| To predict dynamic behavior of 'built-up' structures, the nonlinear damping and stiffness effects of joints need to be understood. The primary objective of this work is to explore the dynamic behavior of fixed joints under different load conditions toward matching experimental results with those of simulations based on a recently developed model. The energy dissipation per cycle and equivalent stiffness are two main quantities of interest. Simulations are run to discover the effects of friction coefficient, pre-load, normal load, tangential load and phase between normal and tangential loads. An experimental setup is built to study the behavior of a cup-lid joint under multi-dimensional time varying loading. The tangential displacement and force are directly measured, from which hysteric loops are derived. The loop area equals the energy dissipation per cycle, and the loop diagonal line slope is the equivalent stiffness. The model is calibrated by a test without normal time varying load. The model is validated with a test that exhibits time varying normal load at 90 degrees phase. Test results are reported on various load conditions. Inertial and non-uniform distributed normal load are introduced to the model for a simulation study of their effects. |
