Experimental and numerical analysis of sandwich panels with hybrid core

2016 ◽  
Vol 20 (3) ◽  
pp. 271-286 ◽  
Author(s):  
Robert Studziński ◽  
Zbigniew Pozorski
Keyword(s):  
Numerical Model ◽  
Polyurethane Foam ◽  
Laboratory Tests ◽  
Sandwich Panels ◽  
Interface Layer ◽  
Mineral Wool ◽  
Bending Test ◽  
Damage Initiation ◽  
The Core ◽  
Four Point Bending

The paper presents the experimental and numerical studies of sandwich panels with a hybrid core. The sandwich panel consists of external steel facings and a core, which is made of polyurethane foam or mineral wool or a combination of those two materials. The polyurethane foam material has a low weight and high thermal insulation properties, while the mineral wool material can provide high acoustic insulation and excellent fire resistance. Various proportions of the core materials are taken into account. It is assumed that a proper combination can provide the benefits of both materials. The structural behavior of a sandwich structure with a hybrid core is observed during laboratory tests. The failure mechanism is investigated in a four-point bending test. The material parameters of the core and facings are determined in standardized tests. The obtained parameters are used for FE simulations of the four-point bending tests. The criteria of damage initiation and propagation are defined in the interface layer of the numerical model. A satisfactory correlation between laboratory tests and numerical results is reported. Additionally, the sensitivity analysis of the numerical model response to the variation of the parameters of the interface is presented.

scholarly journals Experimental Study on Bending Performance of Composite Sandwich Panel with New Mixed Core

2019 ◽  
Vol 275 ◽  
pp. 02018
Author(s):  
Jing Zhang ◽  
Xiamin Hu ◽  
Wan Hong ◽  
Bing Zhang ◽  
Chengli Zhang
Keyword(s):  
Experimental Investigation ◽  
Polyurethane Foam ◽  
Failure Mode ◽  
Shear Failure ◽  
Sandwich Panels ◽  
Tensile Failure ◽  
Bending Test ◽  
Bending Performance ◽  
Composite Sandwich Panels ◽  
Composite Sandwich

This paper presents an experimental investigation of bending performance of composite sandwich panels with new mixed core, sandwich panels were tested by four-point bending test. Parametric study was conducted to investigate the influence of different core materials on the failure mode, ultimate bearing capacity, stiffness and ductility of composite sandwich panels. The results of the experimental investigation showed that the mixed core can change the failure mode of sandwich panels. The failure mode of wooden panels is characterized by tensile failure of bottom wood, and the failure mode of composite sandwich panels with wood core is that the surface layer and core are stripped and the webs are damaged by shear, while the failure mode of composite sandwich panels with wood and polyurethane foam mixed core is the shear failure of the web. Composite sandwich panels with GFRP-wood-polyurethane foam core have better bending performance and can effectively reduce the weight of panels.

scholarly journals Validation of a Numerical Bending Model for Sandwich Beams with Textile-Reinforced Cement Faces by Means of Digital Image Correlation

2019 ◽  
Vol 9 (6) ◽  
pp. 1253 ◽  
Author(s):  
Jolien Vervloet ◽  
Tine Tysmans ◽  
Michael El Kadi ◽  
Matthias De Munck ◽  
Panagiotis Kapsalis ◽  
...  
Keyword(s):  
Numerical Model ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Numerical Models ◽  
Sandwich Panels ◽  
Surface Strain ◽  
Image Correlation ◽  
Four Point Bending ◽  
Reinforced Cement ◽  
Correlation System

Sandwich panels with textile-reinforced cement (TRC) faces merge both structural and insulating performance into one lightweight construction element. To design with sandwich panels, predictive numerical models need to be thoroughly validated, in order to use them with high confidence and reliability. Numerical bending models established in literature have been validated by means of local displacement measurements, but are missing a full surface strain validation. Therefore, four-point bending tests monitored by a digital image correlation system were compared with a numerical bending model, leading to a thorough validation of that numerical model. Monitoring with a digital image correlation (DIC) system gave a highly detailed image of behaviour during bending and the strains in the different materials of the sandwich panel. The measured strains validated the numerical model predictions of, amongst others, the multiple cracking of the TRC tensile face and the shear deformation of the core.

scholarly journals Experimental and Theoretical Study of Sandwich Panels with Steel Facesheets and GFRP Core

2016 ◽  
Vol 2016 ◽  
pp. 1-12 ◽  
Author(s):  
Hai Fang ◽  
Huiyuan Shi ◽  
Yue Wang ◽  
Yujun Qi ◽  
Weiqing Liu
Keyword(s):  
Fem Simulation ◽  
Sandwich Panels ◽  
Transformation Method ◽  
Steel Plates ◽  
Bending Test ◽  
Composite Sandwich ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Ultimate Failure

This study presented a new form of composite sandwich panels, with steel plates as facesheets and bonded glass fiber-reinforced polymer (GFRP) pultruded hollow square tubes as core. In this novel panel, GFRP and steel were optimally combined to obtain high bending stiffness, strength, and good ductility. Four-point bending test was implemented to analyze the distribution of the stress, strain, mid-span deflection, and the ultimate failure mode. A section transformation method was used to evaluate the stress and the mid-span deflection of the sandwich panels. The theoretical values, experimental results, and FEM simulation values are compared and appeared to be in good agreement. The influence of thickness of steel facesheet on mid-span deflection and stress was simulated. The results showed that the mid-span deflection and stress decreased and the decent speed was getting smaller as the thickness of steel facesheet increases. A most effective thickness of steel facesheet was advised.

Failure mode maps for four-point-bending of hybrid sandwich structures with carbon fiber reinforced plastic face sheets and aluminum foam cores manufactured by a polyurethane spraying process

2017 ◽  
Vol 21 (8) ◽  
pp. 2654-2679 ◽  
Author(s):  
Peter Rupp ◽  
Peter Elsner ◽  
Kay A Weidenmann
Keyword(s):  
Carbon Fiber ◽  
Failure Mode ◽  
Aluminum Foam ◽  
Failure Modes ◽  
Sandwich Panels ◽  
Bending Tests ◽  
The Core ◽  
Four Point Bending ◽  
The Face ◽  
Spraying Process

This work focuses on failure mode maps of sandwich panels exposed to bending load, which were produced using a polyurethane spraying process. This process allows for an automated production of sandwich panels omitting a separate bonding step of the face sheets to the core. The investigated sandwich panels consisted of carbon fiber reinforced face sheets in various configurations, and four different core structures of aluminum foam or Nomex honeycomb. After production, measurements of the pores inside the core foam structures, the fiber package thickness inside the face sheets, and the density homogeneity of the core structure were made using X-ray computed tomography. The failure mode maps were based on the individual mechanical properties of the face sheets and the core, determined by mechanical testing. The critical forces determining the failure modes were partially modified to fit the application on foam core structures and face sheets with a porous matrix. The verification of the failure modes was performed with four-point bending tests. Since all tested configurations of sandwich specimens were produced using the same process route, the applied models for the creation of the failure mode maps could be verified for numerous parameter combinations. Except for two parameters with inconstant properties, the failure modes determined by the failure mode maps matched the observed failure modes determined by the bending tests.

scholarly journals Blast Test and Failure Mechanisms of Soft-Core Sandwich Panels for Storage Halls Applications

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 70 ◽  
Author(s):  
Robert Studziński ◽  
Tomasz Gajewski ◽  
Michał Malendowski ◽  
Wojciech Sumelka ◽  
Hasan Al-Rifaie ◽  
...  
Keyword(s):  
Sandwich Panel ◽  
Shear Failure ◽  
Failure Mechanisms ◽  
Sandwich Panels ◽  
Core Layer ◽  
Mineral Wool ◽  
Expanded Polystyrene ◽  
Blast Load ◽  
Steel Columns ◽  
The Core

In this paper, an experimental investigation is presented for sandwich panels with various core layer materials (polyisocyanurate foam, mineral wool, and expanded polystyrene) when subjected to a justified blast load. The field tests simulated the case for when 5 kg of trinitrotoluene (TNT) is localized outside a building’s facade with a 5150 mm stand-off distance. The size and distance of the blast load from the obstacle can be understood as the case of both accidental action and a real terroristic threat. The sandwich panels have a nominal thickness, with the core layer equal 100 mm and total exterior dimensions of 1180 mm × 3430 mm. Each sandwich panel was connected with two steel columns made of I140 PE section using three self-drilling fasteners per panel width, which is a standard number of fasteners suggested by the producers. The steel columns were attached to massive reinforced concrete blocks via wedge anchors. The conducted tests revealed that the weakest links of a single sandwich panel, subjected to a blast load, were both the fasteners and the strength of the core. Due to the shear failure of the fasteners, the integrity between the sandwich panel and the main structure is not provided. A comparison between the failure mechanisms for continuous (polyisocyanurate foam and expanded polystyrene) and non-continuous (mineral wool) core layer materials were conducted.

Sandwich Beam in Four-Point Bending Test: Experiment and Numerical Models

2014 ◽  
Vol 969 ◽  
pp. 316-319 ◽  
Author(s):  
Stanislav Piovár ◽  
Eva Kormaníková
Keyword(s):  
Stress Condition ◽  
Numerical Models ◽  
Sandwich Beam ◽  
Bending Test ◽  
Plane Stress Condition ◽  
Element Analysis ◽  
The Core ◽  
Four Point Bending ◽  
The Finite Element Analysis ◽  
Four Point Bending Test

The numerical modeling of lightweight sandwich beam in four-point bending, using combination of finite elements by help of two modeling approaches 2-D and 3-D models is presented. The mechanical results of hot-dipped zinc steel face layers and polyurethane foam core, obtained from comprehensive material testing program, were used as input data in order to implement the finite element analysis by the commercial ANSYS code. The material nonlinearities, most pronounced in the core, as well as geometric nonlinearities are included in the models. As was shown an advantage of plane stress condition can be applied in numerical models in one-way bending.

Specific bending stiffness of in-mould-assembled hybrid sandwich structures with carbon fibre reinforced polymer face sheets and aluminium foam cores manufactured by a polyurethane-spraying process

2017 ◽  
Vol 21 (8) ◽  
pp. 2779-2800 ◽  
Author(s):  
Peter Rupp ◽  
Peter Elsner ◽  
Kay A Weidenmann
Keyword(s):  
Carbon Fibre ◽  
Sandwich Panels ◽  
Aluminium Foam ◽  
Face Sheet ◽  
The Core ◽  
Four Point Bending ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
The Face ◽  
Fibre Reinforced Polymer

In this paper, the bending stiffness-to-weight-ratio of novel hybrid sandwich structures is investigated. The build-up of the sandwich panels consisted of face sheets made from carbon fibre reinforced polymer, aluminium foam cores and an interface of foamed polyurethane. The sandwich panels were produced in a single step, infiltrating the face sheet fibres and connecting the face sheets to the core simultaneously. By means of mechanical characterization, specimens with several variations of face sheet architecture and thickness, core structure and interface properties were examined. Quasi-static four-point bending and flatwise compression tests of the sandwich composites were conducted, as well as tensile tests of the face sheets. The results of the tensile and compressive tests were integrated in analytical models, describing the sandwich stiffness depending on the load case and the face sheet volume fraction. The effective Young’s modulus of the composite, measured in the four-point bending test, correlates well to the modelled effective bending modulus calculated from the single components face sheet and core. The model underestimates the effective density of the bending specimens. It could be shown that this underestimation results from the polyurethane foam connecting the face sheets to the core, as the mass of this polyurethane is not included in the model.

Numerical Simulation of Fatigue Behavior of Honeycomb Sandwich Panels

2012 ◽  
Vol 525-526 ◽  
pp. 113-116
Author(s):  
Jie Lu ◽  
Guang Ping Zou ◽  
Peng Fei Yang
Keyword(s):  
Residual Life ◽  
Fatigue Behavior ◽  
Sandwich Panels ◽  
Local Maximum ◽  
Local Stress ◽  
Local Deformation ◽  
Maximum Deformation ◽  
The Core ◽  
Four Point Bending ◽  
Honeycomb Sandwich

In this study, based on Goodman stress correction algorithm, four point bending fatigue behavior of brazed steel honeycomb sandwich panels at room temperature is simulated using Fe-safe emulation module. The cyclic load was sinusoidal with a frequency f= 10 Hz. The residual life and security coefficient are given in the condition of design fatigue lifetime of 106 cycles. The results show that, in the local deformation, local maximum deformation occurs in the core wall under the load region, indicate that this region is the failure region of fatigue. And the residual life of the core wall in this region is less because of local stress concentration, the probability of failure becomes high, while the residual life in the region far away from the mid-span is high.

scholarly journals A three-dimensional numerical analysis of moisture flow in wood and of the wood’s hygro-mechanical and visco-elastic behaviour

2021 ◽  
Author(s):  
Sara Florisson ◽  
Johan Vessby ◽  
Sigurdur Ormarsson
Keyword(s):  
Numerical Model ◽  
Fibre Orientation ◽  
Three Dimensional ◽  
Bending Test ◽  
Elastic Behaviour ◽  
Tension Stress ◽  
Clear Wood ◽  
Moisture Flow ◽  
Finite Element Software ◽  
Four Point Bending

AbstractA three-dimensional numerical model was employed in simulating nonlinear transient moisture flow in wood and the wood’s hygro-mechanical and visco-elastic behaviour under such conditions. The model was developed using the finite element software Abaqus FEA®, while taking account of the fibre orientation of the wood. The purpose of the study was to assess the ability of the model to simulate the response of wood beams to bending and to the climate of northern Europe. Four-point bending tests of small and clear wood specimens exposed to a constant temperature and to systematic changes in relative humidity were conducted to calibrate the numerical model. A validation of the model was then performed on the basis of a four-point bending test of solid timber beams subjected to natural climatic conditions but sheltered from the direct effects of rain, wind and sunlight. The three-dimensional character of the model enabled a full analysis of the effects of changes in moisture content and in fibre orientation on stress developments in the wood. The results obtained showed a clear distinction between the effects of moisture on the stress developments caused by mechanical loads and the stress developments caused solely by changes in climate. The changes in moisture that occurred were found to have the strongest effect on the stress state that developed in areas in which the tangential direction of the material was aligned with the exchange surface of the beams. Such areas were found to be exposed to high-tension stress during drying and to stress reversal brought about by the uneven drying and shrinkage differences that developed between the outer surface and the inner sections of the beams.

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