Showing papers on "Sandwich-structured composite published in 2022"

The efficient design of hybrid and metallic sandwich structures under air blast loading

Abstract: A novel hybrid composite honeycomb sandwich structure (HCHSS) and metallic honeycomb sandwich structure (MHSS) were developed to obtain realistic and blast resistance parameters for the consideration of blast loading. Hybrid composite square honeycomb sandwich structure (HCSHSS) and metallic honeycomb sandwich structure with different cores such as square, hexagonal, octagonal, and circular were modelled to obtain the target protection level (lowest deflection) for the vehicle armour structure. The Johnson-Cook and Donadon failure criteria were incorporated into finite element analysis (FEA) for MHSS and HCSHSS, respectively. For the progressive damage modelling of the HCSHSS, the Donadon criterion was implemented in ABAQUS/Explicit software as a user-defined subroutine. The HCSHSS showed the fibre failure, matrix failure and delamination modes of failure in composite laminates and the plastic deformation failure of the core and metal plates. The HCSHSS was shown to have excellent blast worthiness properties in comparison to the MHSS. The metallic circular honeycomb sandwich structure (MCHSS) was shown to have the minimum deflection of the top and bottom face plates as compared to the square, hexagonal and octagonal honeycomb sandwich structures. A novel HCSHSS has obtained the minimum deflection for both the top and the bottom face plates in comparison to the other MHSS.

Mechanical and energy absorption properties of the composite XX-type lattice sandwich structure

Abstract: In this paper, two types of the composite XX-type lattice sandwich structure (XX (Ⅰ) and XX (Ⅱ)) were made of panels (medium-density fiberboard and plywood) and core (birch) by using a type of insertion-glue method. An out-of-plane compressive test and a short beam shear test were carried out to investigate the failure modes, mechanical and energy absorption properties of the composite XX-type lattice sandwich structure. Results showed that the compression and short beam shear failure modes of composite XX-type lattice sandwich structure were mainly the shear failure of the core and the failure of panels. The sandwich structure with the core diameter of 8 mm had good compression property. The XX (Ⅱ)-type lattice sandwich structure of the combination of Plywood + birch had better compression, short beam shear, and energy absorption properties. The combination of MDF + birch was more suitable for the compressive theoretical model.

Mechanical and energy absorption properties of the composite XX-type lattice sandwich structure

Abstract: In this paper, two types of the composite XX-type lattice sandwich structure (XX (Ⅰ) and XX (Ⅱ)) were made of panels (medium-density fiberboard and plywood) and core (birch) by using a type of insertion-glue method. An out-of-plane compressive test and a short beam shear test were carried out to investigate the failure modes, mechanical and energy absorption properties of the composite XX-type lattice sandwich structure. Results showed that the compression and short beam shear failure modes of composite XX-type lattice sandwich structure were mainly the shear failure of the core and the failure of panels. The sandwich structure with the core diameter of 8 mm had good compression property. The XX (Ⅱ)-type lattice sandwich structure of the combination of Plywood + birch had better compression, short beam shear, and energy absorption properties. The combination of MDF + birch was more suitable for the compressive theoretical model.

Investigation on the flexural properties of sandwich beams with auxetic core

Abstract: Availing cellular structures as the core of sandwich beams is an innovative approach to improve the efficiency of them. Nonetheless, the flexural characteristics of sandwich beams are affiliated to the core topology. Accordingly, choosing an appropriate core can have a significant efficacy on the performance of sandwich beams. The purpose of the present study is to assess the influence of using auxetic cores in flexural properties of sandwich beams. Specifically, experimental and finite element approaches were implemented to evaluate the flexural behavior, energy absorption and the stiffness of fully integrated 3D printed polymeric sandwich beams, made of square node anti-tetra chiral, arrowhead and re-entrant auxetic cores, compared with the conventional honeycomb core. Fabrication of specimens was performed using the FDM 3D printing method, and three-point bending tests were conducted on the printed specimens. Results indicated that selection of proper core topology has remarkable effect on the flexural properties of sandwich beams, and using auxetic core is potentially an efficient method to enhance mechanical properties of sandwich beams due to high load bearing capacity.

Physical property and failure mechanism of self-piercing riveting joints between foam metal sandwich composite aluminum plate and aluminum alloy

Abstract: Self-piercing riveting is a promising method to join thin-wall structures in the automobile industry, especially for the connection of different materials. Due to their excellent strength-to-weight ratios and vibration/noise reduction characteristics, foam metal sandwich composite aluminum plates are the best choices for modern automobiles. In this paper, the self-piercing riveting forming qualities and joint strengths of foam iron-nickel/copper sandwich composite aluminum plates with AA5052 aluminum alloys are investigated, and the fracture morphologies of tensile failure samples are characterized. The results showed that: the foam metal sandwich composite aluminum plates can increase the interlock width and improve the self-locking performance of the joints, and the bottom thicknesses are significantly increased when the foam metal sandwich composite aluminum plates are riveted as the bottom plates. In the tension-shear tests, the foam sandwiches reduce the maximum failure loads and increase the maximum failure displacements of the joints. Moreover, the macro/micro-structure characteristics of the foam metal sandwich composite aluminum plates affect the failure modes of the joints. When the foam metal sandwich composite aluminum plates are used as the top plates, the failure mode is that the composite aluminum plates break down in the direction perpendicular to the loading of the plates. When they are riveted as the bottom plates, the failure mode is that the rivets are entirely pulled out from the bottom base plates of the composite plates, partially separated from the foam metal sandwich composite aluminum plates, and the top base plates and the sandwich metals are torn apart at the same time.

Three-point bending performance of sandwich panels with various types of cores

Abstract: In this paper, the bending performances of sandwich panels with corrugated triangular, honeycomb, aluminum foam, pyramidal truss, double sine corrugated (DSC), and 3D re-entrant auxetic cores are assessed and compared, both experimentally and numerically. Three-point bending experiments were performed on corrugated, honeycomb, aluminum foam, and truss core sandwich panels with identical face-sheets and core height. The experimental and numerical results compared well for panels with corrugated, honeycomb and truss cores. Parametric studies were subsequently performed, using ABAQUS, and three distinct modes of deformation were identified. The specific energy absorption (SEA) of the panels was found to increase with the core relative density; the one with a honeycomb core will be shown to have the greatest SEA, for the same core relative density, compared to the rests.

Postbuckling of pressure-loaded auxetic sandwich cylindrical shells with FG-GRC facesheets and 3D double-V meta-lattice core

Abstract: The sandwich cylindrical shells with auxetic 3D double-V meta-lattice core and graphene-reinforced composite (GRC) facesheets are designed, modeled and analyzed to predict their postbuckling behaviors under external pressure. The 3D double-V meta-lattices, developed form the 2D double arrowed honeycombs, are designed that can be self-adapted to meet the requirements of the curvature variation of sandwich cylindrical shells. By means of micromechanical modeling according to the extended Halpin–Tsai model, the material properties are determined for GRC facesheets. Moreover, with the consideration of thermal environments, all the material properties are taken to be temperature-dependent. The GRC facesheets are further designed to have different distributions of graphene sheets along the shell radial direction, to make the sandwich cylindrical shells possess functionally graded (FG) configurations, which has a distinct influence on the buckling and postbuckling behaviors, as demonstrated by numerical results from full-scale FE simulations. The effects of thermal environments, strut radii, shell lengths and curvature radii are also discussed in detail.

Bio-based/green sandwich structures: A review

Abstract: Sandwich panels are one of the most applied designs in the aerospace, construction and automotive structures due to their excellent stiffness-to-weight ratio. Recent advances in the design of eco-friendly sandwich structures with bio-based and/or recycled/recyclable components indicate a clear move towards reducing the environmental impacts of the resulting designs while preserving mechanical performance. This movement is driven by strict environmental legislation and the need to save material costs and fuel consumption, requiring the use of greener components in the transport and building sector with higher loading performance and a smaller environmental footprint. This work presents the most recent efforts in the development of eco-friendly sandwich structures by classifying different approaches to the environmental optimisation of structures. A consistent classification of sandwich panels as either eco-friendly, bio-based, or quasi/fully-green structures is proposed according to their amount of bio-based components. The main components of bio-based/green sandwich panel skins, cores, and adhesives are listed, identifying the most promising designs under different mechanical properties. The environmental benefits and limitations of bio-based/green components are balanced by considering the eco-efficiency of the structures and outlining the challenges that are expected in the future.

Nonlinear free and forced vibration analysis of sandwich cylindrical panel with auxetic core and GPLRC facing sheets in hygrothermal environment

Abstract: In this study, the free and forced vibration analysis of composite sandwich panel subjected to the harmonic force excitation in the hygrothermal environment is investigated. The sandwich panel is composed of three-phase composites with polymer/Graphene platelet/fiber skins at the top and bottom surfaces and double-V auxetic honeycombs core layer with a negative Poisson’s ratio. Governing equations of motion within the framework of higher-order shear deformation theory (HSDT) and von Kármán nonlinearity are obtained. Applying the generalized differential quadrature method (GDQM) and homotopy perturbation technique, respectively the linear and nonlinear equations of motion results in solving the vibration problem. In the numerical illustration, at first validation of the present formulation is carried out by comparing the numerical results with those available in the open literature. Then the effects of several parameters such as geometric parameters of double-V auxetic core, force excitation, GPL volume fraction, and different boundary conditions on the nonlinear frequencies–amplitude of sandwich panel is studied. Finally, the important findings of this research indicate that the ratio of core thickness, inclined angle, and thickness to inclined length have significant effects on nonlinear frequencies–amplitude response. Based on the results of this article designers can development of different parts of aircraft.

Multifunctional cellular sandwich structures with optimised core topologies for improved mechanical properties and energy harvesting performance

Abstract: This paper developed a multifunctional composite sandwich structure with optimised design on topological cores. As the main concern, full composite sandwich structures were manufactured with carbon fibre reinforced polymer (CFRP) facesheets and designed cores. Three-point bending tests have been performed to assess the mechanical performance of designed cellular sandwich structures. To evaluate the energy harvesting performance, the piezoelectric transducer was integrated at the interface between the upper facesheet and core, with both sinusoidal base excitation input and acceleration measured from real cruising aircraft and vehicle. It has been found that the sandwich with conventional honeycomb core has demonstrated the best mechanical performance, assessed under the bending tests. In terms of energy harvesting performance, sandwich with re-entrant honeycomb manifested approximately 20% higher RMS voltage output than sandwiches with conventional honeycomb and chiral structure core, evaluated both numerically and experimentally. The resistance sweep tests further suggested that the power output from sandwich with re-entrant honeycomb core was twice as large as that from sandwiches with conventional honeycomb and chiral structure cores, under optimal external resistance and sinusoidal base excitation.

Thermo-mechanical postbuckling analysis of sandwich cylindrical shells with functionally graded auxetic GRMMC core surrounded by an elastic medium

Abstract: In this paper, modeling and analysis of postbuckling of sandwich cylindrical shells surrounded by an elastic medium are presented. The sandwich cylindrical shells consist of two metal face sheets and auxetic graphene-reinforced metal matrix composite (GRMMC) core with in-plane negative Poisson’s ratio (NPR). Two cases of the compressive postbuckling of sandwich cylindrical shells under axial compression in thermal environments and the thermal postbuckling of sandwich cylindrical shells caused by a uniform temperature rise are considered. Each ply of auxetic GRMMC core possesses in-plane NPR and can have different graphene volume fraction to achieve a piece-wise functionally graded (FG) distribution through the thickness domain of the core. The thermo-mechanical properties of both metal face sheets and the GRMMC core are temperature dependent. The governing equations are formulated based on the Reddy’s third order shear deformation shell theory coupled with von Kármán kinematic nonlinearity. The shell-foundation interaction and the thermal effects are considered in the modeling. Applying a singular perturbation technique in conjunction with a two-step perturbation approach, we obtain the postbuckling solutions for perfect and imperfect sandwich cylindrical shells. The effects of the FG pattern, the face sheet-to-core-to-face sheet thickness ratio, and the foundation stiffness on the postbuckling behaviors of sandwich cylindrical shells with auxetic GRMMC core are studied in detail.

Experimental and numerical investigation on bending and compressive behavior of carbon-epoxy sandwich panel with novel M-shaped core

Abstract: Present paper has experimentally and numerically investigated the mechanical behavior of composite sandwich panel with novel M-shaped lattice core subjected to three-point bending and compressive loads. For this purpose, a composite sandwich panel with M-shaped core made of carbon fiber has been fabricated in this experiment. In order to fabricate the sandwich panels, the vacuum assisted resin transfer molding (VARTM) has been used to achieve a laminate without any fault. Afterward, polyurethane foam with density of 80 kg/m3 has been injected into the core of the sandwich panel. Then, a unique design was presented to sandwich panel cores. The study of force-displacement curves obtained from sandwich panel compression and three-point bending tests, showed that an optimum mechanical strength with a considerable lightweight. It should be noted that the experimental data was compared to numerical simulation in ABAQUS software. According to the results, polyurethane foam has improved the flexural strength of sandwich panels by 14% while this improvement for compressive strength is equal to 23%. As well as, it turned out that numerical results are in good agreement with experimental ones and make it possible to use simulation instead of time-consuming experimental procedures for design and analysis.

Sound Propagation of Three-Dimensional Sandwich Panels: Influence of Three-Dimensional Re-Entrant Auxetic Core

Abstract: Re-entrant auxetic cellular structures (RACSs) offer various mechanical properties. Specifically, their high acoustic absorption and dissipation properties turn them into proper candidates to effectively increase the sound insulation characteristics of sandwich plates. Accordingly, this approach proposes an analytical strategy to investigate the exact effect of using three-dimensional (3D)-RACS in order to determine the sound transmission loss (STL) coefficient of a sandwich panel. Therefore, the dynamic equations of fluid–structure interaction are extracted using 3D stress distribution, and then the obtained equations are solved analytically based on the state vector method. The reliability and precision of the outcomes are checked according to previous works. The results obtained are significant because the designed sandwich model seems to improve the sound characteristics of the system based on the STL comparisons between the current approach and the single-layer plates as well as sandwich panels with other core geometries. The achievements of this study can provide novel insights into the STL of 3D-RACS sandwich systems with a complex core model.

Compressive and flexural properties of the novel lightweight tailored bio-inspired structures

Abstract: In this study, novel cellular structures were derived from the bird’s feathers. Experimental and numerical analysis of the fused filament fabricated (FFF) structures subjected to uni-axial compressive and three-point bending load is carried out. The effect of strut thickness, shape, loading direction and functional grading on compressive behavior is studied. The comparison between the novel bio-inspired designs and other types of cellular structures already reported in the literature showed the superior compressive performance of bird’s feather-inspired designs. Furthermore, the effect of strut shape on the flexural properties is studied using a three-point bending test. The flexural performance of the bird feather inspired panels is compared with the honeycomb and topology optimized panels. Both honeycomb and topology optimized based panels showed global failure after the first crack. However, the bio-inspired panels keep on absorbing energy even after the complete failure of the bottom plate of the panels. Overall, these novel designs hold potential for lightweight multi-functional 3D printed structures. • Designed, fabricated and tested the novel cellular structures and sandwich panels that are inspired from bird’s feather. • The structures are printed with ABS material using FFF process. • Structures and panels are studied under compressive and three-point bending load. • Mechanical response of bio-inspired structures is similar to stretch-dominated structures. • Both experimental and numerical results showed better performance of novel lightweight structures.