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Total Design Market Assessment Specification Concept Design Detail Design Manufacture Sell is a systematic activity: Identification of the market need.

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Presentation on theme: "Total Design Market Assessment Specification Concept Design Detail Design Manufacture Sell is a systematic activity: Identification of the market need."— Presentation transcript:

1 Total Design Market Assessment Specification Concept Design Detail Design Manufacture Sell is a systematic activity: Identification of the market need → sale of product to meet that need. Product, Process, People, Organization, etc. Design Core Market Analysis Specification Concept Design Detailed Design Manufacturing Sales Product Design Specification (PDS) Envelopes all stages of the design core THE DESIGN CORE

2 The Design Core Market Assessment Specification Concept Design Detail Design Manufacture Sell DETAIL DESIGN A vast subject. We will concentrate on: Materials Selection Process Selection Cost Breakdown

3 Materials Selection Metals and Alloys Polymers Ceramics and Glasses Steel-cord tyres CFRPGFRP Filled polymers Wire-reinforced cement Cermets MMCs Composites

4 Materials Properties MATERIAL Mechanical tribology fatigue K IC σ y UTS E Thermal α K H T m T Transition Environmental recycling energy consumption waste Other feel look Physical optical magnetic electrical Chemical corrosion oxidation FUNCTIONAL MATERIALS STRUCTURAL MATERIALS

5 Young’s Modulus, E MaterialE (GPa)MaterialE (GPa)MaterialE (GPa) Diamond Tungsten carbide, WC Cobalt/WC cermets Borides of Ti, Zr, Hf Silicon carbide, SiC Boron Tungsten Alumina, Al 2 O 3 Beryllia, BeO Titanium carbide, TiC Molybdenum and alloys Tantalum carbide, TaC Niobium carbide, TaC Silicon nitride, Si 3 N 4 Chromium Beryllium and alloys Magnesia, MgO Cobalt and alloys Zirconia, Zr0 Nickel and alloys CFRP Iron Iron based superalloys Steels Cast irons Tantalum and alloys Platinum Uranium Boron/epoxy composites Copper and alloys Mullite Vanadium Titanium and alloys Palladium Brasses and bronzes Niobium and alloys Silicon Zirconium and alloys Silica glass, SiO 2 (quartz) Zinc and alloys Gold Aluminium and alloys Silver Calcite (marble, limestone) Soda glass Granite Tin and alloys Concrete, cement Magnesium and alloys GFRP Graphite Alkyds Common woods, ║ to grain Lead and alloys Ice, H 2 O Melamines Polyimides Polyesters Acrylics Nylom PMMA Polystyrene Epoxies Polycarbonate Common woods,  to grain Polypropylene Polyethylene (high density) Polyethylene (low density) Foamed polyurethane Rubbers PVC Foamed polymers

6 Yield Strength (σ y ) & UTS (σ TS ) Material σ y (MPa) σ TS (MPa)Material σy (MPa) σ TS (MPa) Pressure-vessel steels Low alloy steels Molybdenum and alloys Tungsten Nickel alloys Carbon steels Titanium and alloys Tantalum and alloys CFRPs Cobalt/WC cermets Cast irons Copper alloys Concrete (steel reinforced) Stainless steel (austenitic) Aluminium alloys Brasses and bronzes Stainless steels (ferritic) Zinc alloys Zirconium alloys Mild steel GFRPs Magnesium alloys Beryllium and alloys PMMA Ice, H 2 O Polyimides Nickel Nylons Epoxies Copper Silver ABS/polycarbonate Polystyrene Iron Pure ductile metals Acrylic/PVC Aluminium Gold Lead and alloys Polyurethane Polypropylene Tin and alloys Polyethylene (high density) Concrete (non-reinf’d, comp’n) Polyethylene (low density) Ultrapure fcc metals Foamed polymers (rigid) Polyurethane foam

7 Density, ρ Material ρ (Mgm -3 )Material ρ (Mgm -3 )Material ρ (Mgm -3 ) Osmium Platinum Tungsten and alloys Gold Uranium Tungsten carbide, WC Tantalum and alloys Molybdenum and alloys Cobalt/WC cermets Lead and alloys Silver Niobium and alloys Nickel and alloys Cobalt and alloys Copper and alloys Brasses and bronzes Iron Iron-based superalloys Steels Tin and alloys Cast irons Titanium carbide, TiC Zinc and alloys Chromium Zirconium carbide, ZrC Zirconium and alloys Titanium and alloys Alumina, Al 2 O 3 Magnesia, MgO Silicon carbide, SiC Silicon nitride, Si 3 N 4 Mullite Beryllia, BeO Calcite (marble, limestone) Aluminium and alloys Silica glass, SiO 2 (quartz) Soda glass Concrete/cement GFRPs Carbon fibres PTFE Boron/epoxy composites Beryllium and alloys Graphite (high strength) CFRPs PVC Polyesters Polyimides Epoxies Polycarbonate Polyurethane PMMA Nylon Polystyrene Polyethylene (high density) Ice, H 2 O Polyethylene (low density) Polypropylene Rubber Common woods Foamed polymers Foamed polyurethane

8 Specific Properties Material E (GPa) σ (MPa) ρ (Mgm -3 ) E/ρ mean (10 6 m 2 s -2 ) σ/ρ mean (10 3 m 2 s -2 ) Cobalt/WC cermets Beryllium and alloys Low-alloy steels CFRP Aluminium alloys Common woods, ║ to grain Lead and alloys Polypropylene Foamed polymers EE/ρ mean σσ/ρ mean Cobalt/WC cermets Beryllium and alloys Low-alloy steels CFRP Aluminium alloys Common woods, ║ to grain Lead and alloys Polypropylene Foamed polymers Beryllium and alloys CFRP Cobalt/WC cermets Aluminium alloys Low-alloy steels Common woods, ║ to grain Lead and alloys Polypropylene Foamed polymers Low-alloy steels Cobalt/WC cermets CFRP Aluminium alloys Beryllium and alloys Common woods, ║ to grain Lead and alloys Polypropylene Foamed polymers CFRP Low-alloy steels Aluminium alloys Beryllium and alloys Common woods, ║ to grain Cobalt/WC cermets Polypropylene Lead and alloys Foamed polymers

9 Materials Selection without Shape Generic materials selection Problem statement Model Function, Objective, Constraints Selection Examples Oars Mirrors for large telescopes Low cost building materials Flywheels Springs Safe pressure vessels Precision devices

10 Generic Materials Selection p:Performance of component;f(F,G,M) F: Functional requirement, e.g. withstanding a force G:Geometry, e.g. diameter, length etc. M:Materials properties, e.g. E, K IC, ρ Separable function if: P = f 1 (F) · f 2 (G) · f 3 (M) TASK:Maximize f 3 (M) where M is the “performance index”

11 Procedure for Deriving “M” (a)Identify the attribute to be maximized or minimized (weight, cost, energy, stiffness, strength, safety, environmental damage, etc.). (b)Develop an equation for this attribute in terms of the functional requirements, the geometry, and the material properties ( the objective function). (c)Identify the free (unspecified) variables. (d)Identify the constraints; rank them in order of importance. (e)Develop equations for the constraints (no yield, no fracture, no buckling, maximum heat capacity, cost below target, etc.). (f)Substitute for the free variables from the constraints into the objective function. (g)Group the variables into three groups: functional requirements, F, geometry, G, and materials properties, M. (h)Read off the performance index, expressed as a quantity, M, to be maximized. (i)Note that a full solution is not necessary in order to identify the material property group.

12 The Materials Selection Map Guidelines for M = Prop2/Prop1 Search Region M = 40

13 Example I: A light strong tie So, to minimize mass m, maximise f 1 (F)f 2 (G)f 3 (M) Search Region M = 100Nm/g

14 Example II: A light stiff column (circular) f 1 (F)·f 2 (G)·f 3 (M) So, to minimize mass m, maximise Search Region

15 Example III: Pressure Vessel So, to minimize mass m, maximise f 1 (F)·f 2 (G)·f 3 (M) Light weight cylindrical vessel of fixed radius Search Region

16 Performance Indices: Elastic Design Component and design goalMaximise Springs: Specified energy storage, volume to be minimized Springs: Specified energy storage, mass to be minimized Elastic hinges: Radius of bend to be minimized Knife edges, pivots: Minimum contact area, maximum bearing load Compression seals and gaskets: Maximum contact area with specified maximum contact pressure Diaphragms: Maximum deflection under specified pressure of force Rotating drives, centrifuges: Maximum angular velocity, radius specified, wall thickness free Ties, columns: Maximum longitudinal vibration frequencies Beams: Maximum flexural vibration frequencies Plates: Maximum flexural vibrationfrequencies Ties, columns, beams, plates: Maximum self-damping σ f 2 /E σ f 2 /Eρ σ f /E σ f 3 /E 2 & E σ f /E & 1/σ f σ f 3/2 /E σ f /ρ E/ρ E 1/2 /ρ E 1/3 /ρ η Note: σ f = failure strength; E = Young’s modulus; ρ = density; η = loss coefficient

17 Performance Indices: Min. Weight Component and loadingStiffness: Maximize Strength: Maximize Tie (tensile strut): Load, stiffness, length specified, section area free Torsion bar or tube: Torque, stiffness, length specified, section area free Beam: Loaded externally or by self-weight in bending; stiffness, length specified, section area free Column (compression strut): Failure by elastic buckling or plastic compression; collapse load and length specified, section area free Plate: Loaded externally or by self-weight in bending; stiffness, length, width specified, thickness free Plate: Loaded in-plane; failure by elastic buckling or plastic compression; collapse load, length and width specified, thickness free Rotating disks, flywheels: Energy storage specified Cylinder with internal pressure: Elastic distortion, pressure and radius specified, wall thickness free Spherical shell with internal pressure: Elastic distortion, pressure and radius specified, wall thickness free E/ρ G 1/2 /ρ E 1/2 /ρ E 1/3 /ρ - E/ρ E/(1-ν)ρ σ f /ρ σ f 2/3 /ρ σ f /ρ σ f 1/2 /ρ σ f /ρ Note: σ f = failure strength; E = Young’s modulus; G = shear modulus; ρ = density

18 Performance Indices: Min. Weight Component and loadingCrack lengthfixed: Maximize ≈ min section: Maximize Tie (tensile strut): Load, length specified, section area free Torsion bar or tube: Torque, length specified, section area free Beam: Loaded externally or by self-weight in bending; stiffness, length specified, section area free Column (compression strut): Failure by elastic buckling or plastic compression; collapse load and length specified, section area free Plate: Loaded externally or by self-weight in bending; load, length, width specified, thickness free Plate: Loaded in-plane in tension; collapse load, length and width specified, thickness free Rotating disks, flywheels: Energy storage specified Cylinder with internal pressure: Elastic distortion, pressure and radius specified, wall thickness free Spherical shell with internal pressure: Elastic distortion, pressure and radius specified, wall thickness free K IC /ρ K IC 2/3 /ρ K IC 1/2 /ρ K IC /ρ K IC /(1-ν)ρ K IC 4/3 /ρ K IC 4/5 /ρ K IC 2/3 /ρ K IC 2 /ρ K IC /ρ K IC 2 /ρ K IC 2 /(1-ν)ρ Note: K IC = fracture toughness ρ = density

19 Nomenclature a,R,r a C A C,C 1,n C R E F F buckling g G I J K K IC L m M p Q S B S T t Radius Half crack length Cross-sectional area Constant dependent upon loading system Relative cost Young’s modulus Force Critical force for the onset of buckling Acceleration due to gravity Shear modulus Second moment of area Polar moment Resistance to twisting of section Fracture toughness Beam, shaft etc. length Mass Performance index; Bending moment Pressure Section modulus in torsion Bending stiffness Torsional stiffness Thickness TToUVymWVxZαδεηθλνρσσfφψωTToUVymWVxZαδεηθλνρσσfφψω Temperature; Torque Initial temperature Kinetic energy Volume Distance from neutral axis to highest stressed surface Stored energy Distance Section modulus in bending Linear coefficient of thermal expansion Deflection Strain Loss coefficient Angle of twist Thermal conductivity Poisson’s ratio Density Stress Failure stress Maximum surface shear stress Macro-shape factor Micro-shape factor Angular velocity

20 Materials for Large Telescopes DESIGN REQUIREMENTS FunctionPrecision mirror ObjectiveMinimize mass Constraints (a)Radius a specified (b)Must not distort more than δ under its own weight (c)High dimensional stability: no creep, no moisture absorbtion, low thermal expansion f1(F)·f2(G)·f3(M) So, to minimize mass m, maximise

21 Materials for Large Telescopes Search Region M = 2 (GPa) 1/3 m 3 /Mg MaterialMComment Steel Concrete Al alloys Glass GFRP Mg alloys Wood Beryllium Foamed polystyrene CFRP Very heavy. The original choice. Heavy. Creep, thermal distortion problems. Heavy. High thermal expansion. The present choice. Not dimensionally stable enough. Lighter than glass, but high thermal expansion. Dimensionally unstable. Very expensive. Good for small mirrors. Very light, but not dimensionally stable. Very light, but not dimensionally stable: use for radio telescopes.

22 Materials for Oars DESIGN REQUIREMENTS FunctionLight, stiff beam ObjectiveMinimize mass Constraints(a)Length specified (b)Bending stiffness specified (c)Toughness > 1 kJ/m 2 (d)Cost <$100/kg So, to minimize mass m, maximise Second moment of area:

23 Materials for Oars MaterialMComment Woods CFRP GFRP Ceramics Cheap, traditional, but with natural variability. As good as wood, more control of properties. Cheaper than CFRP, but lower M, thus heavier. Good M, but toughness low and cost high. Search Region M = 6 (GPa) 1/2 m 3 /Mg

24 Materials for Buildings DESIGN REQUIREMENTS FunctionFloor beams ObjectiveMinimize cost Constraints(a)Length specified (b)Stiffness: must not deflect too much under design loads (c)Strength: must not fail under design loads σ=σyσ=σy y F b b Floor Beam

25 Materials for Buildings M 2 = 6.8 Search Region M 1 = 1.6 Search Region

26 Materials for Safe Pressure Vessels DESIGN REQUIREMENTS FunctionPressure vessel =contain pressure p ObjectiveMaximum safety Constraints(a)Must yield before break (b)Must leak before break (c)Wall thickness small to reduce mass and cost Yield before break Leak before break Minimum strength

27 Materials for Safe Pressure Vessels Search Region M 3 = 100 MPa M 1 = 0.6 m 1/2 MaterialM 1 (m 1/2 ) M 3 (MPa) Comment Tough steels Tough Cu alloys Tough Al alloys Ti-alloys High strength Al alloys GFRP/CFRP > Standard. OFHC Cu. 1xxx & 3xxx High strength, but low safety margin. Good for light vessels.

28 Materials for Springs DESIGN REQUIREMENTS FunctionElastic spring Objective(a)Maximum stored elastic energy per unit volume (b)Maximum stored elastic energy per unit mass Constraints(a)No failure by yield, fracture or fatigue, i.e. σ <σ f everywhere (b)Adequate toughness: G C >1 kJ/m 2 σfσf σ ε σ f /E Energy Stored

29 Materials for Springs M 1 = 6 MJ/m 3 Search Region MaterialM 1 (MJ/m 3 ) Comment Ceramics Spring steel Ti alloys CFRP GFRP Glass (fibres) Nylon Rubber Brittle in tension; good only in compression. The traditional choice: easily formed and heat treated. Expensive, corrosion resistant. Comparable in performance with steel; expensive. Almost as good as CFRP and much cheaper. Brittle in torsion, but excellent if protected against damage; very low loss factor. The least good; but cheap and easily shaped, but high loss factor. Better than spring steel, but high loss factor.

30 Materials for Springs M 2 = 2 kJ/kg Search Region MaterialM 2 (kJ/kg) Comment Ceramics Spring steel Ti alloys CFRP GFRP Glass (fibres) Wood Nylon Rubber Brittle in tension; good only in compression. Poor because of high density. Better than steel; corrosion resistant, expensive. Better than steel; expensive. Better than steel; less expensive than CFRP. Brittle in torsion, but excellent if protected against damage; very low loss factor. On a weight basis, wood makes good springs. As good as steel; but has a high loss factor. Outstanding;10 times better than steel, but has a high loss factor.

31 Materials for Flywheels DESIGN REQUIREMENTS FunctionFlywheel for energy storage ObjectiveMaximize kinetic energy per unit mass Constraints(a)Must not burst (b)Adequate toughness to give crack tolerance DESIGN REQUIREMENTS FunctionFlywheel for child’s toy ObjectiveMaximize kinetic energy per unit volume ConstraintsOuter radius fixed Kinetic energy: Polar moment of inertia: Mass: Stress:

32 Materials for Flywheels Search Region M 1 = 100 kJ/kg Maximizing energy/volume Maximizing energy/mass

33 Materials for Flywheels MaterialM (kJ/kg) Comment Ceramics Composites: CFRP GFRP Beryllium High strength steel High strength Al alloys High strength Mg alloys Ti alloys (Compression only) Brittle and weak in tension – eliminate. The best performance – a good choice. Almost as good as CFRP and cheaper – an excellent choice. Good, but expensive, difficult to work and toxic. All about equal performance. Steel and Al alloys cheaper than Mg and Ti alloys. Pb alloys Cast iron High density makes these a good (and traditional) selection when performance is velocity limited, not strength limited.

34 Materials for Precision Devices DESIGN REQUIREMENTS FunctionForce loop (frame) ObjectiveMaximize positional accuracy (minimize distortion) Constraints(a)Must tolerate heat flux (b)Must tolerate vibration Heat flow : Thermal strain : 

35 Materials for Precision Devices MaterialM1M1 M2M2 Comment Diamond5x Oustanding M 1 and M 2 ; expensive Si4x Excellent M 1 and M 2 ; cheap SiC2x Excellent M 1 and M 2 ; potentially cheap Be10 7 9Less good than Si or SiC Al Poor M 1, but very cheap Ag Cu Au 2x High density gives poor M 2 W Mo Invar 3x10 7 2x10 7 3x Better than Cu, Ag or Au, but less good than Si, SiC or diamond M 1 = 10 7 W/m Search Region Diamond Si SiC Al Ag Au Be Cu Mo W


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