Residual stress analysis by X-ray diffraction using robotic device


Up to now, in situ stress measurements on large parts were done by using XRD devices. In order to permit the portability, source power, goniometry and detection were minimized. Inel and CETIM developped PRECIX, a new instrument based on a 6-axis robotic arm from the latest generation : the technological performance is to use X-Ray source, a position sensitive detection component with energy discrimination, and then a positioning metrology on a robot and do residual stress evaluations with polar coordinates.

Here, the robot does not hold the sample, the robot moves about the sample holding the source and detector. The sample being measured doesn't have to move and it does not have any restrictions in size or weight.



Precix system has been developed to perform residual stress analysis on big parts that cannot fit on a classical goniometer. For this reason the robot carries the complete X-Ray source, the detector and the laser positioning system. The robot places the complete head over the sample to realize Psi scans.

The system is based on a high precision 6 axis standard robot with a nearly spherical workspace of 900 mm radius. This means that it is possible to record every sample placed within 900 mm around of the system.
 

A specially designed laser positioning system has been developed to ensure automatic position correction of the robot over the part to be analyzed. This system is sensitive to height (precision of few µm), Omega and Psi (better than 0.1° accuracy). 


Specific software runs in real time in the robot controller to convert spatial coordinates from Eulerian workspace (diffraction) to Cartesian (robotic).

 

Then, from the users point of view, the robot is seen like a goniometer with an X, Y, Z translation stage and Omega, Psi and Phi rotation table.

Thus, it is totally compatible with latest version of Inel software, like a classical motion controller unit.


The robot is computer controlled, as well as the X-ray generator, detector electronics and laser triangulation device. All information is automatically checked for inconsistencies and, if determined necessary, the sofware is able to perform an emergency stop of the robot.

     With this technique

     Ensure knowleddge and quality of products from conception, and during production monitoring
     Optimize product with aid for development (fatigue, heat treatments, manufacturing processes)
     Guarantee delivery with results
     Meet requirements to your customers
     Ensure analysis repeatability
     Dispose of the expertise from certified laboratory

Download PRECIX documentation