Mechanical Testing of Materials


 Mechanics of Materials Testing
zum Bild Mechanics of Materials Testing

Mechanical Testing of Materials offers mechanical material characterization as scientific-technical service for all departments of the institute as well as for external customers. Mechanical material tests are performed under various loads, which can be uniaxial but also biaxial. Measurements are possible in air, vacuum, and corrosive environments at varying temperature ranges (-196° up to +1,400°C).

A special expertise of the group is fatigue and fracture mechanics testing of all engineering materials including metals, ceramics, composites and multi-material hybrids. Investigations of crack growth behavior with determination of the threshold ΔKth, monitoring of da/dN - ΔK-curves, determination of crack resistance curves, and fracture toughness at different temperatures are part of the testing portfolio.

For answering current scientific and technical questions, experimental test plans are designed and special testing methods as well as test facilities are developed. The results from mechanical testing are evaluated involving microscopic characterization of the material before and after testing in order to investigate changes such as deformation, damage, crack growth, and failure. These tasks are performed in close collaboration with the institute’s departments and the microanalytic group. Examples for in-house developments of test facilities are

- test facility for investigating thermal gradient mechanical fatigue of protective coating systems for gas turbine blades by using hollow specimens, which are heated by using a radiation furnace and internally cooled with pressurised air. In doing so, testing conditions very similar to the service conditions of internally cooled gas turbine blades are achieved.

- test setup for fracture mechanics characterization of delamination cracking of fiber reinforced polymers and hybrid laminates under clearly defined mixed mode crack opening conditions,

- test setups for investigating stress corrosion cracking under constant load in special corrosive media.

The mechanical testing laboratory owns several servo-hydraulic testing machines for uniaxial and biaxial loading, electro mechanical testing machines for different load ranges, mechanical resonance testing machines for cyclic loading at high frequencies, and constant load test rigs. For experiments on very small specimens a new testing laboratory has been established. Besides machines with smaller load capacity and high accuracy, modified hardness test machines are employed for exploring local mechanical properties. For testing at high or cryogenic temperatures, several furnaces, cooling and vacuum chambers are available. The laboratory equipment includes special measuring devices for monitoring forces, strains, temperatures, and crack propagation.

Mechanical material characterization is performed also in co-operations with universities, other research institutions, and industry partners.

Janine Wischek
German Aerospace Center

Institute of Materials Research
, Mechanics of Materials Testing
Tel: +49 2203 601-2833

Fax: +49 2203 696480

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