TTCI performed the shaker test on a computer controlled, electro-hydraulic structural test device used for applying dynamic inputs directly to full-scale railcar bodies, highway vehicles and other heavy structures. The Simuloader uses up to 11 actuators with capacities up to 750,000 lbs and a 6 inch stroke, a longitudinal actuator operating in FORCE control mode, vertical and lateral actuators operating in displacement control mode.
In order to correctly design the accelerated test, the following input signals forming the Environmental Data for both a Fatigue Analysis and an Accelerated Fatigue Test were needed:
TTCI were able to analyze the data gathered during the accelerated test using solely nCode GlyphWorks. "GlyphWorks enables us to import the test data. GlyphWorks fully supports filtering, spikes removal, data editing and offset. All the data treatment is done using standard embedded processes within GlyphWorks that require no customization. It was easy to get our signal data ready to be analyzed for fatigue damage," explains Juan C. Valdes-Salazar, Principal Investigator II at Transportation Technology Center.
The fatigue damage is then calculated from all the strain channels and the resulting damage is correlated with the environmental variables of vertical and lateral accelerations as well as the longitudinal coupler force. Accelerations at the carbody to suspension interface (truck bolster) are analyzed at the corresponding critical damage events to identify the associated carbody motions.
After the fatigue analyses have been performed, the procedure to generate the driver files to be used as inputs for the SMU is the following:
The procedure described in this article allows TTCI to successfully conduct both Fatigue Analyses and Accelerated Fatigue Test using nCode GlyphWorks. "We were able to generate the SMU driver files for the accelerated test by using nCode GlyphWorks. No customization was necessary during the process and we were able to accurately monitor the accelerated test and ensure proper damage was being applied. The results of the accelerated test confirmed the pre-test damage fatigue calculations," concludes Mr. Valdes-Salazar.