scholarly journals Vibration behaviour of a bio-composite sandwich with auxetic core

2019 ◽  
Vol 283 ◽  
pp. 09004
Author(s):  
Khawla Essassi ◽  
Jean-Luc Rebiere ◽  
Abderrahim El Mahi ◽  
Mahamane Toure ◽  
Mohamed amine Ben Souf ◽  
...  
Keyword(s):  
Composite Structures ◽  
Sandwich Structures ◽  
Dynamic Properties ◽  
Flexural Vibration ◽  
Flax Fibre ◽  
Sandwich Composite ◽  
Fibre Reinforcement ◽  
Damping Properties ◽  
Honeycomb Core ◽  
Composite Sandwich

This paper describes the flexural vibration and damping performances of an eco-composite sandwich structure with re-entrant honeycomb core. The main objective of this study is to analyse the effect of flax fibre reinforcement composite and the densities of the auxetic core on the dynamic properties of the sandwich structures. The damping properties and the sandwich stiffness are determined in bending beams for different free lengths in a clamped-free configuration. Firstly, the dynamic properties of the skins were investigated in order to develop the evolution of mechanical properties as well as damping coefficient for each material. Then, the same characterization was tested on the sandwich structures with different core densities. The results obtained showed that both core densities and flax fibre as reinforcement plays a major role on the dynamic properties of the sandwich composite structures.

Influence of Processing Parameters Production of Sandwich Composite Structures Designed Especially for the Construction of Machine Tool Parts

2014 ◽  
Vol 616 ◽  
pp. 333-343 ◽  
Author(s):  
Sona Rusnáková ◽  
Daniel Kučerka ◽  
Martin Podařil ◽  
Ján Kmec ◽  
Vladimir Rusnák ◽  
...  
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Composite Structures ◽  
Sandwich Structures ◽  
Machine Construction ◽  
Sandwich Composite ◽  
Composite Sandwich ◽  
Number Of Layers ◽  
Machine Industry ◽  
Moving Parts

All components of a huge machine tool need to work together perfectly to ensure not only a quality finished product, but operator safety. One of those many components is the material of support panels and moving parts in the machine construction. Mechanical structure of the machine, in most cases does not reach the technical level of regulatory techniques or electric drives and potential increase in dynamics, speed or accuracy of the machines remain unused. Used classic construction materials, steel or light alloy then zoom in to limit their physical capabilities. Designers have machine tools or robots are forced to solve the formidable task in the form of reducing the weight of the moving parts while maintaining or even increasing stiffness with respect to the thermal stability or damping. Laminates are for construction of production machines, robots and manipulators of crucial importance. One big advantage is the high rigidity while maintaining low specific weight. The presented paper is focused on the investigation of composite sandwich construction produced by prepreg technology, which is the suitable production choose for construction of machine tools parts. First of all, the production of sandwich structures with cork core, honeycomb core and foam cores are compared and described. In terms of the production process it is a method very friendly to the environment, since there are no leaks styrene vapours into the air. Since it is important from the perspective of a manufacturer of transport or machine industry manufactured from environmentally friendly materials, so naturally from materials that are from the perspective of safety of passengers (operators of machine tools or robots) at a high level, when any accident was lowest possible hazard due to fire (burn materials used) and terms of the strength of composite materials. This is one of the major scientific articles and to find the most ideal surveyed composite sandwich materials that would be the greatest possible extent fulfils the required properties. In the experimental part of the article are compared and investigated the mechanical characteristics of composite sandwich structures with regard to varying number of layers of predimpregnated skin materials due to the different types of core materials suitable for use in the machine industry. In addition, these characteristics are an important part of the article research because described the influence number of layers to values of the bending stiffness those composite structures.

Effects of honeycomb core damage on the performance of composite sandwich structures

2019 ◽  
Vol 54 (16) ◽  
pp. 2159-2171
Author(s):  
William T King ◽  
William E Guin ◽  
J Brian Jordon ◽  
Mark E Barkey ◽  
Paul G Allison
Keyword(s):  
Finite Element ◽  
Shear Modulus ◽  
Composite Structures ◽  
Sandwich Structures ◽  
Honeycomb Core ◽  
Element Analysis ◽  
Composite Sandwich ◽  
Core Damage ◽  
Composite Sandwich Structures ◽  
Aluminum Honeycomb

This work presents an experimental and numerical investigation of the effects of pre-existing core damage on aluminum honeycomb core composite sandwich structures. Quasi static flexural and compression experiments were performed, where the effects of core damage on the shear modulus and Young's modulus were quantified. In addition, finite element analysis was performed on the sandwich structures to elucidate the effects of the core damage on the structural response. Comparisons of experimental and finite element responses are presented for sandwich structures consisting of carbon fiber facesheets and an aluminum honeycomb core. The pre-existing core damage is observed to cause up to an 8% reduction in shear modulus and a 9% reduction in elastic modulus. It is also determined that the presence of pre-existing core damage results in an asymmetrical compressive load distribution in the composite structures.

scholarly journals Experimental Analysis of Perimeter Shear Strength of Composite Sandwich Structures

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 12
Author(s):  
Łukasz Święch ◽  
Radosław Kołodziejczyk ◽  
Natalia Stącel
Keyword(s):  
Experimental Analysis ◽  
Sandwich Structures ◽  
Maximum Load ◽  
Core Material ◽  
Foam Core ◽  
Honeycomb Core ◽  
Loading Test ◽  
Composite Sandwich ◽  
Destruction Mechanism ◽  
Static Loading Test

The work concerns the experimental analysis of the process of destruction of sandwich structures as a result of circumferential shearing. The aim of the research was to determine the differences that occur in the destruction mechanism of such structures depending on the thickness and material of the core used. Specimens with a Rohacell foam core and a honeycomb core were made for the purposes of the research. The specimen destruction process was carried out in a static loading test with the use of a system introducing circumferential shear stress. The analysis of the tests results was made based on the load-displacement curves, the maximum load, and the energy absorbed by individual specimens. The tests indicated significant differences in the destruction mechanism of specimens with varied core material. The specimen with the honeycomb core was characterized by greater stiffness, which caused the damage to occur locally in the area subjected to the pressure of the punch. In specimens with the foam core, due to the lower stiffness of that core, the skins of the structure were bent, which additionally transfers compressive and tensile loads. This led to a higher maximum force that the specimens obtained at the time of destruction and greater energy absorption.

Influence of the Honeycomb Geometry on the Sandwich Composite Plate Behavior

2017 ◽  
Vol 1143 ◽  
pp. 139-144 ◽  
Author(s):  
Florentina Rotaru ◽  
Ionel Chirica ◽  
Elena Felicia Beznea
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Sandwich Plate ◽  
Compressive Loading ◽  
Sandwich Composite ◽  
Orthotropic Materials ◽  
Honeycomb Core ◽  
Element Analysis ◽  
Composite Sandwich ◽  
The Impact

In this paper the influence cell honeycomb geometry on the mechanical behaviour of a composite sandwich plate is analyzed. Three cell geometries (circular, hexagonal and square) are static analysed so that to select the best type of honeycomb that will be used in the manufacturing the sandwich plate core. The main aim is to develop approach models of equivalent orthotropic materials to replace the real model of honeycomb core with their properties so that to quickly calculate the sandwich plate made out of composite when is used a finite element analysis code. Geometry and material properties of the honeycomb are delivered by the material provider. Comparative analysis, by using Finite element analysis is performed for all geometries, in the same boundary conditions. Since in the impact loading of the composite sandwich plate the core is mainly loaded to compression, comparative study of the three cell geometries honeycomb was performed for this type of compressive loading. Since the cell is the basic element of the honeycomb core, the calculus is performed for one unit volume of sandwich, concerning also the part of skins.

Moisture Absorption of Composite Sandwich Structures

2014 ◽  
Author(s):  
Todd Coburn
Keyword(s):  
Composite Structures ◽  
Detrimental Effect ◽  
Failure Modes ◽  
Moisture Absorption ◽  
Sandwich Structures ◽  
Material Strength ◽  
Composite Sandwich ◽  
Composite Sandwich Structures ◽  
Moisture Effects ◽  
Secondary Failure

It is widely understood that moisture can have a detrimental effect on the strength of composite structures. Traditional analysis often focuses on the effects to solid laminates or on the facesheets of composite sandwich structures. However, this focus is often not sufficient to ensure material strength and performance. It has been found that moisture effects on sandwich structures can also have a detrimental effect on secondary failure modes such as shear crimping and facesheet wrinkling, and that these effects can be significant, especially at temperature. A proper assessment of moisture effects on composite sandwich structures involves five key components: development of moisture diffusion constants, prediction of structural moisture levels, development of material allowables at predicted moisture levels, analysis of structure, and modification of the design, when warranted. This paper describes each component of this process, and introduces a simple algorithm to integrate the analysis.

On Mechanical Properties of Composite Sandwich Structures With Embedded Piezoelectric Fiber Composite Sensors

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Hari P. Konka ◽  
M. A. Wahab ◽  
K. Lian
Keyword(s):  
Composite Structures ◽  
Sandwich Structure ◽  
Sandwich Structures ◽  
Fiber Composite ◽  
Composite Sandwich ◽  
Composite Sandwich Structures ◽  
Analysis Technique ◽  
Short Beam ◽  
Piezoelectric Fiber Composite ◽  
Piezoelectric Fiber

The smart sandwich structures have been widely used in the aerospace, automobile, marine, and civil engineering applications. A typical smart sandwich structure is usually comprised of two stiff face skins separated by a thick core with variety of embedded sensors to monitor the performance of the structures. In this study, the smart composite sandwich structure (CSS) samples are fabricated with glass microballoons syntactic foam core and resin infused glass-fiber face skins (with piezoelectric fiber composite sensors (PFCS) embedded inside the resin infused glass-fiber face skins). One of the main concerns associated with embedding sensors inside composite structures is the structural continuity, compatibility, and interface stress concentrations caused by the significant differences in material property between sensor and host structures. PFCS are highly flexible, easily embeddable, highly compatible with composite structures and their manufacturing processes, which makes them ideal for composite health monitoring applications. In this study, in-plane tensile, tension–tension fatigue, short beam shear, and flexural tests are performed to evaluate the effect on strengths/behavior of the CSS samples due to embedded PFCS. Then carefully planned experiments are conducted to investigate the ability of the embedded PFCS to monitor the stress/strain levels and detect damages in CSS using modal analysis technique. The tensile tests show that both the average ultimate strength and the modulus of elasticity of the tested laminate with or without embedded PFCS are within 7% of each other. The stress–life (S-N) curves obtained from fatigue tests indicates that the fatigue lives and strengths with and without the PFCS are close to each other as well. From short beam and flexural test results, it is observed that embedded PFCS leads to a reduction of 5.4% in the short beam strength and 3.6% in flexural strength. Embedded PFCS’s voltage output response under tension–tension fatigue loading conditions has been recorded simultaneously to study their ability to detect the changes in input loading conditions. A linear relationship has been observed between the changes in the output voltage response of the sensor and changes in the input stress amplitude. This means that by constantly monitoring the output response of the embedded PFCS, one could effectively monitor the magnitude of stress/strain acting on the structure. Experiments are also performed to explore the ability of the embedded PFCS to detect the damages in the structures using modal analysis technique. Results from these experiments show that the PFCS are effective in detecting the initiations of damages like delamination inside these composite sandwich structures through changes in natural frequency modes. Hence embedded PFCS could be an effective method to monitor the health of the composite sandwich structures’ in-service conditions.

Wave propagation in composite structures

2009 ◽  
Vol 225 (3) ◽  
pp. 639-648
Author(s):  
O Bareille ◽  
M N Ichchou
Keyword(s):  
Numerical Method ◽  
Composite Structures ◽  
Wave Number ◽  
Sandwich Composite ◽  
Flexural Wave ◽  
Honeycomb Core ◽  
Matching Criterion ◽  
Wave Numbers ◽  
Identification Technique ◽  
Measured Displacement

Dynamic behaviour of honeycomb-core composite structures forms the framework of this article. The wave numbers of propagative waves are the elements of comparison between a numerical method (wave finite-element method) and an experimental identification technique (inhomogeneous wave correlation). The numerical method is based on the description of the dynamics of periodic waveguides. The experimental technique uses a matching criterion with the measured displacement field to obtain the corresponding wave numbers for a wave-based description of the displacement. Both approaches are applied to a sandwich composite beam with a honeycomb core. They seem to be in quite good accordance with analytical results for the flexural wave number.

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