Transducers NDT & SHM
Categories
Sounds and ultrasounds transducers
3 January 2001
The Active Materials Applications in the fiel of Motors and Actuators systems are in full expansion at CEDRAT RECHERCHE ans their very general characteristics (which have led to the piezo products) have justified the regular presentations in the flux magazine up to present.
Structural damage identification
19 June 2023
This paper presents two approaches for structural damage identification, each based on a different philosophy. The Virtual Distortion Method is a model-updating method of damage assessment, utilizing gradient-based optimization techniques to solve the resulting inverse dynamic problem in the time domain. Case-Based Reasoning is a soft-computing method utilizing wavelet transformation for signal processing and neural networks for training a base of damage cases to use for retrieving a similar relevant case.
Study of a dome shaped PVDF loudspeaker
2 March 2020
PVDF loudspeakers are used for some applications in audio and could be used for applications in active control where light structures are needed, for example in aeronautics. For all these applications, it is necessary to be able to predict the acoustic response of such systems in order to help the designer. Some papers propose models for calculating the acoustic pressure radiated by these loudspeakers.
Giant dynamic strains in magnetostrictive actuators and transducers
19 June 2023
Magnetostriction occurs in the most ferromagnetic materials and leads to many effects [1,2]. The most useful one to refer to is the Joule effect. It is responsible for the expansion (positive magnetostriction) or the contraction (negative) of a rod subjected to a longitudinal static magnetic field. In a given material, this magnetostrain is quadratic and occurs always in the same direction whatever is the field direction. Giant Magnetostrictive Materials (GMM), especially Rare earth-iron discovered by A.E.Clark [3], feature magnetostrains which are two orders of magnitude larger than Nickel. Among them, bulk Tb0.3Dy0.7Fe1.9, called Terfenol-D, presents the best compromise between a large magnetostrain and a low magnetic field, at room temperature.
Tubular ultrasonic transducer: MUST with axial excitation versus conventional with radial excitation
19 June 2023
This paper presents comparison between two excitation solutions for tubular ultrasonic transducer. The axial excitation is widespread in conventional ultrasonic transducer. The radial excitation is proposed in order to have an uniform acoustic energy all along the tube. This excitation approach is also proposed to allow the modularity by adding several tubes.
Improving Lamb Wave detection for SHM using a dedicated LWDS electronics
19 June 2023
In the context of Condition Based Maintenance (CBM) for aircrafts, Structural Health Monitoring (SHM) is one main field of
research. Detection and localization of damages in a structure request reliability of the equipment and repeatability of the measurements and process. An electronic device called Lamb Wave Detection System (LWDS) have been developed and manufactured to manage piezo-electric patches either in emission or reception mode with a high commutation rate. Besides, integration of the piezo patches is another crucial aspect of reliability. Several methods as modelling and dispersion curves can define the frequency range of Lamb waves to optimize the piezo-electric coupling.
This work which takes part of the H2020 ReMAP project about adaptative aircraft maintenance planning, is presented in the article.