Multi-body modelling and ride comfort analysis of a seated occupant under whole-body vibration

Abstract

Seated occupants of any on/off-road vehicle are continuously exposed to undue low-frequency mechanical whole-body vibration ( WBV) owing to the vibration conveyed from seat and backrest because occupants need to compromise with comfort and safety, leading to several musculoskeletal disorders and injuries in the body. Pain in the lumbar region is one of the most common problems that develop because of force transmitted from the backrest. Thus, consideration of backrest is highly essential while developing a biomechanical model for ride comfort analysis. For this purpose, a 20 degrees-of-freedom ( dofs) biomechanical model has been proposed with a backrest to analyse cross-coupled segmental transmissibility. The interconnection between different segments of mass and backrest are modelled using eight linearized (direct as well as cross-coupled) stiffness and damping parameters. Biomechanical model parameters are estimated and optimized through a multi-objective firefly algorithm by minimizing the sum of squares error difference between analytical results and experimental segmental transmissibility published in the literature. Subsequently, ride comfort analysis is performed by integrating the proposed model with 7- dofs passenger car model. For different body segments, simulated results are obtained in terms of vertical accelerations and compared with ride comfort standards as per ISO 2631-1:1997. Additionally, a sensitivity analysis (±20% variation in mass, stiffness and damping) is performed to enhance the ride comfort of the occupant. The findings suggest that designers must focus on the pelvis, lower and upper back regions to improve the ride comfort of the occupants. The concepts and ideas outlined in this article are directly applicable in making human dummies, car suspension and seat design in the industry.

Ride comfort and segmental vibration transmissibility analysis of an automobile passenger model under whole body vibration

“…This model was stretched to 14- dofs by the authors in 16 improved the model efficiency. Recently, the authors in 17 , 18 developed 10- dofs biomechanical model to mimic real human structure. With modal and sensitive analysis, they observe the magnitude of biodynamic responses that get affected more by pelvis and least by head parameters.…”

“…To perform ride comfort analysis, harmonic excitations ( z = Ze jωt ) with an amplitude ( Z = 0.025 m) at four wheels are given as input. The coupled equation of motion of humans with a full car model derived by 18 is modified with 32- dofs seated occupant model. To acquire the acceleration response of various segments (head, thorax, abdomen, and pelvis) a code is written on MATLAB.…”

Ride comfort and segmental vibration transmissibility analysis of an automobile passenger model under whole body vibration

“…Since, the brain, which is a vital component of the head, connects the human organs and sensory systems. The vibration coming on to the head has been given prime importance and corrective measures have been taken to reduce the amount of vibration passing to the head (Guruguntla and Lal, 2020), (Guruguntla and Lal, 2022c). Hence, the in uence of magnitude variation in characteristic parameters on the biodynamic response (STHT) is performed in this section.…”

“…In the past, number of MB models have developed to represent seated human occupants but none of these models considered thighs, legs and feet, in this way the present work is novel. The thighs, legs, and feet are included in this work, which is an expansion of (Guruguntla and Lal, 2022c). Since the dynamic behaviour of the seated human is characterized equally by seat-to-head transmissibility (STHT) and apparent mass (AM).…”