1. INTRODUCTION
Many innovations in aerospace and transportation industries depend on high-performance structural materials. Metal-matrix composites (MMCs) have received considerable attention due to their superior physical, mechanical and thermomechanical properties as compared to those of most conventional materials. MMCs offer a high specific strength, stiffness and wear resistance, that is much higher than that of monolithic materials. They are also capable to survive higher temperature environments. High performance metal matrix composites such as 6061 Al/SiC are now used in, or being considered for use in, variety of applications within the aerospace and automotive industries [1]. Ceramic material such as Silicon carbide (SiC) is being used widely in high temperature structural applications and utilised as reinforcement in composite material to improve the mechanical properties such as stiffness and wear resistance.
Types of reinforcement in MMCs are generally in the form of continuous fibers, discontinuous fibers (or Whiskers), particulates (or platelets). Among the most commonly used reinforcements, continuous fiber reinforcements are popular because the modulus and the strength of the fibers are completely transferred to the composite. They offer superior mechanical and physical properties as compared to discontinuously reinforced MMCs.
MMCs reinforced with continuous fiber are anisotropic and their degree of anisotropy depends mainly on the degree of fiber orientation [2,3]. In fiber reinforced composites, loads are being carried by fibers and matrix transfer and distribute the load among fibers. Fiber/matrix interphase behavior critically influences the thermo-mechanical and mechanical behavior of fiber-reinfor...
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...ix Composites (MMCs) have been simulated. Normal stress profiles along 00 and 450 on the interface in radial direction of the fiber have been obtained. It was observed from the result that stress transfer from matrix to fiber at a particular tensile loading varies with varying volume content of the reinforcement. In the first, stress transfer increases monotonically with increase in volume fraction of fiber, as the debonding progresses at fiber/matrix interfaces stress transfer decreases. Maximum stress transferred was observed for the 30% volume fraction of the fiber which implies higher efficiency of fiber at particular volume fraction. Interfacial shear stress distribution has also been simulated for various volume fraction of SiC fiber and it was found to be maximum at 30% volume fraction of the fiber. Shear stress was observed to be maximum at the fiber tip.
Composite restoration usage in dentistry is increasing. Because of this interest in the longevity and reliability of composite fillings also is increasing1. One problem that can occur with composite restorations is micro-leakage. This is when microgaps at the tooth-restoration interface allow fluids and bacteria into the restoration2. These gaps are formed when the material is polymerized and shrinks, which causes the material to pull away from the margins of the preporation2. Problems that can arise from micro-leakage are secondary carries, hypersensitivity, pulp stimulation, and marginal discoloration3. This is why dentists are trying to find ways to reduce micro-leakage of composite restorations.
We use metals to construct all kinds of structures, from bridges to skyscrapers to elevators. The strength as well as durability of materials that are crafted out of metal make the materials ideal not only for construction but also for many other applications.
Some ceramics are used in orthopaedic applications such as bone repair, bone augmentation and joint replacement but their use in this field is not as extensive or widespread as metals and polymers because ceramics have poor fracture toughness. This severely limits the use of ceramics in load bearing applications (Davis, 2003).
This paper presents how Labeling theory and strain theory can explain the crimes that The White family from West Virginia commit on a daily basis. The wonderful White of West Virginia portrays corruption and poverty. They do not conform to any authority or rules; all they want to do is fuss, fight and party. The White family takes part in shoot-outs, robberies; gas huffing, drug dealing, pill popping and murders. They are famously known for their Hill Billy tap dancing and wild criminal ways. West Virginia being the poorest state in the United States they do not have the resources to a good education system or available employment. Therefore, frustration sets in, leading to failed aspirations causing the Whites to resort to violent and illegal ways to survive in a declining economy, to obtain a slight chance to their perspective of the American dream. However, being labeled as the rebels of the south just makes that slight chance of the American dream much harder to obtain.
4 A. Paul, D.D. Jayaseelan, S. Venugopal, E. Zapata-Solvas, J. Binner, B. Vaidhyanathan, A. Heaton, P. Brown, W.E. Lee, “UHTC composites for hypersonic applications” American Ceramics Society Bulletin, 91 [1] 22–30 (2012).
Deviance is a natural part of and necessary for stability and social order in society, this according to functionalist theorist Emile Durkheim (MindEdge, Inc., 2016). Traditionally, society is generally successful in providing motivation for individuals to aspire for goals of some sort, whether through wealth, prestige or perceived power (Henslin, 2011). However, from a functional perspective, theories have been developed in identifying when lawful and equal access is not afforded to certain individuals in the process of obtaining such goals. This restriction and inequality to opportunity for access in the quest to achieve success is what is now referred to as structural strain theory, which was developed by sociologist Robert Merton (Henslin,
How the polymer chains are put together is important, as it improves the properties of the material. The flexibility, strength and stiffness of Kevlar fiber, is dependent on the orientation of the polymer chains. Kevlar fiber is an arrangement of molecules, oriented parallel to each other. This orderly, untangled arrangement of molecules is described as a “Crystalline Structure”. A manufacturing process known as ‘Spinning’ is needed to achieve this crystallinity structure.
The term biomechanics means the study of the structure and function of biological systems using the methods of mechanics. Biomechanics studies the process of kinematics and develops artificial limbs and footwear specifically to aid the body in performance. The study of biomechanics also includes the stress testing on crash dummies in car accidents and any sport where stress is placed on the body in order to produce performance. The type of stress specifically is the joint stimulation and bone modeling stress.
Composite materials have become extremely useful and since been adapted for aviation. They have been in development ever since the use of aluminum in the early 1920’s. Composites are components that are mixtures of two or more inorganic or organic compounds. One material acts as a matrix, which is the compound that keeps everything together, while the other material provides a reinforcement, in the form of fibers embedded in the matrix.
...an be seen that composite teeth form a high stability bond than PMMA teeth. This is due to the filler content allowing for low shrinkage, increased wear resistance and better cross-linkage with the base. In overall consensus the technique of heat-curing is believed to achieve significantly more polymer cross-linkage than that of self-curing the acrylic resin PMMA base - giving us a stronger base to teeth interface. It should be noted however that both techniques can be used for denture fabrication to achieve a desired result and it is up to the dentist and the technician to determine which one they prefer however, composite teeth bonded to a heat-cured PMMA base works best. Though the tooth and base by themselves may be strong, if the interface between them is not strong, this will result in the overall denture produced being weak independent of material selection.
The majority of structural parts made of composites are made with three main types of matrix, namely epoxy, vinylester and polyester.
Micro Electro-Mechanical Systems (MEMS) is the integration of mechanical elements, sensors, actuators and electronics on a common silicon substrate using microfabrication techniques. MEMS are a hot area of research because they integrate sensing, analyzing and responding on the same silicon substrate hence promising realization of complete systems-on-a-chip. As MEMS are manufactured using batch fabrication techniques similar to IC technology, MEMS are expected to deliver high functionality at low prices.
Materials used in aircrafts, range from metal alloys such as Aluminium-lithium alloys and many more different aluminium alloys, for instance; 2024, 2090, each having desirable properties causing it to be used in industry. To Composites which can range from carbon composites to graphite, aramid, fibre glass. These can also be used together to create graphite-aramid, graphite-aramid-fibreglass, graphite-fibre gl...
There are many attributes that affect the properties of a composite material, based on their intrinsic properties of the constituents. The properties that are harnessed to reinforce a composite material are essentially governed by the similar factors that affect other fiber composite materials, namely the fiber architecture and the fiber–matrix interface.
Composite is the combination of matrix and reinforcement material, which will have more strength when compared to the matrix and reinforcement material. The reinforcement material may present in the form of particulates, flakes and fibers. The strength and stiffness of the composite material is depends on the shape, size and way of orientation of reinforcements arranged in the matrix material. The different types of composite materials are metal matrix composites (MMC), ceramic matrix composites (CMC) and polymer matrix composites (PMC).