Material Fatigue

Repetitive changes in pressure, temperature, torques, and forces within a mechanical system can induce variable stresses and strains over time, which after a certain number of applications may result in the initiation and propagation of cracks, or even lead to component fracture. This type of process involving permanent, localized, and progressive structural change is known as fatigue.

Material fatigue is one of the mechanisms of damage in nuclear components, the aerospace industry, and automotive, among others. For this reason, it is important to characterize the behavior of structural materials under variable loads and study the mechanisms involved in crack propagation.

The Physical Metallurgy Division (CAB-CNEA) investigates the phenomenon of fatigue applied to various materials, such as SA533 and SA508 pressure vessel steels, AISI 316L stainless steel, Nitronic steels, Zry-4 zirconium alloys, and AA 6061 T6 aluminum used in nuclear applications, shape memory materials based on Ni-Ti used in medical applications, and fatigue in materials manufactured by additive manufacturing.

![Fatigue Testing]

The research group has suitable experimental infrastructure for various experiments. This includes two servo-hydraulic MTS machines with a loading capacity of 100 kN (MTS 810 and MTS Landmark 370) capable of conducting tests at temperatures up to 540°C, and two electromechanical Instron testing machines (Instron 1123 and Instron 5567) with a significant variety of accessories.

In recent years, the acquisition of digital image correlation (DIC) equipment and a FLIR thermal camera (A655sc) has expanded the analysis capabilities.

Currently, the possibility of applying infrared thermography (IRT) to fatigue characterization of various materials is being studied. This aims to contribute to the understanding of fatigue phenomena through a detailed study of thermal evolution during fatigue tests, as well as to evaluate the feasibility of developing IRT-based tools for in-situ crack detection.

Figura Temorgrafía Infraroja

Techniques Used:

• Optical Microscopy.
• Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM).
• X-ray Diffraction.
• Digital Image Correlation (DIC) Measurement.
• Infrared Thermography (IRT).

Publications in Journals and Conferences:

• I. Bustos, G. Bertolino, A. Yawny. Environmental Effects on Fatigue Design of Nuclear Components. SAM-CONAMET 2018. ISBN 978-987-1323-62-3

Thesis Works (Undergraduate and Postgraduate):

• Bustos, R. Ignacio- ‘Environmental Effects on Fatigue Design of Class 1 Nuclear Components’. Postgraduate Thesis (Master’s in Engineering). Balseiro Institute (2018).