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Full-Text Articles in Aerospace Engineering
Ultrasonic Rayleigh Wave Inspection Of Waviness In Wind Turbine Blades: Experimental And Finite Element Method, Sunil Kishore Chakrapani, Vinay Dayal, Daniel J. Barnard, Aaron Eldal, Ryan Krafka
Ultrasonic Rayleigh Wave Inspection Of Waviness In Wind Turbine Blades: Experimental And Finite Element Method, Sunil Kishore Chakrapani, Vinay Dayal, Daniel J. Barnard, Aaron Eldal, Ryan Krafka
Sunil Kishore Chakrapani
This paper presents the investigation of discrete, out-of-plane waviness in thick composite plates with applications to wind turbine blades. The investigation was carried out with the help of air coupled ultrasonics and a two-step procedure was framed to assist production line implementation. The first step involved detection of marcels, and the second step involved the characterization of these marcels with the help of an index called aspect ratio. A set of standardized samples with known aspect ratios were fabricated and used for this study. Finite element models were created to understand the wave propagation in wavy composite plates. All the …
Inspection Of Helicopter Rotor Blades With The Help Of Guided Waves And "Turning Modes": Experimental And Finite Element Analysis, Daniel J. Barnard, Sunil Kishore Chakrapani, Vinay Dayal
Inspection Of Helicopter Rotor Blades With The Help Of Guided Waves And "Turning Modes": Experimental And Finite Element Analysis, Daniel J. Barnard, Sunil Kishore Chakrapani, Vinay Dayal
Sunil Kishore Chakrapani
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. …
Investigation Of Waviness In Wind Turbine Blades: Structural Health Monitoring, Sunil Kishore Chakrapani, Vinay Dayal, Daniel J. Barnard
Investigation Of Waviness In Wind Turbine Blades: Structural Health Monitoring, Sunil Kishore Chakrapani, Vinay Dayal, Daniel J. Barnard
Sunil Kishore Chakrapani
Waviness in composite wind turbine blades was detected and characterized with the help of air coupled ultrasonics. Based on the aspect ratio, the detected marcels are either accepted or rejected. A passive structural health monitoring approach has been presented here to monitor the accepted marcels above a threshold. The fatigue life of specimen is most affected in the presence of a marcel. Hence this study focused on the damage evaluation after fatigue testing. Wavy laminate was subjected to fatigue load to investigate the fracture mechanisms near the marcel. Different types of defects were identified from this study and were used …