Paper Honeycomb Research Articles

Effect of hygrothermal ageing on the shear creep behaviour of eco-friendly sandwich cores

The development of sustainable sandwich materials is needed in the transportation sector to address environmental concerns related to the production and operation of vehicles. In addition to biobased composite skins, alternatives to classic synthetic core materials must be found to reduce the ecological footprint of whole sandwich-structured composites. This study focused on three eco-friendly lightweight core materials: balsa wood, paper honeycomb, and recycled PET foam. The effect of the hygrothermal ageing on their shear creep/recovery behaviour has been here investigated. Two different environmental conditions were tested: 23 °C-50% RH and 70 °C-65% RH. The results indicate that the maximum shear strain , the time-delayed strain and the residual strain increase for the three core materials with the severity of the hygrothermal conditions. This was attributed to the softening of the constitutive polymeric materials of the cell walls at temperatures close to 70 °C. The balsa wood exhibits the best creep resistance under the two environmental conditions. The identification of the viscoelastic properties highlights that the release times and the shear viscous parameters of the balsa wood and the PET foam depend on the stress level and the hygrothermal conditions.

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.

Cementitious Insulated Drywall Panels Reinforced with Kraft Paper Honeycomb Structures

Cementitious Insulated Drywall Panels Reinforced with Kraft Paper Honeycomb Structures

Cementitious Insulated Drywall Panels Reinforced with Kraft Paper Honeycomb Structures

Cementitious Insulated Drywall Panels Reinforced with Kraft Paper Honeycomb Structures

Preparation and Ballistic Performance of a Multi-Layer Armor System Composed of Kevlar/Polyurea Composites and Shear Thickening Fluid (STF)-Filled Paper Honeycomb Panels.

In this study, the ballistic performance of armors composed of a polyurea elastomer/Kevlar fabric composite and a shear thickening fluid (STF) structure was investigated. The polyurea used was a reaction product of aromatic diphenylmethane isocyanate (A agent) and amine-terminated polyether resin (B agent). The A and B agents were diluted, mixed and brushed onto Kevlar fabric. After the reaction of A and B agents was complete, the polyurea/Kevlar composite was formed. STF structure was prepared through pouring the STF into a honeycomb paper panel. The ballistic tests were conducted with reference to NIJ 0101.06 Ballistic Test Specification Class II and Class IIIA, using 9 mm FMJ and 44 magnum bullets. The ballistic test results reveal that polyurea/Kevlar fabric composites offer better impact resistance than conventional Kevlar fabrics and a 2 mm STF structure could replace approximately 10 layers of Kevlar in a ballistic resistant layer. Our results also showed that a high-strength composite laminate using the best polyurea/Kevlar plates combined with the STF structure was more than 17% lighter and thinner than the conventional Kevlar laminate, indicating that the high-strength protective material developed in this study is superior to the traditional protective materials.

Dynamic cushioning energy absorption of paper composite sandwich structures with corrugation and honeycomb cores under drop impact

The paper composite sandwich structure with corrugation and honeycomb cores has been widely used in civil and national defense industries, and the cushioning energy absorption characteristic is a key indicator to evaluate the performance of this composite structure. Therefore, this paper is focused on the influences of honeycomb thickness on the shock acceleration response and deformation characteristics to analyze cushioning energy absorption performance of the composite structure by various experimental tests. The experimental result shows that the paper corrugation layer firstly comes into crushed, and then the paper honeycomb layer is crushed. Additionally, the large honeycomb thickness may cause the secondary collapse of paper honeycomb layer. Under the same impact energy or impact mass, the cushioning energy absorption of the single-sided composite sandwich structure is better than that of the double-sided structure with the same honeycomb thickness. However, the impact resistance of the double-sided composite structure is better than that of the single-sided structure. For the paper composite sandwich structures with the honeycomb thicknesses 10, 15, 20, and 25 mm, the increase of honeycomb thickness would decrease the cushioning energy absorption of the whole structure under the drop impact with low energy. However, under the drop impact with high energy, the influence of honeycomb thickness on cushioning energy absorption is contrary. For the paper composite sandwich structure, the specific energy absorption, unit volume energy absorption, and stroke efficiency for the honeycomb thicknesses 10, 15, 20, and 25 mm are higher than those for the honeycomb thickness 70 mm. Therefore, the low honeycomb thickness is more advantageous for the cushioning energy absorption of paper composite sandwich structure.

Heat transfer characteristics of straw-core paper honeycomb plates II: Heat transfer mechanism with hot-above and cold-below conditions

Considering the large amount of cement consumed in construction and that straw and other renewable resources are discarded in considerable amounts every year, the heat transfer mechanism of solid-core functional paper honeycomb plates (FHPs) was investigated by calculating and analyzing the equivalent thermal conductivity λE of honeycomb plates (HPs) to develop functional sandwich plates and realize the utilization of straw as a resource. The results led to the following conclusions: (1) Under normal temperatures and hot-above/cold-below conditions, radiative heat transfer, which is usually neglected under normal temperatures, was the primary heat transfer mode in HPs. (2) Local convection occurred in HPs due to weak disturbances when the plate thickness h was greater than 15–20 mm. Accordingly, a technical approach was proposed for improving the heat insulation performance of HPs through multilayer substitution. (3) The filling materials could effectively prevent radiative and local convective heat transfer by drastically reducing the cavity size in the honeycomb structure. The heat conduction among solid particles had little influence on the λE of the FHPs. This paper lays a theoretical foundation for studying the heat transfer mechanism of FHPs at normal temperatures.

Design and construction of the mechanical structure for thin-gap RPC triplets for the upgrade of the ATLAS muon spectrometer

The advent of thin-gap RPCs, with 1 mm gas gaps instead of 2 mm in the present RPCs, opened the possibility to instrument the inner barrel layer of the ATLAS muon spectrometer where there is very limited amount of space in radial direction from the beam line. The environment is particularly dense in the barrel end-cap transition region. A compact mechanical structure coping with the expected thickness variations of the assembled RPCs is needed to fit into the limited available space. At the same time the mechanical structure must be sufficiently rigid to keep the deformations of the RPC packages within the allowed envelopes. The tight space constraints make it impossible to achieve the required rigidity with thick paper honeycomb plates as used in the present ATLAS RPCs. For the phase I upgrade of the barrel end-cap transition region of the ATLAS muon spectrometer three 1 mm gap RPCs are put into an aluminium frame. In this frame the RPC triplet is compressed with pre-bent 2 mm thick aluminium plates. The rigidity of the frame is achieved by stiffening rods connecting the lateral structure of the frame. The same concept can be used for the phase II upgrade of the inner layer of the muon spectrometer.

Modelling multiple impacts on the out‐of‐plane cushioning properties of honeycomb paperboard

In order to simulate the multiple impacts on the packaging in logistics transportation, the honeycomb paperboard was subjected to constant amplitude multiple impacts with the dropping height of 5, 20, 40 and 60 cm, respectively. A critical dropping height was defined to divide the intensity to low ones (the dropping height of 5 cm) and high ones (the dropping heights of 20, 40 and 60 cm). Then, quasi‐static compression was performed to study the constitutive model of paper honeycomb. The cushioning response of honeycomb paperboard under out‐of‐plane multiple impacts was studied. A model for the initial peak stress under multiple impacts at low intensity was derived, depending on the critical buckling load of cell walls in elastic region. The effects of high‐intensity multiple impacts on elastic strain, plastic strain and Young's modulus were analyzed, and the theoretical models were also developed respectively. Finally, the model of energy absorption performance of honeycomb paperboard under multiple impacts was suggested and shown great agreement with the experimental results. The results should be helpful for protective packaging design in practical logistics and honeycomb paperboard structure optimization.

Heat transfer characteristics of straw-core paper honeycomb plates (beetle elytron plates) I: Experimental study on horizontal placement with hot-above and cold-below conditions

Abstract To develop functional sandwich plates (FHPs) and identify new ways to use straw, straw-core paper honeycomb plates (SHPs) were prepared. The mechanisms of the influence of the spatial distribution of various filling systems on the heat transfer performance of SHPs were investigated, and the following results were obtained. 1) The equivalent thermal conductivity (λE) of the three FHPs were significantly lower than that of the honeycomb plate (HP), and the λE of all the FHPs met or approached the requirements of high-efficiency heat insulation materials for envelope structures. Moreover, the λE values of the three FHPs were closest to each other at the upper and lower limits of the tested thickness. 2) The spatial distribution characteristics of the spherical particle and slender filling systems under natural filling conditions, their corresponding simple heat transfer models and the concept of divisional local radiative (DLR) heat transfer were presented for the first time. 3) The fundamental factor determining the magnitudes of the λE of the HP and FHPs was the presence of DLR in the core layer structures, and the heat transfer characteristics of the FHPs were the result of the combined actions of the DLR and filling material properties.

Analysis of the convective heat transfer and equivalent thermal conductivity of functional paper honeycomb wall plates

ABSTRACT For the development of functional honeycomb plates (FHPs) and efficient resource utilization of straw, based on the measurement of the equivalent thermal conductivity (λE) of paper honeycomb plates (HPs) and FHPs, including straw-core paper honeycomb plates (SHPs), under cold-left and hot-right conditions, the influence mechanism of the system geometry parameters on the convective heat transfer of HPs and the heat insulation performance of FHPs by fillers are discussed. The results are as follows. 1) Compared with the case of hot-above and cold-below conditions, the convective heat transfer ratio of HP increases substantially under cold-left and hot-right conditions. 2) The main heat transfer modes of the FHPs are radiative heat transfer between the wall (including the panel and side) and filling material and solid heat conduction in the filling material, supplemented by a small amount of heat conduction through air or local convection heat transfer in the void. 3) The higher the temperature is, the greater the FHP equivalent thermal conductivity, with little influence from the heat transfer direction. 4) It is relatively conservative to use the heat transfer effect of HPs and FHPs to evaluate that of beetle elytron plates (BEPs) and functional beetle elytron plates (FBEPs). This study lays a foundation for the application of multifunctional BEPs and HPs in building envelopes.

Relation between the geometric parameters and the composite heat transfer of paper honeycomb plates under cold-above/hot-below conditions and the corresponding influence mechanism

To develop functional honeycomb plates (HPs) with great thermal performance, This paper uses a heat flow meter to determine the equivalent thermal conductivity λ E of honeycomb plates (HPs) positioned horizontally under cold-above/hot-below conditions and combined with theoretical calculations, the influence mechanism of their geometric parameters on their heat transfer performance were investigated with different thicknesses h and cell wall lengths of 8 mm and 16 mm (HP8 and HP16, respectively). The results show that the thermal insulation performance of HPs with different cell side lengths varies with the plate thickness. HP8 presented a better thermal insulation performance when h = 40–60 mm. Based on this, the concepts of matching honeycomb structure and matching convection and the suggestions that according to the needs of a project, HP8 or HP16 can be reasonably selected, and the stacking of two kinds of plates can be optimized were first proposed. And it can be obtained that if the experimental λ E results of a HP are applied to a beetle elytron plate with the same thickness and honeycomb structure size, the heat insulation of the beetle elytron plate (BEP) would be superior to that of the HP. This paper lays a theoretical foundation for the research and development of multifunctional BEPs with heat insulation properties was verified. Finally, the internal influence mechanism of the difference in temperature distribution on the upper and lower surfaces and the three-dimensional size of the honeycomb cells on the matching honeycomb structure and matching convection. • HP 8 is a matching honeycomb structure when h = 10–20 mm, so its convection is stronger than HP 16 . • The increase in the convection of HP 16 was significantly faster than that of HP 8 and the radiation of two plates. • The conclusions can be applied to the multifunctional biomimetic beetle plate. • Four inferences point out the direction for further research in this field.

Mechanical Properties Of Glass Fibers Reinforced Composites: A Concise Review

The utility of composites in today’s modern world is not hidden from anyone. From tiny objects like football to aerospace, everything involves the use of composites. Composites nearly form the backbone of our society. Composites are basically made from matrices and reinforcement. Out of the majority of reinforcement being used, Glass fibers usage cannot be neglected. These are made of fine fibers of glass (made of SiO2). They are used to reinforce various materials like arrows, bows and crossbows, translucent roofing panels, tent poles, boat hulls and paper honeycomb. This review paper is a study of various research papers related to mechanical properties of glass fibers when used with different type of matrices namely, tensile strength, impact strength and flexural strength.

Lightweight Panel for Building Construction Based on Honeycomb Paper Composite/Core-Fiberglass Composite/Face Materials

Lightweight panels for indoor constructions are typically made from composite materials with honeycomb and corrugated structures. The reinforcements are used in this study, one is fiberglass and the other is cellulose fiber, which cellulose from recycled paper. Experimental results indicate that the weight of honeycomb paper panel is light, only 13.6% of fiberglass composite and 32.6% of plywood. The presence of honeycomb structure has a significant effect on mechanical behaviors of composite panels. Both flexural and compressive strengths increase by replacing corrugated structure into honeycomb structure. During compression, the compressive strength and modulus of two-layer honeycomb/core panel are higher than those of monolayer honeycomb/core. Particularly, the honeycomb cell-wall thickness has a little effect on the weight, but has an important effect on mechanical properties. These results can be created low cost and lightweight environment-friendly panels by using recycled paper honeycomb structure.

Effect of Relative Humidity on Main Resonance Frequency for Paper Honeycomb Packaging System

Paper honeycomb sandwich plate is often used as transport packaging for the good cushioning and vibration isolation properties. However, the change of relative humidity has a great influence on the vibration performance of paper honeycomb sandwich plate because of its strong water vapor absorbing characteristics. In order to avoid the system resonance and reduce the product vibration damage, the main resonance frequencies for the paper honeycomb packaging system were evaluated by the sinusoidal vibration tests, further the effects of relative humidity, static compression stress, and the geometric parameters of honeycomb core on the main resonance frequencies were investigated. The results show that the main resonance frequency decreases with the increase of relative humidity, static compression stress, honeycomb cell length, and plate thickness.

A meso-mechanics-based experimental method for characterizing the in-plane compressive properties of aramid paper

Aramid paper honeycomb cores have been extensively used in lightweight structures. However, compressive properties of the paper, which are important for predicting the mechanical behaviors of honeycomb cores, can hardly be accurately measured due to the weak out-of-plane bending stiffness. Here, we propose an experimental method to characterize the in-plane compressive properties of the paper, in which the paper is processed into a laminate by the adhesive between layers to prevent the out-of-plane buckling. We also conducted a meso-mechanics model to analyze the compressive behavior. The compressive modulus of the hybrid paper obtained from our proposed method is basically identical to the tensile modulus, and the strength is much larger than previous estimations due to effectively avoiding the buckling. Then the compressive properties are used in numerical simulations to study the compressive properties of hybrid paper honeycombs, and the simulation calculated compressive modulus and strength agree well with experimental results, which verifies the accuracy of our method. This meso-mechanics-based characterization method can be applied to other types of paper and paper-like materials as well.

Ballistic Performance of Shear Thickening Fluids (STFs) Filled Paper Honeycomb Panel: Effects of Laminating Sequence and Rheological Property of STFs

In order to exploit future soft body armor to achieve a more comprehensive protection than just the torso part of the body, in this study, shear thickening fluids (STFs) with different rheological properties are fabricated by planetary mixer and three-roller mills to investigate the mixing process effect on the resultant rheological behavior. Rheological results indicate the critical shear rate and the maximum viscosity of STF are deeply influenced by the dispersion degree of nano-silica particles in PEG. These STFs are then filled into a paper honeycomb partition to prepare a STF-based protective structure. Different laminating sequences of the composite panels composed one STF structure layer and nineteen layers of Kevlar fabric are obtained by simply placing the STF structure at different positions in the composite panels. The ballistic tests are conducted according to the NIJ 0101.06—Type II standard using 9 mm Full Metal Jacketed Round Nose bullets. Our results show that the absorbed energy of the composite panel with STF that thickens at higher shear rate is higher compared to that using STF that thickens at a lower shear rate. It suggests the STF with higher critical shear rate would be optimally used in ballistic impacts. In addition, ballistic testing results confirm that the STF structure placed at the rear position can significantly contribute to the increase in impact resistance.

Cushioning Energy Absorption of Paper Honeycomb Sandwich Tube Single-filled by Polyethylene Foam under Axial Drop Impact

Cushioning Energy Absorption of Paper Honeycomb Sandwich Tube Single-filled by Polyethylene Foam under Axial Drop Impact

A Review of Novel Wooded-Based Sandwich Composite with Paper Honeycomb Core

A Review of Novel Wooded-Based Sandwich Composite with Paper Honeycomb Core

Shear property characterization of aramid paper and its application to the prediction of honeycomb behaviors

Aramid paper honeycomb cores have been widely used in lightweight structures. However, shear properties of aramid paper can hardly be obtained accurately due to the shear buckling of the paper. Therefore, we make the paper into a laminate to prevent buckling and apply the v-notched beam test method to the laminate to obtain the in-plane shear properties of aramid paper. The shear strength and failure strain of aramid paper are characterized experimentally for the first time. The properties are then used in finite element simulations to study the shear behaviors of paper honeycombs and the good agreement with the experimental results indicates the validity of the shear properties. Furthermore, the failure mode map of the paper honeycomb subjected to combined shear and compressive loads is obtained, which presents the importance of the accurate characterization on the shear properties of the paper. This characterization method can also be applied to other types of paper.