The ride comfort of heavy trucks is related to many factors, which include vehicle operating scenarios and vehicle structure parameters. An investigation of the influence of different factors on the ride comfort of heavy trucks was conducted. Based on the elastic theory of a uniform Euler-Bernoulli beam with both ends free, a 6 degree of freedom (DOF) half rigid-elastic vibration model of the vertical dynamic response was developed. The rigid-elastic model is more suitable to describe the actual movement of heavy trucks. The DOFs include vertical displacements of the body and each of two axles, the pitch displacement of the body, and the first and second order bending displacements of the body.
The root mean square (RMS) values of body accelerations, dynamic deflections and relative dynamic loads form the evaluation index. Based on the rigid-elastic model, the influence of different factors on the ride comfort of heavy trucks is analyzed in the frequency domain. The results are as follows: (1) the vehicle speed has a large influence on the ride comfort of heavy trucks, and the ride comfort decreases with increased speed; (2) the influence of the road grade on the ride comfort of heavy trucks is immense, and the ride comfort decreases as the road profile worsens; (3) the influence of suspension parameters on the ride comfort of heavy trucks is very large and complex; (4) the tire stiffness has a great influence on body accelerations and relative dynamic loads and has a relatively small influence on dynamic deflections; (5) the body stiffness has a great influence on the ride comfort, as it mainly affects body accelerations, and greater body accelerations are related to lower body stiffness; (6) the load has a tremendous influence on body accelerations and relative dynamic loads and a relatively small influence on dynamic deflections, and the ride comfort decreases with smaller loads.