title: Nondestructive evaluation of helicopter rotor blades using guided Lamb modes.
abstract: This paper presents an application for turning and direct modes in a complex composite laminate structure. The propagation and interaction of turning modes and fundamental Lamb modes are investigated in the skin, spar and web sections of a helicopter rotor blade. Finite element models were used to understand the various mode conversions at geometric discontinuities such as web-spar joints. Experimental investigation was carried out with the help of air coupled ultrasonic transducers. The turning and direct modes were confirmed with the help of particle displacements and velocities. Experimental B-Scans were performed on damaged and undamaged samples for qualitative and quantitative assessment of the structure. A strong correlation between the numerical and experimental results was observed and reported.
authors.affiliation: Department of Aerospace Engineering and Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50011, USA. Electronic address: csk@iastate.edu.
authors.forename: Sunil Kishore
authors.initials: SK
authors.lastname: Chakrapani
authors.affiliation: Center for Nondestructive Evaluation, Iowa State University, 1915 Scholl Road, Ames, IA 50011, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Barnard
authors.affiliation: Department of Aerospace Engineering and Center for Nondestructive Evaluation, Iowa State University, Ames, IA 50011, USA.
authors.forename: Vinay
authors.initials: V
authors.lastname: Dayal
mesh_terms: D000401:Aircraft / Q000295:instrumentation*; D003198:Computer Simulation; D004867:Equipment Design; D019544:Equipment Failure Analysis; D020342:Finite Element Analysis; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation*; D008962:Models, Theoretical; D012542:Scattering, Radiation; D014159:Transducers; D014463:Ultrasonography / Q000295:instrumentation*
keywords: FEA; Guided Lamb wave; Helicopter rotors; Turning modes