Engineering for Industrial Designers and Inventors

Chapter 3. Material Mechanics

Designers worry their designs will break. We must have a deep, intuitive sense for the behavior of materials so that among the flourishing ideation, we don’t end up with designs that can never work in the real world. Therefore, we need to understand the behavior of solid objects when a load is applied so we know whether it will break or bend to the point where it can’t do its job. Designers also need to understand how shape affects the rigidity of an object, how much it will bend or twist when it is being used. While the theory of material mechanics must not intrude on the creative process, it must hold a place in refining ideas so products are not designed to break. While Louis Sullivan’s aphorism that “form should follow function” is not always true, there exists design chauvinism when designs flaunt the laws of nature. Flaunting of nature can be appealing, sometimes suggesting motion and instability. It can have artistic merit. The goal of this section is to understand material behavior so we have a sense for how our designs will work in real-world applications. Like the fine arts, the designer should sit in the driver’s seat and not just hope an engineer will rescue your design from failure.

We want to understand how a solid object responds to being used. We will look at the relationship between stress and an object’s shape as well as sneaky things such as fatigue fractures, buckling, and thermal expansion. These insights will allow you to synthesize ...