We're working hard to write our manual, but aren't done with this section yet.
This is a summary of the theory with the relevant references. Just drop us an email at firstname.lastname@example.org if there's anything you're wondering about.
Ashes utilizes the finite element method (FEM) in conjunction with a co-rotational formulation of beam elements to determine the dynamic response of the structure.
In short, the FEM is a mathematical method that we use to solve the differential equations that describe the structural behaviour of an Ashes model. The parameters of these equations are a mass, a stiffness, a damping and a loads matrix, which are built from the structural model.
The co-rotational formulation leads to accurate results in arbitrarily large displacements and rotations in space. For instance, centrifugal forces appear naturally in e.g. the blades. A linear solution of the equations of motion can be used in cases where nonlinear effects are unimportant, while a full Newton-Raphson iterative scheme can be utilized when nonlinear effects are of interest.