Maximum acceleration on a 5-cm standard pothole
10.6 Modeling for Performance Evaluation
295 In this discussion on analytical modeling, a number of issues were raised: ■ What level of accuracy is needed? Analytical models can be used instead of physical models only when there is a high degree of confidence in their fidelity. ■ Are analytical models available of sufficient fidelity to give the needed accuracy? If not, then physical models are required. Often it is valuable to do both to confirm one’s understanding of the product. ■ Are deterministic solutions sufficient? They probably are in the early evalu- ation efforts. However, as the product is finalized, they are not sufficient, as knowledge of the effect of noises on the dependent parameters is essential in developing a quality product. ■ If no analytical techniques are available, can new techniques be developed? In developing a new technology, part of the effort is often devoted to generating analytical techniques to model performance. During a design effort, there is usually no time to develop very sophisticated analytical capabilities. ■ Can the analysis be performed within the resource limitations of time, money, knowledge, and equipment? As discussed in Chap. 1, time and money are two measures of the design process. They are usually in limited supply and greatly influence the choice of the modeling technique used. Limitations in time and money can often overwhelm the availability of knowledge and equipment. 10.6.5 Step 5: Understand the Physical Modeling Capabilities Physical models, or prototypes, are hardware representations of all or part of the final product. Most design engineers would like to see and touch physical real- izations of their concepts all the way through the design process. However, time, money, equipment, and knowledge—the same resource limitations that affect analytical modeling—control the ability to develop physical models. Generally, the fact that physical models are expensive and take time to produce, controls their use. However, the ability to develop physical prototypes of complex components has improved greatly since the mid-1980s. During this period, rapid prototyp- ing methods were developed. These systems use solid models of components to deposit materials or laser-harden polymers to rapidly make a physical model. The components made by some of the methods are actually usable in tests; others are only visual and usable to test fit and interference. You can’t BS hardware.Parts
» Mechanical engineering design process
» Introduction Measuring the Design Process with Product
» The History of the Design Process The Life of a Product
» The Many Solutions for Design The Basic Actions of Problem Solving
» Summary Mechanical Design Languages
» Different Types of Mechanical Constraints, Goals, and
» Product Decomposition Summary Introduction
» The Individual Designer: A Model of Human Mental Processes That Occur
» Characteristics of Creators The Structure of Design Teams
» Building Design Team Performance Overview of the Design Process
» Designing Quality into Products Product Discovery
» Choosing a Project Summary Sources Exercises On the Web
» Product, Project, and Decision Risk
» In engineering design, the designer uses three types of knowledge: knowl-
» A design process that results in a quality product can be learned, provided
» Improved material on project planning.
» Insist on rights of humanity and nature to coexist
» Recognize interdependence. On the Web
» Accept responsibility for the consequences of design
» Create safe objects of long-term value.
» Eliminate the concept of waste.
» Rely on natural energy flows.
» Understand the limitations of design.
» Seek constant improvement by the sharing of knowledge.
» Respect relationships between spirit and matter.
» Engineering Changes Patent Applications Design for End of Life Sources Placing a piece in a puzzle
» Decompose a simple system such as a home appliance, bicycle, or toy into its assemblies,
» For the device decomposed, list all the important features of one component.
» Select a fastener from a catalog that meets these requirements:
» Sketch at least five ways to configure two passengers in a new four-wheeled commuter
» You are a designer of diving boards. A simple model of your product is a cantilever beam.
» Find five examples of mature designs. Also, find one mature design that has been recently
» Teams develop decisions by consensus rather than by authority. This leads to
» Beneficial team behaviors. Well-defined decision process.
» Use of sound generationevaluation approach.
» Standardizes, organizes, and controls operations.
» Provides for consistent dissemination of information.
» Encourages improvement. Team nam
» Generate alternatives Team nam
» Identify criteria importance Team nam
» Based on the evaluation results, decide what to do next. This decision will
» “What I want for myself out of this.” Refine criteria.
» Refine evaluation—work to gain consensus and reduce uncertainty.
» Choose an alternative—you’ve made a decision, document it and address
» Develop a list of original design problems that you would like to do at least 3. Choose
» Make a list of features you don’t like about products you use. One way to develop this
» Executive summary: Team Members:
» Gantt chart: All diagrams, figures, and tables should be accurately and clearly labeled
» References: Appendices: All diagrams, figures, and tables should be accurately and clearly labeled
» For the features of the redesign problem Exercise 4.2 develop a plan as in Exercise 5.1.
» Develop a plan for making a breakfast consisting of toast, coffee, a fried egg, and juice. Be
» Developing the specifications or goals for the product
» Finding out how the specifications measure the customers’ desires
» Determining how well the competition meets the goals
» Developing numerical targets to work toward
» The QFD method can be applied to the entire problem and any subprob-
» Both competitors have good lifting position when transferring the passenger
» Both products have poor stability. Clearly, this is a market opportunity.
» The Colub is easy to move and Delton is not, need to determine why and do
» For most of adjustment requirements, neither of the competitors score above 3,
» Each specification should measure at least one customers’ requirement at
» Each specification should be measurable. Every specification should be writ-
» The first specification “seat width relative to frame width” is not clear. What
» Two points about specifications that are in terms of “number of steps”:
» For a design problem Exercise 4.1, develop a house of quality and supporting informa-
» The interface to the jam plate. Energy flows between the trigger and the jam
» Articulate the conflicting positions or functions. Identify the needs forcing the two positions.
» Articulate the conflicting positions
» Identify the issue, the objective of the needs
» Articulate injections that can relieve the conflict while meeting the objective.
» Many of the problems that engineers face contain elements that have already
» There are predictable patterns of technological change that can be applied to
» Increase degree of an object’s segmentation
» Arrange objects so they can go into action without time loss
» Stating the overall function.
» Decomposing the overall function into subfunctions. If assumptions are needed to
» Identifying all the objects nouns used and defending their inclusion in the functional
» For the redesign problem Exercise 4.2, apply items a–c from Exercise 7.1 and also study
» Which subfunctions must remain unchanged during redesign?
» Which subfunctions if any must be changed to meet new requirements?
» Which subfunctions may cease to exist?
» For the functional decomposition developed in Exercise 7.1,
» A perpetual motion machine. In recent times the patent office has refused to consider
» Use brainstorming to develop at least 25 ideas for
» A way to fasten together loose sheets of paper.
» A device to keep water off a mountain-bike rider.
» A way to convert human energy to power a boat.
» A method to teach the design process.
» Use brainwriting to develop at least 25 ideas for
» A device to leap tall buildings in a single bound.
» Are the critical parameters identified?
» Are the safe operating latitude and sensitivity of the parameters known?
» Have the failure modes been identified?
» Does hardware exist that demonstrates positive answers to the preceding four
» Is the technology controllable throughout the product’s life cycle?
» The source of the component.
» Wheel and chain must clear frame for all deflections. Wheel should move straight up and down.
» Your body while holding a 5-kg weight straight out in front of you with your
» Maximum acceleration on a standard street
» Maximum acceleration on a 5-cm standard pothole
» Identify the critical parameters and interfaces for evaluation.
» Develop a P-diagram for each.
» Choose whether to build physical models for testing or run an analytical experiment
» Perform the experiments or analysis and develop the most robust product.
» For the redesign problem Exercise 4.2, repeat the steps in Exercise 10.1.
» You have just designed a tennis-ball serving machine. You take it out to the court, turn it
» Does your machine have an accuracy or a variation problem?
» Itemize some of the potential causes of each type of error. Consider the types of
» A new, spring-powered can opener
» A diving board for your new swimming pool
» An art nouveau shelf bracket
» From what material is the component to be machined?
» The overall dimensions are 9.46 cm 3.72 in. by 4.52 cm 77 in. in the
» The wall thickness is 3.2 mm 0.125 in..
» The number of components to be manufactured is 1 million.
» The labor hourly rate is 35.
» Find the Theoretical Minimum Number of Components. Examine each
» hr R Mechanical engineering design process
» For the product developed in response to the design problem begun in Exercise 4.1,
» For the redesign problem begun in Exercise 4.2, estimate the changes in selling price
» Estimate the manufacturing cost for a plastic injection-molded component:
» Compare the costs for manufacturing volumes of 100, 1000, 10,000, and 100,000.
» Compare the cost for a change in tolerance.
» Why does changing the material have virtually no effect on cost at low plastic
» Perform a design-for-assembly evaluation for one of these devices. Based on the results
» A simple toy fewer than 10 parts
» Read as many similar instruction manuals as you can. Many companies post
» Organize instructions into sections to make it easy to find answers. Do not
» Recruit members of the user community not familiar with the product to test
» Know your goals and your vendor’s goals. Building a strong vendor relation-
» Involve vendors early. When dealing with vendors, you cannot afford delays
» Establish relationships. It is important to have vendor partners who under-
» Communicate. Put everything in writing—responsibilities, expected sales
» Stay professional. Things go wrong in life. When they go wrong in a relation-
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