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Experimental determination and analysis of dynamic fracture toughness data of ductile cast iron
(2017)
Ductile Cast Iron materials (DCI) have become important structural materials. Neverthe-less, to draw maximum benefit from DCIs property potential, tailored testing methods must be provided. The established dynamic Jd-R and CTOD 5d-R curve procedures are based on material specifically developed, independent experimental techniques but pro-vide almost matching results. This can be seen as additional validation of the Jd procedure which was mandatory.
Experimental determination and analysis of dynamic fracture toughness data of ductile cast iron
(2017)
Ductile Cast Iron materials (DCI) have become important structural materials. Neverthe-less, to draw maximum benefit from DCIs property potential, tailored testing methods must be provided. The established dynamic Jd-R and CTOD 5d-R curve procedures are based on material specifically developed, independent experimental techniques but pro-vide almost matching results. This can be seen as additional validation of the Jd procedure which was mandatory.
A device has been designed, built and tested that allows the investigation of effects of dynamic loads on the leak tightness of elastomer seals at low temperatures. With the test setup, the compression of the tested seal can be reduced by a defined degree in a time period of less than 1 s. For the evaluation of the leak tightness, leakage rates can be determined.
It was shown that the rapid partial release of an elastomer seal leads to its failure already at the beginning of the rubber–glass transition and, therefore, at significantly higher temperatures than the loss of leak tightness observed under static conditions.
This paper presents the impact of dynamic loading on the deterioration of ballasted track. Firstly it is discussed which types of loading can be observed at the track. The effects of cyclic and dynamic loading on the ballast assembly are discussed with respect to the different boundary conditions of physical model tests compared to those existing in reality. For dynamic loading, on the one hand, the displacements and rotations of single particles at the surface become more important. On the other hand, the load distribution caused by an impact like loading is different from a quasistatic loading. Finally, large scale tests are presented. When comparing the dynamic loading sequences with the solely cyclic loading, limits are found for a vibration level that is associated with an accelerated accumulation of permanent deformations.