Edgewise Compression Research Articles

Finite Element-Based Simulation for Edgewise Compression Behavior of Corrugated Paperboard for Packaging of Agricultural Products

Since most goods are transported and stored in a unit-load form in today’s global supply chain, there has been a growing concern regarding the compression strength of corrugated paperboard boxes for packaging of agricultural products. The best predictor of the compression strength of corrugated boxes is the edgewise compression test (ECT) value; therefore, its efficient measurement or prediction is crucial for the design of more efficient corrugated boxes for food and agricultural and industrial products. This study investigated the edgewise compression behavior (load vs. displacement plot, ECT, and failure mechanism) of corrugated paperboard based on different types of testing standards and flute types using finite element analysis (FEA) and experimental analysis. The results of this study showed that the magnitude of the ECT values produced by the FEA was different from the values produced by the experiment. The difference in the ECT can be possibly explained by layer thickness approximations, together with glue line width assumptions between fluting and the liners in the numerical models. However, the trends of the values were the same. If the material properties of corrugated paperboard components and modeling methods of the corrugated paperboard are further studied, the FE (finite element)-based simulation technique will be a useful alternative tool that can replace the edgewise compression test.

Repair of Thin Face Sheet Sandwich Structure with Small Holes and Impact Damage

This manuscript presents experimental results of compression tests of repaired sandwich structure typical of a launch vehicle Payload Adapter Fitting (PAF) that is being considered for the National Aeronautics and Space Administration’s (NASA) Space Launch System (SLS) launch vehicle. Specimens with 8-ply quasi-isotropic carbon/epoxy face sheets and aluminum honeycomb core were damaged with representations of misdrilled holes, barely visible impact damage (BVID) or visible impact damage (VID). A patch repair technique not requiring removal of any material is presented and assessed for residual in-plane compressive load-carrying capability on each of the three types of damage. Edgewise compression tests on specimens demonstrated the repairs could recover all measured undamaged compressive load-carrying capability of the misdrilled hole and BVID specimens. For the specimens with VID, an average of about 91% of the average measured undamaged compressive load carrying capability was recovered indicating that larger patches, or perhaps removal and replacement of the damaged material, may be needed for more severe damage if all the measured undamaged compression strength needs to be regained.

Edgewise compression of novel hexagonal hierarchical and asymmetric unit cells honeycomb metamaterials

This work describes the behavior of a novel class of hierarchical slotted and asymmetrical edge cellular shapes honeycombs with auxetic and non-auxetic configurations subjected to edgewise compression. Hierarchical (slotted) and non-hierarchical specimens including hexagonal, re-entrant and asymmetric re-entrant have been 3D printed by using PLA plastic and tested under edgewise compression along the in-plane directions. The material properties of the PLA plastics have been determined via tensile tests, and Finite Element analyses have been performed using the LS-DYNA code to benchmark force-displacement curves with the experimental results. The numerical models were validated by comparing the load-displacement responses with the experimental results for each sample. Linear elastic properties, crashworthiness and energy absorption capability of the novel honeycomb structures are evaluated from the experimental and numerical standpoint. Specific metrics like compressive normalized modulus, compressive strength and specific energy absorption (SEA) are evaluated. The Poisson’s ratio of the novel honeycomb configurations has been evaluated and the impact of the deformation mechanisms of the different cellular shapes during crashworthiness has been studied. The results show that the use of the slotted and asymmetric cells proposed in this work could increase strength, stiffness and energy absorption capacity and also increase the stability of the samples during deformation.

Simulation Study of Adhesive Material for Sandwich Panel under Edgewise Compression Condition.

In order to study the interfacial adhesive material simulation method of a sandwich structure with aluminum alloy panels and a low-density foam core under edgewise compression condition, two finite element models were defined using material model no. 185 (MAT 185) adhesive element and tiebreak contact, respectively, by LS-DYNA. Under the conditions of different loading rates, and element sizes, the effects of peak load, energy absorption, failure mode of adhesive layer and the influence degree of the changing condition on the calculated results were compared between the two models, and then compared with the experiment results and theoretical results. The higher the loading rate was, or the smaller the element size was, the higher the peak load was. The simulation results obtained using MAT 185 were closer to the experimental results under the edgewise compression condition.

Effective elastic moduli of metal honeycombs manufactured using selective laser melting

PurposeHoneycomb cellular structures exhibit unique mechanical properties such as high specific strength, high specific stiffness, high energy absorption and good thermal and acoustic performance. This paper aims to use numerical modeling to investigate the effective elastic moduli, in-plane and out-of-plane, for thick-walled honeycombs manufactured using selective laser melting (SLM).Design/methodology/approachTheoretical predictions were performed using homogenization on a sample scale domain equivalent to the as-manufactured dimensions. A Renishaw AM 250 machine was used to manufacture hexagonal honeycomb samples with wall thicknesses of 0.2 to 0.5 mm and a cell size of 3.97 mm using 304 L steel powder. The SLM-manufactured honeycombs and cylindrical test coupons were tested using flatwise and edgewise compression. Three-dimensional finite element and strain energy homogenization were conducted to determine the effective elastic properties, which were validated by the current experimental outcomes and compared to analytical models from the literature.FindingsGood agreement was found between the results of the effective Young’s moduli ratios numerical modeling and experimental observations. In-plane effective elastic moduli were found to be more sensitive to geometrical irregularity compared to out-of-plane effective moduli, which was confirmed by the analytical models. Also, it was concluded that thick-walled SLM manufactured honeycombs have bending-dominated in-plane compressive behavior and a stretch-dominated out-of-plane compressive behavior, which matched well with the simulation and numerical models predictions.Originality/valueThis work uses three-dimensional finite element and strain energy homogenization to evaluate the effective moduli of SLM manufactured honeycombs.

Effects of bio-composites in sandwich panels with an optimum corrugated cores under edgewise compression loading

Effects of bio-composites in sandwich panels with an optimum corrugated cores under edgewise compression loading

Effects of bio-composites in sandwich panels with an optimum corrugated cores under edgewise compression loading

This paper presents the optimum design, manufacturing, and testing of corrugated sandwich panel structures under edgewise compression loading. A bio-composite was integrated in both the core and the skin in corrugated sandwich panels. The cases tested were all-carbon fibre, hemp skin with carbon fibre core, carbon fibre skin with hemp core and all-hemp. Compression loading tests were conducted on varying lengths of single-ligament panels utilising trapezoidal corrugation as the core and a flat plate as the skin. The ultimate load and stiffness were investigated for each sample, as well as the failure modes seen. It is shown that, first, hemp fibres are viable as a substitute for certain sections of the traditional composite structure, and second, integrating hemp fibres can solve the problems of debonding seen in the all-carbon fibre samples seen in previous research.

Comparison between honeycomb and composite corrugated cores in sandwich panels under compression loading

The study is to evaluate the compression properties of the polymeric composite corrugated-core sandwich structure against the honeycomb-core structure. The skin facings are from the prepreg carbon fibre composite laminate, while the core is made of different materials. Four core types are suggested; carbon fibre corrugated-core, fibreglass corrugated-core, Nomex honeycomb-core, and Kevlar honeycomb-core. The study is based on an experimental work of edgewise compression testing, and the comparison between alternatives are based on the specific properties-to-weight ratio. The analysed results prove there is superior compression capacity of the polymeric composite corrugated-core sandwich members to the honeycomb-core members, in particular in the nonlinear stage of compression test. The bonded surface between the honeycomb structure and the skins is often less than that of the corrugated profile for the same sandwich panel sizes. This contact area between the core and skin facings plays an important role in carrying load mechanism.

Buckling and crushing behavior of foam-core hybrid composite sandwich columns under quasi-static edgewise compression

Buckling and crushing behavior of foam-core hybrid composite sandwich columns under edgewise compressive load is dealt in this study. Composite laminates with different stacking sequence configurations made of glass and Dyneema-woven fabrics and AL 2024-T3 sheets were used in combination of polyvinyl chloride foam core to manufacture the specimens. Effects of face sheet thickness and stacking sequence configuration, slenderness ratio, boundary conditions, and sandwich reinforcement with through-thickness resin pins on the buckling and crushing behavior of the specimens were investigated. The results revealed that using the resin pins changes the unstable Euler buckling mode to a more stable progressive end-crushing and significantly increases the buckling load, specific buckling load, and energy absorption capability, which are highly favorable. Also, the results showed that in the specimens with fiber metal laminates, the major failure modes are face sheet-core debonding and face sheet delamination. However, based on the results, specimen with hybrid face sheets made from Dyneema fabrics and aluminum plates has the highest buckling load as well as the highest specific buckling load. Also, a specific fixture was designed to laterally clamp the sandwich column which causes a reduction in the probability of specimen end-crushing and significantly increases the buckling load.

Compression Capacity of Corrugated Core Hybrid Composite Sandwich Structure

Improvement of mechanical properties of light-weight corrugated core sandwich structures is a big demand in aerospace applications. Among these applications, space vehicles which encounter pressure loads and severe aerodynamic heating during ascent and reentry. The open-cell corrugated core is useful for active cooling of the sandwich structures. In this work, hybrid composite structural members with fiberglass corrugated core and carbon fiber skin facings were manufactured using vacuum bag technique. Different specimen configurations with rectangular cross-section area have been subjected to the load in the longitudinal direction of the corrugation and examined by edgewise compression test. The proposed testing has been applied to take advantage of the highest inertia of the specimen in such orientation. The test provides a basis for estimating the load carrying capacity when these structure members are used as individual webs in the aircraft interiors. Also as the core sheet is turned by 90° to the regular load direction, this structure member is similar to the so-called honeycomb when ordered in parallel rows and hence it is appropriate for floor sandwiching. In contrary to a honeycomb, this core consists of fiberglass laminate and therefore higher compressive resistance is associated. The results exhibit high values of both stiffness and ultimate compression force in the corrugation direction. For the rectangular area and the open corrugated contour, specific properties relative to the weight are extremely high. Also, the results and graphs indicate that there must be at least three corrugated ligaments with a trapezoidal cross section of 0.5” height and 63o per cell to grantee stability under load and high absorbed energy in the non-linear stage as well.

Effect of energy-absorbing materials on the mechanical behaviour of hybrid FRP honeycomb core sandwich composites

ABSTRACTHybrid FRP (70 % of carbon and 30 % of ‘E’ glass) is used to develop the honeycomb core sandwich panels filled with energy absorbing materials by Vacuum bag moulding technique.Mechanical behaviour of the sandwich panels has been experimentally investigated by three-point bending, edgewise compression, flatwise compression and Charpy impact tests as per the ASTM standards. The failure mechanisms of the tested composites are analysed through Macro morphology. Experimental results indicated that though the change of materials satisfactorily increased the mechanical properties, the PUF filled honeycomb sandwich panel improved the high strength, specific stiffness, critical load and rigidity than other two sandwich structures. The experimental values are analyzed in ANSYS 16.0 Release software. On analyzing the performance of the composites, the PUF filled Hybrid FRP sandwich panel is best suitable at low cost and lightweight structures such as marine vehicles, airplane floors and helicopter fuselages.

Low-velocity impact responses and CAI properties of synthetic foam sandwiches

This paper presents experimental and analytical studies on impact and compression after impact (CAI) responses of sandwiches with glass fiber reinforced polymer (GFRP) skins and synthetic foam cores under low-velocity impacting. The impact test results showed that the penetration depth of GFRP panels with synthetic foam is much smaller than that of bare synthetic foam panels. The edgewise compression test results indicated the facesheet debonding dominates the failure mode of the sandwich panels without lattice webs, while the failure mode of the sandwich panels with lattice webs is predominated by the wrinkling and delamination of the facesheets and the crushing of foam core. The influences of applied impact energy, GFRP lay-up, synthetic foam density and the existence of webs on the impact and post impact behavior of sandwich panels are discussed herein. Analytical models are proposed to predict the residual ultimate edgewise compressive load capacity of sandwich panels with lattice webs after impacts, using energy principles and variational methods in applied mechanics. The influences from impact damage, the local buckling of the facesheets and the confined strength of the foam core are measured and compared well with proposed analytical models.

Compressive failure of quasi-static indented CFRP/aluminium honeycomb sandwich panels

The present study examines sandwich panels, which are made of carbon fiber facesheets with aluminium honeycomb core and focuses on how varying factors (skin thickness, layup, core density and diameter of hemispherical indenter) are affecting collapse of artificially damaged panels in edgewise compression. Damage in the middle of sandwich specimens was introduced using quasi-static indentation. Hemispherical indenters of two diameters, namely, 20 mm and 150 mm, were applied. The residual strength was estimated through the edgewise compression test of damaged specimens. The study demonstrated that increase of the honeycomb density led to decrease in the safety margin in structure. Thicker skins may also lead to a catastrophic propagation of indent.

Design and mechanical properties of hierarchical isogrid structures validated by 3D printing technique

Based on general lattice structure, a hierarchical isogrid (isotropic grid) structure with T-ribs was designed to enhance the buckling resistance and plastic performance, and manufactured by three-dimensional (3D) printing technique. It is proposed that under edgewise compression, the latticed panel has three structural failure modes, including material failure, global buckling and local buckling. Hierarchical topology simultaneously improves the out-of-plane and in-plane rigidity of the lattice ribs, as T-ribs balance the global bending rigidity and the local rib bending rigidity, endowing the panel higher buckling resistance. In the stage of post-failure plastic bending, the T-rib lattice shows good load-carrying ability and deforming ductility. Based on three failure modes, a multi-failure theory was built and verified by experiments and finite element method (FEM). A plastic model for the hierarchical isogrid panels was built to predict the post-failure deformation. The failure mode map method was proposed, providing reference for further optimal design.

The energy absorption and bearing capacity of light-weight bio-inspired structures produced by selective laser melting

Sandwich structures are widely used in aviation and aerospace fields because they can absorb vast energy due to their excellent continuous compression behaviors. And in this work, the light-weight bio-inspired sandwich structure of titanium alloy was designed based on cybister elytra and produced by selective laser melting (SLM). The results show that bio-inspired structures can realize the light-weight effectively by increasing the core height. The specific and ultimate flatwise compressive strengths first increase and then decrease when core height increases. The load-displacement curves of bio-inspired structures during flatwise compression consists of elastic deformation, buffer and compaction zone. Comparatively, the edgewise compression lacks buffer zone. And the bio-inspired structure has an excellent flatwise comprehensive performance when its core height is 6 mm, whose peak flatwise compressive strength and specific volume energy absorption are 84.30 MPa, 101.30 MJ/m3, respectively. The specific ultimate strength of bio-inspired structures is optimized at the core height of 4 mm on the edgewise compression tests. And the fracture of the side arc damaged area shows an obviously ductile fracture and the panel and core of the middle area are brittle fracture in the flatwise compressive tests. Finally, The ANSYS simulation results are consistent with experimental results during the whole compressions, which will provide an accurate guidance in next researches

Experimental characterization of a novel balsa cored sandwich structure with fiber metal laminate skins

Balsa cored sandwich structures with fiber-reinforced polymer (FRP) skins are widely used to produce lightweight, high-stiffness and cost-effective structural components used in marine applications. However, balsa is a hydrophilic material, which is severely susceptible to moisture attacks. Unintended water penetration from the damaged FRP skins into the balsa cored sandwich structures can lead to the core decay and delamination of the core near the free edges. Thus, in this work, a concept for improving the damage tolerance of balsa cored sandwich structures by replacing the FRP skins with fiber metal laminates (FMLs) is proposed. To characterize the mechanical properties of these novel sandwich structures, a wide range of mechanical tests including three-point bending, edgewise compression with buckling as well as Charpy and high-velocity impact test were carried out on balsa cored sandwich specimens made of FMLs. A traditional sandwich structure made of woven E-glass fiber/epoxy skins was also prepared and tested for exploring the effect of skin material on the mechanical response of the studied sandwich structures. The experimental results showed that balsa cored sandwich structures composed of FML skins have an outstanding mechanical performance compared with those having the E-glass fiber/epoxy skins.

An Experimental Study on the Edgewise Compressive Failure of Paper Honeycomb Sandwich Panels with Respect to Various Aspect Ratios

The present work investigates the edgewise compression failure for honeycomb paperboards. Various panels are tested under a fixed loading rate with varying aspect ratios. The influence of the varying properties aspect ratio on yield strength is recorded. The experimental results indicate that the honeycomb paperboards are subject a decrease in yield strength with an increase in aspect ratio towards more slender bodies. Buckling was not observed in any of the tested specimens. All experiments are conducted under the general framework of ASTM C364/C364M -16 with a few noted changes.

Mechanical characterization of natural nano-structured zeolite/polyurethane filled 3D woven glass fiber composite sandwich panels

3D woven glass fibers sandwich panels have become the focus of interest due to their inherent light weight and, thus, their remarkable stiffness. However, a question is that whether their hollow galleries could be filled with still light materials which even at the same time contribute to their mechanical performance. This work examines the effect of porous polymer nanocomposites filling galleries of such panels on mechanical response of newly formed hybrid composites. To achieve this, the nanocomposites of natural nano-structured zeolite/polyurethane foams were fabricated and injected within 3D woven glass fibers sandwich panels. Mechanical characterization techniques including the flatwise compression, edgewise compression, three-point bending and drop weight impact were carried out to understand the effect of addition of the reinforced foam on the mechanical response of the specimens. It is shown that the polyurethane foam reinforced with natural nano-structured zeolite particles significantly improves the flexural strength, ultimate load and energy absorption of the filled composite sandwich panels. It is also demonstrated that the damage and local wrinkling failure compared with other typical sandwich panels do not occur due to the presence of the glass fiber yarns vertically located between panel sheets. These type of composites provide high specific strength results from high-performance and low-density structure.

Structural Behavior of Durable Composite Sandwich Panels with High Performance Expanded Polystyrene Concrete

Sandwich panels comprising prefabricated ultra-high performance concrete (UHPC) composites can be used as eco-friendly and multi-functional structural elements. To improve the structural and thermal performance of composite sandwich panels, combinations of UHPC and expanded polystyrene (EPS) beads were investigated. High-performance expanded polystyrene concrete (HPEPC) was tested with various EPS bulk ratios to determine the suitability of the mechanical properties for use as a high-strength lightweight aggregate concrete. As a core material in composite sandwich panels, the mechanical properties of HPEPC were compared with those of EPS mortar. The compressive strength of HPEPC is approximately eight times greater than that of EPS mortar, and the thermal conductivity of approximately a quarter that of EPS mortar. The structural behavior of composite sandwich panels was empirically analyzed using different combinations of cores, face sheets, and adhesive materials. In the flatwise and edgewise compression tests, sandwich panels with HPEPC cores had high peak strengths, irrespective of the type of face sheets, as opposed to the specimens with EPS mortar cores. In the four-point bending tests, the sandwich panels with HPEPC cores, or reinforced UHPC face sheets combined with adhesive mortar, exhibited higher peak strengths than the other specimens, and failed in a stable manner, without delamination.

Mechanical performance of polyester pin-reinforced foam filled honeycomb sandwich panels

Abstract Honeycomb sandwich panels entice continuously enhanced attention due to its excellent mechanical properties and multi-functional applications. However, the principal problem of sandwich panels is failure by face/core debond. Novel lightweight sandwich panels with hybrid core made of honeycomb, foam and through-thickness pin was developed. Reinforcing polyester pins between faces and core is an effectual way to strengthen the core and enhance the interfacial strength between the face/core to improve the structural performance of sandwich panels. To provide feasibility for pin reinforcement, honeycomb core was pre-filled with foam. Mechanical properties enhancement due to polyester pinning were investigated experimentally under flatwise compression, edgewise compression and flexural test. The experimental investigations were carried out for both “foam filled honeycomb sandwich panels” (FHS) and “polyester pin-reinforced foam filled honeycomb sandwich panels” (PFHS). The results show that polyester pin reinforcement in foam filled honeycomb sandwich panel enhanced the flatwise, edgewise compression and flexural properties considerably. Moreover, increasing the pin diameter has a larger effect on the flexural rigidity of PFHS panels. PFHS panels have inconsequential increase in weight but appreciably improved their structural performance.