Estimation of influence of ride smoothness of transport-technological machines on driving safety in off-road conditions

BACKGROUND: Driving safety of transport-technological machines, especially in off-road conditions, largely depends on the stiffness and damping of suspension. These properties directly affect the ride smoothness and static transverse stability of the machine on a slope, ensure the ability of long-term motion on rough roads in the range of operating velocities without exceeding the established limits of vibration accelerations, causing unpleasant sensations and rapid fatigue of a driver, constant contact of wheels with the ground, as well as avoiding excessive wheel bump. Therefore, it is necessary to provide the suspension with the required elastic and damping characteristics by using a pneumohydraulic shock absorber in the design and to evaluate its effect on the safety of driving in off-road conditions. AIM: Development of a method for assessing the impact of ride smoothness of transport and technological machines on the main indicators of driving safety in off-road conditions in the development of new technical solutions aimed at improving the ride smoothness. METHODS: Modeling of oscillatory processes of the machine masses connected with each other by stiffness-damping links at unsteady and steady oscillations, modeling of the influence of the stiffness of the elastic suspension element on the static transverse stability of the machine on a slope are performed in the Mathcad software environment. RESULTS: As a result of mathematical modeling of oscillatory processes of masses of the machine it was established that the application of the proposed shock absorber allows in case of driving over a single bump of 0.08 m height at a speed of 30 km/h to reduce body displacement from 0,070 m to 0,056 m and its acceleration from 3,50 m/s2 to 1,35 m/s2, there by achieving complete damping of the oscillatory process of the masses already in the fourth period, and in the case of driving over a sinusoidal bump, the oscillatory process is largely stabilized, the wheel copies the profile of the bump, as a result of which the movement of the body decreases from 0,045 m to 0,030 m, and the acceleration of the body after the transition process decreases from 2,2 m/s2 to 0,8 m/s2. The analysis of evaluation of influence of smooth running on static transverse stability of the machine has shown that as a result of taking into account the elasto-hydraulic characteristics of the shock absorber and the pneumatic tires themselves it is possible to increase the angle of static stability on lateral overturning from 38° to 43° with maximum permissible angle of body roll of 8.4°. CONCLUSION: The knowledge of methods of estimation of influence of ride smoothness of transport-technological machines on the main indicators of driving safety in off-road conditions makes it possible to analyze the efficiency of application of the proposed technical solutions aimed at increasing the ride smoothness of the machine in off-road conditions.