Within the aerospace and transportation industries, it is always desirable to minimize weight without sacrificing strength. One such method of achieving this in aircraft wings and other aircraft structures is to use honeycomb paneling. Such structures are susceptible to damage from things like hail or tool drop, however, and the damage may not be noticeable from the surface. The face sheet may rebound, leaving crushing to the honeycomb core hidden beneath the surface. Accurately determining impact damage in aluminum honeycomb aircraft panels is critical to evaluating the remaining lifetime of these structures. The hidden crushed core decreases the residual strength of the panels, so it's important to detect it. Based on using a dial depth gauge for measuring dents, determining the impact damage in honeycomb aircraft panels can be laborious and subjective. If the impact damage also includes crushing of the internal honeycomb core, a manual tap tester is often used, which is both manual and subjective. Eddy current testing (ECT) thus represents a promising, semi-automated alternative, which is already a popular non-destructive evaluation (NDE) technique used to inspect cracks in aerospace components. Scanning over dented aluminum honeycomb core covered by a face sheet ultimately revealed that the sizes and locations of crushed core could be detected by scanning with an eddy current array. However, verifying these findings presented some challenges, and engineering simulation helped visualize the eddy current array. ANSYS Discovery AIM was used to simulate the eddy current testing and frequency response of a coil array hovering above an aluminum honeycomb panel, and ultimately helped verify the experimental electromagnetic findings.
Simulation provides valuable insight on how eddy current testing and measurements in honeycomb panels may vary from typical crack-detecting inspections, where eddy currents flow through essentially continuous medium. The simulation results showing the behaviors of eddy currents generated in complex geometries are important for designing eddy current probes specifically tailored to complex geometries, as might be the case when designing probes to inspect honeycomb structures, or probes to inspect other complex geometries such as aircraft wings or steam generators. These simulation results are also essential when validating experimental electromagnetic data. As a result, as companies continue to develop advanced NDE technologies such as eddy current testing for industries such as aerospace and petroleum, they may do so using the power of next-generation pervasive engineering simulation.
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