THE ACCESSIBILITY OR AVAILABILITY OF SUITABLE MATERIALS IS RESPONSIBLE FOR THE DEVELOPMENT OF CIVILIZATION

Thesis Overview

<p> INTRODUCTION<br><br>Material selection is a step in the process of designing any physical object. In the context of product design, the main goal of material selection is to minimize cost while meeting product performance goals. Systematic selection of the best material for a given application begins with properties and costs of candidate materials.<br><br>Understanding the material selection process is necessary for any form of application or design. The set of properties for a particular material is called the material attributes. Material selection involves seeking the best match between the design requirements and the material attributes. [“Material Selection”, 2014][1]<br><br>The selection of materials on a purely rational basis is a very difficult process, the process is not only often made difficult by insufficient property data but is typically one of decision making in the face of multiple constraints without a clear objective function.<br><br>The problem of material selection usually involves one or two difficulties such as;<br><br>Selection of the material for a new product or design.<br><br>Reevaluation of existing product or design to reduce cost, increase reliability, improves performance e t c.<br><br>Material selection like any other aspect of engineering design is a problem solving process whose steps can be defined by:<br><br>Analysis of material/application requirement: This is to determine the conditions of service and environment that the product must be able to withstand.<br><br>Possible materials: Possible materials are defined by the application requirements. For example; you cannot use clothes to build a bicycle. It also has to do with comparing the needed properties with a large material property data base to select a few materials that look promising for the application i.e. screening out of materials that fail the design constraints.<br><br>Selection of Candidate Material: This is to analyze candidate materials in terms of trade-off of product performance, cost, processibility and availability to select the best material for the application.<br><br>Development of Design Data: This is to determine experimentally the key material property of the selected material to obtain reliable statistical measures of the material performance under specific conditions to be encountered in service.<br><br>Strengthening of Materials Using Material Selection Technique<br><br>If the materials available do not meet the requirements or do not have all the properties needed; the properties of the material can be changed using methods that are learned through Material Science Technique. Though, there are many manufacturing techniques used to strengthen and form materials; three common physical principles used for functional material strengthening are densification, composites and alloying.<br><br>Densification is the most common way to strengthen any material. Generally, this increases the tensile strength by reducing the porosity of the material. [“Material Selection”, 2014][1]<br><br>Composites are materials that are comprised of various parts. They can be natural e. g wood, rocks e t c and they can be manmade e.g.concrete. One of the major reasons for the prevalent use of composite materials in construction is the adaptability of the composite to many kinds of applications. The standard composite rule of mixtures is when standard matrix is soft and the reinforcing material is tensile strong. The selection of mixture proportions can result in the change of the mechanical properties of the material.<br><br>Alloying of metals is one of the oldest and most fundamental material processing techniques. An alloy is a solid solution that is composed of two or more elements. There is a solvent (majority composite) and a solute. The solute element can strengthen the overall solid solution by different element size, density and other material properties. [Mahmoud Farag, 2000][2]<br><br>The goal of design is to create products that perform their function effectively, safely and at an acceptable cost.<br><br>Given the application requirements, possible materials and physical principles (i.e. strengthening mechanism), we can select the best material. [George E. Dieter, 1997][3]<br><br>Summary<br><br>The selection of materials for design involves:<br><br>Deciding on the application requirements.<br><br>Analysis of possible materials that can be used in the application.<br><br>Deciding on the change in material properties that are needed and <br><br>Choosing the material that best fulfills the requirements of the application given possible changes in the material properties.<br><br>Material Properties<br><br>Material properties can be divided into:<br><br>Physical properties i.e. Density, melting point, vapour pressure, viscosity, porosity, permeability.<br><br>Chemical properties i.e. Corrosion, oxidation, thermal stability, stress corrosion.<br><br>Electrical properties: Conductivity, coersive force, hysteresis and dielectric constant.<br><br>Thermal Properties: Conductivity, specific heat, thermal expansion and emissivity.<br><br>Mechanical properties: Hardness, elastic constants, yield strength, fracture toughness, wear resistance, ballistic performance. <br></p>