Hybrid numerical methods in static and dynamic fracture mechanics

Modern methods in experimental mechanics require considerable expenditure of theoretical considerations with concern to the experimental methods themselves as well as with concern to reliable evaluation and interpretation of the measured data. Because of the high resolving power and the exact data recording it is necessary to consider comprehensively all, even very small effects, which may have influence on the results of measurement. Otherwise the impression of an apparent accuracy may arise. On the other hand it is necessary to transform the originally measured data into the finally wanted information, which generally do not coincide with the measured quantities. Therefore the conventional interpretation of observed phenomena, i.e. measured data, must be substituted by advanced mathematical algorithms, enabling correct evaluation of data into wanted information in order to better approaching the reality. As measurements yield discrete information only the mathematical algorithms must be translated into discrete numerical procedures. Under these considerations application of modern experimental methods, especially optical methods, and the performance of experimental analysis consequently require proper computer capacity for controlling the measurement process, for digital image processing, data recording and evaluation and thus extensive software. Such entire concept of combining experiment and measurement, respectively, with numerical evaluation procedures to analyse problems in mechanics can be summarised under the notion "hybrid techniques". The meaning of this notion will be demonstrated exemplarily by application in photoelastic/photoviscoelastic and holographic-interferometric experiments.