![]() ![]() Being a non-redundant component, it is important to monitor the structural state of the spline section using real-time and non-intrusive nondestructive evaluation (NDE) methods. As the spline section of the gearbox is subjected to externally-cyclic loading (e.g., torque, tensile and bend), it is susceptible to develop fatigue cracks and spalling. The function of the gearbox in a helicopter transmission system is to keep the engine torque stable at optimum levels and transmit the power. The performance of the new sensor array is compared with the conventional AE sensors in terms of signal to noise ratio and the ability to detect fatigue cracking. The correlation of the cumulative AE events at the notch tip and the strain data is used to predict crack growth. The frequency spectra of continuous emissions and burst emissions are compared to understand the differences of plastic deformation and sudden crack jump. A significant amount of continuous emission due to the plastic deformation accompanied with the crack growth is observed. The AE data is continuously collected together with strain gauges strategically positioned on the structure. The fatigue crack growth of a notched and flattened gearbox spline component is monitored using a new piezoelectric sensor array and conventional sensors in a laboratory environment with the purpose of developing source models and testing the new sensor performance. In this paper, the new piezoelectric sensor array is introduced with the purpose of placing them within the gearbox to minimize the wave propagation path. Spline ridges are cut into this plate, a through-notch is cut perpendicular to the spline to model fatigue crack initiation, and tensile cyclic loading is applied parallel to the spline to propagate the crack. Here, to model how AE may detect fault propagation in a hollow cylindrical splined shaft, the splined section is essentially unrolled into a metal plate of the same thickness as the cylinder wall. The acoustic emission (AE) method is a direct way of detecting such active flaws, but its application to detect flaws in a splined shaft in a gearbox is difficult due to the interference of background noise and uncertainty about the effects of the wave propagation path on the received AE signature. Thus, early detection of flaws is required to prevent catastrophic failures. The splined section of the shaft is a critical and non-redundant element which is prone to cracking due to complex loading conditions. In many rotating machinery applications, such as helicopters, the splines of an externally-splined steel shaft that emerges from the gearbox engage with the reverse geometry of an internally splined driven shaft for the delivery of power. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |