DOF3FreeP is a set of Matlab codes to perform preform bifurcation analysis on a typical aeroelastic section with freeplay in the pitch or control degree of freedom. Some of the codes in this distribution are heavily modified versions of codes released with [1].
The bifurcation analysis is carried out using three methods: Equivalent Linearization, Harmonic Balance, and Shooting. All three approaches are combined with a numerical continuation procedure and stability analysis, so that folds, branch points and other secondary bifurcations of limit cycle branches are detected. Two-parameter continuation can be used, in terms of either the airspeed or the preload angle.
DOF3FreeP is demonstrated on three experimental test cases from the literature:
- Conner et al 1997 [2]
- Tang and Dowell 2010 [3]
- Verstraelen et al 2017 [4]
You can download the latest version of the software here.

- Introduction to Nonlinear Aeroelasticity
- Nonlinear behaviour of a typical airfoil section with control surface freeplay: a numerical and experimental study
- Aeroelastic Airfoil with Free Play at Angle of Attack with Gust Excitation
- Two-domain and three-domain limit cycles in a typical aeroelastic system with freeplay in pitch
