Abstract: This paper deals with a new fabrication technique of carbon fiber-reinforced thermoplastic (CFRTP) honeycomb cores and all-CFRTP honeycomb sandwich panels. The CFRTP core was made of plane woven carbon fiber-reinforced polypropylene prepreg sheets. The stacked CFRTP prepreg sheets were periodically hot-pressed at the node locations, and then expanded to form an all-CFRP honeycomb core. The resultant CFRTP honeycomb cores were glued with the same polypropylene-based plain-woven CFRTP skin plates. The mechanical performance of the all-CFRTP honeycomb sandwich panels was evaluated by flexural tests. The experimental results showed the effectiveness of proposed all-CFRTP sandwich panels.

Abstract: Recently various types of sandwich panel are applied for constructing bridge and ship structures. Sandwich panel is material that consists of lightweight core material and two metal faceplates. The application of sandwich panel in ship structures makes the structure less-complex and ship’s selfweight lighter because of the reduction of secondary stiffeners. This paper discusses sandwich panel that was fabricated using synthetic resin core material and two steel faceplates. This study is aimed to analyze stresses developed in the sandwich panel of 750 GT Ro-Ro ship car deck structure when it was subjected to the deck design load. The finite element analysis was carried out to obtain the stress distribution and maximum deformation on the car deck structures. The stress of the ship car deck constructed using conventional steel structure, i.e. steel plate and stiffener, was compared with the stress of the deck that was built using sandwich panel.