Technically, this example demonstrates how to utilize a function as input argument to a function in a model.
From a modeling point of view, the example demonstrates in very simplified way the basic approach to model distributed systems with the Ritz method.
The displacement field u(c,t) of a particle (where c is the undeformed position and t is time) is hereby approximated by space-dependent mode shapes Φ(c) and time-dependent modal amplitudes q(t), that is u = Φ(c)*q(t). When inserting this decomposition in the equations of motion and then integrating over all particles, terms such as ∫(Φ(c) dc)*q(t) appear, where the time-invariant integral term can be computed beforehand once with the Lobatto method. By this approach the partial differential equations are transformed to a system of ordinary differential equations.