scholarly journals Fire - mechanical behaviour of sandwich composite beam

2020 ◽  
pp. 22-26
Author(s):  
Tran Van Luan, Le Minh Tien Tran
Keyword(s):  
Mechanical Behaviour ◽  
Sandwich Beam ◽  
Extreme Temperature ◽  
Chemical Degradation ◽  
Sandwich Composite ◽  
Composite Sandwich ◽  
Materials Used ◽  
Marine Applications ◽  
Sandwich Materials ◽  
Physical And Chemical

We have analyzed the fire-mechanical behaviour of sandwich composite materials used in marine applications, as a function of the combustion time. In this light, sandwich beam samples are analyzed in terms of fire resistance kinetic and of post-combustion mechanical strength. We have shown that the materials undergo a strong degradation during 100 s of fire exposure at 750 ° C and this degradation is linked to the top skin. Finally, a finite element modelling work is being developed to predict the thermal behavior of composite sandwich materials; this modelling must include all thermal, physical and chemical degradation processes in order to realistically report resistance of materials in extreme temperature environment.

Nondestructive Characterization of Composite Sandwich Materials Under Fatigue Loading

2007 ◽  
Author(s):  
Emmanuel Ayorinde ◽  
Feizhong Deng ◽  
Godwin Chungag ◽  
Samikumar Soni
Keyword(s):  
Acoustic Emission ◽  
Wavelet Transforms ◽  
Low Cycle Fatigue ◽  
Fatigue Loading ◽  
Sandwich Composite ◽  
Time Frequency ◽  
Composite Sandwich ◽  
Marine Applications ◽  
Sandwich Materials

Applications of sandwich composite materials are constantly increasing to many more civilian and military areas, and they have become quite important for the construction of many structures. In this work the application of basic and reliable NDE methods to the characterization of sandwich materials suitable for marine applications has been explored. Vibroacoustic methods have been utilized, with emphasis on vibration and acoustic emission methods, on account of their rapidity of use, and reliability where applicable. Composite sandwich materials with both carbon-based and glass-based composite facings have been tested statically and in bending fatigue. The progress of damage-indicative characteristics with fatigue life has been followed with these methods from the unfatigued state. Usual vibration and acoustic emission parameters and, more informatively, those based on new joint time-frequency and wavelet transforms, are utilized to effectively characterize the materials with advancing damage under low-cycle fatigue loading. This approach was shown to be quite reliable.

Chemical and geotechnical analysis of the mortar and rammed earth from merinid walls of the Morrocan historical monument Chellah-Rabat for detection of alteration products and the origin of the original materials used.

2020 ◽  
Author(s):  
Siham Belhaj ◽  
Imane Jaouda ◽  
Hanane Souidi ◽  
Mohammed Aqil
Keyword(s):  
Building Materials ◽  
Particle Size Analysis ◽  
World Heritage Site ◽  
Chemical Degradation ◽  
Size Analysis ◽  
Intangible Heritage ◽  
Heritage Site ◽  
Unesco World Heritage Site ◽  
Materials Used ◽  
Physical And Chemical

<div> <div> <div> <div> <div> <div>Rabat, the capital of the Moroccan Kingdom, listed as a UNESCO World Heritage Site in 2012, has several historic monuments testifying its diversity and richness in tangible and intangible heritage, cultural richness, architectural diversity that perpetuates the different dynasties that are succeeded over time on this Kingdom.</div> <div>The Chellah monument testifies to this diversity by including within its walls a variety of civilizations.</div> <div>This special monument by its architecture, its history, its situation in the city of Rabat, knows physical and chemical degradation due to its location and the peculiarity of its building materials as well as the techniques used for the construction or for the rehabilitation.</div> <div>In this work we have tried to decipher these causes and to quantify these degradations by the petrographic, mineralogical, geotechnical and chemical identifications of the products of the alteration, via laboratory analyzes such as the scanning electron microscope equipped with the EDX system, the diffraction X-ray ,fluorescence and  particle size analysis. This is to optimize the choice of alternative materials, while taking into account all the multidisciplinary scientific mechanisms and processes necessary for a better protection of the built material heritage that constitutes a collective memory of this country.</div> <div> </div> </div> <div> </div> </div> </div> <div> </div> </div> </div>

Micro-Ribbons and Micro-Wires Silica Synthesis Using Bottom-Top Technique

2020 ◽  
Vol 1008 ◽  
pp. 33-38
Author(s):  
Marwa Nabil ◽  
Hussien A. Motaweh
Keyword(s):  
Selection Process ◽  
Chemical Properties ◽  
Industrial Applications ◽  
Preparation Process ◽  
Pure Silica ◽  
One Step ◽  
Materials Used ◽  
Sonication Technique ◽  
Silica Synthesis ◽  
Physical And Chemical

Silica is one of the most important materials used in many industries. The basic factor on which the selection process depends is the structural form, which is dependent on the various physical and chemical properties. One of the common methods in preparing pure silica is that it needs more than one stage to ensure the preparation process completion. The goal of this research is studying the nucleation technique (Bottom-top) for micro-wires and micro-ribbons silica synthesis. The silica nanoand microstructures are prepared using a duality (one step); a combination of alkali chemical etching process {potassium hydroxide (3 wt %) and n-propanol (30 Vol %)} and the ultra-sonication technique. In addition, the used materials in the preparation process are environmentally friendly materials that produce no harmful residues. The powder product is characterized using XRD, FTIR, Raman spectrum and SEM for determining the shape of architectures. The most significant factor of the nucleation mechanism is the sonication time of silica powder production during the dual technique. The product stages are as follows; silica nanoparticles (21-38 nm), nanoclusters silica (46 – 67 nm), micro-wires silica (1.17 – 6.29 μm), and micro-ribbons silica (19.4 – 54.1 μm). It's allowing for use in environmental applications (multiple wastewater purification, multiple uses in air filters, as well as many industrial applications).

scholarly journals Impact test of composite sandwich beam with built-in FBG sensor

2018 ◽  
Vol 397 ◽  
pp. 012028
Author(s):  
Haiping Pei ◽  
Yingying Wei ◽  
Yongzhen Chen ◽  
Li Wan ◽  
Weiqing Liu
Keyword(s):  
Impact Test ◽  
Sandwich Beam ◽  
Composite Sandwich ◽  
Fbg Sensor

A numerical-experimental dynamic analysis of composite sandwich beam with magnetorheological elastomer honeycomb core

2019 ◽  
Vol 209 ◽  
pp. 242-257 ◽  
Author(s):  
Felipe de Souza Eloy ◽  
Guilherme Ferreira Gomes ◽  
Antonio Carlos Ancelotti ◽  
Sebastião Simões da Cunha ◽  
Antonio José Faria Bombard ◽  
...  
Keyword(s):  
Dynamic Analysis ◽  
Sandwich Beam ◽  
Honeycomb Core ◽  
Magnetorheological Elastomer ◽  
Composite Sandwich

scholarly journals Enzymes Involved in Plastic Degradation

2021 ◽  
pp. 95-110
Author(s):  
S.Z.Z. Cobongela
Keyword(s):  
Polyethylene Terephthalate ◽  
Synthetic Polymers ◽  
Chemical Degradation ◽  
Natural Resistance ◽  
Aquatic Life ◽  
Carbon Backbone ◽  
Catabolic Enzymes ◽  
Plastic Degradation ◽  
Global Increase ◽  
Physical And Chemical

The global increase in production of plastic and accumulation in the environment is becoming a major concern especially to the aquatic life. This is due to the natural resistance of plastic to both physical and chemical degradation. Lack of biodegradability of plastic polymers is linked to, amongst other factors, the mobility of the polymers in the crystalline part of the polyesters as they are responsible for enzyme interaction. There are significantly few catabolic enzymes that are active in breaking down polyesters which are the constituents of plastic. The synthetic polymers widely used in petroleum-based plastics include polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC), polyurethane (PUR), polystyrene (PS), polyamide (PA) and polyethylene terephthalate (PET) being the ones used mostly. Polymers with heteroatomic backbone such as PET and PUR are easier to degrade than the straight carbon-carbon backbone polymers such as PE, PP, PS and PVC.

scholarly journals Ansys code applied to investigate the dynamics of composite sandwich beams

2021 ◽  
Vol 25 (1) ◽  
pp. 62-71
Author(s):  
Agnieszka Chudzik
Keyword(s):  
Sandwich Beam ◽  
Strength Properties ◽  
Effect Of Temperature ◽  
Material Strength ◽  
Beam Model ◽  
The Finite Element Method ◽  
Ansys Software ◽  
Composite Sandwich ◽  
Viscoelastic Core ◽  
Influence Of Temperature On

Abstract A numerical analysis of the effect of temperature on the dynamics of the sandwich beam model with a viscoelastic core is presented. The beam under analysis was described with a standard rheological model. This solution allows one to study the effect of temperature on material strength properties. Calculations were performed with the Finite Element Method in the ANSYS software. The analysis of the results of the numerical calculations showed a significant influence of temperature on the strength properties of the model under test. The analysis confirmed damping properties of viscoelastic materials.

scholarly journals Medidas de adesão entre agregado e ligante asfáltico

TRANSPORTES ◽  
2008 ◽  
Vol 16 (1) ◽  
Author(s):  
Kamilla Lima Vasconcelos ◽  
Amit Bhasin ◽  
Dallas N. Little ◽  
Jorge Barbosa Soares
Keyword(s):  
Chemical Interaction ◽  
Asphalt Binder ◽  
Fatigue Cracking ◽  
Adhesion Measurement ◽  
Materials Used ◽  
Enthalpy Of Immersion ◽  
Physical And Chemical ◽  
Energy Components

<p>A adesão entre agregado e ligante asfáltico vem sendo apontada como uma propriedade de grande importância para a causa de defeitos encontrados em pavimentos asfálticos, tais como trincas por fadiga, e dano por umidade. Diferentes mecanismos existem na literatura para explicar a adesão entre os dois materiais, porém, estes mecanismos podem ser resumidos em três grandes grupos: inter- travamento mecânico, adesão física, e interação química. A ocorrência de mais de um mecanismo simultaneamente parece ser o fenô- meno mais provável, sendo a relevância de cada um dependente das características físicas e químicas do agregado e do ligante asfálti- co. No presente trabalho, dois procedimentos foram utilizados para acessar a adesão entre agregado e ligante. O primeiro constou do cálculo do trabalho de adesão através da energia livre de superfície dos materiais envolvidos e o segundo, da determinação da entalpia de imersão quando soluções de asfalto são postas em contato com o agregado. Todos os materiais usados foram provenientes da biblio- teca de referência do SHRP sendo um pedregulho como agregado, e três diferentes ligantes asfálticos. Os resultados mostraram a capa- cidade do microcalorímetro em detectar possíveis interações químicas na adesão entre agregado e ligante asfáltico, em conjunto com adesão física. A presença de grupos funcionais mais fortemente adsorvidos pela superfície dos agregados justificou os maiores valores de entalpia de imersão para as combinações onde esses grupos se encontravam presentes.</p><p><em><strong>Abstract</strong> Adhesion between the asphalt binder and the aggregate is critical to the performance and durability of asphalt mixtures. According to the literature, distresses mechanisms such as fatigue cracking and moisture induced damage are correlated to the nature and quality of adhesion between these two materials. Different mechanisms already exist to explain adhesion, but they can be summa- rized in three main groups: mechanical interlocking, physical adhesion and chemical interaction. Although discussions of isolated theo- ries and mechanisms help to clarify the understanding of adhesion, they can rarely be separated completely to each other. The physical and chemical characteristics of asphalt and aggregate will in fact determine the relevance of each of these mechanisms. This study presents the results of two procedures for adhesion measurement: (i) an indirect method based on the surface free energy components of asphalt binder and aggregate; and (ii) the determination of the enthalpy of immersion through the use of a microcalorimeter. The materials used, a gravel as aggregate and three different neat asphalts, were provided by the Strategic Highway Research Program's Material Reference Library. The results showed the capacity of the microcalorimeter in detecting possible chemical reactions together with physical adhesion. The presence of functional groups more strongly adsorbed by the aggregate surface justified the higher values of the heat of immersion. </em></p>

Some Results and Issues in the Non-Destructive Evaluation of Sandwich Composite Structures

2001 ◽  
Author(s):  
Emmanuel O. Ayorinde ◽  
Ronald F. Gibson ◽  
Feizhong Deng
Keyword(s):  
Composite Structures ◽  
Failure Modes ◽  
Sandwich Beam ◽  
Sandwich Composite ◽  
Glass Composite ◽  
Transverse Loading ◽  
Three Point Bending ◽  
Damage States ◽  
Vibration Modal ◽  
Non Destructive

Abstract This paper focuses on the use of basic NDE methods like ultrasonics, imaging and vibration testing to assess the integrity of some sandwich composites which have been subjected to transverse loading. Samples of a foam core, glass composite facing sandwich beam of varying thicknesses and end notch lengths were tested in three point bending and assessed by these NDE methods. The results show that core shear and indentation failures appear to be the prominent failure modes for these geometries and materials, and that changes in the damping and vibration modal frequencies of the beams can indicate damage states.

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