Nanomechanics

 

The Nanomechanics research group investigates the micro- and nano scale mechanical properties of different classes of materials like metals and ceramics. Besides the mechanical strength, the focus is on the fracture toughness, fatigue and time-dependent deformation properties.

Various instruments at the institute make it possible to characterize the different mechanical properties e.g. via nanoindentation and Focused Ion Beam enhanced micropillar compression and in-situ microcantilever bending. Furthermore, the properties of thin films (down to 50 nm thickness) can be accessed by bulge testing.

In May 2022, Benoit Merle was appointed professor to the University of Kassel and is now heading the lab for Mechanical Properties of Materials.

Dr. mont. Michael Wurmshuber

Group Leader Nanomechanics

Department of Materials Science and Engineering
Chair of General Materials Properties

Prof. Dr. rer. nat. Mathias Göken

Head of Institute, Group Leader Nanomechanics

Department of Materials Science and Engineering
Chair of General Materials Properties

Matthias Glosemeyer, M. Sc.

Department of Materials Science and Engineering
Chair of General Materials Properties

Bone shows remarkable combinations of stiffness and fracture toughness considering its rather soft (collagen) or brittle (hydroxyapatite) constituents. The reason for this property amplification lies in the hierarchical structure of bone and the accompanying toughening mechanisms. One such important mechanism is the deflection and arrest of cracks in cement lines, very thin sheets (thickness 1-5 µm) surrounding osteons in cortical bone microstructure. Due to experimental challenges as a result of their small dimensions, the composition and mechanical properties of cement lines has not been investigated in detail yet, despite their crucial role in bone as crack deflector.
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Metallic thin films are used in many applications like sensors and micro electronic mechanical sensors (MEMS) where they are often subjected to cyclic loading. Due to their low thickness in the range of several nanometers to a few micrometers the properties and failure mechanisms of thin films are different comparing to bulk material. The interface character plays an dominant part in how fatigue damage and failure occurs in thin films. The interfaces between thin film and substrate can be considered as hard (thin film on metal or ceramic substrate), soft (thin film on polymer) or free-standing (thin film without substrate).
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Highly alloyed material systems, based on Co, Ni or Fe have gained huge scientific interest in the last few decades. With the improvement of electron microscopy, the opportunity to analyse and characterize their broad variety of deformation mechanisms and therefore outstanding mechanical properties is enabled. High temperature steels based on FeNiCr which show remarkable mechanical properties, oxidation resistance as well as good processing and economical aspects are used widely.
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Due to the current development of different machine learning models as well as the possibility of additive manufacturing, new material systems are being researched and synthesized ever more quickly and efficiently. However, whether these systems are also used often depends on suitable mechanical properties, which also should be determined in the shortest possible time. These include the stress-strain curve, fracture toughness and fatigue life.
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