Review of Progress in Quantitative Nondestructive Evaluation
Modern helicopter rotor blades constructed of composite materials offer significant inspection challenges, particularly at inner structures, where geometry and differing material properties and anisotropy make placement of the probing energy difficult. This paper presents an application of Lamb waves to these structures, where mode conversion occurs at internal geometric discontinuities. These additional modes were found to successfully propagate to the targeted regions inside the rotor and back out, allowing evaluation of the structure. A finite element model was developed to simulate wave propagation and mode conversion in the structure and aid in identifying the signals received in the laboratory experiment. A good correlation between numerical and experimental results was observed.
American Institute of Physics
Barnard, Daniel J.; Chakrapani, Sunil Kishore; and Dayal, Vinay, "Inspection of helicopter rotor blades with the help of guided waves and "turning modes": Experimental and finite element analysis" (2012). Center for Nondestructive Evaluation Conference Papers, Posters and Presentations. 18.