Many types of engineering structures exhibit nonlinear behavior under real operating conditions. Sometimes the unpredicted nonlinear behavior of a system results in catastrophic failure. In civil engineering, grandstands at sporting events and concerts may be prone to nonlinear oscillations due to looseness of joints, friction, and crowd movements. In the aerospace industry, nonlinear motions may have serious implications for fatigue life. In the automotive industry, examples include brake sequel and undesirable engine mounting oscillations. Engineers of all types encounter nonlinear behavior...