Strain analysis on ductile cast iron containers at drop tests Original Research Article

Ductile cast iron (DCI) containers for transportation and deposition of radioactive waste have to be designed carefully in order to avoid unacceptable damages and leakages in case of an accident. Therefore various calculations and experimental methods are used during development and licensing of the containers. Besides others the container has to suffer severe impacts (e.g. falling from a height of several meters onto a concrete base). The level of strains must not exceed a value which would adversely affect the package in such a way that it would fail to meet the applicable requirements. In practice complex events such as drop tests are very difficult to calculate. Both the position of maximum stress and the time of its occurrence are not easily predicted with the method of FEM. The uncertainty of the material modelling for plastic deformation by dynamic loading rates is the limiting factor. Therefore holography as an integral measuring technique in combination with strain gauge techniques were used to fit the FEM. By using the FEM calculations in the case of licensing, the FE and the material model have to be verified. The verification of the FE model has to be done by comparison of the local maxima measured by strain gauges and by comparison of the vibration modes. These vibration modes we take from holographic measurements. In this paper we explain container vibrations after impact analysed with holographic measurements, FEM calculations and the comparison of the results. The comparison of the local maxima (strain gauges/FEM) is reported elsewhere (Schreiber, D. et al., 1993. Trans. 12th Int. Conf. J04, 5, pp. 101–108; Völzer, W. et al., 1997. Technical Semin. on Brittle Fracture. Krefeld 27–28.10.94, RAMTRANS (in press)).