Numerical models based on cohesive zones are usually used to model and simulate the mechanical behavior of laminated carbon fiber reinforced polymers (CFRP) in automotive and aerospace applications. The codes of these models require different interlaminar properties under single and combined loading conditions. The current work focuses on determining the interlaminar energy release rate (GI) under Mode I loading of a double cantilever beam (DCB) specimen of unidirectional CFRP, serving as reference material. The novelty of the investigation lies within the improvement of the testing methodology by introducing digital image correlation (DIC) as an extensometer. This tool allows for crack growth measurement, phenomenological visualization and quantification of different effects under Mode I loading. Multiple methodologies from different international standards and further common techniques for the determination of the evolution of GI as crack resistance (R-)curves are compared. Primarily metrological sources of uncertainty - in contrast to material specific related uncertainties - will be discussed as a sensitivity analysis. Additionally, the current work offers a detailed insight into the constraints and assumptions as well as an exploration of different methods for the determination of further material parameters with the help of DIC. The main aim is an improvement of the measurement and an increase in the reliability of measured data as a future outlook for rate dependent testing for crashworthiness simulations.
21. Symposium Verbundwerkstoffe und Werkstoffverbunde
July 5-7, 2017
R-curve, crack tip tracking, fracture toughness, DIC, DCB, Standards, Metrology, PMC