tailieunhanh - Ebook Engineering design process: Part 2

(BQ) Part 2 book "Engineering design process" has contents: Specifications, developing concepts, concepts evaluation, embodiment design, detailed design, selection of design projects. | C H A P T E R • 6 Specifications At the specification stage of the design process, the engineer can continue to provide clarification of the needs statement. This rider needs to stay dry when biking through a wet forest. How can the bike’s splashguard be designed to fill such a need? (Inc/Shutterstock) 152 Objectives 153 OBJECTIVES By the end of this chapter, you should be able to 1. 2. 3. Quantify qualitative objectives. Utilize techniques to organize specifications into categories. Further clarify the need statement. Product Concept Functions Chapter 6 S Chapter 5 Specifications pecifications are important to achieving a successful design. At the specification stage of the design process, you continue to provide additional clarification of the need statement. This is the last step in defining the problem before you begin to suggest possible solutions. So far, the objective tree provided a tool with which to list customer needs and design team objectives into categories. It defines the vague statements that are introduced by the customer. The function structure provided a mechanism with which to activate the objectives. However, the objective tree and the structural functions do not set specific limits on the different functions and objectives. The objective tree or function structures are statements of what a design must achieve or do, but they are not normally set in terms of precise limits, which is what a performance specification does. For example, an objective may be stated to develop a product which has low weight. Yet the term low weight is not clearly defined. Does it mean 20 kg or 100 kg? A specification consists of a metric and a value. For example, “average time to assemble” is a metric, while “less than 75 seconds” is the value of this metric. Note that the value may take on several forms, including a particular number, a range, or an inequality. Values are always labeled with the appropriate units. Together, the metric and .