Universal testing machine for the investigation of material fatigue in polymers

• Subject Area: Materials Engineering
• Term: Funded in 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 571456542

Progressive digitalization and the development of new numerical methods, such as machine learning (ML) and big data analysis, have opened up possibilities that will change engineering sciences in the long term. However, these methods require a very strong link to experimental investigations, such as for training and validation of neural networks (NN). Among others, this trend is clearly visible in material modeling, which is being researched in the department applying for funding. The focus here is primarily on polymer-like materials such as hydrogels, carbon fiber-reinforced and recycled plastics. The testing device applied for is a combination of a static-dynamic testing machine, a DIC camera for optical stress and strain analysis and a data acquisition system. The selected combination is known as a universal testing machine and is an optimal solution for the fracture mechanics testing of additively manufactured polymers. Here, the optical stress and strain analyses enable to detect the crack initiation and to determine the crack growth per load cycle during the fatigue tests. This function is enabled by the data acquisition system that gathers and analyses measurement data and stores them in the case of crack initiation. The data acquisition system has half-bridge and full-bridge circuits, voltage inputs and interfaces to LabVIEW and the DIC camera system for precise video sequence analysis. The universal testing machine will significantly contribute to increase the spectrum of the research results at several ongoing and future scientific projects. Its application is, for example, planned in a project investigating usage of plastic recyclates for the development of a resource-efficient and high-quality railroad sleepers fulfilling the requirements of modern climate-friendly constructions. Hydrogels with a wide range of applications, from medical research to biomechanics will be investigated as well. For these studies, tests will be partially carried out in a water bath in order to simulate application-specific conditions. A series of investigations supporting the development of ML-based homogenization strategies for the simulation of additively manufactured carbon reinforced polymers are another application field showing that the universal testing machine opens up numerous opportunities to achieve result of high novelty and relevance simultaneously for science and the practical application.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Universalprüfmaschine zur Untersuchung der Materialermüdung in Polymeren
• Instrumentation Group: 2910 Dynamische Prüfmaschinen und -anlagen, Pulser
• Applicant Institution: Technische Universität Berlin
• Leader: Professorin Dr.-Ing. Sandra Klinge