Statistical approach to evaluating active reduction of crack propagation in aluminum panels with piezoelectric actuator patches

• Published in: Smart materials and structures Vol. 20; no. 8; pp. 085009 - 1-11
• Main Authors: PLATZ, R, STAPP, C, HANSELKA, H
• Format: Journal Article
• Language: English
• Published: Bristol Institute of Physics 01.08.2011
• Subjects: Aluminum; Crack propagation; Cracks; Exact sciences and technology; Fatigue failure; Fracture mechanics; Fracture mechanics (crack, fatigue, damage...); Fundamental areas of phenomenology (including applications); General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Panels; Physics; Piezoelectric actuators; Reduction; Solid mechanics; Structural and continuum mechanics; Transducers; Uncertainty; Statistical analysis; Piezoelectric sensor; Probabilistic approach; Thin shell; Surface crack; Rupture; Aluminium; Surface transducer; Modeling; Fatigue crack; Crack propagation; Uncertain system; Stress intensity factor; Piezoelectric actuators; Strength; Damaging; Panel surface
• ISSN: 0964-1726; 1361-665X
• DOI: 10.1088/0964-1726/20/8/085009

Fatigue cracks in light-weight shell or panel structures may lead to major failures when used for sealing or load-carrying purposes. This paper describes investigations into the potential of piezoelectric actuator patches that are applied to the surface of an already cracked thin aluminum panel to actively reduce the propagation of fatigue cracks. With active reduction of fatigue crack propagation, uncertainties in the cracked structure's strength, which always remain present even when the structure is used under damage tolerance conditions, e.g. airplane fuselages, could be lowered. The main idea is to lower the cyclic stress intensity factor near the crack tip with actively induced mechanical compression forces using thin low voltage piezoelectric actuator patches applied to the panel's surface. With lowering of the cyclic stress intensity, the rate of crack propagation in an already cracked thin aluminum panel will be reduced significantly. First, this paper discusses the proper placement and alignment of thin piezoelectric actuator patches near the crack tip to induce the mechanical compression forces necessary for reduction of crack propagation by numerical simulations. Second, the potential for crack propagation reduction will be investigated statistically by an experimental sample test examining three cases: a cracked aluminum host structure (i) without, (ii) with but passive, and (iii) with activated piezoelectric actuator patches. It will be seen that activated piezoelectric actuator patches lead to a significant reduction in crack propagation.