Overview
PIBRAC complied with the strategic objective 'Open Upstream Research for strengthening the competitiveness of the aeronautical industry in the global market', responding to the challenge of delivering more economical, higher performing and better quality products and services. It addressed the strategic objective 'of reducing the operating costs by 20% and 50% in the short and long term' through reduction in weight, peak energy demand for braking at landing and of maintenance costs of brakes. PIBRAC developed two approaches, with a medium-term perspective for rotational actuator design and a long-term one for linear design.
Emerging high-power, piezoelectric vibration motor technology, thanks to its high torque/force - low-speed characteristic, high-power density and very low inertia, could lead to overcoming the drawbacks (peak power demand, mass) of EMA fitted with electromagnetic motors.
The aim of PIBRAC was to run specific research, on the basis of existing research results on high-power piezoelectric motors, and to carry-out specific research and validation that will allow the use of this promising technology in aircraft brake actuators. The general PIBRAC objective was to demonstrate the feasibility of a piezoelectric brake actuator, including power electronics and the control system. Two different actuator configurations were considered: for the rotational configuration, two prototypes were built and tested, while work for the linear configuration was limited to paper study and modelling. A final technical and economic evaluation of these piezoelectric brake actuators will be provided.
PIBRAC work helped to overcome the critical issues of a new technology and demonstrated the ability of this emerging, high-power, piezoelectric motor technology to be applied to brake actuation. The expectation is to demonstrate, when compared to an EMA, a great improvement as regards compactness and power delivered: a weight, including the power electronics, reduced by a factor of two and a peak energy power demand reduced by at least a factor of three and hopefully five.
The PIBRAC's objective was to study, design and test an innovative type of piezoelectric brake actuator and its control electronics. PIBRAC was a three-year project divided into five Work Packages that include specifications and assessment criteria, research on different functions, technology integration, technology evaluation and results dissemination. They will address both configurations of actuators, which will be studied in parallel, with a final assessment presenting conclusions on each technology and on the comparison of both. The reason for this approach is that partners are convinced that there is a high chance of success for the rotational actuator, while the linear actuator may require complementary work with higher risk because nothing exists in this domain at the required power level.
The main topics to be addressed are:
- architecture of brake actuator with piezoelectric motor
- wear of the friction surfaces of piezoelectric elements inside the motor
- elimination of mechanical jamming of internal parts in case of motor failure
- electrical power management
- high-frequency control of piezoelectric motor
- test of validation models.
The PIBRAC consortium gathers all the skills needed from research establishments to components manufacturers and an aircraft manufacturer. It is led by SAGEM, a worldwide equipment company. It includes Airbus, the world's leading aircraft manufacturer, Messier Bugatti, a worldwide aeronautic equipment provider, BAM, a renowned material research centre, NOLIAC, a competitive piezoelectric component manufacturer (SME), two specialised SMEs in modelling, electronics and testing, and two technical universities specialised in control electronics and R&D result dissemination. The necessary critical mass of competencies is reached within this relatively compact grouping of skilled partners. This is rather unique, considering the number of new technologies and testing facilities required.
Funding
Results
Two different configurations of piezoelectric motor structures were considered, namely rotational and linear. For the former configuration, two prototypes were built and tested while work for the linear one was limited to paper study.
PIBRAC yielded better performances than EMAs, which former actuators had a specific piezoelectric motor design with an f+2f normal mode electric excitation. Considering the amount of work to demonstrate the feasibility of the 2f mode implementation, as well as the limited project budget, it was decided to design and manufacture a simpler actuator equipped with an 1f design motor.