Modellierung von Schädigung und verbleibenden Eindrücken bei Impact auf Verbundwerkstoffe
Materialien und Werkstoffe der Sinterprozesse und der generativen Fertigungsverfahren
Zusammenfassung der Projektergebnisse
Two impact test series were carried out. After the first series of tests, it became apparent that the measurement by means of a dial gauge shows strong scattering of the indentation compared to the measurement with the profilometer. This was particularly evident at low impact energies (30 J). Therefore, the energy was increased in the second impact test series (25 J, 50 J, 75 J). In addition, quasi-static indentation tests (QSI tests) were carried out. In these tests, an indenter pressed on a sample in a displacement-controlled manner. The tests were stopped after the maximum displacement from the impact tests was reached. The QSI tests were intended to visualise the evolution of damage in the samples. They showed strong deviations between the load-displacement curves and also in the permanent indentations compared to the impact tests. The load plateau and the more pronounced fibre failure in the static tests were attributed to a strain rate dependence of the material. However, the material characterisation in WP2 could only be done quasi-statically. The calibration of the constitutive model was also carried out on the quasi-static characterisation tests and a parameter study on a simplified substitute model was used to determine numerical parameters such as the element formulation, but also to investigate the influence of the BK parameter, for example. Using the impact simulation model from WP4, the load-shift curve of the tests could only be represented to a limited extent for all impact energy levels. Both the stiffness and the maximum force were underestimated in the simulations. Therefore, simulation models of the QSI tests were built and calculated, the modelling method remained the same. There was sufficient agreement on both the plate stiffness and the maximum reaction force. Due to the chosen element deletion strategy and the modelling of the laminate, the "locking" of the fibres, which primarily contributed to the permanent indentation, could not be reproduced.
