Mechanical Behavior of Polypropylene-based Honeycomb-Core Composite Sandwich Structures (original) (raw)
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Laboratory Study of Polypropylene-based Honeycomb Core for Sandwich Composites
Spektrum Industri, 2021
Article history : The polypropylene-based honeycomb core is one of the most common hybrid materials currently used to reinforce the structure of sandwich composites. This material is widely used in various science, technology, and engineering fields, including aerospace applications, due to its high strength properties. Therefore, this research evaluated the mechanical properties of the well-known hybrid composites of carbon fiber (CF) and glass fiber (GF) under reinforced sandwich composites. The different curingpressure values of each material were analyzed to determine the pressure responsible for the superior performances and properties. The specimens were moulded using the hand lay-up or cloth laying angle technique of the carbon fiber. Furthermore, by changing direction, the greatest load-bearing direction based on the bending test was determined. According to the ASTM standard on strength determination, an increase in curing pressure leads to a rise in flexural stress. By placing the material orientation in the right order (i.e., [CF90/CF0/GF0/Core/GF0/ CF0/GF0]) the highest strength is obtained. However, when the strain reaches its maximum value, the fracture of the specimen, followed by the fiber orientation of the fabric. The experimental results showed that the lower the curing pressure, the thicker the workpiece decreased fiber volume fraction. The results also showed that changes in the curing pressure and laying angle affect the mechanical properties of the sandwich composites.
Archives of Metallurgy and Materials, 2014
Sandwich structures are widely used in lightweight construction especially in aerospace industries because of their high specific strength and stiffness. This paper investigates the effect of core thickness and intermediate layers on the mechanical properties of a polypropylene honeycomb core/composite facing multilayer sandwich structure under three points bending. We developed a theoretical model which makes it possible to calculate the shear properties in multi-cores. The results obtained by this model are agreed with our experimental results, and the results obtained with bending test showed that the mechanical properties of the composite multilayer structures increase with core thickness and intermediate layers.
Journal of Sandwich Structures & Materials, 2016
The behavior of a simple and innovative multi-layer sandwich panels having a polypropylene honeycomb core has been investigated carefully, theoretically and experimentally. A four-point bending test was performed to detect the mechanical characteristics of the multi-layer core. The experimental results emphasize a better rigidity of the multi-layer structure compared to the weakness displayed by the single-layer configuration. In fact, a small increase in the final weight of the component leads to a significant increase of the mechanical properties. In the second part of this study, analytical and numerical homogenization approaches were developed to compute the effective properties of the single polypropylene honeycomb core. The numerical model complies with the experimental protocol, and the simulation conducted is aiming to reproduce a typical four-point bending test on a polypropylene honeycomb multi-layer sandwich panel. Both numerical and experimental results are presented in ...
2015
In this paper we have experimentally determined, using some known methods, the equivalent elasticity modulus for new types of sandwich bars characterized by: polypropylene honeycomb core, with a thickness of 20 mm, having the exterior layers made of epoxy resin reinforced (on the upper and lower sides) with 5 and 10 layers of steel wire mesh. We have considered as a reference method for elasticity modulus determination the modal analysis. We have determined the first three eigenmodes and used them to determine the elasticity modulus. The obtained results were checked with another experimental method characterized by bending loading of the bars in three points. In the last part of the paper, we have made a comparative study between the flexural rigidity values obtained from different sandwich structures with polypropylene honeycomb core that have thickness of 20 mm. The bars have different face sheets: bar 1 has one layer of fiber-glass with epoxy resin, bar 2 has two layers of fiber...
Journal of Applied Mechanics, 2009
Sandwich panels with aluminum alloy face sheets and a hierarchical composite square honeycomb core have been manufactured and tested in out-of-plane compression. The prismatic direction of the square honeycomb is aligned with the normal of the overall sandwich panel. The cell walls of the honeycomb comprise sandwich plates made from glass fiber/epoxy composite faces and a polymethacrylimide foam core. Analytical models are presented for the compressive strength based on three possible collapse mechanisms: elastic buckling of the sandwich walls of the honeycomb, elastic wrinkling, and plastic microbuckling of the faces of the honeycomb. Finite element calculations confirm the validity of the analytical expressions for the perfect structure, but in order for the finite element simulations to achieve close agreement with the measured strengths it is necessary to include geometric imperfections in the simulations. Comparison of the compressive strength of the hierarchical honeycombs wit...
Proceedings of the Estonian Academy of Sciences, 2012
Experimental study of deformation behaviour of sandwich structures with a honeycomb core in the cases of quasi-static loading was carried out. The object of investigation was the static bending of the sandwich composite used for safety important structures made of woven glass fibre and polyvinylester resin composite facesheets with a polypropylene hexagonal honeycomb core. The results were obtained using equations of laminate theory; modified equations of beam theory were compared to experimental ones. As the analytically obtained results were in good agreement with the experimentally obtained ones, this methodology was used for the strength analysis of the investigated structure. The influence of geometrical parameters on the static behaviour of the sandwich structure was evaluated and their dependence on strength properties of the layered structure was assessed.
2014
This study will present the Experimental, numerical and analytical characterizations of composite sandwich structures needed to optimize structure design. In this study, the effects of varying honeycomb core ribbon orientation and varying face sheet thickness's have on the flexural behavior of honeycomb sandwich structures was investigated. Honeycomb sandwich panels were constructed using Hexcel 6367 A250-5H carbon fiber face sheets and Hexcel Nomex HRH-10-1/8-5 honeycomb cores. The mechanical properties of the constituent materials were discovered experimentally using ASTM standards and theoretical models using honeycomb mechanics and classical beam and plate theory are described. A failure mode map for loading under three point bending is developed from previous works by Triantafillou and Gibson 26 , showing the dependence of failure mode on face sheet to core thickness and honeycomb core ribbon orientation. Beam specimens are tested with the effects of Honeycomb core ribbon orientation and unequal face sheet thickness's examined. Experimental data sufficiently agrees with theoretical predictions. A finite element model was developed in ABAQUS/CAE to validate experimental and analytical analysis and produced agreeable results. Optimal bending stiffness and strength with respect to minimum weight was analyzed. The results reveal an important role core ribbon orientation has in a sandwich beam's bending behavior, and design of unequal ply count face sheets can produce higher stiffness to weight ratios than conventional symmetric sandwich structures of similar weight when subjected to a single static load.
Transportation Research Record: Journal of the Transportation Research Board, 2003
Stiffness and ultimate load-carrying capacities of glass fiber-reinforced polymer honeycomb sandwich panels used in bridge applications were evaluated. Eleven full-scale panels with cross-section depths ranging from 6 to 31.5 in. (152 to 800 mm) have been tested to date. The effect of width-to-depth ratio on unit stiffness was found to be insignificant for panels with a width-to-depth ratio between 1 and 5. The effect of this ratio on the ultimate flexural capacity is uncertain because of the erratic nature of core-face bond failures. A simple analytical formula for bending and shear stiffness, based on material properties and geometry of transformed sections, was found to predict service-load deflections within 15% accuracy. Although some factors influencing the ultimate load-carrying capacity were clearly identified in this study, a reliable analytical prediction of the ultimate flexural capacity was not attained. This is because failures occur in the bond material between the out...
A compression after impact study has been conducted to determine the residual strength of three sandwich panel constructions with two types of thin glass fiber reinforced polymer face-sheets and two hexagonal honeycomb Nomex® core densities. Impact testing is conducted to first determine the characteristics of damage resulting from various impact energy levels. Two modes of failure are found during compression after impact tests with the density of the core precipitating the failure mode present for a given specimen. A finite element analysis is presented for prediction of the residual compressive strength of the impacted specimens. The analysis includes progressive damage modeling in the face-sheets. Preliminary analysis results were similar to the experimental results; however, a higher fidelity core material model is expected to improve the correlation.
Experimental testing of curved aluminum honeycomb/CFRP sandwich panels
Composites Research, 2013
This paper presents the fabrication and 3-point flexion testing of carbon fiber reinforced polymer (CFRP) composite face/aluminum honeycomb core sandwich panels. Specimen sandwich panels were fabricated with three honeycomb types (3.18 mm, 4.76 mm, and 6.35 mm cell size) and three panel radii (flat, r = 1.6 m, r = 1.3 m). The curved sandwiches were fabricated normally with the core in the W-direction. The tensile mechanical properties of the CFRP 2 X 2 twill fabric face laminate were evaluated (modulus, strength, Poisson's ratio). The measured values are comparable to other CFRP fabric laminates. The flat sandwich 3-point flexion test core shear strength results were 11-30% lower than the manufacturer published data; the test set-up used may be the cause. With a limited sample size, the 1.3 meter panel curvature appeared to cause a 0.8-3.8% reduction in ultimate core shear strength compared to a flat panel.