Developing strategies for assessing elasto-plastic fracture mechanics

The elasto-plastic fracture mechanics is well established at the micron scale. However, can test protocols be easily downscaled to the micrometer length scale?

Within this project we are assessing various different geometries of the sample and the pre-notch, methods for measuring the crack extension and looking into the impact of the testing machine. All experiments are conducted using nanoindenter systems placed inside a scanning electron microscope. Materials in our focus are – macroscopically – brittle. They comprise nano-crystalline W, Cr and Zr thin films as model matrials. The established protocols are further used to investigate daily life alloys like white etching layers (WELs) in rail steel.

Fracture experiment of a WEL.