ME 72 Design What is design?

ME 72 Design What is design? What is a good design? – How do you determine what a good design is?

ME 72 Design What is design? What is a good design? – How do you determine what a good design is? What is involved in design?

ME 72 Design What is design? What is a good design? – How do you determine what a good design is? What is involved in design? Design stages? – Identify problem – Conceptual design, analysis – Preliminary design, analysis – Developing and evaluating prototypes – Detailed design, analysis – Is the design satisfactory?

ME 72 Design What is design? What is a good design? – How do you determine what a good design is? What is involved in design? Design stages? – Identify problem – Conceptual design, analysis – Preliminary design, analysis – Developing and evaluating prototypes – Detailed design, analysis – Is the design satisfactory? How do you approach design? – Concurrent design – Brainstorming – Thinking about it

ME 72 Schematic Design Process

ME 72 Exercise: You need to develop additions to a children’s swing set that minimize injuries. – What are some constraints? – What are some design ideas? – What ideas seem to be the best? – Why?

ME 72 Objectives Tree: Convenient, Safe, Attractive Transport System System Low risk of structural collapse Efficient, cheap design

ME 72 Morphological Chart: Potato Harvester

ME 72 Selecting Designs By Evaluating Alternatives List design objectives (e.g lightweight.easy to fabricate, maneuverable) Assign each objective a relative weight (importance), with the weights summing to one if desired For each alternative design, establish utility scores for each objective – e.g. 0-10, with 0 for a useless solution and 10 for an excellent solution Calculate and compare the relative utility metric for each alternative by summing the product of each objective’s weight by the alternative’s utility score (inner product of the weight vector and the utility score vector). This should provide a utility metric for selecting the most promising (highest-scoring) design alternatives.

ME 72 Evaluating Design Objectives

ME 72 Weighted Objectives Evaluation of Three Auto Designs

ME 72 Weighted Objectives Evaluation of Three Auto Designs

ME 72 Small City Car Alternative Design Evaluation Chart

ME 72 Example Automotive Subsystems 1.4. Body and Chassis Body Electrical Heating Cooling Body panels Doors Windows Seats Interior appointments Gauges Controls Fuel supply Finish 1.5. Suspension Springs Dampers Control Arms 1.5.6Wheels and tires 1.6. Steering Rack Control Rods Power pump Power controls Ball joints 1.1. Engine Engine mechanical Ignition Fuel Injection Engine controls Emission control Starting system Cooling system Charging system 1.2. Drive Train Transmission (automatic or manual) Propeller shaft Differential Half-shafts Hub Assemblies Power train control Braking Master cylinder Power Booster Hydraulic lines System sensors Disc and caliper assemblies Antiskid Braking System Electronic Control System?

ME 72 Design Considerations – Dynamics – Layout, weight – Stability – Sensing and Control – Heat dissipation – Power capacity/requirements/distribution – Thrust generation(wheels/tracks/propeller s/jets – Drive mechanisms – Suspension (pneumatic tires?) – Maneuverability/quickness/respon se – Speed/drag – Blocking/Blocking, falling resistance – Flag handling – Vehicle form – Esthetics – Complexity/manufacturability – Ease of repair Overall Contest Strategy and performance needs System Design and Tactics Auxiliary subsystems Vehicles

ME 72 Physical Systems Force Velocity Torque Power Energy Force Velocity Torque Power Energy Force Velocity Torque Power Energy Force Velocity Torque Power Energy Losses Conserve: Total power, energy, linear and angular momentum, charge Don’t Conserve: Force, Velocity, Torque, Position, Entropy Analysis: Mechanics, thermodynamics, strength of materials, electromagnetic theory, etc.