Apparent mass of the seated human body during vertical vibration in the frequency range 2–100 Hz

Huang, Yu; Zhang, Penglin; Liang, Shihao

doi:10.1080/00140139.2020.1769744

Cited by 5 publications

(4 citation statements)

References 18 publications

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“…33,34 The passive thixotropy of soft tissues, rather than the geometric nonlinearity, is the most likely primary cause of the nonlinearity in biodynamic responses. 34,35 Qiu et al 36 and Huang et al 35 found that with the increase of excitation magnitude, the resonance frequency of apparent mass decreased which is similar to the results of this study. When the human body is exposed to higher excitation magnitude, the muscle tension of the subject may increase involuntarily, resulting in an increase in the stiffness of the tissues of the ischial tuberosities which might be the reason for a decrease in the nonlinearity.…”

Section: Effect Of Seat Cushion Parameters and Excitation Magnitudes ...supporting

confidence: 90%

Transmission of vertical vibration through a seat cushion at the seat pan: Effect of foam physical properties during different excitation magnitudes

Luo,

He,

Zhang

et al. 2023

Journal of Low Frequency Noise, Vibration and Active Control

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The vibration characteristics of car seats directly influence the ride comfort. Polyurethane foam is the key part of a seat, and its physical parameters have an important impact on the seat. In this study, the influence of the foam thickness and foam hardness on the vibration characteristics of seat cushion with different excitation magnitudes was investigated by using transmissibility and seat effective amplitude transmissibility (SEAT) value. First, vibration tests were carried out at a vertical vibration simulator with width-limited white noise vibration frequencies from 0.5 to 20 Hz with root-mean-square (r.m.s.) values of 0.4, 0.8, and 1.2 m/s2, the acceleration at the platform and the body-foam interfaces were measured to calculate the transmissibility, and the influence of the foam physical properties on the transmissibility was analyzed. Then, the SEAT value was introduced to assess the vibration isolation efficiency of the foam cushion, and the influence of the foam physical properties of the foam cushion on the vibration isolation efficiency was analyzed. With increasing thickness of the foam and decreasing hardness of the foam at the seat pan, the peak transmissibility increased and the resonance frequency decreased. The SEAT values show that increasing the foam thickness is beneficial to the improvement of the vibration isolation efficiency of the seat, but there is a diminishing return; the combination of physical parameters of low hardness and high thickness could make the vibration isolation performance of the seat better. In addition, the nonlinearity of human-seat system during different vibration magnitude was found.

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Section: Effect Of Seat Cushion Parameters and Excitation Magnitudes ...supporting

confidence: 90%

Transmission of vertical vibration through a seat cushion at the seat pan: Effect of foam physical properties during different excitation magnitudes

Luo,

He,

Zhang

et al. 2023

Journal of Low Frequency Noise, Vibration and Active Control

View full text Add to dashboard Cite

show abstract

“…measured at the head, trunk, thigh, and leg were used as feeding data in the objective function to estimate the unknown stiffness and damping parameters. The parameters were subject to upper and lower bounds obtained from reviewing the published range of values of stiffness and damping in the literature [15,16,[25][26][27]. The specified bounds limit the estimated stiffness and damping coefficients to only positive values and speed up the convergence of the optimization algorithms.…”

Section: Objective Function Formulationmentioning

confidence: 99%

“…However, there is still an exhaustive search for the appropriate optimization method that produces reliable estimates of these human parameters. For instance, Bae and Kang, Shao et al, and Huang et al (2020) [10,15,16] optimized the parameters of 2-, 3-, 4-, and 5-DOF models using the gradient-based MATLAB function, called "fmincon". Zhang et al [17] introduced a reference vector-guided evolutionary algorithm to obtain the parameters of a 7-DOF human model, whereas Zhao et al [18] explored multi-objective and genetic algorithms (GAs) for parameter identification of a 5-DOF model.…”

Section: Introductionmentioning

confidence: 99%

Development of a 7-DOF Biodynamic Model for a Seated Human and a Hybrid Optimization Method for Estimating Human-Seat Interaction Parameters

Alabi,

Song,

Bae

et al. 2023

Applied Sciences

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Existing biodynamic models adopt apparent mass and seat-to-head transmissibility to predict the response of seated humans to whole-body vibration, limiting their ability to capture the actual response of distinct body segments in different excitation conditions. This study systematically develops a 7-DOF seated human model, a vibration experiment, and a novel hybrid optimization to estimate unknown mechanical parameters and predict the response of different human body segments to vertical vibrations. Experimental results showed that the upper trunk and head were most susceptible to transmitted vibrations. Combining the 7-DOF model and HOM resulted in accelerated optimization, improved numerical stability, and significant minimization of the objective function value compared to conventional algorithms. Notably, the estimated parameters, particularly stiffness, remained consistent regardless of increasing excitation magnitude or change in the body segment data used. Additionally, the model captured the non-linearity in human biodynamics through stiffness softening. These findings are applicable in seating systems optimization for comfort and safety.

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“…23 Apparent mass is more convenient to measure accurately and widely used in analysis of whole-body vibration. 24,25 No matter AM, STHT, or MI, they're all frequency response functions used to describe biodynamic characteristics. Therefore, the amplitudefrequency and phase-frequency characteristics of the model should be identified simultaneously.…”

Section: Introductionmentioning

confidence: 99%

Modeling and parameter identification of seated human body with the reference vector guided evolutionary algorithm

Zhang

Shi

Chen

2021

Advances in Mechanical Engineering

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The low frequency vibration of the vehicle in motion has a great influence on the ride comfort of occupants. The research on the vibration response characteristics of human body plays a great role in analyzing and improving ride comfort. The purpose of this study was to investigate the parameter identification of seated human body dynamic model. A seven-degree-of-freedom (DOF) lumped parameter model was established to describe the vibration response characteristics of human body. The derivation processes of apparent mass (AM) and seat to head transmissibility (STHT) were performed. After the theoretical calculation of the human body vibration characteristics, we used several different evolutionary algorithms to identify the 23 parameters of the model, including the mass, stiffness and damping parameters. By comparing the results of the five optimization algorithms and comprehensively analyzing the convergence and distribution of the non-dominated solution set, we found that the reference vector guided evolutionary algorithm (RVEA) shows good competitiveness in solving many-objective optimization problem (MaOP), that is, parameter identification of seated human body model in this paper. The AM and STHT calculated by model identification were compared with their measured by experiment. The result shows that the selected seven-DOF model can well describe the vertical vibration characteristics of seated human body and the identification method used in this paper can accurately identify the parameters of lumped parameter model, which provides convenience for the establishment of a complete “road-vehicle-seat-human body” system dynamic model.

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Apparent mass of the seated human body during vertical vibration in the frequency range 2–100 Hz

Cited by 5 publications

References 18 publications

Transmission of vertical vibration through a seat cushion at the seat pan: Effect of foam physical properties during different excitation magnitudes

Transmission of vertical vibration through a seat cushion at the seat pan: Effect of foam physical properties during different excitation magnitudes

Development of a 7-DOF Biodynamic Model for a Seated Human and a Hybrid Optimization Method for Estimating Human-Seat Interaction Parameters

Modeling and parameter identification of seated human body with the reference vector guided evolutionary algorithm

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