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Materials
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Materials make the manufacture of constituent parts possible, transmit forces, determine
the efficiency levels of machines and the compatibility of medical implants. All three major
materials categories, polymers/plastics, metals and ceramics as well as those derived from
them, e.g. carbon composites and other composite materials, play a significant role in
research and teaching at the department.
Key research areas include ultra-precise antennae which
can be used in space for satellite navigation, manufac-
turing medical components in sterile environments for
use in the human body or the automated manufacture of
load-bearing vehicle or aircraft parts. The State Materials
Testing Laboratory in Mechanical Engineering (part of
the Bavarian government) is another highlight which
illustrates how our wide-ranging material analyses enable
deep insights into all solid materials and provide a nat-
ural interface to various branches of industry interested
in the application of advanced materials based on their
properties.
DeMAnD ‘Dynamic aircraft MAterial property Database’
tures of small aircraft. For a number of aluminum and steel
alloys, fiber-reinforced polymer matrix composites and
foam materials, dynamic tests will be carried out over a
wide range of strain rates, ranging from quasi-static load-
ing up to high strain rates of 500 s-1. The project brings
together renowned experts in the areas of test method
development, static and dynamic testing of aircraft
materials and structures as well as simulation and design
of aeronautical crashworthiness structures. For each strain
rate regime, the optimal test equipment was identified and
is available within the consortium. The equipment ranges
from standard universal testing machines (quasi-static
loading) to special servo-hydraulic high speed testing
machines (medium strain rates) to split-Hopkinson bars
(high strain rate testing). This ensures the determination
of high quality material data and complete stress-strain
curves from static up to high strain rate loading, allow-
ing the derivation of the strain rate dependent material
behavior for all material properties needed for predictive
crashworthiness simulations.
Funded by Horizon 2020
www.cleansky.euTension, torsion and compression split-Hopkinson bars for high strain rate
testing at the Chair of Carbon Composites.
Residual stresses
Residual stresses and their redistribution may significantly
affect the resulting material/component behavior during
processing/fabrication and operating life. Particularly in
components of thermomechanically processed alloys of
complex microstructures, residual stresses act on various
length scales. At elevated temperatures, the mechanisms
governing the microstrain/microstress accumulation may
significantly change, e.g. nickel-base superalloys exhibit
a thermal activation of cube slip systems in addition to
their octahedral slip systems. The interplay of these slip
systems promotes the formation of Kear-Wilsdorf locks
within the
g
‘-phase and results in a yield stress nearly
not decreasing or often even increasing with increasing
temperature (anomalous yielding effect).
In this context, research activities are focused on the evo-
lution of the intergranular and interphase microstrains in
different nickel-base superalloys (Inconel 718 and Haynes
282) during loading and unloading at room temperature
and at elevated temperatures. Owing to the simultaneous
accessibility of different crystallographic directions and
The DeMAnD project was set up to carry out a mechanical
material characterization program to deliver a dynamic
material property data base for typical aircraft materials,
with a special focus on seat and crash-absorbing struc-