File:Animation Controle Non Destructif Courants Français: Schéma d’un contrôle non destructif par courants de Foucault. Download scientific diagram| Principe du CND par courants de Foucault from publication: Design of eddy current microsensor arrays and signals inversion for . Job postings: Spécialiste CND – Ingénieur d’application Ultrason et Courants de Foucault (6 mois) at Olympus NDT Canada, Québec, Québec.

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Contrôle par courants de Foucault

Faraday discovered that when a magnetic field passes through a conductor a material in which electrons move doucault -or when a conductor passes through a magnetic field-an electric current will flow through the conductor if there is a closed path through which the current can circulate.

Variations in the plot correspond to variations in the test piece.

The operator observes the response from the reference standards and then compares the indications from test pieces to these reference patterns to categorize parts. The screen display below shows a nonmetallic coating over aluminum. If the probe and its magnetic field are brought close to a conductive material like a metal test piece, a circular flow of electrons known as an eddy current will begin to move through the metal like swirling water in a stream.

Low frequency probes can be used to locate corrosion on second and third layers of metal that cannot be inspected ultrasonically. There have been many recent developments in eddy current testing, leading to improved performance and the development of new applications. This data is referenced to an encoded position and cournats and represented foucaupt as a C-scan image showing structures in a planar view. Common applications Eddy current instruments can be used in a wide variety of tests.

There are many factors that will affect the capabilities of an eddy current inspection. By Tom Nelligan and Cynthia Calderwood Magnetism, the underlying principle behind electric motors and generators, relays and courantd speakers, is also the force that enables an important category of NDT tools called eddy current instruments.

Higher test frequencies increase near surface resolution but limit the depth of penetration, while lower test frequencies increase penetration.

The top foucaulf shows the signal on aluminum without any coating. Many advances were made throughout the s and s, especially in the aircraft and nuclear industries. While conductivity and permeability are properties of the test material that are outside of the operator’s control, the test frequency, coil type, and coil size can be chosen based on test requirements.


To create this image, the display position had to be changed between each measurement in order to display a separation between each signal.

Foucault built a device that used a copper disk moving in a strong magnetic field to show that eddy currents magnetic fields are generated when a material moves within an applied magnetic field. Eddy current testing is based on foucau,t physics phenomenon of electromagnetic induction. ID probes – Used for inspection of heat exchangers and couramts metal tubing from the inside, available in a variety of sizes. Each individual coil produces a signal relative to the phase and amplitude of the foucaupt below it.

Proper calibration with appropriate reference standards is an essential part of any eddy current test procedure. This includes inspection of the area around fasteners in aircraft and other critical applications. This measurement is most commonly used to determine the conductivity of a material but it will also provide the thickness of a coating which is considered the “Liftoff” from the material or how far the probe is above the surface of the conductive material.

Sliding probes – Also used in testing aircraft fastener holes, offering higher scan rates than donut probes. The inspection measurements are dependent entirely on the comparison of the signal against the reference calibration. Menu More Pour nous joindre. Tubing inspection – Both in-line inspection ofucault tubing at the manufacturing stage and field inspection of tubing like heat exchangers are common eddy current applications.

Bolt Hole Inspection – Cracking inside bolt holes can be detected using bolt hole probes, often with automated xnd scanners.

The second line down is a 0. How it works Eddy current testing is based on the physics phenomenon of electromagnetic induction. Surface Inspection – Surface cracks in machined parts and metal stock can be readily identified with eddy current.

File:Animation Controle Non Destructif Courants Foucault.gif

In an eddy current probe, an alternating current flows through a wire coil and generates an oscillating magnetic field. Eddy current testing is widely used in the aerospace industry and in other manufacturing and service environments that require inspection of thin metal for potential safety-related or quality-related problems. It is always important to select the right probe for each application in order to optimize test performance.


Conductivity Testing – Eddy current testing’s ability to measure conductivity can be used to identify and sort ferrous and nonferrous alloys, and to verify heat treatment. This process involves foicault the baseline display from a given test piece and observing how it changes under the conditions that the test is intended to identify. In a given test, resolution will be determined by the probe type while detection capability will be controlled by material and equipment characteristics.

Eddy current fe can perform a wide variety of tests depending on the type of probe being used, and careful probe selection will help optimize performance. For example, the display below shows a setup for inspection for surface cracks in aluminum.

File:Animation Controle Non Destructif Courants – Wikimedia Commons

In addition to crack detection in metal sheets and tubing, eddy current can be used for certain metal thickness measurements such as identifying corrosion under aircraft skin, to measure conductivity and monitor the effects of heat treatment, and to determine the thickness of nonconductive coatings over conductive substrates.

Sorry, this page is not available in your coourants Let us know what you’re looking for by filling out the form below. Donut probes – Designed to inspect aircraft fastener holes with fasteners in place. Corrosion Detection – Eddy current instruments can be doucault to detect and quantify corrosion on the inside of thin metal such as aluminum aircraft skin. This measurement uses a special conductivity probe that displays the below screen instead of the standard impedance screen shown above.

Sorry, this page is not available in your country Let us know what you’re looking for by filling out the form below. Changes in metal thickness or defects like near-surface cracking will interrupt or alter the amplitude and pattern of the eddy current and the resulting magnetic field.

OD probes – Used for inspection of metal tubing and bars from the outside, with the test piece passing through the coil Reference standards An eddy current system consisting of an instrument and a probe must always be calibrated with appropriate reference standards at the start of a test.