Biodynamic Response Of Human Body Research Articles

Multibody Biomechanical Modelling of Human Body Response to Direct and Cross Axis Vibration

Operators of the vehicles and heavy earth moving machinery are continuously exposed to low frequency whole-body vibration (WBV) of comprehensive magnitudes arising from tire/track-terrain interactions. Research studies shown a high presence of back disorders such as disc degeneration, muscular pain, among the occupational vehicle drivers subjected to whole-body vibration. The modelling and measurement of the biodynamic response of human body is major research topic, with applications to ergonomics, paasive or active suspension control system technologies, adverse effects on the human body that causes discomfort and some health issues. The risk of the vibration exposure depends on three different factors: the time span, the amplitude and the frequency of the transmitted vibration. In the field of automotive engineering, manufacturers and designers require to understand how the acceleration signals are amplified or damped by the human-seat interface in order to increase human comfort.Most of human body models reported in literature are lumped parameter. The limitation with lumped parameter model is that they can be analysed in one direction only. Human body is having complex motion so minimum two dimensional (2D) model need for analysing human body response. The models considered two objective functions with considering vertical or fore and aft vibrations. Multibody human body models of 20 degree of freedom (DOF) developed for seated human, and model parameters are optimized using genetic algorithm (GA) for published experimental data from literature. Model is able to match the published experimental data for Seat to Head Transmissibility (STHT) and Apparent Mass (AM).

Evaluation of Bio-Dynamic Responses of Human Body Subjected to Impacts Due to Speed Humps

Bio-dynamics of seated human subjects exposed to whole body vibration has been a topic of interest over the years. Most of the motorcycle riders are exposed to health risks, due to repeated exposure of mechanical shock when frequently riding over traffic speed humps. The present study describes a novel method to assess the acceleration transmissibility through the body and the apparent mass of the subject while riding a motorised two-wheeler over a speed hump. Sensitivity of human subjects to whole body vibration under low-frequency excitation in seated posture is also addressed by driving point mechanical impedance. Experiment methodology involves use of body mounted accelerometer as motion sensors to track these shocks for four healthy subjects. A four-degree of freedom lumped parameter model is simulated to quantify the instantaneous effects of mechanical shocks. This understanding is likely to aid the driving community, in general, and the motorcycle manufactures to incorporate better suspension and appropriate ergonomics considerations.

Evaluation of bio-dynamic responses of human body subjected to impacts due to speed humps

Bio-dynamics of seated human subjects exposed to whole body vibration has been a topic of interest over the years. Most of the motorcycle riders are exposed to health risks, due to repeated exposure of mechanical shock when frequently riding over traffic speed humps. The present study describes a novel method to assess the acceleration transmissibility through the body and the apparent mass of the subject while riding a motorised two-wheeler over a speed hump. Sensitivity of human subjects to whole body vibration under low-frequency excitation in seated posture is also addressed by driving point mechanical impedance. Experiment methodology involves use of body mounted accelerometer as motion sensors to track these shocks for four healthy subjects. A four-degree of freedom lumped parameter model is simulated to quantify the instantaneous effects of mechanical shocks. This understanding is likely to aid the driving community, in general, and the motorcycle manufactures to incorporate better suspension and appropriate ergonomics considerations.

Determination of reference values of apparent mass responses of seated occupants of different body masses under vertical vibration with and without a back support

The biodynamic response of human body seated without a back support and exposed to vertical whole-body vibration have been standardized in ISO 5982 and DIN 45676 in terms of driving-point mechanical impedance and apparent mass. A comparison of ranges defined in two standards, however, reveal considerable differences in both the magnitude and phase. Greater differences are more evident for the three body mass groups, which suggests the lack of adequate reference values of biodynamic responses of seated human subjects of different body masses. In this experimental study, the biodynamic responses of seated humans within three different body mass ranges are characterized under different magnitudes of vibration and three different sitting postures in an attempt to define reference values of apparent mass for applications in mechanical-equivalent model development and anthropodynamic manikin design. Laboratory measurements were performed with adult male subjects of total body mass in the vicinity of 55, 75 and 98 kg (nine subjects for each mass group) seated with and without an inclined back support and exposed to three different magnitudes of white-noise vertical vibration (0.5, 1.0 and 2.0 m/s 2 unweighted rms acceleration) in the frequency range between 0.5 and 20 Hz. The measured data were analyzed to derive the mean magnitude and phase responses for the three body masses, posture and excitation conditions. The mean magnitude responses of subjects within three mass groups were compared with idealized ranges defined in ISO 5982 and mean values described in DIN 45676 for no back support condition. The results revealed significant differences between the mean measured and standardized magnitudes, suggesting that the current standardized values do not describe the biodynamic responses of seated occupant of different masses even for the back not supported condition. The mean measured responses revealed most important effect of body mass, irrespective of the sitting posture. The reference values of apparent mass responses of seated body subject to vertical whole-body vibration are thus defined for three mass groups and different back support conditions that may be considered applicable for ranges of excitations considered. The responses of the body seated without a back support, also revealed notable influences of excitation magnitude, particularly on the primary peak frequencies.

Limiting Performance Analysis of Underwater Shock Isolation of a System with Biodynamic Response Using Genetic Algorithm

Biodynamic response of shipboard crew to underwater shock is of a major concern to navies. An underwater shock can produce very high accelerations, resulting in severe human injuries aboard a battleship. Protection of human bodies from underwater shock is implemented by installing onboard isolators. In this paper, the optimal underwater shock isolation to protect human bodies is studied. A simple shock-structure-isolator-human interaction model is first constructed. The model incorporates the effect of fluid-structure interaction, biodynamic response of human body, isolator influence. Based on this model, the optimum shock isolation is then formulated. The performance index and restriction are defined. Thirdly, GA (genetic algorithm) is employed to solve the formulated optimization problem. GA is a powerful evolutionary optimization scheme suitable for large-scale and multi-variable optimization problems that are otherwise hard to be solved by conventional methods. A brief introduction to GA is given in the paper. Finally, the method is applied to an example problem and the limiting performance characteristic is obtained.