Engineering Material Selection - CH 560

Engineering Material Selection - CH 560

• Course offered by Prof. Yehia M. Youssef
• Textbook: Ashby, M.F., "Materials Selection in Mechanical Design", 5th ed., Butterworth-Heineman, 2017.
• Other References:
  • Ashby, M., Shercliff, H., and Cebon, D., "Materials: Engineering Science, Processing & Design", 3rd ed., Butterworth-Heineman, 2013.
  • Budinski, K.G. and Budinski, M.K., "Engineering Materials: Properties and selection", 8th ed., Prentice Hall, 2005.

Aims & Objectives

• Provide students with basic knowledge of engineering material structures and properties.
• Introduce different classes of engineering materials, including new materials.
• Enable students to understand material selection concepts and criteria for engineering applications.

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
• 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

Classification of Engineering Materials

• Metals:
  • Ferrous (e.g., Steels, Stainless steels, Tool & die steels, Cast irons)
  • Nonferrous (e.g., Aluminum, Copper, Titanium, Tungsten, Others)
  • Amorphous
• Plastics:
  • Thermoplastics (e.g., Acrylics, ABS, Nylons, Polyolefins, PVC, Others)
  • Elastomers (e.g., Rubbers, Silicones, Polyurethanes)
  • Thermosets (e.g., Epoxies, Phenolics, Polyimides, Others)
• Ceramics:
  • Oxides, Nitrides, Carbides
  • Glasses (soda-lime, borosilicate)
  • Glass ceramics
  • Diamond / Graphite
• Composites:
  • Reinforced-plastics
  • Metal-matrix, Ceramic-matrix, Laminates

Comparison of Material Properties

• Metals & Alloys: Good conductors of heat and electricity, low cost, strong, easy to form.
• Plastics: Plasticity, light weight, wide choice of colours, low electrical conductivity, waterproof, inexpensive.
• Composites: Strong, light weight.
• Ceramics: Strong, high-temperature strength, low thermal and electrical conductivity, resistance to wear.

Evolution of Engineering Materials with Time

• Graph illustrating the relative importance of various material types through history. Shows developments in metals, polymers, and composites over time.

Different Classes of Engineering Materials

• Metals: relatively high stiffness, measured by modulus E. When pure, they are often soft and easily deformed. They can be strengthened by alloying and mechanical/heat treatments. Tough, good thermal/electrical conductivity, but reactive and corrode easily.
• Ceramics: non-metallic, inorganic solids (e.g., alumina, porcelain). Stiff, hard, abrasion resistant, retain strength at high temperatures, good corrosion resistance; most are good electrical insulators but brittle, limited tolerance for stress concentration.
• Glasses: Non-crystalline (amorphous) solids – common are soda-lime and borosilicate. Hard, corrosion resistant, good electrical insulators, transparent to light, but brittle, vulnerable to stress concentration.
• Polymers: Organic solids based on carbon chains. Floppy, low modulus E compared to metals, but strong and have comparable strength-to-weight. Properties vary with temperature, can be tough/flexible at room temperature, but brittle at low temps and rubbery at high temps.
• Elastomers: Polymers with extremely low stiffness (but can be strong/tough). Ability to be stretched significantly and recover their original shape. Examples include Isoprene, Neoprene, Butyl rubber, Natural rubber, Silicones and EVA (Ethylene Vinyl Acetate).
• Hybrids: Combinations of two or more materials to take advantage of properties of each; often expensive and difficult to manufacture. Examples include Glass-fiber reinforced polymers (GFRP).

The Design Process

• Starts with Good Mechanical Design, including the role of materials.
• Mechanical design considers physical properties, proper functioning, and production.
• Industrial Design involves pattern, form, colour, texture, and customer appeal.
• Three types of mechanical design: Original, Adaptive, Variant.
• Material selection is at the component level. (Function, material, shape, and processing interact).

Types of Design

• Original Design: Involves a completely new working principle (e.g., compact disk, flash disk); requires ranging thinking and considering all possible solutions. New materials enable original designs (e.g., High-purity silicon for transistors, high-purity glass for optical fibers).
• Adaptive Design: Incremental improvement in performance through refinement of working principles. Often possible because of material developments (e.g., Polymers replacing metals in household goods).
• Variant Design: Involves changing scale or dimension without changing function; Change of scale can require a change in material (e.g. model plane made of balsa wood compared to a full-scale plane using aluminium alloys. A bicycle wheel involves multiple parts with different materials). Components and assemblies form technical systems

This quiz explores the principles of engineering material selection based on the course offered by Prof. Yehia M. Youssef. It covers various classes of engineering materials, their structures, properties, and selection criteria essential for mechanical design. Students will gain a foundational understanding vital for engineering applications.