# Experimental and Mathematical Study of Flexible-Rigid Rail Vehicle Riding Comfort and Safety
## 4 Experimental Analysis  
An on-track vibration test was created to obtain better knowledge of the vibration transition between primary and secondary suspension systems, as well as the coupled shaking between the suspended equipment and its vehicle body. Accelerometers and displacement sensors were used to monitor accelerations on the bogie frame, wheelset axle-box, and connections between the vehicle body and the suspended equipment and its vehicle body [6]. These sensors were linked by cables to the data collection system in the equipment cabin. The on-track vibration test was developed to capture the vehicle dynamics over a protracted period continuously [31; 32; 33]. The vibration characteristics of the equipment are examined and illustrated in Figure 3.  
After measuring the accelerations of the equipment and the vehicle body in response to various bogie running performances, the vibration source and spectrum composition were analyzed. On a designated stretch of the IR track between Palwal and Mathura, the rolling stock is put through its paces at maximum speeds ten per cent faster than regular operating rates. Oscillation tests were carried out on a track in good condition at different speeds [34; 35].  
The frame acceleration passband frequency range is 0.5 to 12 Hz, while the frame acceleration sampling frequency is 2 kHz. The acceleration measurement device has a passband frequency range of 0.1-200 Hz and a sampling frequency of 1 kHz. An oscillation test performed on the real-world environment by RDSO validates the numerical model. The proposed numerical passive model's ride comfort for passengers is particularly compared to the experimental data acquired by RDSO [6]. RDSO was the organization that conducted the experiments. Oscillation trials are a form of on-track testing performed using a prototype coach that is equipped to record displacement, acceleration, events, and speed. Throughout the oscillation tests, the maximum vertical and lateral ride indices in both unladen and laden states were determined. The RDSO Sperling Ride Index method was used to compute the riding index. The value of the riding index, according to the RDSO Sperling Ride Index, was lower than 2.75 but still between 3.25 and 3.50 at most, with 3.25 being the preferred range. It was determined that the riding behavior of the same was adequate [36]. Yet, there  
Figure 3: (**a**) Rail vehicle test coach for experimental evaluation; (**b**) location of the different sensors for collecting data.  
is room for improvement in the ride index values. The experimental ride index and the numerical ride index are compared in Figure 4, which illustrates the comparison results under unladen and laden settings, respectively. Additionally, the findings generated from the numerical analysis of the suggested model have attained an excellent general agreement with the experimentally measured results. This can be seen by comparing the two sets of data. The difference in the riding index may be attributed, in large part, to factors that were omitted from consideration to simplify the mathematical model.  
Figure 4: Numerical–experimental comparison for (**a**) the unladen and (**b**) the laden state.