Doctorate in Applied and Engineering Physics  

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Thesis Proposal for the

Doctorate Program in Applied and Engineering Physics (DAEPHYS)

Starting in the Academic Year 2016/2017

Proposal 033

Title:Development of an automated system for welding quality control in the automotive industry
Objectives (recommended length: 2000-3000 char):
In this project, we pretend to design and build a prototype of an X-ray fluorescence imaging (XRFI) system, based on a gaseous detector [1,2], for welding point quality evaluation to be applied in the automobile industry. The quality assessment of welding points and bridges is currently performed visually, with an optical microscope, by a dedicated human operator on several hundred pre-prepared samples, one for each welding point. This task could be automated, not only for the well-being of the operator but also to reduce evaluation errors induced by visual artifacts such as specular reflections. The XRFI technique can be very useful for that purpose since it can be employed to perform elemental mappings on pre-prepared samples and when coupled to computerized image analysis allows obtaining all of the interest parameters, such as fold dimensions, thickness of the welding points, and especially the welding metal implantation on the different plates.
This should reduce not only the number of misidentifications, but also speed up the evaluation process, which should also decrease the response time for procedure changing in the lines which might present higher numbers of welding defects. It will also remove the necessity of the tedious work by the skilled operator which could instead be used on other quality control operations.
The main goal of this project is to develop a large area XRFI system based on a gaseous detector which will be designed and built in order to fulfill the specific requirements and features needed for this application. Several features must be take into account, such as: spatial resolution, detection efficiency, energy resolution, counting rate, detection area, etc.
The XRFI system based on a gaseous detector will be used to analyze the same pre-chosen samples with defects studied previously. With the obtained elemental distributions, an image analysis algorithm will be developed for assessing the defect type and for obtaining all of the required parameters for quality control. Once the algorithm is working within the requested uncertainties, the system will be installed in the factory for testing and performance evaluation, where it will run constantly, along with the visual inspection performed by the human operator in order to assess the quality of the automatic system.

[1] A.L.M. Silva, R. Figueroa, A. Jaramillo, M.L. Carvalho, J.F.C.A. Veloso, “Performance of a gaseous detector based energy dispersive X-ray fluorescence imaging system: Analysis of human teeth treated with dental amalgam”, Spectrochimica Acta Part B: Atomic Spectroscopy, 86, 115–122 (2013)
[2] R. G. Figueroa, E. Lozano, F. Belmar, D. Alcaman, A. von Bohlen, C. A. B. Oliveira, A. L. M. Silva and J. F. C. A. Veloso, “Characteristics of a robust and portable large area X-ray fluorescence imaging system”, X-Ray Spectrometry, 43, 126–130 ( 2014)
Framework (recommended length: 500-2000 char):
The LIBPhys-UNL team has an accumulated know-how in the application of X-ray spectroscopy to measure elemental concentrations in several areas, such as biological tissues (plants, animals and humans), archeology, art and industry.
The group Radiation Detection and Medical Imaging (DRIM), part of Aveiro’s pole of the I3N Associated Laboratory, has great expertise in the development of gaseous radiation detectors, for different applications ranging from high energy physics to medical imaging and X-ray fluorescence imaging. It was one of the founding members of the RD51 CERN Collaboration: “RD51: Development of Micro-Pattern Gas Detectors Technologies”, which started in 2008.
Tasks (recommended length: 1000-3000 char):
1. Bibliographic study of EDXRF systems, namely those with a gaseous detector.
2. Study of the quality control procedures for welding evaluation presently used in the Wolkswagen Autoeuropa factory.
3. Design of the spectrometer.
4. Construction of the spectrometer.
5. Development of an algorithm for image evaluation of geometrical defects.
6. Development of an algorithm for elemental map evaluation of welding metal implantation.
7. Test of the spectrometer in the factory and comparison to the present method results.
8. Dissertation writing
Research centre/lab or R&D unit hosting the thesis project:
University to which the thesis project will be presented:
UNL - Universidade Nova de Lisboa
DAEPHYS Scientific Domain in which the project fits:
Relation of the project to the Scientific Domains of DAEPHYS:
The project aims at designing and building an X-ray fluorescence imaging system and a computer code for image analysis of the welding samples that are prepared at the quality control laboratory at the Volkswagen Autoeuropa factory. The gaseous detector will be custom built at Universidade de Aveiro and the XRFI system will be tested at Universidade Nova de Lisboa. The control electronics for the detector will also be developed in Aveiro and the control electronics for the X-ray emission and the image acquisition will be developed in the Lisbon group. The software for image analysis will also be developed in Lisbon.
Candidate profile:
It is expected that the candidate is familiar with X-ray physics, electronics and programming.
Does this proposal involve more than one University?:
Synergies between the two Universities participating in the proposal:
DAEPHYS strongly encourages the presentation of thesis projects in co-supervision by researchers from two of the universities participating in the Program. In this field, explain the benefits resulting from the proposed co-supervision and the involvement of elements from the two universities, e.g. building critical mass teams, profiting from existing infrastructures or advanced equipments, profiting from expert technical know-how, etc. If the proposal involves only one University, write n/a.
(recommended length: 500-1000 char)
: The Lisbon group has great expertise in X-ray fluorescence spectrometry, namely in elemental mapping of two-dimensional samples with X-ray optics. The Aveiro group specializes in X-ray detectors development, namely in two dimensional large areas setups with high spatial resolution. The know how of the Aveiro group will prove invaluable in developing an X-ray imaging system with gaseous detectors, while the expertise of the Lisbon group in X-ray image analysis and computer programming will be crucial.
Does this proposal involve a company?:
Proposals involving a company:
DAEPHYS strongly encourages the presentation of thesis projects involving a company, preferably a high-tech company. These proposals have to: 1) be centered on a technological problem in which the partner company has been (or plan / would like to be) involved; 2) have a co-supervisor on the enterprise; 3) include part of the project to be carried out in the company.
(recommended length: 500-1000 char)
: The problem to be addressed in this thesis proposal arose from the need of automatize the welding quality control in the automobile industry giant, Volkswagen Autoeuropa. The construction and preliminary testing of the system will be carried out in the University labs of UNL and UA, and the final testing of the system will be carried out in the Volkswagen Autoeuropa factory near Palmela.
The Co-Supervisor José Paulo Moreira dos Santos will act as a liason between the FCT UNL and Volkswagen Autoeuropa.



Name:Mauro António Moreira Guerra
Institution:Universidade Nova de Lisboa
link to CV or indication of ORCID ID:



Name:Ana Luisa Monteiro da Silva
Institution:Universidade de Aveiro
link to CV or indication of ORCID ID:



Name:José Paulo Moreira dos Santos
Institution:Universidade Nova de Lisboa
link to CV or indication of ORCID ID:


Uploaded PDF document: proposal-033.pdf