MBDyn is the first and possibly the only free* general purpose Multibody Dynamics analysis software, released under GNU's GPL 2.1 (get a cached copy here).
It has been developed at the Dipartimento di Scienze e Tecnologie Aerospaziali (formerly Dipartimento di Ingegneria Aerospaziale) of the University "Politecnico di Milano", Italy.
MBDyn features the integrated multidisciplinary simulation of multibody, multiphysics systems, including nonlinear mechanics of rigid and flexible bodies (geometrically exact & composite-ready beam and shell finite elements, component mode synthesis elements, lumped elements) subjected to kinematic constraints, along with smart materials, electric networks, active control, hydraulic networks, and essential fixed-wing and rotorcraft aerodynamics.
What is a multibody system? Find out on Wikipedia (but come back, please!)
MBDyn simulates the behavior of heterogeneous mechanical, aeroservoelastic systems based on first principles equations.
MBDyn can be easily coupled to external solvers for co-simulation of multiphysics problems, e.g. Computational Fluid Dynamics (CFD), terradynamics, block-diagram solvers like Scicos, Scicoslab and Simulink, using a simple C, C++ or Python peer-side API.
MBDyn is being actively developed and used in the aerospace (aircraft, helicopters, tiltrotors, spacecraft), wind energy (wind turbines), automotive (cars, trucks) and mechatronic fields (industrial robots, parallel robots, micro aerial vehicles (MAV)) for the analysis and simulation of the dynamics of complex systems.
The extension of available analysis domains to new models and the introduction of new analysis domains is planned, and problem-driven: if you need to solve a specific problem, let us know.
Run-time loading of user-defined modules is leveraged to let users extend the feature library (elements, drives, constitutive laws, and more).
On GNU/Linux, real-time execution is supported under RTAI, the Real-Time Application Interface, and POSIX tight scheduling.
MBDyn participated in Google's Summer of Code in 2015, 2016, and 2017; we are eager to participate in future editions.
Are you using MBDyn for a research or an industrial project? Would you like to share your experience with other users? Send us a link to a webpage describing your work, and a brief description to be listed in the research page.
* Free means freedom (quoting GNU's philosophy, think of free speech rather than free beer).