Sizing optimization of piezoelectric smart structures with meta-modeling techniques for dynamic applications

This article shows an efficient method with a high industrial applicability to design piezoelectric smart structures for dynamic applications. This method allows sizing structures with requirements of dynamic displacements. The first step of this method consists in extracting dynamic reduced models from Finite Element simulations which will enable us to obtain a model for any structure, whatever its complexity, as opposed to analytical modeling methods. These models are computed for a set of design parameters. Then a meta-model, which is a simplified descriptive model of other models, is computed as a surface response model that expresses the design objectives and constraints as a function of the design variables. The combination of the results stemming from the meta-model allows working out the optimal values of the design parameters. The main advantage of the proposed method is to enable the quick design exploration of structures. As an example, the method is applied to a flexible structure whose dynamic displacements need to be controlled in bending and twisting. The theoretical results are validated in the end by experiments

Comparison of extensional and flexural modes for the design of piezoelectric ice protection systems

Many researches focus on piezoelectric ice protection systems with the objectives to develop light and low consumption electromechanical systems for de-icing. These systems use vibrations, generated by the excitation of flexural, extensional or coupled resonance modes, to produce tensile stresses in the ice or shear stresses at the interface ice/support in order to remove ice. The objectives of this work are to analyse flexural and extensional resonance modes according to important design drivers for this type of systems: resonance frequency range, generation of tensile and shear stresses, electromechanical coupling factor, damping and fracture propagation. A final comparison gives pro and cons of each mode type for each design drivers for helping the designer of piezoelectric ice protection systems

Ultrasonic ice protection systems

Protection systems against ice on leading edge conventionally use thermal and pneumatic solutions. In case of thermal solutions with piccolo tubes (the most usual technology), the hot air is extracted from engine, which decrease its efficiency. The trend is to move to all electric deicing systems. Electro-thermal solutions have been implemented but at the cost of a high energy consumption. This work focuses on low-consumption electromechanical deicing solutions based on piezoelectric transducers. After a review of deicing systems, the main features of electromechanical de-icing devices are identified and piezoelectric ceramic-based deicing systems are studied. Numerical simulations allow computing the configurations that lead to low-consumption, compact ultrasonic deicing devices. First tests of piezoelectric de-icing systems are performed on simple cases such as plates. These tests are promising and allow analyzing the key design drivers (the frequency range to use, the impact of the ice thickness on the system performance) for the design of such systems. First results on the voltage and the consumed current of such devices are also given

Evaluation Of Anti-Icing Polymer Coatings

Ice accumulation on aircraft, wind turbines and power lines can have detrimental effects, including efficiency reduction, mechanical failures and the creation of safety hazards. The aim of this study is to investigate the ice adhesion and wear resistance of three hydrophobic and icephobic coatings applied onto an aluminum substrate. Ethylene-tetrafluoroethylene (ETFE) coating was deposited using a plasma spray method while advanced liquid glass (ALG) and silicone R-2180 were both applied using dipping followed by furnace curing. Water was applied and frozen between both bare and coated surfaces using a custom built jig at -20 °C for 24 hours. The ice adhesion strength was measured using a lap shear test done inside an insulated chamber. The results showed low ice adhesion strengths for both ALG and silicone R-2180 coatings when compared to the bare surface. It was also found the silicone R-2180 coating had a higher wear rate than both the ETFE and ALG coatings. By combining icephobic coatings with an ultrasonic de-icing system, the power required by the system can be reduced, creating a low-powered active approach to the de-icing problem

Electromechanical Resonant Ice Protection Systems: Numerical Investigation through a Phase-Field mixed Adhesive / Brittle Fracture Model

Electromechanical resonant de-icing systems provide a low-energy solution against ice accumulation on aircraft. Recent researches show a growing interest towards these systems in the context of more electrical aircraft. Electromechanical de-icing systems consists in electric actuators producing stress within the ice, through micro-vibrations of the surface to be protected, leading to bulk or adhesive failure and, ultimately, ice shedding. The understanding of the mechanisms at play is of prime importance in order to design efficient ice protection systems. Despite a large number of studies in the iterature, there is still a lack when dealing with fracture propagation phenomena in this context. In this work the authors propose a model based on the well established phase-field variational approach to fracture. The approach is applied to the study of crack propagation and debonding of ice under the effect of an electromechanical resonant de-icing system. Numerical experiments are performed in order to assess possible ice shedding mechanisms

Electro-mechanical Resonant Ice Protection Systems: Energetic and Power Considerations

This article focuses on resonant ice protection systems and proposes key performance indicators to analyze the performances of such systems with respect to levels of energy, force, and power required for de-icing. The principle of these systems is to apply vibrations or ultrasonic waves onto the structure that create high-level stresses greater than those required to crack and delaminate to remove the ice accumulated on the structure. The computation of the indicators requires two values: the ice adhesion strength and the critical strain energy release rate. Computations are performed assuming three stages of a de-icing mechanism: firstly an initiation of cohesive fractures by tensile stress at the top surface of the ice layer, secondly, a propagation of cohesive fractures within the ice and thirdly a propagation of adhesive fractures at the ice/substrate interface starting from the base of the cohesive fractures previously created. The proposed key performance indicators provide guidance on the use of flexural and extensional modes in resonant ice protection systems and on the frequency range to favor when looking at fractures initiation and propagation. Calculations based on the key performance indicators show a potential power reduction by ten with resonant electro-mechanical de-icing systems compared to electro-thermal systems

Load allocation problem for optimal design of aircraft electrical power system

More and more electric systems are embedded in today aircraft. As a result, the complexity of electrical power system design is increasing and the need of generic and efficient design methods is today required. Among numerous design tasks, the allocation of electric systems on the busbars of the electrical power system is considered as an important one since it has a direct impact on the aircraft mass. But due to the high number of possible allocations and regarding the large diversity of potential sizing cases for the equipments, finding the optimal allocation of electric loads is a hard task. In this paper, the problem is formalized mathematically. Then, four stochastic optimization methods are assessed on complex load allocation problems. Based on this assessment, a genetic algorithm using niching method is considered as the most appropriate algorithm for solving this aircraft design proble

Analysis of Piezoelectric Ice Protection Systems Combined with Ice-Phobic Coatings

The aeronautics industry is looking for ice protection systems consuming less energy. Electromechanical and especially piezoelectric solutions are a promising area of research for reducing average consumptions. This article provides an analytical model of a simple structure to assess the power and voltage required to obtain the delamination of the accumulated layer of ice at the support/ice interface. This model also allows analyzing the impact of the resonance frequencies used for supplying piezoelectric actuators on the tensile stress into PZT materials. Finally, this article assesses the effect of different ice - phobic coatings combined with piezoelectric ice protection systems. Experimental measurements of ice adhesion for different ice - phobic coatings allow evaluating the shear stress at which ice is detached from the surface. These results are then used to estimate - thanks to the proposed analytical model - the additional gain of power that would be provided by the use of such coatings

Improving mechanical ice protection systems with topology optimization

In the context of more electrical aircraft, electromechanical de-icing systems provide a low-energy solution to protect aircraft surfaces from ice buildup. Such systems produce deformation of the protected surface leading to stress production within the ice and, ultimately, to ice shedding thanks to fracture. However, these systems may show limitations when it comes to completely protecting a given surface. Ice delamination is often restricted to a part of the surface and the remaining ice either requires more energy to be removed or is just impossible to remove. In this paper, topology optimization of the substrate covered by ice is thus investigated to increase fracture propagation and ice shedding. For that purpose, an optimization problem, involving the energy release rate but also the mass and the substrate stress, is formulated. The numerical results show how the delamination efficiency of mechanical-based ice protection systems can be improved through the topology modification of the substrate

Electro-mechanical Resonant Ice Protection Systems: Initiation of Fractures with Piezoelectric Actuators

Recent research is showing growing interest in low-power electromechanical de-icing systems and, in particular, de-icing systems based on piezoelectric actuators. These systems use the vibrations generated by piezoelectric actuators at resonance frequencies to produce shear stress at the interface between the ice and the support or to produce tensile stress in the ice. Many configurations of de-icing systems using piezoelectric actuators have been tested and showed that piezoelectric actuation may be a viable ice removal system. If the many experimental studies already achieved have the advantage to present tests in different configurations, they often lack analysis of the phenomena, which limits the optimization opportunities. This paper proposes a computational method for estimating voltages and currents of a piezoelectric de-icing system to initiate cohesive fractures in the ice or adhesive fractures at the ice/support interface. The computational method is validated by comparing numerical results with experimental results. Other contributions of this paper are the study of the types of mode (extensional or flexural) and of the frequency range with respect to de-icing performances and the proposal of some general rules for designing such systems while limiting their electric power consumption