Engineering Expert Witness Blog

     Imagine a chef without a fry pan, a mixer, or attempting to create a recipe without any idea of how the ingredients will combine.  Is the end result likely to be something you’d want to eat?  Something with just the right visual appeal, aroma, taste, and texture?  Unlikely.  Likewise, what good would a mechanical design be if an engineer had no idea of what kind of materials to use?  The results would be haphazard, and this could lead to problems more serious than lack of palatability.  We’re talking serious consequences here, such as product failure, injury, or death.

     In the mechanical engineering arena, just as in the cooking arena, materials used possess certain properties which render them useful for specific purposes.  Just as a chef has her pantry, an engineer has a wide variety of materials available to her to choose from, and new materials are developed all the time.  The vastness of the materials available to an engineer makes it difficult for all of them and their properties to be committed to memory.  What is possible, however, is to develop a firm understanding of the underlying principles that govern their properties.

     It is this general understanding of materials’ properties that enables engineers to select between materials.  There are key questions to be answered in the search for the ideal materials to do a job.  Which materials would be the most economical?  Which would give optimal performance?  The best durability?

     Materials science provides an understanding of the relationship between the structure of materials at an atomic or molecular level and their macroscopic properties.  In other words, the engineer learns how atoms are arranged and bonded together at a microscopic level, which in turn form the material perceived by the naked eye.  The ultimate arrangement of molecules is based upon how the virgin material was processed into its final form.  By “processed,” I mean the application of heat, cooling, mechanical forces, etc.  Knowing the composition of a material and how it was processed allows engineers to predict how the material will react to things like stress, strain, heat, corrosives, radiation, and electrical currents.

     It’s a big world out there, and it’s filled with materials to explore.  Next week we’ll begin that exploration.

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