Der Einfluss der Kerbgeometrie auf das Ermu Èdungsverhalten von Biegeproben aus der Aluminiumlegierung AA7075 wird im LCF-Bereich untersucht. Neben der kontinuierlichen Aufnahme der Kraft und der Durchbiegung als Zeitfunktionen wird das Risswachstum in den gekerbten Biegeproben mit dem Gleichstrom-Potentialsondenverfahren (PSV) erfasst. Zur Bestimmung der Spannungs-und Dehnungsverteilungen sowie der Dehnschwingbreite im Kerbgrund werden Finite-Elemente-Simulationen mittels des nicht-linearen isotrop-kinematischen Modells nach Chaboche und Lemaitre bestimmt. Anhand der FE-Rechnungen wird die Anrisslebensdauer nach der effektiven Dehnschwingbreitenhypothese ¹ASME Boiler and Pressure Vessel Codeª abgescha Ètzt und der plastischen Energiedissipationshypothese gegenu Èbergestellt.Schlagwort: gekerpte Biegeproben, Aluminium AA7075, Kurzzeitermu Èdung, Rissenstehung, Risswachstum, mehrachsige Ermu Èdung, Lebensdauervorhersage.Pulsating 3P-bending fatigue tests are conducted on edgenotched specimens of AA7075. Measurements of electrical potential drop across notches were used to determine the number of cycles up to crack initiation. Cyclic material data determined from strain±controlled constant amplitude loading are use in FE-analyses to the determination time functions of the local stresses and strains at the notch root using non-linear material model according to Chaboche and Lemaitre. Using these FE computations, the fatigue life is predicted by the equivalent strain approach of the ªASME Boiler and Pressure Vessel Codeº and compared with the results of the plastic strain energy approach. It is found that both approaches lead to relatively good predictions.

The advances in using composite materials in different structural application lead to the need of continuous, robust, and structural health monitoring (SHM) systems. One of the most promising techniques for SHM is electromechanical impedance (EMI) technique which depends mainly on the coupling nature of piezoelectric ceramics. Piezoelectric wafer active sensors (PWAS) can be employed as both a well-controlled actuator and sensor at the same time for diagnostic algorithms based on EMI technique. The study presented in this paper interested in EMI technique application to detect damage in composite laminated plates by applying synchronized system of PWAS array operated remotely by exerting harmonic analysis in desired frequency ranges. Frequency ranges are selected upon modal analysis of the healthy tested structure. Harmonic analysis is carried out for different damage scenarios. Extracted electrical charge spectrum data from each PWAS for the previous scenarios can be processed to plot electrical impedance for each case. The modeling process was carried out using a finite element commercial package, ANSYS v.15.0 in which multiphysics-based modeling can be used for such structure made of laminated composite material. The extracted resultant spectrum, for healthy structure, is used as a datum in which it is related to its damaged counterparts through damage identification indices such as root mean square deviation (RMSD), and damage detection index (DDI). These indices were used as indicators for the changes in the modal parameters and hence, yielded reasonable results for both damage quantification and localization purposes.