Case History Periodic Impulse Detection Vertical stripes indicate - PowerPoint PPT Presentation

Production NVH Test Tools and Methods Case History – Periodic Impulse Detection Vertical stripes indicate periodic impulse events

Production NVH Test Tools and Methods Case History – Periodic Impulse Detection Re-sample the file relative to a reference shaft using 500 orders (1000 pts per rev)

Production NVH Test Tools and Methods Case History – Periodic Impulse Detection 4 Rev Frames stacked into a frame ensemble and viewed top-down form a matrix A column-wise variance statistic indicates periodic impulse

Production NVH Test Tools and Methods Case History – Periodic Impulse Detection The impulse indicator shows angular position of recurring impulse events that are periodic A metric representing the maximum will define the severity of the impulsive event

Production NVH Test Tools and Methods Case History – Periodic Impulse Detection The metric is added to the overall Decision matrix All metrics in the table are computed and tested simultaneously

Production NVH Test Tools and Methods Case History – Periodic Impulse Detection Classification of the periodic impulse is a requirement

Production NVH Test Tools and Methods Case History – Periodic Impulse Detection 4Revs will show a repeating impulse pattern that can be quantified by the relative distance in revs of each impulse event

Production NVH Test Tools and Methods Case History – Periodic Impulse Detection Qualifying peaks above a threshold produce a metric that returns the position of the peak in revs

Production NVH Test Tools and Methods Case History – Periodic Impulse Detection A Formula metric is defined that will report the distance between peaks Rev 3 position – Rev 1 position will equal 2 if this a 1/cycle impulse in the first rotation of the shaft Rev 4 position – Rev 2 position will equal 2 if this a 1/cycle impulse in the second rotation of the shaft Subtract 2 to make the metric = 0 if a periodic impulse in the correct rotation is detected

Production NVH Test Tools and Methods Case History – Periodic Impulse Detection A Boolean metric is created by testing the numeric formula result If a formula metric is = 0, then a periodic impulse is found at the correct interval and position and the Boolean is TRUE

Production NVH Test Tools and Methods Case History – Periodic Impulse Detection A Boolean formula combines two booleans into a single result On the Decision table, classification is simple and intuitive A 1/cyle impulse of sufficient amplitude was found

Production NVH Test Tools and Methods Case History – Periodic Impulse Detection The new metric is applied to 20,000 engines from 4 identical test stands stored in the historical database FCM Pk Amp Metric refinement and expected pass/fail rates are studied before taking this to production