Identification of damping and stiffness parameters of cervical and lumbar spines of supine humans under vertical whole-body vibration

This work presents a methodology to estimate the unknown damping and stiffness parameters of supine humans at the cervical and lumbar regions while reducing errors presented in the data. Modal parameters (natural frequencies, damping ratios, and eigenvectors) determined from experiments on 11 supine-human subjects exposed to vertical whole-body vibration were used in an inverse modal problem to solve for physical parameters (stiffness and damping). Due to uncertainty in the error level in the modal data, a methodology is presented to reduce the error by correcting the phase of the eigenvectors. Constraints that preserve the inter-connectivity of the physical stiffness and damping matrices were utilized via semi-definite programming. A four-degree-of-freedom human model, as suggested by the experimental modal analysis, was used for computational and analysis purposes. The resulting damping and stiffness parameters of the cervical and lumbar regions produced the right structure of the stiffness and damping matrices and satisfied the equation of motion. Validation analysis on the predicted acceleration response in the time domain of the human model, using the resulting damping and stiffness parameters, demonstrated characteristics very close to those found by the experiments. This work presents new information with many potential applications to the field of biomechanics.

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Biodynamic Model of the Seated Human Body under the Vertical Whole Body Vibration Exposure

10.20855/ijav.2019.24.41335 ◽

2019 ◽

Vol 24 (4) ◽

pp. 657-664 ◽

Cited By ~ 1

Author(s):

Vikas Kumar Kumar ◽

V. H. Saran

Keyword(s):

Human Body ◽

Human Subjects ◽

Whole Body Vibration ◽

Whole Body ◽

Apparent Mass ◽

Body Vibration ◽

Phase Errors ◽

Target Values ◽

Identification Technique ◽

Biodynamic Model

The seat-to-head transmissibility and apparent mass characteristics are measured for the seated human subjects exposed to vertical whole-body vibration in the 0.5-20 Hz frequency range at a vibration magnitude of 1.0 m/s2 rms. The experiments are conducted on test subjects seated in an upright posture. A biodynamic model has been developed for bio-mechanical parameters that are estimated on the basis of identified biodynamic responses. The parameters identification technique employs a genetic algorithm for the solution of the function comprising sum of squared magnitude and phase errors related with target values of seat-to-head transmissibility and apparent mass. The developed model presents the target values of magnitude associated with apparent mass and seat-to-head transmissibility. The natural frequencies of the model have been found at up to 5.0896 Hz. The model also presents the resonant frequencies calculated on the basis of both biodynamic response functions very close to that found for seated human body experimentally.

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The Effects of Whole-Body Vibration on the Cross-Transfer of Strength

The Scientific World JOURNAL ◽

10.1100/2012/504837 ◽

2012 ◽

Vol 2012 ◽

pp. 1-11 ◽

Cited By ~ 17

Author(s):

Alicia M. Goodwill ◽

Dawson J. Kidgell

Keyword(s):

Strength Training ◽

Whole Body Vibration ◽

Peak Height ◽

Whole Body ◽

Control Group ◽

Body Vibration ◽

Training Groups ◽

Cross Education ◽

The Cross ◽

The Right

This study investigated whether the use of superimposed whole-body vibration (WBV) during cross-education strength training would optimise strength transfer compared to conventional cross-education strength training. Twenty-one healthy, dominant right leg volunteers (21±3years) were allocated to a strength training (ST,m=3,f=4), a strength training with WBV (ST + V,m=3,f=4), or a control group (no training,m=3,f=4). Training groups performed 9 sessions over 3 weeks, involving unilateral squats for the right leg, with or without WBV (35 Hz; 2.5 mm amplitude). All groups underwent dynamic single leg maximum strength testing (1RM) and single and paired pulse transcranial magnetic stimulation (TMS) prior to and following training. Strength increased in the trained limb for the ST (41%;ES=1.14) and ST + V (55%;ES=1.03) groups, which resulted in a 35% (ES=0.99) strength transfer to the untrained left leg for the ST group and a 52% (ES=0.97) strength transfer to the untrained leg for the ST + V group, when compared to the control group. No differences in strength transfer between training groups were observed(P=0.15). For the untrained leg, no differences in the peak height of recruitment curves or SICI were observed between ST and ST + V groups(P=1.00). Strength training with WBV does not appear to modulate the cross-transfer of strength to a greater magnitude when compared to conventional cross-education strength training.

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A seated human model for predicting the coupled human-seat transmissibility exposed to fore-aft whole-body vibration

Applied Ergonomics ◽

10.1016/j.apergo.2019.102929 ◽

2020 ◽

Vol 84 ◽

pp. 102929 ◽

Cited By ~ 1

Author(s):

Eunyeong Kim ◽

Mohammad Fard ◽

Kazuhito Kato

Keyword(s):

Whole Body Vibration ◽

Human Model ◽

Whole Body ◽

Body Vibration

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Three-Dimensional Modeling of Supine Human and Transport System Under Whole-Body Vibration

Journal of Biomechanical Engineering ◽

10.1115/1.4024164 ◽

2013 ◽

Vol 135 (6) ◽

Cited By ~ 2

Author(s):

Yang Wang ◽

Salam Rahmatalla

Keyword(s):

Dynamic Model ◽

Transport System ◽

Vibration Suppression ◽

Whole Body Vibration ◽

Three Dimensional ◽

Vertical Direction ◽

Human Model ◽

Whole Body ◽

Transport Systems ◽

Body Vibration

The development of predictive computer human models in whole-body vibration has shown some success in predicting simple types of motion, mostly for seated positions and in the uniaxial vertical direction. The literature revealed only a handful of papers that tackled supine human modeling in response to vertical vibration. The objective of this work is to develop a predictive, multibody, three-dimensional human model to simulate the supine human and underlying transport system in response to multidirectional whole-body vibration. A three-dimensional dynamic model of a supine human and its underlying transport system is presented in this work to predict supine-human biodynamic response under three-dimensional input random whole-body vibration. The proposed supine-human model consists of three interconnected segments representing the head, torso-arms, and pelvis-legs. The segments are connected via rotational and translational joints that have spring-damper components simulating the three-dimensional muscles and tissuelike connecting elements in the three x, y, and z directions. Two types of transport systems are considered in this work, a rigid support and a long spinal board attached to a standard military litter. The contact surfaces between the supine human and the underlying transport system are modeled using spring-damper components. Eight healthy supine human subjects were tested under combined-axis vibration files with a magnitude of 0.5 m/s2 (rms) and a frequency content of 0.5–16 Hz. The data from seven subjects were used in parameter identification for the dynamic model using optimization schemes in the frequency domain that minimize the differences between the magnitude and phase of the predicted and experimental transmissibility. The predicted accelerations in the time and frequency domains were comparable to those gathered from experiments under different anthropometric, input vibration, and transport conditions under investigation. Based on the results, the proposed dynamic model has the potential to be used to provide motion data to drive a detailed finite element model of a supine human for further investigation of muscle forces and joint dynamics. The predicted kinematics of the supine human and transport system would also benefit patient safety planners and vibration suppression designers in their endeavors.

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