SHM, NDT, structural control…

12th January 2023

SHM, NDT, structural control… let’s try to clarify these terms

While visiting our website or following our news on Linkedin, you probably saw the terms SHM, NDT, predictive maintenance, structural control… It is not always easy to distinguish one approach or method from another. This article aims at clarifying all these concepts and explains what PYTHEAS Technology offers.

Non-Destructive Testing to evaluate the structures, systems and materials’ health without causing damage

A lot of sectors and activities need more or less frequent controls of equipment and systems, especially to ensure the users’ safety. For example, road structures such as bridges, motoring, aerospace or oil & gas are some sectors in which a failure could have disastrous consequences.

To control their integrity, these systems and structures usually go through some destructive, semi-destructive or non-destructive tests. The goal of Non-Destructive Testing (NDT), or Non-Destructive Evaluation (NDE), is to check the integrity of a specific structure or part without causing damage. Unlike destructive or semi-destructive testing, NDT does not alter the tested component, which, therefore, can be reused normally. This is a way to save both time and money in the products, materials and structures evaluation process.

NDT includes different methods and techniques such as eddy-current testing, holography, magnetic particle inspection, tracer-gas leak testing or ultrasonic testing. There are tens of methods for both surface and volume control.

Non-destructive testing can be carried out during production, to detect manufacturing defects, or in use, to detect fatigue, wear & tear damages.

Structural Health Monitoring to continuously monitor the health of a structure or component

Structural Health Monitoring (SHM) is an inspection technique used to continuously and autonomously monitor the integrity of a structure or system. The concept of SHM implies that the sensors are fixed or integrated into the structure for a continuous diagnosis.

The development of SHM is linked to the increase of safety norms and the will to reduce maintenance costs. By detecting damages and wear marks, SHM can predict necessary maintenance operations and avoid unnecessary preventive maintenance and major structural damages. By allowing operators to intervene at the right place and the right time, SHM reduces maintenance costs without compromising the reliability of the controls.

Predictive maintenance to anticipate failures and breakdowns

Predictive maintenance’s goal is to use the estimated lifespan of equipment or structures to anticipate failures and breakdowns. Based on data collected by different sensors, predictive maintenance alerts when critical thresholds are crossed. These sensors can vary in nature, such as accelerometers, temperature or pressure sensors, they can also use ultrasounds or infrared to measure vibrations or fluid flows.

Predictive maintenance offers several advantages:

• Thanks to automated and continuous controls, machines are rarely blocked for controls and maintenance and these interventions are shorter.
• Maintenance costs are reduced, as the number of breakdowns decreases.
• Maintenance operations can be scheduled with more precision and anticipation.
• Operators save time as the source of the breakdown is identified and localized.
• Equipment lifespan is extended because maintenance operations occur before it’s too late.

Predictive maintenance and smart sensors’ installations can represent an important investment but turn out to be profitable rapidly by maintaining an optimal level of machines’ availability.

What does PYTHEAS Technology offer?

PYTHEAS Technology offers a SHM solution using ultrasonic guided wave imaging.

This imaging technique, also called tomography, can artificially create an image of the structure or material to analyze, thanks to different measures carried out from the outside. Ultrasonic imaging is, for example, a technique used for various medical applications.

By fixing a network of piezoelectric emitters and receivers on the surface or inside a structure, it is possible to detect, localize and characterize defects. These sensors transmit and receive guided waves, which will be used as inputs by tomography algorithms. These algorithms will then map the inspected structure and detect, localize and characterize defects.

For instance, PYTHEAS Technology works with the CNES to design an embedded system to detect, characterize and localize defects on future reusable satellite launchers. If you are interested in this project, you can read this article.