University of Twente Student Theses


Identification of damage precursors in 3D-printed aluminium alloy after fatigue testing

Loobergen, K. van (2020) Identification of damage precursors in 3D-printed aluminium alloy after fatigue testing.

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Abstract:Previous research has indicated that damage precursors can be a promising method for predicting and preventing fatigue damage in metal structures. Test plates made from Scalmalloy were printed using Selective Laser Melting and subjected to fatigue experiments in order to detect damage precursors based on dynamic properties. In this work, the physical properties of these plates that were subjected to fatigue loading are analysed in order to find the cause of change in dynamic behaviour. A batch of test plates made from conventionally produced Al7075-T6 were used as a reference. A number of approaches to define damage precursors is discussed in this work. Material characterization tests were carried out to help understanding the link between change in dynamic behaviour and physical material changes, as this is essential for properly understanding dynamic damage precursors. Methods that were used to analyse physical properties of the test plates include optical microscopy, confocal microscopy, density analysis, CT-scanning, micro- and nano-indentation and EBSD-analysis. The main cause of the previously observed change in dynamic behaviour can be traced back to early stages of fatigue crack growth, but the applied analysis methods did not indicate significant change of material properties before the first fatigue cracks started to appear. Also, some attention is given on how damage precursors could be implemented to improve maintenance policies and increase reliability of systems, and what the limitations of damage precursors are in practical applications.
Item Type:Essay (Master)
Faculty:ET: Engineering Technology
Subject:51 materials science, 52 mechanical engineering
Programme:Mechanical Engineering MSc (60439)
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