Professor Plesha's primary research area is computational mechanics focusing on the development of finite element methods for solving static and dynamic nonlinear problems.He specializes in problems featuring material discontinuities such as sliding surfaces and bimaterial interfaces which occur in fiber-reinforcedcomposite materials. This work involves a variety of exciting, diverse topics and disciplines which are carried out with the cooperation of colleagues throughout the College of Engineering.At the most basic level, the research begins with carefully conducted laboratory studies designed to uncover basic phenomena important in the behavior of a particular material interface system. Then, constitutive models which mathematically characterize the nonlinear and history-dependent behavior of an interface are established. Ongoing with these efforts is the development of effective computer analysis procedures which are applicable to the complex problems that modern technology presents.This work is applied to problems involving mechanical behavior of natural joints in rock, effects of material interface behavior on the high temperature rheology of ceramic composite materials, reliability of soldered lead connections for electronic devices, and effects of crack surface behavior in influencing crack growth in engineering materials.