The impact notch test (INT) is an established material testing method since the early 19th century. Nowadays especially safety components like Castor containments or windmill rotor hubs are designed highly sophisticated and need to be characterized extensively to verificate the functionallity over a defined lifespan. The INT was developed to evaluate the toughness of steels, the results (including an instrumentation) are not expressive enough to describe the behaviour of materials in overload situations and do not meet the today-requirements.
A relatively new approach in material characterization is the fracture mechanic. It is separated in the linear elastic fracture mechanic (LEFM) and the ductile fracture mechanic (DFM). The LEFM is well known for its failure-criterion KIC, which is widespread in industrial applications. The main Problem is, that the LEFM does not support high amounts of plastic deformation, why it is not applicable for analyzing ductile materials. The solution therefor is the DFMs J-Integral, which describes the amount of energy around the crack/notch tip within the HRR-Field and is able to cover high plastic deformations under plain strain conditions.
Within the Integration of the J-Integral into the impact notch test, multiple tasks occur. To determine values, an in-situ crack length and specimen temperature measuring system is necessary. Also the high strain rate (5.5 m/s) and the notch tip sharpness need to be included in the calculation process. The refitable technique will be evaluated on ductile cast Iron specimen via a reference test on a servohydraulic test system with a crack tip opening displacement (CTOD) sensor to match the results and optimize the calculation process.
The presentation will focus on the fracture mechanical approach, the measuring systems and the achieved results, giving an insight in the test-technique development and the possibilities of innovative mechanical-testing research.
|Category||Short file description||File description||File Size|
|Manuskript||Filter application||Phase Offset caused by the use of a Software filter||90 KB||Download|
|Manuskript||Crack length||Crack length as measured within testXpert II. Auto calibrated and manually calibrated curves are shown in this figure.||87 KB||Download|