projects 1 to 3 v2.pdf5_PROJECTS_using_the_CES_EduPack 11.pdf5_PROJECTS_using_the_CES_EduPack 12.pdf5_PROJECTS_using_the_CES_EduPack 13.pdf5_PROJECTS_using_the_CES_EduPack 14.pdf5_PROJECTS_using_the_CES_EduPack 15.pdf5_PROJECTS_using_the_CES_EduPack 16.pdfMSEG302: Homework problemsfor CES + Solutions-6 problems-When opening CES, choosethe level indicated for the problem of choicePb1: CD casez The standard CD (“Jewel” case) cracks easily and, if broken, can scratch the CD. Jewel cases are made of injection moulded polystyrene, chosen because it is transparent, cheap and easy to mould.z CES level: 1z Material choice/Requirements:– Optical properties: transparent or optically clear– Fracture toughness better than polystyrene– Young’s modulus not too different from polystyrene (to make sure the case is stiff enough)– Able to be injection moulded– Cost not more than twice that of polystyrenePb1-Solution: CD casez Material choice/Requirements:– Optical properties: transparent or optically clear⇒ Limit stage: check optical quality + transparent– Fracture toughness better than polystyrene⇒ Limit stage: Minimum = 1.1e6 Pa.m1/2– Young’s modulus not too different from polystyrene (to make sure the case is stiff enough)⇒ Graph stage with Young’s Modulus on the y-axis: the new material must be at least as stiff as PS, so a larger Young’s modulus is desirable– Able to be injection moulded⇒ Tree stage: insert Process universe/Shaping/Moulding/Injection moulding– Cost not more than twice that of polystyrene⇒ Limit stage: Maximum = 4.148 USD/kgz Best materials:– PMMA– PETPb1-Solution: CD caseYoung's Modulus (Pa)1e61e71e81e91e101e11Polyethylene terephthalate (PET)Polymethyl methacrylate (Acrylic, PMMA)Polystyrene (PS)Ionomer (I)Graph stageTree stageLimit stagePb2: Precision Instrumentsz Precision instruments: like clocks, watches, gyroscopes, and scientific equipment often contain moving parts located by knife-edges or pivots. The accuracy of location is limited by the deformation of the knife-edge or pivot and the mating surface.z Elastic deformation is minimized by choosing materials with:– high Young’s modulus– plastic deformation is limited by choosing materials with high hardness. z CES level: 1z Material choice/Requirements:– Young’s modulus: as large as possible– Hardness: as large as possiblePb2-Solution: Precision Instrumentsz Material choice/Requirements:– Young’s modulus: as large as possible– Hardness: as large as possible⇒ Graph stage: Young’s Modulus on one axis and Hardness on the other axis⇒ Make a box selection in the top right cornerz Best materials– Very best:z silicon carbidez tungsten carbide– If the conditions are more relaxed (larger box selection), metals appear and among them, the best choices are:z low alloy steelz high carbon steelz stainless steelPb2-Solution: Precision InstrumentsYoung's Modulus (Pa)1e11 2e11 5e11Hardness - Vickers (Pa)05e91e101.5e102e102.5e103e103.5e104e104.5e10SiliconTungsten alloysAluminaAluminium nitrideSilicon carbideTungsten carbidesStainless steelLow alloy steelHigh carbon steelGraph stageGraph stage/Zoom on relaxed selection boxYoung's Modulus (Pa)1e6 1e7 1e8 1e9 1e10 1e11Hardness - Vickers (Pa)100001000001e61e71e81e91e10Silicon carbideTungsten carbidesPb3: Computer Chipsz The power density of present day computer chips is such that removing the heat generated in them is a major consideration.z The chip is attached to a heat sink that conducts the heat from the chip to a set of fins cooled by fan-driven air flow.z The heat sink must conduct heat well, be able to operate continuously at 150 C and be electrically insulating.z CES level: 1z Material choice/Requirements:– Electrical properties: good insulator– Maximum service temperature > 150 C (423 K)– As large a thermal conductivity as possiblePb3-Solution: Computer Chipsz Material choice/Requirements:– Electrical properties: good insulator⇒ Limit stage: check good insulator– Maximum service temperature > 150 C (423 K)⇒ Limit stage: minimum of maximum temperature = 150C– As large a thermal conductivity as possible⇒ Graph stage: Thermal conductivity on y-axisz Best materials– Aluminum nitridePb3-Solution: Computer ChipsGraph stageLimit stageThermal Conductivity (W/m.K)0.1110100Aluminium nitridePb4: Storage Heaterz A storage heater captures heat over a period of time, then releases it, usually to an air stream, when required.z Those for domestic heating store solar energy or energy from off-peak electricity and release it slowly during the cold part of the day.z Those for research release the heat to a supersonic air stream to test system behavior in supersonic flight.z What is a good material for the storage material? z CES level: 1z Material choice/Requirements:– Maximum service temperature > 150 C (423 K)– Low cost– Specific heat: as high as possiblePb4-Solution: Storage Heaterz Material choice/Requirements:– Maximum service temperature > 150 C (423 K)⇒ Limit stage: minimum of maximum temperature = 150C– Low cost– Specific heat: as high as possible⇒ Graph stage: Cost on one axis and Specific heat on the other axis⇒ Make a box selection in the top left cornerz Best materials:– Brick– Stone– ConcretePb4-Solution: Storage HeaterPrice (USD/kg)0.1 1 10 100Specific Heat (J/kg.K)20050010002000Concrete StoneBrickGraph stageLimit stagePb5: Miniature Connectorsz Miniature connectors like the parallel port of a PC allow up to 20 connection to be made simultaneously.z The material specification from one manufacturer is listed below. What material would be suitable?z CES level: 1z Material choice/Requirements:– Electrical properties: good insulator– Maximum service temperature > 200 C (473 K)– Tensile strength > 100 MPa– Elongation > 2%– Able to be injection moulded– As cheap as possiblePb5-Solution: Miniature Connectorsz Material choice/Requirements:– Electrical properties: good insulator⇒ Limit stage: check good insulator– Tensile strength > 100 MPa⇒ Limit stage: minimum tensile strength = 100MPa– Elongation > 2%⇒ Limit stage: minimum elongation = 2%– Able to be injection moulded⇒ Tree stage: insert Process universe/Shaping/Moulding/Injection moulding– As cheap as possible⇒ Graph stage: cost on y-axisz Best materials:– Without price consideration: PEEK– With price consideration: Polyamides (Nylons)Pb5-Solution: Miniature ConnectorsGraph stageTree