MESEMA, a technology oriented research project, built upon the success of previous EU projects with devotion to accomplish the objectives of the aeronautics priority through designing, producing and testing 'innovative transducer systems based on active materials'. Four fixed and rotary-wing aircraft companies accompanied by SMEs and university research institutes participated in - and benefited from - the developments of primarily magneto-elastic transducers for high-torque actuation, vibration and noise reduction, electrical energy generation and structural health monitoring. Structural dynamics, energy conversion in active materials and control systems represented the scientific fundamentals of the project.
The scientific and technological objectives were the results of an evolution of the activities developed during the previous six years by the group which had promoted the two successful European research projects named 'M.A.D.A.Vi.C.' and 'M.E.S.A.'
The MESEMA objectives consisted mainly of the design and development of five systems, integrating vibration transducers, based on active components aimed at:
- reducing the level of disturbance noise in turbofan aircraft;
- reducing the level of disturbance noise in helicopters;
- examining the health status of aircraft structural components;
- replacing the helicopter rotor blade pitch angle actuation systems;
- transforming mechanical energy related to vibration fields within aircraft into electric one (VIBEL).
The five objectives had a common aspect in that they all required the design and development of a dedicated actuation system (including control algorithms and driving electronics) providing dynamic displacement and force fields on a host structure.
The first twelve months of the MESEMA project (01.01.2004 - 31.12.2004) were mainly characterised by the discussion and definition of requirements as well as the elaboration of specifications in different work packages.
The second twelve months of the MESEMA project (01.01.2005 - 31.12.2005) were mainly characterised by the design and development of first actuator prototypes and assessment of their integration on the technology demonstrator.
The last eighteen months of the MESEMA project (01.01.2006 - 30.06.2007) were mainly characterised by the production and experimental testing of all the devices designed during the first two project years in order to accomplish the requirements of the five selected applications.
The work was structured into work packages (WPs) and yielded findings as follows:
- WP1 has advanced knowledge of magneto-elastic materials, produced samples for consortium, developed sensors and control modules as well as reviewed parallel research activities found in the literature.
- Within WP2.1 (Active noise control for turbofan aircrafts) innovative results were achieved both in terms of devices and concepts:
- magnetostrictive auxiliary mass damper with Bragg sensor;
- light hybrid amplifier;
- identification procedure for dynamic model of flexible structures;
- optimisation procedure for actuator location;
- control algorithm for noise and vibration control.
The experiments clearly showed that the proposed noise control system can actually reduce the overall levels of a broadband noise inside the cabin (-4 dB(A) achieved on the overall sound pressure level counteracting the primary disturb field). Also, the vibration levels of the structural elements of the fuselage is significantly reduced on a wide range of frequencies.
- Within WP2.2 (Noise and vibrations control on helicopters) project targets were accomplished by developing a piezo-force generator system which can be considered ready for the industrial implementation. Tuneable vibration absorbing was demonstrated with the magnetostrictive force generator. Active mode of magnetostrictive FG demonstrated experimentally (proof of concept); achieving high forces will demand further experiments / optimisation. Semi-active mode is very interesting since it would permit to reduce vibration levels with very low electric power.
- Within WP3 (Health monitoring) an innovative system for analysing structural damages was developed in Labview / Matlab environment and tested implementing different data analysis algorithm. Furthermore, an innovative optimisation procedure for actuators positioning was studied and numerically implemented. The experiments clearly showed that the proposed HM system can actually identify and localise damages on metallic and composite aeronautical structural components, employing data acquired by many types of vibration sensors.
- Research in WP4 (High torque actuation) lead to a working prototype of a demonstrator actuator which was tested towards the initial requirements. The power output of hydraulic power generators using smart materials (smart pumps involving piezoelectric or magnetoelastic materials) was significan
The whole project represented a step forward in the basic knowledge of magneto-elasticity, as far as in the detailed analysis of the available materials provided by more and more producers. The database of measurement and analysis of materials properties themselves represent an impulse to this research sector permitting the exploration of a new application in order to exploit materials potentialities (one of the partners of the consortium - Feonic - is already a leader in the field of large scale distribution of devices based on magnetoelastic materials). Several devices / innovations developed for accomplishing the requirements in the five applications represent by themselves independent products that could be exploited (an example are the hysteresis compensation modules, the hybrid amplifiers designed for the actuators, the identification algorithms developed for noise active control or the structural health monitoring system). Obviously, the main success of the project can be assessed by the statement of the industrial partners concerning the application they supported; following a list of these statement for the main applications are collected.