Session: 08 - 01 NDE for Civil Infrastructure

Paper Number: 118643

118643 - Non Destructive Evaluation of Public Lighting Masts Using Nonlinear Resonant Acoustic Spectroscopy 

Non Destructive Evaluation of public lighting masts using nonlinear resonant acoustic spectroscopy

O. Achouam¹, C. Mechri¹, R. El Guerjouma¹, P. Mignot², C. Cluzeau², P. Philippi³

¹ LAUM, Le Mans Université, CNRS, Le Mans, FRANCE

² REI-LUX France, 43 av Jean Joxé, 49100 Angers, France

³ REI-LUX Germany, Bernhard-Hahn-Straße 30a, 41812 Erkelenz

Structural condition assessment of the light masts are usually conducted using visual inspection, displacement-controlled pushover methods that can damage the structure and or linear vibration measurement methods. Nonlinear behavior has been shown in the last years to be features characterizing the elastic behavior of a wide range of materials especially. This behavior is generally related to inhomogeneities within materials such as grain boundaries, fiber matrix interfaces, microcracks, etc. When heterogenous materials are subject to a strong harmonic perturbation (conditioning), they show a frequency shift and attenuation increase, both associated to continuous reversible changes in their viscoelastic properties [3]. These properties do not draw back instantaneously to their initial value when perturbation is removed, but follow a very slow recovery without any damage to the material remaining the method is Non Destructive and very sensitive to damage.

In this study we apply this approach for the Non Destructive Evaluation of the integrity of structures as lighting masts and their anchoring conditions. The mast is represented by a scale model using cylindrical steel tube that is fixed to a metallic plate using four screws. Two piezoelectric sensors are integrated in the structure, one as a transmitter, the second as a receiver. We then use some Nonlinear acoustic features as Resonance frequency shift and quality Q-factor change as a function of the increasing applied acoustic excitation amplitude, to monitor loosening of screws.

The Nonlinear Acoustics behavior is characterized at initial state and progressively loosened states. We observe that Resonance frequency shift increases and that the Q-factor decreases as a function of the degradation of the anchoring conditions. We also observe that the frequency change and Q-factor as function of applied excitation didn't follow the same path for the increasing excitation level and for the decreasing excitation level giving rise to a hysteretic behavior that is dependent on the anchoring conditions.

This work shows the relevance of this approach, that is according to the open literature, used for the first time for the Non Destructive Evaluation of the integrity of structures as lighting masts and their anchoring conditions.

Presenting Author: Rachid El Guerjouma LAUM - Le Mans Université - CNRS

Presenting Author Biography: Rachid EL GUERJOUMA did his graduate studies in University of Bordeaux where he obtained a PhD in physical acoustics in 1990. He was then recruited as Associate professor In the National Institute of Applied Sciences of Lyon (INSA de Lyon), affiliated to the laboratory of Engineering and Materials Sciences INSA de Lyon - CNRS.
He then joined Le Mans University in 2003 as a full professor at the laboratory of acoustics (LAUM-UMR-CNRS). He ensured the co-responsibility of the acoustic and mechanical Team of the Acoustic Lab.
He became co-deputy director of the LAUM from 2008 to 2012. He also ensures, from 2012 to 2020, the presidency of Le Mans University. Involved in research in the fields of acoustics and mechanics of materials, he is also a member of the French Society of Acoustics and the European Society of Acoustics. He served in many managerial and technical committees; he is the coordinator for many industrial related projects that are funded by government, national agency of Research, and private companies.