Issue link: https://cp.revolio.com/i/854494
Four trips were recorded using two different bus models, Mercedes 2000 and MCI 2000. The busses were both approximately 10 years old and loaded at full capacity for each trip. These trips ranged in both road type, interstate highway to secondary roads, and distance, 95 – 1,200 miles. Trip 1 was primarily on secondary roads in the upstate of South Carolina. Trip 2 was a mix of road types but primarily interstate highway between Clemson-Charleston-Columbia, SC. Trip 3 was a round trip from Clemson, SC to Charlotte, NC and involved primarily interstate highway. Trip 4 was a round trip from Clemson, SC to Washington, D.C. Motor coach bus cargo-hold vibration was recorded from a total of 2,315 miles. 3. Data Analysis/ Results All vibration data was analyzed using SaverX software, Lansmont Corporation (Monterey, CA). The timer interval recordings were used to create summary power spectrum density (PSD) plots in the frequency domain for each trip recorded. The data from all three axes of each of the four trips was analyzed. Special attention was given to the vertical axis (y-axis) as is typical of current industry vibration specifications. A PSD graph of the lateral axis compares all four trips, Fig. 4. In Fig. 4, there is a clear difference between Trip 4 and the other trips shown on the PSD. This can be attributed to the fact that Trip 4 was driven with a different model bus than trips 1, 2 and 3. With such significantly different data, this suggests that bus model has a significant impact on vibration response in these vehicles. Figure 6 contains a PSD profile of the longitudinal motion of each trip. Trip 4 again appears different from the others due to the bus model. While the vertical axis is of primary interest in simulation, the lateral and longitudinal axes contain significant vibration input. ista views • July 2017 • www.ista.org Vibration Analysis of Motor Coach Buses Used in the Transport of Goods > CONTINUED FROM PAGE 19 > MORE ON PAGE 22 20 1.E-08 1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1 10 100 PSD (g 2 /Hz) Frequency (Hz) Trip 1 Trip 2 Trip 3 Trip 4 Figure 4: Graph comparing lateral PSD profiles for Trips 1, 2, 3 and 4. TRIP 1 TRIP 4 TRIP 2 TRIP 3 Figure 3: Four trip routes.