# Structural Dynamics and Vibration Lab

## McConnell Engineering Building, Room 122

In Charge: Professor Mathias Legrand

## Scientific orientation

Structural dynamics, vibration of complex systems, reduced-order models, rotordynamics, nonlinear dynamics, friction and contact problems, structural design and shape optimization

## Mission

The laboratory is concerned with theoretical knowledge as well as the development of new tools and methods capable of bringing solutions to practical problems in the industrial sphere. Related research and education are focused on Vibrations, Acoustics, Structural Dynamics, Nonlinear Dynamics, and Wave Propagation.
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## Projects

1 - Dynamics of mistuned bladed-disk assemblies
The blade-to-blade structural property variations in bladed disk assemblies are practically unavoidable due to random nature of manufacturing process or in service wear and tear. This problem is commonly referred to as mistuning. It has a dramatic effect on the vibration behaviour of a bladed disk system. To mention a few, it could potentially lead to spatial localization of vibration energy around one or a limited number of blades, increase the amplitudes and stresses of blades compared to perfectly tuned system. [read more].

2 - Nonlinear dynamics in aircraft engines

 In rotordynamics, nonlinear coupling forces between the rotating and surrounding stationary parts can result in unexpected significant amplitudes of displacement and subsequent high stresses. More specifically in aircraft engines, several different mechanisms can originate such a rotor-to-stator interaction and are usually classified in three main categories [read more].

3 - Normal modes and modal analysis for nonlinear systems
Many techniques exist for determining the response of nonlinear systems that are subjected to periodic excitation. In addition to brute-force simulations, there are a variety of approximate analytical methods, such as the method of multiple scales, harmonic balance, and averaging. When the system is responding in a periodic manner, it is behaving like a low order system, and the question arises as to whether or not a reduced order model can be found that captures the system response [read more].

4 - Centrifugal pendulum vibration absorbers and their applications to rotating flexible structures
Centrifugal Pendulum Vibration Absorbers (CPVAs) are used to suppress vibrations in rotating machinery. They are widely employed in light aircraft engines, helicopter rotors, some high-performance automotive racing engines, diesel camshafts, and other places where vibrations at a given rotation speed are troublesome. Application of CPVAs to bladed disk systems to enhance structural performance is one of the recent interesting subjects [read more].

5 - Intentional mistuning and shape optimization of multi-stage bladed rotors
The scope of this research activity is twofold. The first topic concerns the modelling of mistuned multi-stage bladed rotors and their dynamical analysis. Of particular interest is the introduction of intentional mistuning for the control of flutter instabilities [read more].