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Material Selection

Material Selection. Function dictates the choice of material and shape. . Shape restricts the choice of material and process. . Function. Material. Shape. Process. Process is influenced by material. Process interacts with shape. .

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Material Selection

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  1. Material Selection Function dictates the choice of material and shape. Shape restricts the choice of material and process. Function Material Shape Process Process is influenced by material Process interacts with shape. Material selection and process cannot be separated from the shape and the function of the product, two way interaction. SJSU, ME dept.

  2. Plastics Ferrous Non-ferrous Thermoplastics Thermosets Elastomers Aluminum Copper Zinc Titanium Tungsten Steel Stainless steel Die & tool steel Cast iron Acrylic Nylon ABS Polyethylene Polycarbonate PVC Phenolic Polymide Epoxies Polyester Rubber Polyurethane Silicone Engineering Materials Materials Metals SJSU, ME dept.

  3. Ceramics Glass Composites Carbides Nitrides Graphite Diamond Glasses Glass ceramics Reinforced plastics Metal-Matrix Ceramic-Matrix Laminates Engineering Materials Materials Metals Plastics SJSU, ME dept.

  4. Most Commonly Used Materials The following 25 materials are the most commonly used materials in the design of mechanical products; in themselves they represent the broad range of other materials. Steel and Cast Iron • 1020 (plain carbon steel, hot-rolled or cold-drawn) • 1040 (plain carbon steel, hot-rolled or cold-drawn) • 4140 (heat-treated alloy steel, chromium-molybdenum) • 4340 (heat-treated alloy steel, nickel-chromium-molybdenum) • S30400 (stainless steel) • S316 (stainless steel) • O1 (tool steel) • ASTM20-60 (gray cast iron) SJSU, ME dept.

  5. Aluminum and Copper Alloys • 2024 (aluminum, O, T3, T4 or T6) • 3003 (aluminum, H12 or H16) • 6061 (aluminum, T6) • 7075 (aluminum, T6) • C268 (copper) Other metals • Titanium 6-4 • AZ63A (magnesium) Most Commonly Used Materials SJSU, ME dept.

  6. Ceramics • Alumina • Graphite Composite materials • Douglas fir • Fiberglass • Graphite/epoxy Most Commonly Used Materials Plastics • ABS • Polycarbonate • Nylon 6/6 • Polypropylene • Polystyrene SJSU, ME dept.

  7. Application of Most Commonly Used Materials Component Material SJSU, ME dept.

  8. Application of Most Commonly Used Materials Component Material SJSU, ME dept.

  9. Material Component Application of Most Commonly Used Materials SJSU, ME dept.

  10. Properties of Most Commonly Used Materials Ultimate Strength in tension SJSU, ME dept.

  11. Properties of Most Commonly used Materials Yield strength SJSU, ME dept.

  12. Properties of Most Commonly used Materials Fatigue endurance limit (strength under cyclic loading) SJSU, ME dept.

  13. Properties of Most Commonly used Materials Density SJSU, ME dept.

  14. Cost of Most Commonly used Materials SJSU, ME dept.

  15. Example – Materials for table legs Luigi Tavolino, furniture designer, conceives of a lightweight table of daring simplicity: a flat sheet of toughened glass supported on slender, unbraced, cylindrical legs. The legs must be solid and as light as possible (to make the table easier to move). They must support the table top and whatever is placed upon it without buckling.What materials could one recommend. SJSU, ME dept.

  16. Objective function Example – Materials for table legs The Model The leg is a slender column of density ρ and modulus E. The load P and its length l are determined by design (fixed). The radius r of the leg is a variable. We wish to minimize the mass m of the leg. SJSU, ME dept.

  17. = Material properties The weight is minimized by selecting the subset of materials with the greatest value of the material index. Example – Materials for table legs The constraint is that the legs must support a design load without buckling. Euler’s buckling equation where I = π r4/4 Solving for the free variable , r, and substituting it into the equation for m gives, SJSU, ME dept.

  18. The thinnest leg is that made of the material with the largest value of the material index. Two material indices, To minimize the weight, both have to be maximize. Example – Materials for table legs Solving the Euler’s formula for r, gives an equation for the thinnest leg which will not buckle: Material properties SJSU, ME dept.

  19. Procedure for deriving material indices SJSU, ME dept.

  20. Modulus of Elasticity (E) vs. Density (ρ) Charts Constant guidelines SJSU, ME dept.

  21. Modulus of Elasticity (E) vs. Density (ρ) Charts SJSU, ME dept.

  22. Modulus of Elasticity (E) vs. Density (ρ) Charts SJSU, ME dept.

  23. SJSU, ME dept.

  24. Summary of materials for table legs SJSU, ME dept.

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