Background
Southwest Research Institute (SwRI) has been heavily involved in designing and installing condition-based maintenance (CBM) systems in rugged environments. SwRI is pursuing future CBM programs which require us to refine our methods for efficiency, cost, and performance to be competitive. A CBM system relies on accelerometers to assess condition. The accelerometer original equipment manufacturer (OEM) prescribed surface preparation and sensor mounting method is not practical for many CBM applications. SwRI explored alternative accelerometer installation methods that are better suited for CBM systems.
Figure 1: Test Article on Shaker Table
Approach
The primary objective of this project was to assess the efficacy of accelerometers installed with alternate mounting methods and prepared surface conditions, to quantify any decrease in accuracy or fault detection capability compared to the OEM prescribed methods.
SwRI considered three alternate mounting methods and five different surface conditions. Combinations of mounting and surface methods were represented with 19 test articles with two accelerometers each. Each article was subjected to three vibration test profiles on an Unholtz-Dickie SA30E shaker table operated by Division 18.
Accomplishments
Most alternative methods were found to have a small loss in accuracy compared to the OEM control group; however, this loss was not enough to hinder condition assessment. Of particular interest, the method that was least expensive proved nearly identical to the OEM in performance and is now favored for future CBM projects.