Engineering design

Editor's Notes

• #4: If you take a moment to observe your surroundings, you will see examples of technological creativity. The physical objects you see, whether they are telephones, automobiles, bicycles, or electric appliances, all came into being through the creative application of technology. These everyday inventions did not miraculously appear but originated in the minds of human beings and took time to develop. Engineering is the creative process of turning abstract ideas into physical representations (products or systems). What distinguishes engineers from painters, poets, or sculptors is that engineers apply their creative energies to producing products or systems that meet human needs. This creative act is called design.
• #5: Most engineering designs can be classified as inventions-devices or systems that are created by human effort and did not exist before or are improvements over existing devices or systems. Inventions, or designs, do not suddenly appear from nowhere. They are the result of bringing together technologies to meet human needs or to solve problems. Sometimes a design is the result of someone trying to do a task more quickly or efficiently. Design activity occurs over a period of time and requires a step-by-step methodology. We described engineers primarily as problem solvers. What distinguishes design from other types of problem solving is the nature of both the problem and the solution. Design problems are open ended in nature, which means they have more than one correct solution. The result or solution to a design problem is a system that possesses specified properties.
• #6: Design problems are usually more vaguely defined than analysis problems. Suppose that you are asked to determine the maximum height of a snowball given an initial velocity and release height. This is an analysis problem because it has only one answer. If you change the problem statement to read, "Design a device to launch a 1-pound snowball to a height of at least 160 feet," this analysis problem becomes a design problem. The solution to the design problem is a system having specified properties (able to launch a snowball 160 feet), whereas the solution to the analysis problem consisted of the properties of a given system (the height of the snowball). The solution to a design problem is therefore open ended, since there are many possible devices that can launch a snowball to a given height. The original problem had a single solution: the maximum height of the snowball, determined from the specified initial conditions.
• #7: Solving design problems is often an iterative process: As the solution to a design problem evolves, you find yourself continually refining the design. While implementing the solution to a design problem, you may discover that the solution you've developed is unsafe, too expensive, or will not work. You then "go back to the drawing board" and modify the solution until it meets your requirements. For example, the Wright brothers‘ airplane did not fly perfectly the first time. They began a program for building an airplane by first conducting tests with kites and then gliders. Before attempting powered flight, they solved the essential problems of controlling a plane's motion in rising, descending, and turning. They didn't construct a powered plane until after making more than 700 successful glider flights. Design activity is therefore cyclic or iterative in nature, whereas analysis problem solving is primarily sequential. The solution to a design problem does not suddenly appear in a vacuum. A good solution requires a methodology or process. There are probably as many processes of design as there are engineers. Therefore, this lesson does not present a rigid "cookbook" approach to design but presents a general application of the five-step problem-solving methodology associated with the design process. The process described here is general, and you can adapt it to the particular problem you are trying to solve.
• #10: 1. DEFINE THE PROBLEMYou need to begin the solution to a design problem with a clear, unambiguous definition of the problem. Unlike an analysis problem, a design problem often begins as a vague, abstract idea in the mind of the designer. Creating a clear definition of a design problem is more difficult than, defining an analysis problem. The definition of a design problem may evolve through a series of steps or processes as you develop a more complete understanding of the problem.Identify and Establish the NeedEngineering design activity always occurs in response to a human need. Before you can develop a problem definition statement for a design problem, you need to recognize the need for a new product, system, or machine. Thomas Newcomen saw the need for a machine to pump the water from the bottom of coal mines in England. Recognizing this human need provided him the stimulus for designing the first steam engine in 1712. Before engineers can clearly define a design problem, they must see and understand this need. Although engineers are generally involved in defining the problem, they may not be the ones who initially recognize the need. In private industry, market forces generally establish the need for a new design. A company's survival depends on producing a product that people will buy and can be manufactured and sold at a profit. Ultimately, consumers establish a need, because they will purchase and use a product that they perceive as meeting a need for comfort, health, recreation, transportation, shelter, and so on. Likewise, the citizens of a government decide whether they need safe drinking water, roads and highways, libraries, schools, fire protection, and so on. Develop a Problem StatementThe first step in the problem-solving process, therefore, is to formulate the problem in clear and unambiguous terms. Defining the problem is not the same as recognizing a need. The problem definition statement results from first identifying a need.  Consider for example the statement "Design a better mousetrap." This statement is not an adequate problem definition for an engineering design problem. It expresses a vague dissatisfaction with existing mousetraps and therefore establishes a need. An engineer would take this statement of need and conduct further research to identify what was lacking in existing mousetrap designs. After further investigation the engineer may discover that existing mousetraps are inadequate because they don't provide protection from the deadly Hantavirus carried by mice. Therefore, a better mousetrap may be one that is sanitary and does not expose human beings to the Hantavirus. From this need, the problem definition is modified to read, "Design a mousetrap that allows for the sanitary disposal of the trapped mouse, minimizing human exposure to the Hantavirus." The problem statement should specifically address the real need yet be broad enough not to preclude certain solutions. A broad definition of the problem allows you to look at a wide range of alternative solutions before you focus on a specific solution. The temptation at this point in the design process is to develop a preconceived mental "picture" of the problem solution. For example, you could define the better mousetrap problem as "Design a mousetrap that sprays the trapped mouse with disinfectant." This statement is clear and specific, but it is also too narrow. It excludes many potentially innovative solutions. If you focus on a specific picture or idea for solving the problem at this stage of the design process, you may never discover the truly innovative solutions to the problem. A problem statement should be concise and flexible enough to allow for creative solutions.Here is one possible problem definition statement for our better mousetrap problem: A Better Mousetrap: Certain rodents such as the common mouse are carriers and transmitters of an often fatal virus, the Hantavirus. Conventional mousetraps expose people to this virus as they handle the trap and dispose of the mouse. Design a mousetrap that allows a person to trap and dispose of a mouse without being exposed to any bacterial or viral agents being carried on the mouse. Establish Criteria for SuccessCriteria for success are the specifications a design solution must meet or the attributes it must possess to be considered successful. You should include criteria in the problem statement to provide direction toward the solution. At this point in the design process, the criteria are preliminary. As the design solution develops, you will most likely find that the initial criteria need to be redefined or modified. Preliminary criteria must not be too specific so they allow flexibility through the design process. The following is a list of preliminary criteria for a better mousetrap design. This list would be included in the problem definition statement.· The design must be low cost.· The design should be safe, particularly with small children.· The design should not be detrimental to the environment.· The design should be aesthetically pleasing.· The design should be simple to operate, with minimum human effort.· The design must be disposable (you don't reuse the trap).· The design should not cause undue pain and suffering for the mouse.
• #11: 3. GENERATE MULTIPLE SOLUTIONSThe next step in the design process begins with creativity in generating new ideas that may solve the problem. Creativity is much more than just a systematic application of rules and theory to solve a technical problem. You start with existing solutions to the problem and then tear them apart-find out what's wrong with those solutions and focus on how to improve their weaknesses. Consciously combine new ideas, tools, and methods to produce a totally unique solution to the problem. This process is called synthesis. Casey Golden, age 13, did this when he invented the BIOtee. Casey noticed that discarded and broken wooden golf tees littered golf courses, damaging the blades and tires of lawn mowers. He decided to design a new biodegradable tee.  After experimenting with different mixtures, he devised a recipe made of recycled paper fiber and food byproducts coated with a water-soluble film. When the film is broken, moisture in the ground breaks down the tee within 24 hours. As a result of his creative efforts, Casey's family started a company to manufacture BIOtees producing several million tees per year. Psychological research has found no correlation between intelligence and creativity.People are creative because they make a conscious effort to think and act creatively.Everybody has the potential to be creative. Creativity begins with a decision to take risks.Listed below are a few characteristics of creative people. These are not rigid rules to be followed to experience creativity. You can improve your creative ability by choosing to develop these characteristics in yourself. Curiosity and tolerance of the unknown. Creative people have a positive curiosity of the unknown. They are not afraid of what they don't understand.Openness to new experiences. Creative people have a healthy and positive attitude toward new experiences.Willingness to take risks. Creative people are not afraid to take risks and try new experiences or ideas, knowing that they may be misunderstood and criticized by others. They are self-confident and not afraid to fail.Ability to observe details and see the "whole picture." Creative people notice and observe details relating to the problem, but they also can step back and see the bigger picture.No fear of problems. Creative people are not afraid to tackle complex problems, and they even search for problems to solve. They seek solutions to problems with their own abilities and experience if possible. They have the attitude of "if you want something done, you'd better do it yourself."Ability to concentrate and focus on the problem until it's solved. Creative people can set goals and stick to them until they're reached. They focus on a problem and do not give up until the problem is solved. They have persistence and tenacity. Solutions to engineering design problems do not magically appear. Ideas are generated when people are free to take risks and make mistakes. Brainstorming at this stage is often a team effort in which people from different disciplines are involved in generating multiple solutions to the problem.