Influence of layer architecture and constituent selection on the quasi-static and cyclic fracture mechanical behavior of metallic laminate materials.

• Applicant: Privatdozent Dr.-Ing. Heinz-Werner Höppel
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 492276977

It is known from experimental literature that defined material inhomogeneity effects at interfaces can have a positive effect on the fatigue life of laminated metallic composites (LMCs). On the other hand, existing numerical models can quantitatively predict crack bifurcation, delamination and shielding effects of the crack tip driving force near individual interfaces with dissimilar properties. However, it is currently not possible to predict the effects of dissimilar properties at interfaces on cyclic crack propagation in LMCs, based on which a quantitative fracture mechanics model description could be derived.Therefore, the overall objective of this research project is to investigate the different effects of dissimilar properties at interfaces on the fracture mechanical behavior under cyclic as well as under quasi-static loading and to identify the corresponding material system-, laminate architecture- and loading-side influencing factors as well as associated damage mechanisms of metallic laminates. In addition, the effects of toughening mechanisms at interfaces in LMCs on the damage processes will be identified by means of in-situ experiments in the unique GK-REM. On this basis, an analytical cross-material model is to be developed that takes into account the synergetic interaction of the various influencing variables on the fracture mechanical behavior. Based on this model, a fracture-mechanically optimized laminate design will be derived and subsequently manufactured and investigated to validate the model.The focus is on the interaction of dissimilar properties with the lamellar architecture. The influences of the variation of the lamellar architecture, such as the interfacial density and the layer thickness, on the fracture mechanical behavior will be systematically investigated in addition to the effects of strength gradients and gradients in the elastic modulus at the interfaces. In order to investigate the influence of the dissimilar properties at the interfaces, different LMCs and bimetals are to be specifically produced by means of the ARB process, which are then investigated under a quasi-static or cyclic loading with regard to their fracture mechanical properties. This makes it possible to understand the influencing variables on the fracture-mechanical behavior in detail, both in isolation and in combination with each other, and to derive an optimized material design from this.

• DFG Programme: Research Grants