The present study considers an experimental study of tribological performance of Al-7.5&#x25; SiCp metal matrix composite and optimization of tribological testing parameters based on the Taguchi method coupled with grey relational analysis. A grey relational grade obtained from grey relational analysis is used as a performance index to study the behaviour of Al-7.5&#x25; SiCp MMC with respect to friction and wear characteristics. The tribological experiments are carried out by utilizing the combinations of tribological test parameters based on the L<sub>27</sub> Taguchi orthogonal design with three test parameters, namely, load, speed, and time. The material Al-7.5&#x25; SiCp metal matrix composite is developed by reinforcing LM6 aluminium alloy with 7.5&#x25; (by weight) SiC particle of 400 mesh size (<i>&#x7e;</i>37&#x2009;<i>&#x3bc;</i>m) in an electric melting furnace. It is observed that sliding time has a significant contribution in controlling the friction and wear behaviour of Al-7.5&#x25; SiCp MMC. Furthermore, all the interactions between the parameters have significant influence on tribological performance. A confirmation test is also carried out to verify the accuracy of the results obtained through the optimization problem. In addition, a scanning electron microscopy (SEM) test is performed on the wear tracks to study the wear mechanism.

Shouvik Ghosh

Prasanta Sahoo

Goutam Sutradhar

Tribological Performance Optimization of Al-7.5&#x25; SiCp Composites Using the Taguchi Method and Grey Relational Analysis

The Al/Mg laminated composite was fabricated by an accumulative roll bonding (ARB) technique using Al-1100 and Mg-AZ31 at 573&#x2009;K. Tensile properties along rolling direction under different ARB cycles were evaluated at the ambient temperature. The tensile strength of the Al/Mg composite increased gradually till three ARB cycle and then decreased after the fourth ARB cycles. Scanning electron microscopy (SEM) was used to investigate the microstructure evolution and the failure mechanism. The Al/Mg interface with interface angles between 30&#xb0; and 35&#xb0; has minimum tensile strength. A higher or lower interface angle improves the tensile strength, and the interface angle can be reduced by increasing the number of cycles in the ARB process. Thus, the crack at the coarse intermetallic compounds and rupture of the Al layer after fourth cycle caused the premature failure of the specimens during the tensile test.

Chih-Chun Hsieh

Ming-Che Chen

Weite Wu

Mechanical Property and Fracture Behavior of Al/Mg Composite Produced by Accumulative Roll Bonding Technique

Fiber reinforced plastics (FRPs) have replaced conventional engineering materials in many areas, especially in the field of automobiles and household applications. With the increasing demand, various modifications are being incorporated in the conventional FRPs for specific applications in order to reduce costs and achieve the quality standards. The present research endeavor is an attempt to study the effect of natural fillers on the mechanical characteristics of FRPs. Rice husk, wheat husk, and coconut coir have been used as natural fillers in glass fiber reinforced plastics (GFRPs). In order to study the effect of matrix on the properties of GFRPs, polyester and epoxy resins have been used. It has been found that natural fillers provide better results in polyester-based composites. Amongst the natural fillers, in general, the composites with coconut coir have better mechanical properties as compared to the other fillers in glass/epoxy composites.

Vikas Dhawan

Sehijpal Singh

Inderdeep Singh

Effect of Natural Fillers on Mechanical Properties of GFRP Composites

Ablative nanocomposites were prepared by incorporating multiwall carbon nanotubes (MWCNT) into phenolic resin and then impregnating them into rayon-based carbon fabric. MWCNT were blended into phenolic resin at 0.5, 1, and 2 wt&#x25; loadings using a combination of sonication and high shear mixing to insure uniform dispersion of MWCNT. The composite test specimens were tested by using an oxyacetylene test bed (OTB) applying a heat flux of 1000&#x2009;W/cm<sup>2</sup> for duration of 45 seconds. Composite specimens with 2&#x2009;wt&#x25; MWCNT showed reduction in mass loss, recession in length, and in situ temperatures compared to control composites.

J. S. Tate

S. Gaikwad

N. Theodoropoulou

E. Trevino

J. H. Koo

Carbon/Phenolic Nanocomposites as Advanced Thermal Protection Material in Aerospace Applications

This paper deals with the analysis of active constrained layer damping (ACLD) of smart skew laminated composite plates. The constraining layer of the ACLD treatment is composed of the vertically/obliquely reinforced 1&#x2013;3 piezoelectric composites (PZCs). A finite element model has been developed for accomplishing the task of the active constrained layer damping of skew laminated symmetric and antisymmetric cross-ply and antisymmetric angle-ply composite plates integrated with the patches of such ACLD treatment. Both in-plane and out-of-plane actuations by the constraining layer of the ACLD treatment have been utilized for deriving the finite element model. The analysis revealed that the vertical actuation dominates over the in-plane actuation. Particular emphasis has been placed on investigating the performance of the patches when the orientation angle of the piezoelectric fibers of the constraining layer is varied in the two mutually orthogonal vertical planes. Also, the effects of varying the skew angle of the substrate laminated composite plates and different boundary conditions on the performance of the patches have been studied. The analysis reveals that the vertically and the obliquely reinforced 1&#x2013;3 PZC materials should be used for achieving the best control authority of ACLD treatment, as the boundary conditions of the smart skew laminated composite plates are simply supported and clamped-clamped, respectively.

R. M. Kanasogi

M. C. Ray

Active Constrained Layer Damping of Smart Skew Laminated Composite Plates Using 1&#x2013;3 Piezoelectric Composites

Nowadays, polymeric nanocomposites have emerged as a new material class with rapidly growing use in industrial products because of good mechanical, thermal, and physical properties. Recently, the requirement of the direct machining of these materials has increased due to the production of the most of them by extrusion method in simple cross section and the increased demand for personalized products. In this work, the effect of turning parameters (cutting speed and feed) and nano calcium carbonate content on the machinability properties of polyamide 6/nano calcium carbonate composites was investigated by analysis of variance. A novel modeling approach of modified harmony search-based neural network was also utilized to create predictive models of surface roughness and total cutting force from the experimental data. The results revealed that the nano calcium carbonate content on polyamide 6 decreased the cutting forces significantly but did not have a significant effect on surface roughness. Moreover, the results for modeling total cutting forces and surface roughness showed that modified harmony search-based neural network is effective, reliable, and authoritative in modeling the turning process of polyamide 6/nano calcium carbonate composite.

Mehdi Haghi

Reza Farshbaf Zinati

Mohammad Reza Razfar

Experimental and Modeling Study of the Turning Process of PA 6/Nano Calcium Carbonate Composite

Thin film polystyrene composite scintillators containing <svg     style="vertical-align:-3.27605pt;width:31.987499px;" id="M1" height="19.987499" version="1.1" viewBox="0 0 31.987499 19.987499" width="31.987499"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
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</svg> and organic fluors have been fabricated and tested as thermal neutron detectors. Varying fluorescence emission intensities for different compositions are interpreted in terms of the Beer-Lambert law and indicate that the sensitivity of fluorescent sensors can be improved by incorporating transparent particles with refractive index different than that of the polymer matrix. Compositions and thicknesses were varied to optimize the fluorescence and thermal neutron response and to reduce gamma-ray sensitivity. Neutron detection efficiency and neutron/gamma-ray discrimination are reported herein as functions of composition and thickness. Gamma-ray sensitivity is affected largely by changing thickness and unaffected by the amount of <svg     style="vertical-align:-3.27605pt;width:31.987499px;" id="M2" height="19.987499" version="1.1" viewBox="0 0 31.987499 19.987499" width="31.987499"  xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
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</svg> in the film. The best neutron/gamma-ray discrimination characteristics are obtained for film thicknesses in the range 25&#x2013;150&#x2009;<i  >&#x3bc;</i>m.

Andrew N. Mabe

John D. Auxier

Matthew J. Urffer

Stephen A. Young

Dayakar Penumadu

George K. Schweitzer

Laurence F. Miller

Thin Film Polymer Composite Scintillators for Thermal Neutron Detection

This paper presents an analytical and experimental investigation of cure cycle effect on carbon-fiber reinforced high-temperature polymer composite structures molded by vacuum assisted resin transfer molding (VARTM). The molded composite structure consists of AS4-8 harness carbon-fiber fabrics and a high-temperature polymer (Cycom 5250-4-RTM). Thermal and resin cure analysis is performed to model the cure cycle of the VARTM process. The temperature and cure variations with time are determined by solving the three-dimensional transient energy and species equations within the composite part. Several case studies were investigated by the developed analytical model. The same cases were also experimentally investigated to determine the ultimate tensile strength for each case. This study helps in developing a science based technology for the VARTM process for the understanding of the process behavior and the effect of the cure cycle on the properties of the molded high-temperature polymer composites.

Ahmed Khattab

Cure Cycle Effect on High-Temperature Polymer Composite Structures Molded by VARTM

The aim of this work was to study the activity of several ionic liquids (alkylimidazolium salts) that are used to improve the dispersion of coagent particles in peroxide-cross-linked hydrogenated acrylonitrile butadiene elastomer (HNBR). Hydrotalcite grafted with monoallyl maleate was applied as a coagent for the HNBR vulcanization. In this paper, we discuss the effect of the ionic liquids (alkylimidazolium salts) with respect to their anion (bromide, chloride, tetrafluoroborate, and hexafluorophosphate) and the length of alkyl chain in the cation (allyl-, ethyl-, butyl-, hexyl-, and octyl-) on the vulcanization kinetics of rubber compounds. The influence of ionic liquids on the cross-link density, the mechanical properties of the vulcanizates, and their resistance to weather ageing were also studied. Alkylimidazolium salts seem to improve the dispersion of the coagent particles and to be active in the cross-linking of HNBR with peroxide. The type of ionic liquid considerably influences the activity of the coagent particles toward the HNBR. The application of ionic liquids increases the cross-link density of the vulcanizates and improves their resistance to weather aging.

Magdalena Maciejewska

Marian Zaborski

Ionic Liquids Applied to Improve the Dispersion of Coagent Particles in an Elastomer

Composite structures are increasingly used in the transport industry especially in the aeronautical sector thanks to their favorable strength-to-weight ratio with respect to metals. However, this is true if the final part is <i>defects free</i> and complies with quality requirements. A main weakness in composites is porosity, which is likely to be introduced during manufacturing processes and which may knock down the material characteristics affecting its performance in service. Porosity plays a key role in sandwich structures, which involve novel metal foams as core, since the foam performance strongly depends on size and distribution of pores. The determination of porosity is mostly attained by destructive methods, which supply only a general indication linked to the production part number. Conversely, composites may entail local significant variation of porosity, which may be discovered only with effective nondestructive techniques. The attention of the present work is focused on the possibility to use infrared thermography to get information about the amount and distribution of porosity. In particular, two techniques: flash thermography and lock-in thermography are used to comply with requirements of both monolithic composites and metal foams.

Cinzia Toscano

Carosena Meola

Giovanni Maria Carlomagno

Porosity Distribution in Composite Structures with Infrared Thermography

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Journal of Composites