scholarly journals Development and performance evaluation of large-scale auxetic protective systems for localised impulsive loads

2019 ◽  
Vol 10 (3) ◽  
pp. 390-417 ◽  
Author(s):  
Alex Remennikov ◽  
Dulara Kalubadanage ◽  
Tuan Ngo ◽  
Priyan Mendis ◽  
Gursel Alici ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
High Performance ◽  
Sandwich Panel ◽  
Sandwich Panels ◽  
Dynamic Loads ◽  
Low Density Polyethylene ◽  
Honeycomb Core ◽  
Protective System ◽  
Static And Dynamic Loads ◽  
Protective Systems

Cellular core structures with a negative Poisson’s ratio, also known as auxetic core structures, are gaining attention due to their unique performance in sandwich panel systems for protecting critical infrastructures and military vehicles that are at high risk of blast and impact loads due to accidental and deliberate events. To help develop a high-performance protective system, this article outlines the performance evaluation of five different auxetic cell configurations based on a quantitative/qualitative review of an experimental load–deformation relationship of three-dimensional-printed auxetic panels from nylon plastics and the overall performance evaluation of metallic re-entrant honeycomb core sandwich panels as one type of lightweight protective system under static and dynamic loads via experimental testing and numerical simulations. The re-entrant honeycomb design displayed the most consistent auxetic behaviour. Quasi-static compression and drop hammer impact tests were performed using the proposed full-scale sandwich panel design with two different configurations as a protective system for concrete wall structures in combination with plastic face plates. The effect of the internal angle of the re-entrant honeycomb design and the effect of the core material under static and dynamic loads were evaluated using full-scale sandwich panels. Furthermore, two separate materials – acrylonitrile butadiene styrene and low-density polyethylene – were used as face plates, and the low-density polyethylene was effective for lightweight and smooth load transferring and distribution into the auxetic core. Auxetic panel deformation under static and dynamic load was examined using a normal speed camera and high-speed video recording data and all auxetic panels indicated excellent systematic crushing behaviour with drawing materials into the load path to effectively resist the impact load. Numerical simulations were performed using LS-DYNA and indicated good agreement with the experimental results. Finally, protective systems utilising sandwich panels with a re-entrant honeycomb core indicated strong potential for the development of high-performance lightweight impact-resistant protective systems.

scholarly journals Investigating the Pre-Damaged PZT Sensors under Impact Traction

2018 ◽  
Vol 6 (4) ◽  
pp. 142 ◽  
Author(s):  
Sakineh Fotouhi ◽  
Mohamad Fotouhi ◽  
Ana Pavlovic ◽  
Nenad Djordjevic
Keyword(s):  
Sandwich Panel ◽  
Piezoelectric Sensors ◽  
Dynamic Loads ◽  
Impact Loads ◽  
Elastic Plates ◽  
Factors Affecting ◽  
Reliable Performance ◽  
Vibration Impact ◽  
Static And Dynamic Loads ◽  
Marine Applications

Ships are usually under vibration, impact, and other kinds of static and dynamic loads. These loads arise from water flow across the hull or surfaces, the propeller cavitation, and so on. For optimal design purposes and reliable performance, experimental measurements are necessary. These sensors are often used under or near the water, working conditions that improve the risk of sensor damage. This paper aims at investigating, by the use of finite elements, the behavior of damaged piezoelectric sensors under traction and impact loads. The numerical method was calibrated using results available in the literature regarding piezoelectric and elastic plates with a central crack. After calibration, the simulation was used on two types of Lead-Zirconium-Titanium oxide (PZT) sandwich panel structures reinforced by aluminum skins. The results proved that the damage size and impact energy are important factors affecting the response of piezoelectric sensors; therefore, special attention might be considered when using these sensors for marine applications.

scholarly journals High Temperature Mechanical Properties of a Vented Ti-6Al-4V Honeycomb Sandwich Panel

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3008
Author(s):  
Lei Shang ◽  
Ye Wu ◽  
Yuchao Fang ◽  
Yao Li
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Cell Walls ◽  
Sandwich Panel ◽  
Sandwich Panels ◽  
Honeycomb Core ◽  
Compression Performance ◽  
High Temperature Mechanical Properties ◽  
Honeycomb Sandwich ◽  
The Face

For aerospace applications, honeycomb sandwich panels may have small perforations on the cell walls of the honeycomb core to equilibrate the internal core pressure with external gas pressure, which prevent face-sheet/core debonding due to pressure build-up at high temperature. We propose a new form of perforation on the cell walls of honeycomb sandwich panels to reduce the influence of the perforations on the cell walls on the mechanical properties. In this paper, the high temperature mechanical properties of a new vented Ti-6Al-4V honeycomb sandwich panel were investigated. A vented Ti-6AL-4V honeycomb sandwich panel with 35Ti-35Zr-15Cu-15Ni as the filler alloy was manufactured by high-temperature brazing. The element distribution of the brazed joints was examined by means of SEM (scanning electron microscopy) and EDS (energy-dispersive spectroscopy) analyses. Compared to the interaction between the face-sheets and the brazing filler, the diffusion and reaction between the honeycomb core and the brazing filler were stronger. The flatwise compression and flexural mechanical properties of the vented honeycomb sandwich panels were investigated at 20, 160, 300, and 440 °C, respectively. The flatwise compression strength, elastic modulus, and the flexural strength of the vented honeycomb sandwich panels decreased with the increase of temperature. Moreover, the flexural strength of the L-direction sandwich panels was larger than that of the W-direction sandwich panels at the same temperature. More importantly, the vented honeycomb sandwich panels exhibited good compression performance similar to the unvented honeycomb sandwich panels, and the open holes on the cell walls have no negative effect on the compression performance of the honeycomb sandwich panels in these conditions. The damage morphology observed by SEM revealed that the face-sheets and the brazing zone show ductile and brittle fracture behaviors, respectively.

Sound transmission loss characteristics of sandwich aircraft panels: Influence of nature of core

2016 ◽  
Vol 19 (1) ◽  
pp. 26-48 ◽  
Author(s):  
MP Arunkumar ◽  
Jeyaraj Pitchaimani ◽  
KV Gangadharan ◽  
MC Lenin Babu
Keyword(s):  
Sandwich Panel ◽  
Transmission Loss ◽  
Sheet Material ◽  
Low Frequency ◽  
Sandwich Panels ◽  
Sound Transmission ◽  
Sound Transmission Loss ◽  
Honeycomb Core ◽  
Transmission Characteristics ◽  
The Impact

Sandwich panel which has a design involving acoustic comfort is always denser and larger in size than the design involving mechanical strength. The respective short come can be solved by exploring the impact of core geometry on sound transmission characteristics of sandwich panels. In this aspect, the present work focuses on the study of influence of core geometry on sound transmission characteristics of sandwich panels which are commonly used as aircraft structures. Numerical investigation has been carried out based on a 2D model with equivalent elastic properties. The present study has found that, for a honeycomb core sandwich panel in due consideration to space constraint, better sound transmission characteristics can be achieved with lower core height. It is observed that, for a honeycomb core sandwich panel, one can select cell size as the parameter to reduce the weight with out affecting the sound transmission loss. Triangular core sandwich panel can be used for low frequency application due to its increased transmission loss. In foam core sandwich panel, it is noticed that the effect of face sheet material on sound transmission loss is significant and this can be controlled by varying the density of foam.

Experimental and numerical study of buckling behavior of foam-filled honeycomb core sandwich panels considering viscoelastic effects

2020 ◽  
pp. 109963622097516
Author(s):  
M Safarabadi ◽  
M Haghighi-Yazdi ◽  
MA Sorkhi ◽  
A Yousefi
Keyword(s):  
Energy Absorption ◽  
Viscoelastic Properties ◽  
Sandwich Panel ◽  
Sandwich Panels ◽  
Face Sheet ◽  
Honeycomb Core ◽  
Buckling Behavior ◽  
Foam Filling ◽  
Foam Filled ◽  
Composite Face

Honeycomb sandwich panels are widely used in marine, aerospace, automotive and shipbuilding industries. High strength to weight and excellent energy absorption are features that make these structures unique. Foam filling the honeycomb core enhances the mechanical properties of sandwich panels considerably. In the present study, the buckling behavior of Nomex honeycomb core/glass-epoxy face sheet sandwich panel for both bare and foam-filled honeycomb core is investigated numerically and experimentally, considering the viscoelastic properties of the sandwich panel. Indeed, the viscoelastic properties of the composite face sheet and foam are determined by relaxation test and are implemented in ABAQUS using VUmat code. The finite element method is also performed using ABAQUS to model the buckling behavior of the sandwich panel incorporating both elastic and viscoelastic material behaviour. The effects of composite face sheet lay-up, core thickness, core cell size, and foam filling are also evaluated. The experimental and numerical results show that the foam increases the critical buckling load and energy absorption.

Ultralight micro-perforated sandwich panel with hierarchical honeycomb core for sound absorption

2021 ◽  
pp. 109963622199388
Author(s):  
Wei He ◽  
Xiangjun Peng ◽  
Fengxian Xin ◽  
Tian Jian Lu
Keyword(s):  
Theoretical Model ◽  
Sound Absorption ◽  
Sandwich Panel ◽  
Structural Parameters ◽  
Sandwich Panels ◽  
Honeycomb Core ◽  
Physical Mechanisms ◽  
Wide Range ◽  
Model Predictions ◽  
Absorption Performance

A theoretical model is developed to study the superior sound absorption performance of ultralight mirco-perforated sandwich panels with double-layer hierarchical honeycomb core. Numerical simulations are performed to validate theoretical model predictions and explore physical mechanisms underlying the sound absorption. Systematic parametric study is implemented to investigate the influence of specific structural parameters on sound absorption. To maximize sound absorption, optimal structural parameters of the hierarchical sandwich are obtained using the method of simulated annealing. It is demonstrated that viscous dissipation of the air inside micro-perforations and around inlet/outlet regions dominates sound absorption. Compared to micro-perforated sandwich panels with regular honeycomb core, not only the proposed hierarchical construction has much improved load-bearing capacity, but also significantly enhanced sound absorption covers a wide range of frequency.

Nonlinear Dynamic Buckling of Sandwich Panels

1976 ◽  
Vol 43 (3) ◽  
pp. 459-463
Author(s):  
N. K. Adi Murthy ◽  
R. S. Alwar
Keyword(s):  
Nonlinear Dynamic ◽  
Sandwich Panel ◽  
Sandwich Panels ◽  
Dynamic Buckling ◽  
Dynamic Loads ◽  
Static Case ◽  
Algebraic Equations ◽  
Newton’S Iterative Method ◽  
Initial Curvature ◽  
Transverse Loads

Nonlinear dynamic buckling of simply supported rectangular sandwich panels with isotropic cores and with initial curvature under transverse loads is analyzed. The large deflection sandwich panel equations proposed by Reissner are solved using a trigonometric series spacewise and by Houbolt scheme for timewise integration. The resulting nonlinear algebraic equations are solved by Newton’s iterative method to yield the deflection coefficients at all time intervals. The present investigation essentially deals with the influence of dynamic loads on the snap-through behavior of sandwich panels. The effect of the initial curvature and core modulus is studied in detail. Static snap-through collapse loads are also calculated and compared with dynamic loads. As a check for the present analysis the results obtained for the static case for a homogeneous plate are compared with the available results. It has been shown that for a given sandwich panel with a given initial curvature, the dynamic snap-through loads can be estimated directly from the static snap-through loads without actually resorting to dynamic analysis.

scholarly journals DETERMINATION OF MECHANICAL PROPERTIES OF COMPOSITE SANDWICH PANEL WITH ALUMINIUM HONEYCOMB CORE

2021 ◽  
Vol 2021 (6) ◽  
pp. 5353-5359
Author(s):  
MICHAL SKOVAJSA ◽  
◽  
FRANTISEK SEDLACEK ◽  
MARTIN MRAZEK ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Numerical Simulation ◽  
Sandwich Panel ◽  
Analytical Calculation ◽  
Sandwich Panels ◽  
Honeycomb Core ◽  
Composite Sandwich Panels ◽  
Composite Sandwich ◽  
Three Point Bend Test ◽  
Honeycomb Cores

This paper deal with comparison of mechanical properties of composite sandwich panel with aluminium honeycomb core which is determined by experimental measurement, analytic calculation and numerical simulation. The goal was to compared four composite sandwich panels. The composite sandwich panels were made of two different aluminium honeycomb cores with density 32 and 72 kg.m-3 and two different layup of skin with 4 and 5 layers. The comparison was performed on a three-point bend test with support span 400 mm. This paper confirms the possibility of a very precise design of a composite sandwich panel with an aluminium honeycomb core using analytical calculation and numerical simulation.

scholarly journals A numerical study of the impact perforation of sandwich panels with graded hollow sphere cores

2021 ◽  
Vol 13 (4) ◽  
pp. 168781402110094
Author(s):  
Ibrahim Elnasri ◽  
Han Zhao
Keyword(s):  
Boundary Conditions ◽  
Hollow Sphere ◽  
Sandwich Panel ◽  
Numerical Study ◽  
Sandwich Panels ◽  
Hopkinson Bar ◽  
Core Density ◽  
The Core ◽  
The Impact ◽  
Force Displacement

In this study, we numerically investigate the impact perforation of sandwich panels made of 0.8 mm 2024-T3 aluminum alloy skin sheets and graded polymeric hollow sphere cores with four different gradient profiles. A suitable numerical model was conducted using the LS-DYNA code, calibrated with an inverse perforation test, instrumented with a Hopkinson bar, and validated using experimental data from the literature. Moreover, the effects of quasi-static loading, landing rates, and boundary conditions on the perforation resistance of the studied graded core sandwich panels were discussed. The simulation results showed that the piercing force–displacement response of the graded core sandwich panels is affected by the core density gradient profiles. Besides, the energy absorption capability can be effectively enhanced by modifying the arrangement of the core layers with unclumping boundary conditions in the graded core sandwich panel, which is rather too hard to achieve with clumping boundary conditions.

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