Mechanical Parameters of Standing Body and Applications in Human–Structure Interaction

2017 ◽  
Vol 09 (02) ◽  
pp. 1750021 ◽  
Author(s):  
Huixuan Han ◽  
Ding Zhou ◽  
Tianjian Ji
Keyword(s):  
Dynamic Characteristics ◽  
Human Body ◽  
Damping Ratio ◽  
Coupled System ◽  
The Body ◽  
Degree Of Freedom ◽  
Least Square ◽  
Mechanical Parameters ◽  
Structure Interaction ◽  
Body Model

In this paper, the dynamic interaction of human body and structure is studied The shaking table experiment with a person standing on a rigid table supported by springs is firstly carried out to determine the dynamic characteristics of the coupled system. It is shown that the body mainly contributes only one degree of freedom to the human-structure coupled system. Then, the two-degree-of-freedom (TDOF) coupled model of the human-structure system is developed through the energy variation by considering the standing human body as an elastic bar of two segments with distributed mass, stiffness and damping. Based on the experiment data, the dynamic parameters of the TDOF coupled system are determined by using the least square method (LSM). The mechanical parameters such as the damping ratio and the distributions of mass and stiffness of the human body model of two segments are identified by adopting the inversing technique Finally, the determined body model is applied to analyze the free vibration of beams and plates occupied by standing persons. The governing differential equations of the human-beam system and the human-plate system are, respectively, derived out. The dynamic characteristics of the human-structure interaction are obtained by the use of the complex mode theory. The results are compared with the experimental ones and those from the finite element simulations. Good agreement is observed for all cases.

scholarly journals Identification of Dynamic Parameters of Pedestrian Walking Model Based on a Coupled Pedestrian–Structure System

2021 ◽  
Vol 11 (14) ◽  
pp. 6407
Author(s):  
Huiqi Liang ◽  
Wenbo Xie ◽  
Peizi Wei ◽  
Dehao Ai ◽  
Zhiqiang Zhang
Keyword(s):  
Negative Correlation ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Field Testing ◽  
The Body ◽  
Structural Vibration ◽  
Pedestrian Dynamics ◽  
Structure Interaction ◽  
Mass Spring ◽  
Stiffness And Damping

As human occupancy has an enormous effect on the dynamics of light, flexible, large-span, low-damping structures, which are sensitive to human-induced vibrations, it is essential to investigate the effects of pedestrian–structure interaction. The single-degree-of-freedom (SDOF) mass–spring–damping (MSD) model, the simplest dynamical model that considers how pedestrian mass, stiffness and damping impact the dynamic properties of structures, is widely used in civil engineering. With field testing methods and the SDOF MSD model, this study obtained pedestrian dynamics parameters from measured data of the properties of both empty structures and structures with pedestrian occupancy. The parameters identification procedure involved individuals at four walking frequencies. Body frequency is positively correlated to the walking frequency, while a negative correlation is observed between the body damping ratio and the walking frequency. The test results further show a negative correlation between the pedestrian’s frequency and his/her weight, but no significant correlation exists between one’s damping ratio and weight. The findings provide a reference for structural vibration serviceability assessments that would consider pedestrian–structure interaction effects.

A New Method to Concentrate Electromagnetic Field Within ROI Using a High Dielectric Material in 3T Body MRI

2013 ◽  
Author(s):  
Bu S. Park ◽  
Sunder S. Rajan ◽  
Leonardo M. Angelone
Keyword(s):  
Numerical Simulation ◽  
Electromagnetic Field ◽  
Human Body ◽  
Region Of Interest ◽  
Dielectric Materials ◽  
The Body ◽  
Human Body Model ◽  
Body Model ◽  
Simulation Results ◽  
High Dielectric

We present numerical simulation results showing that high dielectric materials (HDMs) when placed between the human body model and the body coil significantly alter the electromagnetic field inside the body. The numerical simulation results show that the electromagnetic field (E, B, and SAR) within a region of interest (ROI) is concentrated (increased). In addition, the average electromagnetic fields decreased significantly outside the region of interest. The calculation results using a human body model and HDM of Barium Strontium Titanate (BST) show that the mean local SAR was decreased by about 56% (i.e., 18.7 vs. 8.2 W/kg) within the body model.

Parametric Human Body Model for Digital Apparel Design

2013 ◽  
Vol 365-366 ◽  
pp. 121-124
Author(s):  
Shu Xia Wang ◽  
Sheng Feng Qin ◽  
Cong Ying Guan ◽  
Sui Huai Yu
Keyword(s):  
Cross Section ◽  
Human Body ◽  
Body Shape ◽  
Body Part ◽  
The Body ◽  
Human Model ◽  
Body Model ◽  
Key Points ◽  
Cloud Points ◽  
Body Scanner

With the advance in 3D body scanning technology, it opens opportunities for virtual try-on and automatic made-to-measure in apparel products domain. This paper proposed a novel feature-based parametric method of human body shape from the cloud points of 3D body scanner [T2. Firstly, we improved the skeleton construction through adding and adjusting the position of joints. Secondly, automatic extraction approach of semantic feature cross-sections is developed based on the hierarchy. According to the unique distribution of cloud points of each cross-section of each body part, the extraction method of key points on the cross-section is described. Thirdly, we presented an interpolation approach of key points which fit cardinal spline to cross-section for each body part, in which tension parameter is used to represent the simple deformation of body shape. Finally, a connection approach of body part is proposed by sharing a boundary curve. The proposed method has been tested with our virtual human model (VHM) system which is robust and easier to use. The process generally requires about five minutes for generating a full body model that represents the body shape captured by 3D body scanner. The model can be imported in a CAD environment for application to a wide variety of ergonomic analyses.

The Key Role of Headrest Optimization in Driver Comfort

2019 ◽  
Vol 24 (3) ◽  
pp. 592-599
Author(s):  
Hamid Gheibollahi ◽  
Masoud Masih-Tehrani ◽  
Mohammadmehdi Niroobakhsh
Keyword(s):  
Human Body ◽  
The Body ◽  
Human Body Model ◽  
Sitting Posture ◽  
Conventional Vehicle ◽  
Body Model ◽  
Basic Model ◽  
Proposed Model ◽  
Stiffness And Damping

In this study, adding a headrest to the conventional vehicle driver seat is investigated to improve the driver comfort and decrease the driver damages. For this purpose, a conventional biomechanical human body model of wholebody vibrations is provided and modified by adding a head degree of freedom to the body model and a headrest to the seat model. The basic model is in the sitting posture, lumped parameters and has nine DOFs for the human body, on contrary to the proposed model which has ten DOFs. The new human body DOF is the twisting motion of the head and neck. This new DOF is generated because of headrest adding to the driver’s seat. To determine the head discomforts, the Seat to Head (STH) indexes are studied in two directions: horizontal and vertical. The Genetic Algorithm (GA) is used to optimize the STH in different directions. The optimization variables are stiffness and damping parameters of the driver’s seat which are 12 for the basic model and are 16 for a new seat. The integer programming is used for time reduction. The results show that new seat (equipped by headrest) has very better STH in both directions.

Identification and Experimental Validation of Damping Ratios of Different Human Body Segments Through Anthropometric Vibratory Model in Standing Posture

2006 ◽  
Vol 129 (4) ◽  
pp. 566-574 ◽  
Author(s):  
T. C. Gupta
Keyword(s):  
Human Body ◽  
Damping Ratio ◽  
Physical Structure ◽  
The Body ◽  
Anthropometric Data ◽  
Body Segments ◽  
Lumped Parameter ◽  
Mass Damper ◽  
Linear Spring ◽  
Experimental Response

A 15degrees of freedom lumped parameter vibratory model of human body is developed, for vertical mode vibrations, using anthropometric data of the 50th percentile US male. The mass and stiffness of various segments are determined from the elastic modulii of bones and tissues and from the anthropometric data available, assuming the shape of all the segments is ellipsoidal. The damping ratio of each segment is estimated on the basis of the physical structure of the body in a particular posture. Damping constants of various segments are calculated from these damping ratios. The human body is modeled as a linear spring-mass-damper system. The optimal values of the damping ratios of the body segments are estimated, for the 15degrees of freedom model of the 50th percentile US male, by comparing the response of the model with the experimental response. Formulating a similar vibratory model of the 50th percentile Indian male and comparing the frequency response of the model with the experimental response of the same group of subjects validate the modeling procedure. A range of damping ratios has been considered to develop a vibratory model, which can predict the vertical harmonic response of the human body.

scholarly journals Rubber Hand Illusion does not arise from comparisons with internal body models: a new multisensory integration account of the sense of ownership

2018 ◽  
Author(s):  
Piotr Litwin
Keyword(s):  
Multisensory Integration ◽  
Human Body ◽  
The Body ◽  
Rubber Hand Illusion ◽  
Multisensory Perception ◽  
Top Down ◽  
Rubber Hand ◽  
Sense Of Ownership ◽  
Body Model ◽  
Internal Body

Human body sense is surprisingly flexible – precisely administered multisensory stimulation may result in the illusion that an external object is part of one’s body. There seems to be a general consensus that there are certain top-down constraints on which objects may be incorporated: in particular, to-be-embodied objects should be structurally similar to a visual representation stored in an internal body model for a shift in one’s body image to occur. However, empirical evidence contradicts the body model hypothesis: the sense of ownership may be spread over objects strikingly distinct in morphology and structure (e.g., robotic arms or empty space) and direct empirical support for the theory is currently lacking. As an alternative, based on the example of the rubber hand illusion (RHI), I propose a multisensory integration account of how the sense of ownership is induced. In this account, the perception of one’s own body is a regular type of multisensory perception and multisensory integration processes are not only necessary but also sufficient for embodiment. In this paper, I propose how RHI can be modeled with the use of Maximum Likelihood Estimation and natural correlation rules. I also discuss how Bayesian Coupling Priors and idiosyncrasies in sensory processing render prior distributions interindividually variable, accounting for large interindividual differences in susceptibility to RHI. Taken together, the proposed model accounts for exceptional malleability of human body perception, fortifies existing bottom-up multisensory integration theories with top-down models of relatedness of sensory cues, and generates testable and disambiguating predictions.

A Momentum-Based Algorithm for Identifying the Inertia Properties of a Human Body: A Preliminary Study

2010 ◽  
Author(s):  
Qi Lu ◽  
Ou Ma
Keyword(s):  
Human Body ◽  
Measurement Errors ◽  
Equations Of Motion ◽  
Least Square Method ◽  
Internal Force ◽  
Momentum Equation ◽  
The Body ◽  
Least Square ◽  
Identification Algorithm ◽  
Force Data

The body segment parameters (BSP) of a human body are critical information for modeling, simulating, and understanding human dynamics. The determination of BSPs of human bodies has received increasing attention in biomechanics, sport science, ergonomics, rehabilitation and other fields. This paper presents a momentum-based identification algorithm for dynamically estimating the BSPs of a human body. The human body is modeled as a multibody dynamical system, and the momentum equation of the system can be derived by applying the principle of impulse and momentum. It is possible to formulate the momentum equations corresponding to a set of experiment tests into a linear regression form with respect to the unknown BSPs, which then can be solved using the least square method or other methods. The momentum-based algorithm requires inputting position, velocity, and external force data only. Since acceleration and all the internal force data is not needed, the algorithm is less demanding on measurements and is also less sensitive to measurement errors. As a result, it is practically more appealing than the algorithms depending on the equations of motion. The paper presents the momentum-based inertia identification algorithm along with a simulation study of the algorithm using a simplified trunk-leg model representing a main portion of a human body.

Study on Dynamic Responses of Human-Structure Interaction System

2013 ◽  
Vol 438-439 ◽  
pp. 775-778
Author(s):  
Yi He Wang ◽  
Na Yang
Keyword(s):  
Dynamic System ◽  
Fundamental Frequency ◽  
Dynamic Characteristics ◽  
Degrees Of Freedom ◽  
Natural Frequencies ◽  
Coupled System ◽  
Dynamic Responses ◽  
Major Topic ◽  
Integer Multiple ◽  
Structure Interaction

t has previously been shown that human-structure dynamic system received much attention as a major topic in the serviceability performance and safety problems. In this study, the structure occupied by human are considered as a two degrees-of-freedom system. The dynamic characteristics of human-structure system are investigated by deriving the eigenvalue equation of the system. The response of structure to a person walking across it at various rates of walking is also researched. The results show that the pair natural frequencies of coupled system have a contrary trend when the crowd densities increase. It also demonstrates that the resonant situation occurs when structural fundamental frequency is equal to or an integer multiple of the pacing frequency.

An Analysis of the Dynamic Characteristics of a Force Plate

1972 ◽  
Vol 5 (3) ◽  
pp. 102-106 ◽  
Author(s):  
J P Marsden ◽  
S R Montgomery
Keyword(s):  
Dynamic Characteristics ◽  
Ground Reaction Force ◽  
Total Mass ◽  
Damping Ratio ◽  
Reaction Force ◽  
Force Plate ◽  
The Body ◽  
Measuring Systems ◽  
Future Design ◽  
Plate System

Experiments have been performed in which the ground reaction force during walking has been measured simultaneously by two different means; a shoe having a spring-loaded heel and fitted with a transducer was worn by subjects walking over a force plate. Discrepancies in the two sets of results led to an analysis of the dynamic characteristics of the force plate which was facilitated by comparing the results of the two measuring systems. The increase in the total mass of the system as the body lands on the plate reduces both the damping ratio and the natural frequency of the force plate system, causing an increase in the dynamic magnification. These effects are analysed quantitatively and recommendations are made for the future design of force plate systems.

Simulation of the Dynamic Characteristics of the Coupled System Structure

2011 ◽  
Vol 71-78 ◽  
pp. 1507-1510 ◽  
Author(s):  
Dong Wang ◽  
Shi Qiao Gao ◽  
Michael Kasperski ◽  
Hai Peng Liu ◽  
Lei Jin
Keyword(s):  
Dynamic System ◽  
Natural Frequency ◽  
Dynamic Characteristics ◽  
Human Body ◽  
Coupled System ◽  
System Structure ◽  
Complex Dynamic ◽  
Complex Dynamic System

The human body forms a complex dynamic system with more than one natural frequency and provides considerable damping capacities. Therefore, the coupled system of a structure and the occupants can hardly be described with its basic dynamic characteristics considering only the mass of the occupants. Depending on the natural frequency of the empty structure, the human body dominantly acts like a mass, a mass and a damper or a damper. If the natural frequency of the empty stand increases 3 Hz, the human body induces considerable damping into the coupled system. In the limit, the dynamic characteristics can be described based on the average values of the characteristics of the human body.

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