Reliability of Lamb waves-based SHM systems for the revalidation of RLV

29 Feb 2024
Job Information

Organisation/Company

ONERA - The French Aerospace Lab

Department

DMAS

Research Field

Engineering » Mechanical engineering
Mathematics » Algorithms
Physics » Acoustics

Researcher Profile

First Stage Researcher (R1)

Country

France

Application Deadline

15 Mar 2024 - 00:00 (Europe/Paris)

Type of Contract

Temporary

Job Status

Full-time

Hours Per Week

39

Offer Starting Date

1 Sep 2024

Is the job funded through the EU Research Framework Programme?

Not funded by an EU programme

Reference Number

24-041

Is the Job related to staff position within a Research Infrastructure?

No

Offer Description

The reuse of launch vehicles has become a major requirement today to reduce space access costs and enhance Europe's competitiveness in the face of various actors, both in the public sector (NASA, ISRO, CNSA, Roscosmos, JAXA) and in the private sector (SpaceX, Blue Origin). To meet this need, CNES and ONERA are considering instrumenting launch vehicles with Structural Health Monitoring (SHM) systems to optimize maintenance operations and authorize/sanction their relaunch. Arrays of sensors such as Piezoelectric Wafer Active Sensors (PWAS) and Fiber Bragg Grating (FBG) integrated into structures will be used on the ground as a means of non-destructive testing (active mode using guided waves), and during the mission in passive mode to detect acoustic events indicating possible generation of damage. This control approach provides access to areas for which conventional non-destructive testing would be economically prohibitive and collects real-time recordings to enhance knowledge of the environments to which launchers are exposed and improve diagnostics during launcher revalidation phases.

One of the main challenges of SHM is to ensure the reliability of the embedded sensors, which must maintain their performance despite the high thermomechanical and vibrational stresses encountered by launch vehicles during space missions. These stresses vary depending on the monitored areas, ranging from cryogenic temperatures (approximately -250°C) to high temperatures (> 300°C), or even high-amplitude low-frequency vibrations. Whether on the ground in active mode during the revalidation phase or in passive mode during flight, the embedded sensors must fulfill their primary function throughout the operational life of the launcher (short-duration flights, periods of inactivity ranging from a few weeks to a few months, and up to ten reuses).

 

The main objective of this thesis is to develop experimental and numerical approaches to assess the capability of a guided wave SHM sensor network to detect and locate damage after exposure to complex thermomechanical and vibrational loads. This involves evaluating malfunctions resulting from the degradation of SHM sensors in terms of information loss, false alarms, and a decrease in damage detection and localization performance (increased minimum detectable damage size, less accurate localization). This thesis will consist of two axes of work: experimental and numerical. Initially, SHM sensor networks will be evaluated as integrated health monitoring means through guided wave generation. Experiments will be conducted to locate different types of damage (delaminations or cracks) induced on simple structures (metallic or composite) and to assess the disturbances that sensor degradation can cause in damage localization. Various existing or to-be-developed localization algorithms will be tested for this purpose. These works will leverage the numerous resources available at ONERA, both for the accelerated generation of damage (climatic chambers, heating lasers, vibratory devices, impact machines) and for sensor diagnostics (laser vibrometry, electrical impedance, FBG interrogators). Following these tests, an understanding of failure mechanisms and sensor drift under the environments to which they will be exposed will be acquired. These results will contribute to the definition of numerical models representing the SHM systems under consideration in healthy and aged conditions. Numerical modeling will be implemented using COMSOL and CIVA software to simulate the propagation of guided waves generated by PWAS and assess the disturbances that sensor degradation (PWAS and FBG) can cause in damage localization.The second axis of work will be devoted to evaluating SHM system performance by considering appropriate metrics, such as detection and localization probabilities, and localization errors. To achieve this, numerical models will be implemented using COMSOL and CIVA software to simulate the propagation of guided waves generated by PWAS sensors and assess the nuisances that sensor degradation (PWAS and FBG) can cause in damage localization. 

The MAPOD (Model Assisted Probability of Detection) numerical approach, commonly used in the non-destructive testing field, will be used to develop a surrogate model that will facilitate the evaluation of different damage scenarios (damage type, position, extent) while taking into account the various sources of variability inherent to sensor properties, structure, or environment. Given the impossibility of experimentally testing all these variabilities, a transfer learning approach, offering the possibility of using knowledge acquired from a rich database (simulation) and transferring it to a less populated database (experimental), will also be implemented to adapt the results from the MAPOD modeling to a specific use case defined in collaboration with CNES.

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For more Information about the topics and the co-financial partner (found by the lab !); contact Directeur de thèse - [email protected]

Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online  before March 15th, 2024 Midnight Paris time !

https://recrutement.cnes.fr/fr/annonce/2699021-24-041-reliability-of-la…

Requirements

Research Field

Engineering » Aerospace engineering

Education Level

Master Degree or equivalent

Research Field

Engineering » Mechanical engineering

Education Level

Master Degree or equivalent

Research Field

Engineering » Materials engineering

Education Level

Master Degree or equivalent

Research Field

Engineering » Industrial engineering

Education Level

Master Degree or equivalent

Research Field

Engineering » Control engineering

Education Level

Master Degree or equivalent

Research Field

Engineering

Education Level

Master Degree or equivalent

Languages

FRENCH

Level

Good

Languages

ENGLISH

Level

Good

Research Field

Engineering » Aerospace engineeringEngineering » Mechanical engineering

Additional Information
Work Location(s)

Number of offers available

1

Company/Institute

ONERA

Country

France

City

Chatillon

Postal Code

92320

Geofield

Where to apply

Website

https://recrutement.cnes.fr/fr/annonce/2699021-24-041-reliability-of-lamb-waves…

Contact

State/Province

Île-de-France

City

Chatillon

Website

https://www.onera.fr/en/dmas

Street

29 av division leclerc

Postal Code

92320

E-Mail

[email protected]
[email protected]

STATUS: EXPIRED