Investigating the Effect of Wavy Roughness on the Comfort of Vehicle Passengers Using IRI Index

Estimating the safety and comfort of the occupants of a road-using vehicle is one of the most important issues facing researchers in the field of road and road safety. Road safety is examined in different branches. One of the most important parts of road safety assessment and maintenance management is the assessment and monitoring of road surface failures. The Road Roughness Index (IRI) is used for this purpose. . In order to evaluate the path of the road, in addition to evaluating the geometric design, it is also necessary to evaluate the geometry of the faults. If a criterion can be found to assess the situation, the critical state of the criterion can be found and if it reaches a critical state, the road condition can be considered unsafe or in need of improvement. In this research, the dynamic response of the vehicle while moving on roads with different rough shapes but with the same IRI (the case where the two-wheel IRI of the vehicle is equal to 10) is simulated by the software. In addition to examining the dynamic response of the front axle of the vehicle (due to the application of more force on the front axle) on common parameters such as: vertical acceleration, maximum vertical acceleration and the minimum root of vertical acceleration, to determine whether in a symmetrical roughness, again a response Is there dynamics for the left and right wheels? If a clear relationship can be established between the roughness created by the definition of the IRI index at the road surface and the shape of the roughness (wavelength and amplitude), it is possible to prioritize the breakdowns with critical wavelengths (most inconvenient). The results show that by further examination of the vertical acceleration at different speeds, it can be seen that in the amplitude of longer waves, the highest values ​​of vertical acceleration entered by the vehicle at speed. High speeds occur and also maximum vertical acceleration values ​​occur at lower wavelengths at lower speeds. For example, in parabolic failure, the maximum acceleration values ​​for the wave amplitudes of 0.1(m), 0.05(m), 0.01(m), 0.005(m) occur at speeds above 60 km / h. Vertical acceleration values ​​for wave amplitudes of 0.0025, 0.0015 and 0.001 occur at speeds of less than 40 km / h. At a speed of nearly 80 km / h, the value of the vertical acceleration of sinusoidal roughness (according to IRI) shows a significant difference of about 0.2 m / s relative to the parabolic.