3. Parameter Identification of a Linear Substitution Model for Nonlinear Contact and Damping Inside Lap Joints Using Distributed Optimization

The numerical simulation of flexible system dynamics considering nonlinear contact and friction forces inside joints is a very time-consuming process. In this work, a simple linear substitution model for the joint contact is proposed and the parameters are identified. Subsequently, it is numerically examined whether this model is predictive and transferable. The identified parameters are the tangential stiffness, normal stiffness, tangential damping and the contact area. All parameters are assumed to be a function of the bolt preload. The reference is a high fidelity Finite Element (FE) model of two strips of metal bolted together with three bolts. The solution of the reference model is calculated with distributed, nonlinear contact and friction forces. During the optimization, the Fourier coefficient of the first mode was fitted. To speed up the large number of time integrations a distributed optimization method is investigated. This decentralized method accelerates the optimization process almost by the factor of the used computers. The determined parameters are used in a modified setting and compared with a corresponding reference solution. The aim is to use the obtained substitute model for predictive and tendential investigations of jointed structures.