Review on material selection process

Review on material selection process - Review on material...

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Review on material selection process Habiba Bougherara
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Page 2 Strategy to select material and process
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Page 3 Strategy to select process
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Mode of loading of structural elements Page 4 5 basic structural elements Shell member =
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Mode of loading of structural elements Page 5
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Tension Failure modes of structural elements Page 6 Yielding (σy) Brittle Fracture (σf) Necking (σu) Creep Fatigue Brittle Fracture (σf) Yielding (σy) Fatigue Buckling Barrelling Compression
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Flexion Mode of loading of structural element Page 7 Torsion Yielding (σy) Brittle Fracture (σf) Fatigue Large deflection Brittle Fracture (σf) Yielding (σy) Fatigue Creep
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Page 8 Example Now we must select materials and processes suitable for this product? i.e. a light lever, a strong screw, a strong needle, Casting, moulding etc…
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Common constraints
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Rank Materials using the performance index
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Performance index
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Common performance indices Stiffness-limited design at minimum mass FUNCTION AND CONSTRAINTS MAXIMISE TIE (tensile strut) stiffness, length specified; section area free E / ρ SHAFT (loaded in torsion) stiffness, length, shape specified, section area free G 1/2 / ρ stiffness, length, outer radius specified; wall thickness free G / ρ stiffness, length, wall-thickness specified; outer radius free G 1/3 / ρ BEAM (loaded in bending) stiffness, length, shape specified; section area free E 1/2 / ρ stiffness, length, height specified; width free E / ρ stiffness, length, width specified; height free E 1/3 / ρ COLUMN (compression strut, failure by elastic buckling) buckling load, length, shape specified; section area free E 1/2 / ρ PANEL (flat plate, loaded in bending) stiffness, length, width specified, thickness free E 1/3 / ρ PLATE (flat plate, compressed in-plane, buckling failure) collapse load, length and width specified, thickness free E 1/3 / ρ CYLINDER WITH INTERNAL PRESSURE elastic distortion, pressure and radius specified; wall thickness free E / ρ SPHERICAL SHELL WITH INTERNAL PRESSURE elastic distortion, pressure and radius specified, wall thickness free E / (1-ν) ρ
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General rule To minimise cost, use the above criteria for minimum weight, replacing density ρ by C m ρ, where C m is the material cost per kg. To minimise energy content, use the above criteria for minimum mass replacing density ρ by qρ where q is the energy content per kg. To minimise environmental impact , replace density ρ by I e ρ instead, where I e is the eco-indicator value for the material E = Young's modulus for tension, the flexural modulus for bending or buckling; G = shear modulus; ρ = density, q = energy content/kg; I e = eco-indicator value/kg.
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Strength-limited design at minimum mass Common performance indices FUNCTION AND CONSTRAINTS MAXIMISE TIE (tensile strut) stiffness, length specified; section area free σ f / ρ SHAFT (loaded in torsion) load, length, shape specified, section area free
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This note was uploaded on 01/18/2012 for the course MECH MTL 700 taught by Professor Habiba during the Fall '11 term at Ryerson.

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Review on material selection process - Review on material...

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