New method for the evaluation of residual compressive strengths of sandwich panels via four-point bending

2019 ◽  
Vol 136 ◽  
pp. 103075
Author(s):  
Gang Zhou ◽  
Hiu ling Leung ◽  
Ben Robinson ◽  
Can Zheng
Keyword(s):  
Sandwich Panels ◽  
New Method ◽  
Four Point Bending

scholarly journals Bending Response of 3D-Printed Titanium Alloy Sandwich Panels with Corrugated Channel Cores

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 556
Author(s):  
Zhenyu Zhao ◽  
Jianwei Ren ◽  
Shaofeng Du ◽  
Xin Wang ◽  
Zihan Wei ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Heat Dissipation ◽  
Sandwich Panels ◽  
Face Sheet ◽  
Collapse Mechanism ◽  
Corrugated Channel ◽  
Four Point Bending ◽  
Numerical Predictions ◽  
Load Carrying ◽  
3D Printed

Ultralight sandwich constructions with corrugated channel cores (i.e., periodic fluid-through wavy passages) are envisioned to possess multifunctional attributes: simultaneous load-carrying and heat dissipation via active cooling. Titanium alloy (Ti-6Al-4V) corrugated-channel-cored sandwich panels (3CSPs) with thin face sheets and core webs were fabricated via the technique of selective laser melting (SLM) for enhanced shear resistance relative to other fabrication processes such as vacuum brazing. Four-point bending responses of as-fabricated 3CSP specimens, including bending resistance and initial collapse modes, were experimentally measured. The bending characteristics of the 3CSP structure were further explored using a combined approach of analytical modeling and numerical simulation based on the method of finite elements (FE). Both the analytical and numerical predictions were validated against experimental measurements. Collapse mechanism maps of the 3CSP structure were subsequently constructed using the analytical model, with four collapse modes considered (face-sheet yielding, face-sheet buckling, core yielding, and core buckling), which were used to evaluate how its structural geometry affects its collapse initiation mode.

scholarly journals Flexural behavior of sandwich panels with cellular wood, plywood stiffener/foam and thermoplastic composite core

2017 ◽  
Vol 21 (2) ◽  
pp. 784-805 ◽  
Author(s):  
Edgars Labans ◽  
Kaspars Kalnins ◽  
Chiara Bisagni
Keyword(s):  
Mechanical Performance ◽  
Sandwich Panels ◽  
Experimental Tests ◽  
Design Tool ◽  
Thermoplastic Composite ◽  
Flexural Behavior ◽  
Four Point Bending ◽  
Reliable Design ◽  
Sufficient Strength ◽  
Core Part

A series of experimental tests have been carried out on three types of novel sandwich panels mainly designed for application in lightweight mobile housing. Two types of the panels are manufactured entirely from wood-based materials while the third one presents a combination of plywood for surfaces and corrugated thermoplastic composite as a core part. All sandwich panels are designed to allow rapid one-shot manufacturing. Mechanical performance has been evaluated in four-point bending comparing the data to the reference plywood board. Additionally, finite element simulations were performed to evaluate global behavior, stress distribution and provide the basis for a reliable design tool. Obtained results show sufficient mechanical characteristics suitable for floor and wall units. Compared to a solid plywood board, sandwich alternative can reach up to 42% higher specific stiffness, at the same time maintaining sufficient strength characteristics.

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 Structural Performance of Wood Based Sandwich Panels in Four Point Bending

2017 ◽  
Vol 172 ◽  
pp. 628-633 ◽  
Author(s):  
Labans Edgars ◽  
Zudrags Kaspars ◽  
Kalnins Kaspars
Keyword(s):  
Sandwich Panels ◽  
Structural Performance ◽  
Four Point 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.

scholarly journals A Novel Implementation of the LDEM in the Ansys LS-DYNA Finite Element Code

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7792
Author(s):  
Andrea Zanichelli ◽  
Angélica Colpo ◽  
Leandro Friedrich ◽  
Ignacio Iturrioz ◽  
Andrea Carpinteri ◽  
...  
Keyword(s):  
Finite Element ◽  
Fracture Behaviour ◽  
Sandwich Panels ◽  
Experimental Tests ◽  
Finite Element Code ◽  
Three Point Bending ◽  
Four Point Bending ◽  
Experimental Findings ◽  
The University ◽  
Bending Failure

In this paper, a novel implementation of the Lattice Discrete Element Method (LDEM) is proposed: in particular, the LDEM is implemented in the Ansys LS-DYNA finite element code. Such an implementation is employed to evaluate the fracture behaviour of sandwich panels under bending. First, the novel hybrid model proposed is validated by simulating some three-point bending experimental tests carried out at the University of Parma, and then it is used to model the fracture behaviour of sandwich panels under four-point bending. Failure mechanisms, damage locations, and load-deflection curves are numerically determined by employing such a novel model, and the results show a good agreement with the available experimental findings.

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