TABLE OF CONTENTS Many problems in the mechanics of solids can be solved in a very efficient way through the use of certain theorems involving the concept of energy. In some cases, use of these theorems leads to an exact solution requiring much less effort on the part of the analyst than the Newtonian methods, which involve the use of Newton's first and second laws, learned thus far. In those cases where an exact solution is not feasible, these energy theorems may be used to develop approximate methods that are extremely powerful. It is these approximate methods that enable engineers to solve the complex problems typically encountered in designing the many technological devices used by our society.
In this chapter we develop the first and second laws of thermodynamics for continuous media and then specialize these for problems in the mechanics of solids. Once the laws of thermodynamics are developed, we introduce the concept of strain energy and then proceed to develop several energy theorems useful for solving problems in solid mechanics.
In the nomenclature of thermodynamics a system is a particular collection of matter being studies. It may consist of a part of a material body, an entire body, or perhaps several bodies. We envision a system as being separated from all remaining matter by a clearly defined system boundary. All matter not contained in the system constitutes the surroundings. The influence of the surroundings on the system is accounted for by allowing...
