Investigation of three-dimensional coupled vibration response of driver-vehicle-road system

Vibrations generated during driving have significant impacts not only on driving comfort, health risks, and work efficiency, but also on vehicle performance and road structural safety. Although existing studies have addressed, to some extent, the coupled vibration responses among the driver, vehicle, and road, most of them simplify the human body as a single-degree-of-freedom (DOF) or lumped mass model, failing to capture the differentiated responses of multiple body parts. Moreover, current coupling models typically employ idealized tire-road contact assumptions, which are inadequate for describing the dynamic behaviors of tire enveloping and filtering effects. In this context, this study investigated the three-dimensional (3D) coupled vibration behaviors of the driver-vehicle-road system and proposed a comprehensive modeling framework based on a 3D flexible roller contact tire model. A multi-level and expandable analytical approach was established, ranging from refined driver response analysis and multi-source excitation modeling to vehicle-road structural response assessment, providing theoretical support for evaluating coupled vibration effects under complex driving conditions. The work began with a focused review of advances in functional pavement research, arguing for a methodological shift from traditional tire-pavement coupling toward comprehensive vehicle-pavement interaction analysis. This review synthesized the advantages and limitations of existing tire-pavement coupling studies for addressing functional-pavement challenges and demonstrated that integrating multifunctional tire formulations into vehicle-system analysis enables the study of more complex dynamic interactions, broader engineering questions, and enhanced practical relevance. The review concludes that transitioning to vehicle-pavement interaction analysis is essential for advancing functional pavement science. Based on this conceptual foundation, 3D pavement-surface models with varying roughness levels were generated using fractal theory and fractal interpolation. A 3D flexible roller contact tire model was developed to represent spatial contact and deformation between a tire and a rough pavement surface, where the pavement was treated as a rigid plate (i.e., road structural vibration is neglected). Integration of the road-surface and tire formulations yielded a 3D vehicle dynamic model, which was validated against classical point-contact theory and experimental measurements. Results indicated that the 3D contact formulation captured spatial deformation and coupling effects that transferred additional energy into the vehicle system, producing larger predicted acceleration responses than conventional point-contact models and improving model fidelity for vehicle-level vibration prediction. Building on the validated vehicle model, the human response was refined through a coupled 18-DOF 3D driver-vehicle model that explicitly represented eleven anatomical components of the seated occupant. Under stochastic pavement-roughness excitation, organ-level vibration exposure, driving comfort, and motion sickness index (MSI) were evaluated. The analysis showed that pavement unevenness is the dominant factor influencing comfort and MSI; vehicle speed has a limited effect on MSI under fixed trip durations; and the stomach, lumbar spine, liver, and head are the most sensitive organs in descending order. Complementarily, shock-excitation scenarios composed of multiple representative 3D pothole conditions were investigated using a simplified driver-vehicle model. Assessment metrics included ISO 2631-1 weighted root-mean-square (RMS) and total vibration dose value (VDVtotal) measures, together with partial-correlation analysis to reveal nonlinear relations among excitation parameters. Findings indicated that pothole depth substantially outweighs speed in determining shock severity and that asynchronous tire excitations could help mitigate occupant discomfort. Finally, considering that road structural responses cannot be neglected under heavy-duty truck operation conditions, this study introduced another innovative tire dynamic model named the advanced 3D flexible roller contact tire model, improving upon traditional tire-pavement coupling formulations by accounting for the dynamic coupling deformation behavior of the tire and the road structure during rolling motion. Based on this model, a fully coupled 3D driver-vehicle-road vibration model was established, enabling simultaneous dynamic analysis of the human body, vehicle, and road structure. A comprehensive evaluation was conducted using overall vibration total value (OVTV), dynamic load coefficient (DLC), and vertical pavement deformation metrics. The effects of pavement roughness level, driving speed, and ambient temperature on driver comfort and road structural safety were systematically examined. The results showed that the proposed model could calculate dynamic responses across all subsystems. The energy transfer capability of the proposed innovative tire model significantly enhanced the fidelity of the system-level vibration coupling expression. Pavement roughness remained the dominant factor affecting driving comfort, dynamic loading, and road structure safety.In summary, this dissertation established a systematic 3D driver-vehicle-road coupled vibration analysis framework that linked theoretical progression from tire-road coupling to vehicle-road interaction, developed and validated innovative 3D tire-vehicle-road formulations under both rigid- and deformable-road assumptions, and provided comprehensive tools for intelligent driving control, vibration-induced health risk assessment, and resilient pavement design. The research exhibits strong engineering applicability and broad potential for academic extension.