About the Role of Interfaces on the Fatigue Crack Propagation in Laminated Metallic Composites

• Published in: Materials 2021-05, Vol.14 (10), p.2564
• Main Authors: Pohl, Philip Manuel, Kümmel, Frank, Schunk, Christopher, Serrano-Munoz, Itziar, Markötter, Henning, Göken, Mathias, Höppel, Heinz Werner
• Format: Article
• Language: English
• Subjects: Aluminum; Composite materials; Computed tomography; Constituents; Crack bridging; Crack initiation; Crack propagation; Cyclic loads; Damage tolerance; Deflection; Dissimilar materials; Dissimilar metals; Elastic properties; Fatigue failure; High cycle fatigue; Interfaces; Laminates; Low cycle fatigue; Mechanical properties; Metal fatigue; Modulus of elasticity; Monolithic materials; Numerical analysis; Propagation; Stress propagation; Synchrotron radiation; Synchrotrons; Titanium; Yield strength; Yield stress
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14102564

The influence of gradients in hardness and elastic properties at interfaces of dissimilar materials in laminated metallic composites (LMCs) on fatigue crack propagation is investigated experimentally for three different LMC systems: Al/Al-LMCs with dissimilar yield stress and Al/Steel-LMCs as well as Al/Ti/Steel-LMCs with dissimilar yield stress and Young’s modulus, respectively. The damage tolerant fatigue behavior in Al/Al-LMCs with an alternating layer structure is enhanced significantly compared to constituent monolithic materials. The prevalent toughening mechanisms at the interfaces are identified by microscopical methods and synchrotron X-ray computed tomography. For the soft/hard transition, crack deflection mechanisms at the vicinity of the interface are observed, whereas crack bifurcation mechanisms can be seen for the hard/soft transition. The crack propagation in Al/Steel-LMCs was studied conducting in-situ scanning electron microscope (SEM) experiments in the respective low cycle fatigue (LCF) and high cycle fatigue (HCF) regimes of the laminate. The enhanced resistance against crack propagation in the LCF regime is attributed to the prevalent stress redistribution, crack deflection, and crack bridging mechanisms. The fatigue properties of different Al/Ti/Steel-LMC systems show the potential of LMCs in terms of an appropriate selection of constituents in combination with an optimized architecture. The results are also discussed under the aspect of tailored lightweight applications subjected to cyclic loading.