Mitigation of biodynamic response to vibratory and blast-induced shock loads using magnetorheological seat suspensions

2005 ◽  
Vol 219 (6) ◽  
pp. 741-753 ◽  
Author(s):  
Y-T Choi ◽  
N M Wereley
Keyword(s):  
Human Body ◽  
Lumped Parameter Model ◽  
Shock Load ◽  
Shock Loads ◽  
Seat Suspension ◽  
Military Vehicles ◽  
Lumped Parameter ◽  
Suspension Model ◽  
Yield Force ◽  
Constant Yield

The mitigation of biodynamic response to vibratory and blast-induced shock loads using a magnetorheological (MR) seat suspension is addressed in this study. To this end, an MR seat suspension model for military vehicles including seated personnel is constructed in terms of a detailed lumped parameter model. The lumped parameter model of the human body consists of four parts: pelvis, upper torso, viscera, and head. From the model, the governing equation of motion of the MR seat suspension considering the human body is derived. Based on this equation, a semi-active nonlinear optimal control algorithm appropriate for the MR seat suspension is developed. The simulated control performance of the MR seat suspension is evaluated under three different excitations of sinusoidal and random vibration and tremendous shock load due to a mine explosion. In addition, the mitigation of injuries to humans due to such a shock load is evaluated and compared with a passive hydraulic seat suspension and a passive MR seat suspension with a constant yield force.

Mitigation of Biodynamic Response to Vibratory and Blast-Induced Shock Loads Using Magnetorheological Seat Suspensions

Aerospace ◽  
2003 ◽  
Author(s):  
Young-Tai Choi ◽  
Norman M. Wereley
Keyword(s):  
Human Body ◽  
Control Algorithm ◽  
Random Vibration ◽  
Lumped Parameter Model ◽  
Shock Load ◽  
Hydraulic Damper ◽  
Seat Suspension ◽  
Military Vehicles ◽  
Lumped Parameter ◽  
Suspension Model

This study investigates biodynamic response mitigation to three different excitations of sinusoidal and random vibrations and shock load using a magnetorheological (MR) seat suspension. In doing so, an MR seat suspension model for military vehicles, with a detailed lumped parameter model of the human body, was developed. The lumped parameter model of the human body consists of four parts: pelvis, upper torso, viscera and head. From the model, the governing equation of motion of the MR seat suspension considering the human body was derived. Based on this equation, a semi-active nonlinear optimal control algorithm appropriate for the MR seat suspension was developed. The simulated control performance of the MR seat suspension was evaluated under three different excitations of sinusoidal and random vibration and tremendous shock load due to a mine explosion. In addition, the mitigation of injuries to humans due to such shock load was also evaluated and compared with the passive seat suspension using a passive hydraulic damper.

Mitigation of Biodynamic Response to Shock Loads Using Semi-Active Vertically Stroking Crew Seats

2010 ◽  
Author(s):  
Harinder J. Singh ◽  
Norman M. Wereley
Keyword(s):  
Human Body ◽  
Control Algorithm ◽  
Equations Of Motion ◽  
Comprehensive Analysis ◽  
Lumped Parameter Model ◽  
Force Model ◽  
Body Parts ◽  
Governing Equations ◽  
Lumped Parameter ◽  
Yield Force

This study addresses mitigation of biodynamic response due to an initial velocity impact of a vertically stroking crew seat using an adaptive magnetorheological energy absorber. Under consideration is a multiple degree-of-freedom detailed lumped parameter model of a human body falling with prescribed initial crash velocity (sink rate). The lumped parameter model of the human body consisted of four main parts: pelvis, upper torso, viscera and head. The governing equations of motion of a vertically stroking crew seat incorporating a human body were derived using parameters such as available damper stroke as well as MR yield force. The control algorithm for smooth landing of a rigid occupant was examined for compliant occupant and was modified accordingly. Four MR yield force models were analyzed to shape decelerations experienced by human body and an appropriate model was selected for comprehensive analysis. The simulated responses were analyzed with selected MR yield force model for a crew seat with an occupant corresponding to 90th percentile male at sink rates varying from 8 to 12 m/s. In addition, the mitigation of injuries to the human body parts due to load transmissions corresponding to crash velocities was also evaluated for the selected MR yield force model along with terminal conditions necessary for smooth landing.

Optimized Biodynamic Shock Attenuation Performance Using an Adaptive Seat Suspension

2011 ◽  
Author(s):  
Harinder J. Singh ◽  
Norman M. Wereley
Keyword(s):  
Equations Of Motion ◽  
Lumped Parameter Model ◽  
Local Optimum ◽  
Shock Attenuation ◽  
Energy Absorber ◽  
Seat Suspension ◽  
Lumped Parameter ◽  
Cubic Polynomial ◽  
Yield Force ◽  
Vertical Impact

Design optimization-based techniques are presented for the minimization of biodynamic loads of a seated occupant subjected to a shock due to an initial velocity vertical impact. A 95th percentile male occupant was modeled using a multiple degree-of-freedom biodynamic lumped parameter model (BLPM) seated on a vertically stroking adaptive seat suspension with a semi-active magnetorheological energy absorber (MREA). The governing equations of motion of the adaptive MREA-based seat suspension with biodynamic lumped parameter model were developed. The variation of magnetorheological yield force with respect to the energy absorber stroke was shaped using cubic polynomial for the maximum shock attenuation. Three cost functions were devised with a common goal of minimizing biodynamic decelerations. Constraints were established based on limitation of MREA stroke and, yield force as well as stroking load. The MREA yield force and damper stroke were crucial parameters for improved biodynamic response mitigation to shock loads. A globally optimized biodynamic response was analyzed among several local optimum responses for better shock attenuation.

A comparison of different models of passive seat suspensions

2021 ◽  
pp. 095440702199092
Author(s):  
Raj Desai ◽  
Anirban Guha ◽  
P. Seshu
Keyword(s):  
Human Body ◽  
Separate Analysis ◽  
Vehicle Model ◽  
Human Body Model ◽  
Human Comfort ◽  
Vehicle Handling ◽  
Seat Suspension ◽  
Handling Characteristics ◽  
Suspension Model ◽  
Suspension Models

Long duration exposure to vehicle induced vibration causes various ailments to humans. Amongst the various components of the human-vehicle system, the seat suspension plays a major role in determining the level of vibration transferred to humans. However, optimising the suspension for maximising human comfort leads to poor vehicle handling characteristics. Thus, predicting human comfort through various seat suspension models is a widely researched topic. However, the appropriate seat suspension model to be used has not been identified so far. Neither has any prior work reported integrating models of all the components necessary for this analysis, namely human body, cushion, seat suspension and vehicle chassis, each with the appropriate level of complexity. This work uses a two-dimensional 12 DoF seated human body model with inclined backrest support, a nonlinear cushion model, a seat suspension model and a full vehicle model. Two kinds of road profiles – one with random roughness and one with a bump – have been used. It then compares the performance of five different seat suspension models based on a number of human comfort related parameters (seat to head transmissibility, suspension travel, seat acceleration, cushion contact force and head acceleration in both vertical and fore-aft directions) and vehicle handling parameters (vertical, rolling and pitching acceleration of chassis). The results clearly show the superiority of the configuration which involves a spring parallel to an inclined multi-stage damper. A separate analysis was also done to judge whether the integration of the vehicle model (with its associated complication) was necessary for this analysis. A comparison of the human body’s internal forces, moments, acceleration, and absorbed power with and without the vehicle model clearly indicates the need of using the former.

scholarly journals Mathematical Model of Suspension Seat-Person Exposed to Vertical Vibration for Off-Road Vehicles

2019 ◽  
Vol 16 (2) ◽  
pp. 6773-6782
Author(s):  
S. Aisyah Adam ◽  
N. A. A. Jalil ◽  
K. A. Md Razali ◽  
Y. G. Ng ◽  
M. F. Aladdin
Keyword(s):  
Human Body ◽  
Degrees Of Freedom ◽  
Low Frequency ◽  
Coupled System ◽  
Vertical Vibration ◽  
Lumped Parameter Model ◽  
Model Parameters ◽  
Road Vehicles ◽  
Lumped Parameter ◽  
Variable Function

Off-road drivers are exposed to a high magnitude of vibration at low frequency (0.5-25Hz), that can cause harm and possibly attribute to musculoskeletal disorder, particularly low-back pain. The suspension seat is commonly used on an off-road condition to isolate the vibration transmitted to the human body. Nevertheless, the suspension seat modelling that incorporates the human body is still scarce. The objective of this study is to develop a mathematical modelling to represent the suspension seat-person for off-road vehicles. This paper presents a three degrees-of-freedom lumped parameter model. A curve-fitting method is used for parameter identification, which includes the constraint variable function (fmincon()) from the optimisation toolbox of MATLAB(R2017a). The model parameters are optimised using experimentally measured of suspension seat transmissibility. It was found that the model provides a reasonable fit to the measured suspension seat transmissibility at the first peak of resonance frequency, around 2-3 Hz. The results of the study suggested that the human body forms a coupled system with the suspension seat and thus affects the overall performance of the suspension system.  As a conclusion, the influence of the human body should not be ignored in the modelling, and a three-degrees degree-of-freedom lumped parameter model provides a better prediction of suspension seat transmissibility. This proposed model is recommended to predict vibration transmissibility for off-road suspension seat.

scholarly journals Comfort Level Refinement of Military Tracked Vehicle Crew through Optimal Control Study

2018 ◽  
Vol 68 (3) ◽  
pp. 265
Author(s):  
N. V. Ramamurthy ◽  
B. K. Vinayagam ◽  
J. Roopchand
Keyword(s):  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Controller Design ◽  
Research Work ◽  
Comfort Level ◽  
Lumped Parameter Model ◽  
Tracked Vehicle ◽  
Machine Model ◽  
Seat Suspension ◽  
Suspension Model

Military tracked vehicle and crew are modelled together in this paper as integrated man-machine lumped parameter model, by integrating the simplified 5 degrees of freedom (DoF) tracked vehicle model, including seat and 4 DoF human bio-dynamic model, thus resulting in a 9 DoF simplified vehicle-occupant model. Then the natural frequency of major mass segment namely the chassis mass is obtained through simulation study, for a known road input. The value obtained is compared with that of an earlier research work, for validation of said man-machine model. Then focusing our study locally at crew seat location, parameters of crew seat suspension for ride comfort are optimised using the optimal digital state space controller designed for this purpose by implementing it in a 2 DoF occupant - seat suspension model and its Simulink model constructed. Simulation results illustrate the attainment of the goal by meeting the controller design requirements.

Transient Behavior of Seated Human Body During Input From Caudophalad Acceleration

2000 ◽  
Author(s):  
Paul C. Lam ◽  
P. Ruby Mawasha ◽  
Ted Conway
Keyword(s):  
Human Body ◽  
High Speed ◽  
Transient Behavior ◽  
Lumped Parameter Model ◽  
Load Factor ◽  
Time Duration ◽  
Bodily Injury ◽  
Lumped Parameter ◽  
Ejection Process ◽  
Short Time

Abstract The objective of this study, is to investigate the dynamic transient response of a four degree-of-freedom lumped parameter model of the seated human body subjected to caudocephalad loading (acceleration from tail to head). The caudocephalad loading used in the model simulated the ejection process of a seated pilot from a high-speed aircraft. During ejection, ejection velocities are high and are developed over short distances hence, the accelerations are also high (10–40 g’s). The model indicates that even though acceleration is applied over short time duration (typically less than 0.25 seconds), serious bodily injury can result due to high dynamic load factor for the frequency range of body resonances.

Ergonomic Level Improving of Armoured Fighting Vehicle Crew

2017 ◽  
Vol 68 (1) ◽  
pp. 33
Author(s):  
N. V. Ramamurthy ◽  
B. K. Vinayagam ◽  
Roopchand J.
Keyword(s):  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Equations Of Motion ◽  
Research Work ◽  
Composite Model ◽  
Seat Suspension ◽  
Lumped Parameter ◽  
Vibration Responses ◽  
Suspension Model ◽  
Parameter Values

<p class="p1">The armoured fighting vehicle (AFV)-occupant composite system is modelled as a lumped parameter system, in this paper, wherein the 4 degrees of freedom (dof) biodynamic occupant model is integrated with 10 dof in-plane AFV model including the crew seat, thus leading to the 14 dof vehicle-occupant composite model and the governing equations of motion are obtained. The composite model is subjected to idealised road input simulating the ground reaction forces. Natural frequencies and the frequency domain vibration responses of various masses of model are obtained. The natural frequency of chassis thus obtained is compared with the result established by an earlier research work, to validate the model. The study is focused on crew seat location. A 2 dof occupant-seat suspension model is formulated and validated through case study. The optimised values of seat suspension parameters for ride comfort are obtained using the said model, through two methods of Invariant points theory and genetic algorithm toolbox of Matlab 2014a software. Acceleration responses of body for the current and optimised parameter values obtained illustrate that comfort of crew is improved with optimised values through minimization in the acceleration responses.</p>

scholarly journals Nonlinear Dynamic Modelling of a Suspension Seat for Predicting the Vertical Seat Transmissibility

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Weitan Yin ◽  
Juyue Ding ◽  
Yi Qiu
Keyword(s):  
Nonlinear Dynamic ◽  
Ride Comfort ◽  
Dynamic Modelling ◽  
Vertical Vibration ◽  
Lumped Parameter Model ◽  
Nonlinear Behaviour ◽  
Seat Suspension ◽  
Lumped Parameter ◽  
Seat Cushion ◽  
Inert Mass

Suspension seats are widely used in heavy vehicles to reduce vibration transmitted to human body and promote ride comfort. Previous studies have shown that the dynamics of the suspension seat exhibits nonlinear behaviour with changed vibration magnitudes. Despite various linear seat models developed in the past, a nonlinear model of the suspension seat capturing the nonlinear dynamic behaviour of the seat suspension and cushion has not been developed for the prediction of the seat transmissibility. This paper proposes a nonlinear lumped parameter model of the suspension seat to predict the nonlinear dynamic response of the seat. The suspension seat model comprises of a nonlinear suspension submodel integrated with a nonlinear cushion submodel. The parameters of the submodels are determined by minimizing the error between the simulated and the measured transmissibility of the suspension mechanism and the force-deflection curve of the seat cushion, respectively. The model of the complete seat is then validated using the seat transmissibility measured with inert mass under vertical vibration excitation. The results show that the proposed suspension seat model can be used to predict the seat transmissibility with various excitation magnitudes.

Evaluation of the Human Body Equilibrium in a Vibration Environment

2015 ◽  
Vol 801 ◽  
pp. 295-299
Author(s):  
Daniela Mariana Barbu ◽  
Mihaela Ioana Baritz
Keyword(s):  
Human Body ◽  
Degrees Of Freedom ◽  
Soft Tissues ◽  
Lumped Parameter Model ◽  
Internal Organs ◽  
Vibratory System ◽  
Lumped Parameter ◽  
Body Dynamics ◽  
Human Balance ◽  
External Sources

In the human body, vibrations are generated by internal or external sources. Because of the soft tissues, bones, joints, internal organs and also because of its anatomical particularities components in general, the human body is a complex vibratory system. The vibrations from external sources can be transmitted to the human body when it is positioned in different manners: standing, sitting, recumbent and moving or at work. The effect of vibration on the human body is related to the natural frequency of affected parts in the human body. This paper studies the dynamic characteristics of a human body system in a vibration environment and sets limits to which the balance is affected. The main result is a multi degrees of freedom lumped parameter model. The model provides an analytical tool for human body dynamics research. The relative displacements of human parts are evaluated, which can be a basis for the assessment of vibration risk and setting limits for keeping human balance.

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