Diagnostic Methods Working Group



M. Sc. Rahul Sharma

Welding and Joining Institute

The core objective of the working group on diagnostic methods is to bundle findings from the field of analytical procedures and observation methods. While at the beginning of the work in the SFB1120 the focus was on the utilization and further development of advanced diagnostic methods in order to enable high-resolution process observation, in the second funding phase the emphasis was placed on the cross-project validation of diagnostic methods with complementary methods. In this way, the methods could be used specifically to support the simulation methods, which serve within the SFB as central tools for building up process understanding. Besides a cross-scale validation of simulation results, physical phenomena could be quantified in the necessary resolution.

In Phase 3 wird die Bedeutung der Diagnosemethoden insbesondere für die aktive Kompensation der präzi-sionsbeeinflussenden Größen ansteigen. Neben einer fortgesetzten Nutzung und Weiterentwicklung der hochgenauen und in ihrer Vielfalt einzigartigen in-situ-Messmethoden ist eine Ableitung von prozessintegrier-ten Sensorprinzipien eine wesentliche Aufgabe der Arbeitskreisgruppe. So werden die bildbasierten Messverfahren in der dritten Phase insbesondere für eine echtzeitnahe Ausführung ertüchtigt, so dass hierdurch Regelkreise gespeist werden können. Die Struktur der Arbeitskreise wurde den neuen Erfordernis-sen bereits zum Ende der zweiten Phase hin entsprechend der nachfolgenden Aufteilung angepasst.


Working Groups

D1: Efficient process monitoring and diagnostics

High-speed Videography is considered a central tool to investigate the formation and movement of melt. Recording frequencies of up to one million images per second make it possible to analyze most dynamic movements of the melt and,

in combination with simulation models, to get an overall picture of melt dynamics. With the help of high-speed thermography, the model and the process description will be extended to address essential questions concerning transient energy transfer.

After a requirement analysis, the various devices available in the labs of the project partners will be made available to the processes that need them the most. A large part of the group’s activities focus on the development of method-specific lighting technologies which help to mask the respective process radiation fractions and thus make it possible to represent specific process details.

Active members: A01 , A02 , A05, A07 , A08 , A11, B08


D2: Data reduction and data evaluation

The acquisition of process understanding on the basis of targeted measurement data acquisition and the subsequent measurement data analysis is a great challenge due to the large number of analysis methods developed. The processing of extensive data from heterogeneous data sources such as high-speed video images or measured values from digital image correlation, as well as transient electrical measurement data, requires targeted and demand-oriented data reduction for subsequent evaluation. The analysis of the reduced data sets already represents the first step towards active control approaches, which can predominantly only be executed with simplified models and reduced data due to the necessary computing power. The methods of data reduction and evaluation already developed in individual subprojects in phase 2 are to be collected and further developed in this working group. Essentially, the goals of the working group can be described as follows:

- Development of a framework for dealing with large amounts of data
- Exchange platform for newly developed methods and tested approaches for data reduction and data evaluation
- Intermediary between subprojects for the efficient use of resources for data evaluation
- Targeted search and collection of cross-project important results and findings for handling data evaluation methods

Active members: A01, A02, A05, A06, A08, A09, A10, A11, B03


D3: State validation of precision-influencing variables

In the third phase of production, validation of the resulting state variables is necessary for mastering the melt-based processes. Working group D3 therefore deals with measurement options to prove the control of various properties of the resulting products. In this context, geometry, dimensional accuracy, chemical composition, residual stresses, internal and surface structure are made comparable with target values by means of metrological recording. The different scales investigated in the subprojects and their corresponding measurement methods are brought together here.

Active members: A01, A02, A06, A07, A08, A10, B01, B08


D4: In situ experiments at large-scale research facilities.

The observation of material changes as a result of the course of manufacturing processes involving melting requires analysis methods that are often only available at large-scale research facilities (high-energy X-rays and neutron radiation). Since the user base of such facilities regularly exceeds the available measurement time for experiments worldwide, the efficient preparation and use of the requested measurement time is essential for successful experiments. The working group bundles the experience gained from the previous funding phase at such large-scale research facilities and serves as an exchange platform for methods and technologies. The bundling of questions in joint experiments (in funding phase 2 between A01/A03/A07/A08 as well as between A02 and A07) is made possible by the working group. In summary, the goals of the working group can be set up as follows:

- Collection of experiences on in-situ experiments at large-scale research facilities.
- Presentation of the possibilities at large-scale research facilities and development of experimental concepts
- Advice on the preparation of applications for measurement time

Active members: A01, A02, A05, A07, A08, A11, A12 ,B08