Lecture 10 - Introduction to Design, Design Philosophies, Design Process, Weighted Trade Study PDF

ECOR1044: Design and Economics Introduction to Design, Design Philosophies, Design Process, Weighted Trade Study 1 Overview What is Design? Design Centres and Philosophies Design Requirements/Specifications Design Cycle Design...

ECOR1044: Design and Economics Introduction to Design, Design Philosophies, Design Process, Weighted Trade Study 1 Overview What is Design? Design Centres and Philosophies Design Requirements/Specifications Design Cycle Design Economics Weighted Trade Study Example Decision Making 2 Introduction: Design and Design Philosophies 3 What is Design? A plan or drawing to show the look, function and/or workings of a building, system, or other object before it is made. 4 What is Design? What is a ‘good’ design? – People prioritize different things in designs, such as value, efficiency, aesthetics, and many other factors. 5 Good vs. Bad Design 6 Good vs. Bad Design 7 Good vs. Bad Design 8 Good vs. Bad Design 9 The Design Process 10 Design Process: Steps The design process consists of many steps and sub-steps, in engineering it is also an iterative process, meaning it will typically loop back on itself. The steps are: 1. Research 2. Design Requirements 3. Feasibility 4. Conceptualization 5. Preliminary Design 6. Detailed Design 7. Integration and Testing 8. Production Planning 11 Design Process: Research Various stages of the design process, and even prior to design work, typically involves a significant amount of time allotted to locating information and research concerning the potential design. When researching, consideration should be given to existing applicable literature, problems and successes associated with existing solutions (though remember intellectual property may introduce some limitations), costs, and the potential market for your product. Be mindful of the source you are using, sources can include the Internet, local libraries, government documents, organizational documents, trade journals, and subject matter experts. 12 Design Requirements This is one of the most important parts of the design process, if done improperly the design is nearly guaranteed to be a failure. Establishing design requirements and conducting requirements analysis, sometimes termed problem definition – effectively what problem are you trying to solve, and how do you plan to solve it? This step essentially guides the design through the rest of the process. At the end, the design is compared to these requirements to ensure the design meets expected functionality. 13 Design Requirements Generally, there are two sets of design requirements: – 1) Customer requirements; these are generally an overview of the required functionality of the product you are designing. – 2) Internal requirements, this is where the company or engineer creates a set of internal, more specific requirements for the design. These are typically more specific and generally speak to the direct functionality of components. There are typically 3 types of statements in a requirements document, they are: – Shall (Requirement) – This must be implemented (and must be testable). – Will (Fact) – This is will state a fact or declaration of purpose for the design. – Should (Goal) – These are non-mandatory, typically define something to optimize. 14 Design Requirements - Examples Shall: – ‘The total mass of the vehicle shall not exceed 3000 kg.’ – Is this testable? Will: – ‘The system will have the timing as defined in reference document ABC.’ – Reference documents could be internal documents of the organization, standards documentation, or other things. Should: – ‘The system should not impede crew mobility’. – How do we test this? 15 Design Process: Feasibility Now we evaluate our design idea, performing a feasibility study and analyzing the designs potential to determine whether the project can proceed into the design phase. These studies are typically based on two criteria: – The project must be based on an achievable idea (The project is technologically feasible) – The project needs to be within cost constraints (The project is economically feasible) It is entirely possible to perform the study and realize the design is not achievable due to several reasons. 16 Design Process: Conceptual Design A concept study is often a phase of project planning that includes producing ideas and considering the pros and cons of implementing those ideas. This stage of a project is done to minimize the likelihood of error, manage costs, assess risks, and evaluate the potential success of the intended project. Things like weighted trade studies can typically be used as a numerical method to evaluate each design idea. Cost vs. Performance: Sometimes, it is about value. 17 Design Process: Conceptual Design Exp.: Rough sketches of an aircraft to give context to conceptual ideas. 18 Conceptual Design of an Aircraft Preliminary Design The overall system configuration is defined, and schematics, diagrams, and layouts of the project may provide early project configuration. During detailed design and optimization, the parameters of the part being created will likely change, but the preliminary design focuses on creating a baseline for the project to be built upon. The system may be broken down into subsystems which will be responsible for various tasks. Exp., for an aircraft preliminary design may provide a rough idea of wing size and location, engine size, control systems on-board, etc. 19 Detailed Design Computer-aided design (CAD) programs have made the detailed design phase more efficient as they allow the ability to both draft and simulate designs quickly, addressing most potential design issues before prototyping. CAD Drawing of Mechanical Component CAD Circuit Schematic 20 Verification and Validation Testing Once the detailed design is finished the design is implemented (in hardware, software, etc.), and must go through another round of evaluations (Verification and Validation). Verification checks that a product, service, or system meets specifications. Validation is intended to check if the operational needs of the user are met. 21 Production Planning Production planning (and tool design) consists of planning how to mass- produce the design, and which tools should be used in mass-production manufacturing process. This step involves selecting the production processes, determining the sequence of operations, and the selection of tools, fixtures, metal cutting and metal or plastics forming tools. This step also aims to ensure mass produced products meet specifications during qualification testing. 22 Design Process: Initial Design 23 Design Process: Production Planning 24 Project Economics While designing our products as engineers, we generally prioritize the best technical solution, however there are other factors we must account for. For example: Costs: – Software – Materials – Upfront costs (tooling, etc.) – Operating costs (electricity, fuel, maintenance) Other: – Safety 25 – Regulation Project Economics Upfront (Fixed) Cost: – Investments in things like factory tooling or purchasing machinery. – Software licensing can cost large sums of money for companies. – Software costs are typically recurring payments every year. Tip: start with the conceptual or preliminary design stages. Operating (Variable) Cost: – Operating costs are typically the costs associated with the manufacturing of the design, such as electricity, fuel, factory maintenance, and the costs of operating any product oversight. – When the design is being manufactured, the materials for manufacturing must first be purchased, this costs occurs continually through production. 26 Weighted Trade Study Example 27 Weighted Trade Study A Weighted Trade Study can be used to compare a number of conceptual designs and determine which design fits your needs. Before the trade study can be performed, you must first determine a number of specifications required from the design. These will then be used to evaluated the potential designs. 28 Weighted Trade Study Weighted trade study steps: 1. Assign weights to each design requirement (how important is each one, the weight is a numerical value). 2. Everyone in the design group evaluates the designs on each requirement giving it a score (Exp.: 1-5, 5: meets or exceeds the requirement, 1: does not fully meet the requirement). 3. The groups scores are averaged so that a single score is given for each requirement. 4. The weight is multiplied by the average score resulting in a weighted average score for each requirement. 5. These weighted scores are then summed for each design giving each design a numerical value that represents how ‘good’ the design is. 29 Weighted Trade Study Weighted trade study example: Purchasing a vehicle. – What are our criteria for the vehicle we’re looking to buy? – A) The vehicle shall cost less than $30,000. – B) Considerations: Cost Mileage Condition of interior (tears, broken plastic), or exterior (broken bumper, cracked headlight) Paint Color 30 Weighted Trade Study 1) We start by assigning weights to each of our criteria, from 1-4, and breaking each criteria into defined ranges: – Cost (4 weighting) 1: $22500-$29,999, 2: $15000-$22499, 3: $7500-$14999, 4: $0-$7499 – Mileage (3 weighting) 1:150,000 km+, 2: 100,000 km – 150,000 km, 3: 50,000 – 99,999 km, 4: 0 – 49,999 km – Condition (3 weighting) 1: Poor, 2: Mild, 3: Good, 4: Great – Color (1 weighting) 31 1: Red, 2: Grey, 3: White, 4: Blue Weighted Trade Study 2) The choices for cars we have found are (Bracketed numbers represent the score for that criteria): Make/Model Cost ($) Mileage (km) Condition Color Honda Civic $14,500 110,000 Good Grey Subaru Impreza $18,000 78,000 Mild Blue Make/Model Cost Mileage (km) Condition Color Honda Civic 3 2 3 2 Subaru Impreza 2 3 2 4 32 Weighted Trade Study 3/4) Multiply the weight of each criteria by the score from the last slide to get the weighted score: Make/Model Cost (4) Mileage (3) Condition (3) Color (1) Honda Civic 3 2 3 2 Subaru Impreza 2 3 2 4 Make/Model Cost Mileage Condition Color Total Score Honda Civic 12 6 9 2 29 Subaru Impreza 8 9 6 4 27 33 Decision Making 34 Steps to success 35 Success 36 Persistence vs. Overdoing Planning vs. Doing 37 Problem Solving Decision Making: The process of examining your possibilities options, comparing them, and choosing a course of action. 38 Decision Making How do you make decisions? 39 Decision Making 40 Decision Making A decision is a choice made between two or more available alternatives. Factors: Goals. Demands. Priorities. Resources. Acceptability. Values. Style. Perception. Risk. Judgement. 41 Six C's of Decision Making Construct a clear picture of precisely what must be decided. Compile a list of requirements that must be met. Collect information on alternatives that meet the requirements. Compare alternatives that meet the requirements. Consider the "what might go wrong" factor with each alternative. Commit to a decision and follow through with it. 42  brainstorming open discussion group tasks agreement seeking outside experts 43 Decision Making 44 Develop decision-making criteria know the company's core values understand the impact on the objective identify the effect on people use a question format give appropriate weight to each criterion devise a scoring system 45 Decision-making criteria 46 Evaluating the execution 47 Evaluating the execution 48 Overthinking: Priority Matrix 49 Discipline Tip: Make a decision and reevaluate when needed. 50 Questions? 51