CH560 Engineering Material Selection PDF

Engineering Material Selection CH 560 Prof. Yehia M. Youssef Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 1 Material Selection Textbo...

Engineering Material Selection CH 560 Prof. Yehia M. Youssef Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 1 Material Selection Textbook: Ashby, M.F., “Materials Selection in Mechanical Design”, 5th ed., Butterworth-Heineman, 2017. Other References: 1) Ashby, M., Shercliff, H. and Cebon, D., “Materials: Engineering Science, Processing & Design”, 3rd ed., Butterworth-Heineman, 2013. 2) Budinski, K.G. and Budinski, M.K., “Engineering Materials: Properties and selection, 8th ed., Prentice Hall, 2005. Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 2 Material Selection  Aims & Objectives To provide the students with the basic knowledge about structure and properties of different engineering materials. To introduce the students to the different classes of engineering materials in addition to new materials. To enable the students to understand the concept of designing with materials and the important criteria used in selecting materials for a particular engineering application. Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 3 Material Selection  Outlines W1: General Introduction Classification of Engineering Materials W2: The Design Process W3: Mechanical System Design Concepts W4: Material Properties summarized on Materials Selection Charts W5: Developing a systematic strategy for material Selection in a given component Case 1 W6: Developing a systematic strategy for material Selection in a given component Case 2 W7: Exam W8: Formal procedures and main principles of materials selection using state-of-the art selection charts Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 4 Material Selection  Outlines W9: Formal procedures and main principles of materials selection using state-of-the art selection charts W10: Material selection for multi-constraint and compound objective problems W11: Optimal material selection factoring cross-sectional shape of the component W12: Exam W13: Case studies in material selection for various practical engineering applications W14: Case studies in material selection for various practical engineering applications W15: Review W16: Final Exam Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 5 Material Selection  Classification of Engineering Materials Engineering Materials Metals Plastics Ceramics Composites Ferrous Thermoplastics Elastomers Nonferrous Reinforced- Thermosets Oxides plastics Nitrides Amorphous Metal-matrix Carbides Ceramic-matrix Epoxies Glasses Acrylics Laminates Phenolics Glass ceramics Steels Aluminium ABS Graphite Polyimides Stainless steels Copper Nylons Diamond Others Tool & die steels Titanium Polyethylenes Cast irons Tungsten PVC Rubbers Others Others Silicones Polyurethanes Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 6 Material Selection  Comparison of Material properties Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 7 Material Selection Evolution of Engineering Materials with Time Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 8 Material Selection  Different Classes of Engineering Materials The different classes of materials include: Metals: They have relatively high stiffness, measured by the modulus, E. Most when pure are soft and easily deformed, meaning that sy is low. They can be made strong by alloying and by mechanical and heat treatment, increasing sy , but they remain ductile, allowing them to be formed by deformation processes. They are tough, with a usefully high fracture toughness K1C. They have good thermal and electrical conductivity, but they are reactive and most corrode rapidly if not protected. Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 9 Material Selection  Different Classes of Engineering Materials Metals include the following families; – Irons and Steels (based on Fe), – Aluminium alloys (based on Al), – Magnesium alloys (based on Mg), – Titanium alloys (based on Ti), – Nickel alloys (based on Ni), – Zinc alloys (based on Zn), and – Copper alloys (based on Cu), including brasses. Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 10 Material Selection  Different Classes of Engineering Materials Ceramics: They are non-metallic, inorganic solids, like porcelain or alumina. They have many attractive features. They are stiff, hard and abrasion resistant, they retain their strength to high temperatures, and they have good corrosion resistance. Most are good electrical insulators. However, unlike metals, they are brittle, with low K1C. This gives ceramics low tolerance for stress-concentration. Therefore, it is more difficult to design with ceramics than with metals. Examples include; – Aluminas, – Silicon carbides, – Silicon nitrides, and – Zirconias. Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 11 Material Selection  Different Classes of Engineering Materials Glasses: They are non-crystalline (amorphous) solids. The most common are the soda-lime and borosilicate glasses familiar as bottles and Pyrex ovenware. The lack of crystalline structure suppresses plasticity, so like ceramics, they are hard and remarkably corrosion resistant. They are excellent electrical insulator, and, of course, they are transparent to light. But like ceramics they are brittle and vulnerable to stress concentration. Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 12 Material Selection  Different Classes of Engineering Materials Different types of glasses: Glass Typical composition wt% Typical uses Soda-lime 70SiO2,10CaO,15Na2O Windows, bottles, etc glass Easily formed and shaped Borosilicate 80SiO2, 15B2O3, 5Na2O Pyrex; cooking and glass chemical glassware; high temperature strength, low coefficient of expansion, good thermal shock resistance Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 13 Material Selection  Different Classes of Engineering Materials Polymers: They are organic solids based on long chains of carbon (or, in a few, silicon) atoms. Polymers are light – their densities r are less than those of metals. Compared with other families they are floppy, with moduli E that are roughly 50 times less than those of metals. But they can be strong, and because of their low density, their strength per unit weight is comparable to that of metals. Their properties depend on temperature, a polymer that is tough and flexible at room temp. may be brittle at -4ºC and may turn rubbery at 100ºC of boiling water. Few have useful strength above 150ºC. Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 14 Material Selection  Different Classes of Engineering Materials If these aspects are allowed for in the design, the advantages of polymers can be exploited. They are easy to shape; complicated parts performing several functions can be moulded from a polymer in a single operation. Their properties are suited for components that snap together, making assembly fast and cheap. A good design in which sizing the mould is done accurately and with precoloring the polymer, no finishing operations are required. Examples include: – PE, PP, PET, PC, PS, PEEK, PA (Nylons), – Polyesters, – Phenolics, and – Epoxies. Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 15 Material Selection  Different Classes of Engineering Materials Elastomers: They are polymers with unique property that their stiffness, measured by E, is extremely low (500 – 5000 times less than those of metals) and their ability to be stretched to many times their starting length yet recover their initial shape when released. Despite their low stiffness, they can be strong and tough. Examples include: – Isoprene, – Neoprene, – Butyl rubber, – Natural rubber, – Silicones, and EVA (Ethylene Vinyl Acetate). Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 16 Material Selection  Different Classes of Engineering Materials Hybrids: They are combinations of two or more materials in an attempt to get the best of both. Glass and Carbon-Fiber-Reinforced polymers (GFRP and CFRP) are examples, so too are sandwich structures, foams and laminates. Almost all natural materials are hybrids (wood, bone, skin, …etc). Hybrid components are expensive and they are relatively difficult to form and join. So, despite their attractive properties, the designer will use them only when the added performance justifies the added cost. Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 17 Material Selection  The Design Process Scope The starting point: Good Mechanical Design including the role of materials. Mechanical Design deals with the following characteristics of mechanical systems: – The physical properties – The proper functioning – The production Industrial Design “the aesthetics” involves: – Pattern – Form – Colour – Texture – Other aspects such as customer appeal Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 18 Material Selection  The Design Process There are three types of mechanical design: – Original – a completely new idea – Adaptive – the evolution of a product – Variant – the change of size or shape without changing the function Our intention is to develop a methodology for materials selection in mechanical design. We briefly review the design process and encounter a new vocabulary (special jargon) involving abstract concepts. Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 19 Material Selection  Types of Design Original Design – Involves a new working principle, e.g. a compact disk, a flash disk – In searching for original designs, the designer must range his thinking as widely as possible – He must consider all possible solutions and then choose (by some sensible procedure) between them New Materials – which offer new, unique combinations of properties enable original designs Examples: – High purity silicon enabled the development of transistors – High purity glass → the optical fiber – High coercive force magnets → the miniature earphone – High temperature alloys → the gas turbine Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 20 Material Selection  Types of Design Sometimes the new material suggests a new product. More often, the new product requires the development of a new material. Gas turbine/Nuclear technologies: – Have required the development of new metallic alloys – Provide the driving force behind the current developments of ceramics and composites Adaptive Design – Searches for incremental advance in performance via a refinement of the working principle – This is often made possible by developments in materials – Examples: Polymers replacing metals in household goods Carbon fibers replacing wood in sports goods Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 21 Material Selection  Types of Design Market share can be won or lost according to whether the manufacturer exploits new materials in developing his product. Variant Design – Involves a change in scale or dimension or design detail without changing function – Change of scale may require change of material – Examples: Model aeroplane made of balsa wood’ full scale plane made of Al alloys. Model boiler made of copper, full scale boiler made of steel. Technical Systems – A technical system consists of assemblies and components put together in a way that performs a function. Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 22 Material Selection  Types of Design – Example A bicycle is a technical system A wheel is an assembly made up of components such as rim, spokes, hub, etc. Each component is made of different material. – The analysis of a technical system involves a breakdown into assemblies and components. – Material selection is at the component level. Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 23 Material Selection  Types of Design Component 1 1 Assembly 1 Component 1 2 Component 1 3 Component 2 1 Technical Assembly 2 Component 2 2 System Component 2 3 Component 3 1 Assembly 3 Component 3 2 Component 3 3 Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 24 Material Selection  Types of Design Materials selection is at the component level: – Some components are standard, common to many designs, e.g. a wood screw – Even among standards there is a choice of material, e.g. a screw can be made of brass, mild steel or stainless steel. The designer must select: 1. The material, 2. The shape, and 3. The processing route Function, material, shape and processing route all interact. Copyright © YM Youssef, 24-Oct-24 CH560 - Engineering 25 Material Selection