Fatigue properties of additively manufactured alloys for extreme lightweight

Important results from the project

The aim of the project was to additively manufacture specimens in amorphous metals and test their mechanical properties in three-point bending monotonically and cyclically. The purpose was to investigate the fatigue properties and produce the first points of a Wöhler curve (load amplitude vs. number cycles to failure). In parallel, a specially designed spring was also planned to be additively manufactured to show the practical utility of amorphous metals. Both goals were met: fatigue studies yielded several data points and the spring showed outstanding resilience.

Expected long term effects

Several results were achieved. First, all fatigue points were collected in a Wöhler curve that sets a frame for later investigations: recommended load level and expected corresponding number of cycles to failure. This opens the way for investigation of other effects such as specimen geometry, orientation, surface finish, testing method ... Secondly it turned out that amorphous metals were not at all as brittle as previously thought. Crack surface inspection in a microscope clearly showed crack growth, which significantly increases the possible range of applications.

Approach and implementation

The project consisted of several parts: literature study, contact with our industrial partners (SKF and Staccato Technologies), process development for defect-free additive manufacturing of specimens and components in amorphous metal, finite element modeling for topology optimization of the spring component, electrode discharge machining and polishing of the specimens, development of a test program, analysis of test data and inspection of crack surface... These tasks were performed as much as possible in parallel and with constant dialogue between the project participants.