Methods and tools for multidisciplinary multi-field modeling, with applications

Research focus

The Peer review has evaluated this group as Excellent

The research activity in this area focuses on the development of robust, consistent and efficient methods for the analysis of the dynamics of complex systems, based on the multibody formalism in a broad sense, which includes nonlinear finite elements for the modeling of the geometrical nonlinearities related to the finite motion of mechanical systems, as well as the interaction with different fields. A distinguishing aspect is represented by the interaction with fluid mechanics for fixed and rotary wing vehicles, which constitutes both a theoretical and computational challenge. The resulting methods, and the related software implementations, are applied to a wide variety of problems, characterized by intrinsic complexity and multidisciplinarity, ranging from helicopter and tilt-rotor dynamics to space manipulators and robots. Integration of DAEs & Index Reduction. Great attention, as testified by a large number of scientific publications, has been dedicated to the problem of accurately solving large differential-algebraic systems of equations (DAE) by Energy Preserving (EP) and Energy Dissipating (ED) algorithms. Significant achievements include the capability to improve the conditioning of the problem and to reduce the index of the DAE system, by splitting the solution procedure in an algebraic sub-problem that corrects the result obtained by integrating the purely differential (ODE) part, in order to account for the algebraic constraints. Finite Rotations. Specific work has also been dedicated to the handling of finite rotations, which represents one of the key issues in the kinematics and dynamics of mechanical systems. Similar topics are discussed, from a continuum mechanics point of view, in research related to Topic 2.2.4.1. Trajectory Optimization. A significant problem in multibody dynamics has been solved by introducing the capability to control the overall dynamics of large and detailed multibody models of maneuvering vehicles, by means of staggered modeling that allows to solve the inverse dynamics problem on a reduced order model, to predict the controls that need to be applied to the detailed model in order to follow a prescribed trajectory or to maximize a given performance index. A key innovation consists in using the resulting motion of the detailed model to update the reduced order model used for the inverse dynamics. Software Development. Significant attention has been continuously dedicated to casting theoretical achievements into robust, reliable and versatile software. The main reason is the need to be able to experiment with new implementations in all aspects of multibody and multi-field analysis, without undue technical or licensing restrictions dictated by commercial software. It is worth mentioning the public release of portions of the code in form of the free software MBDyn, which is now in use by universities, industries and research centers worldwide, in the CAELinux and FreeBSD software distributions, and led to specific grants from industries and public agencies. In parallel to this effort, a similar research activity on the development of finite-element-based multibody software has been led in strict collaboration with the Georgia Institute of Technology, which has resulted in numerous publications and also in the exchange of Ph.D. students. Real-Time Simulation. A relevant achievement is the introduction of the capability to execute generalpurpose multibody software in real-time, exploiting the free Real-Time Application Interface discussed in Topic 2.2.2.2. Running simulations in real-time represents a significant advantage when developing expensive or potentially dangerous experiments, since it allows to replace the experiment with a numerical simulation within the hardware data acquisition and control system. Rotorcraft Dynamics. A distinguishing application of the outlined development is rotorcraft dynamics in a broad sense, ranging from helicopters and tilt-rotors to wind-turbines. Applications of the aforementioned multibody software implementations addressed aeroelastic problems of helicopter rotors, coupled to the hydraulic control system, of tiltrotor aeroelasticity and aeromechanics, and of wind turbine aeroelasticity and active control, often in cooperation with international industries and research centers: AgustaWestland, Consortia of EU sponsored projects, NASA LaRC, ARL, US Army Research Office, Georgia Institute of Technology. System Identification. Attention has been dedicated to the problem of extracting system dynamics information from the time-series obtained by multibody analysis. Specifically, studies have been conducted on the use of the Proper Orthogonal Decomposition (POD) method and on neural-network-based approaches based on the use of the non-linear Kalman-type filtering techniques for the identification of the free parameters.

Dipartimento di afferenza

Dipartimento di Ingegneria Aerospaziale

Docenti afferenti

Marco Borri (Full Professor)
Gian Luca Ghiringhelli (Full Professor)
Massimilano Lanz (Full Professor)
Paolo Mantegazza (Full Professor)
Carlo Luigi Bottasso (Associate Professor)
Giampiero Bindolino (Assistant Professor)
Pierangelo Masarati (Assistant Professor)
Lorenzo Trainelli (Assistant Professor)