Virtual Manikin Research Articles

Application of a thermo-biomechanical virtual manikin used In transient systems

In this paper is developed and applied a thermo-biomechanical virtual manikin used in transient systems. This numerical model, under transient conditions, is applied in the thermal and vibrations of the different sections of the human body. The thermal numerical model, based in energy and mass balance integral equations, considers the first order equations systems, while the vibration numerical model, based in Newton equation, considers the second order equations systems converted in first order equation system. The resolution of the numerical model is made through the Runge-Kutta-Fehlberg method with error control. The thermal numerical model is used in the study of the periodical and randomized airflow fluctuations applied to the human body section and the biomechanical numerical model is used in the study of the periodical and randomized vibrations applied to the feet, that a standing person is subjected. The signals of the stimuli, the power spectrum, the equivalent frequencies and the Draught Risk (DR) of the same signals will be presented. In accordance with the obtained results, is verified that: in the thermal component the DR is evaluated and in the vibration component the body structure reduces the power spectra energy frequency and the equivalent frequency analysis.

Development and application of an integrated virtual thermal-acoustic manikin design used inside an office space

In this study an integrated virtual thermal-acoustic manikin design used inside ventilated and occupied office spaces is developed and applicated. The component of the virtual thermal manikin evaluates the internal airflow and occupants' thermal, thermo-physiology and clothing systems and calculates the thermal comfort and the indoor air quality levels. The component of the virtual binaural manikin evaluates the direct and indirect sound and calculates the reverberation time. The space geometry with complex topology is developed using a Computer Aid Design (CAD), while the occupants' geometry is made using geometric equations. The grid generation, in the surrounding space surfaces and around the external occupants' surfaces geometry, is used to calculate the radiative heat exchanges and the sound propagation. In this study, performed in an office room occupied by eight persons and equipped with personalized ventilation system, the thermal comfort level, the air quality level and the space reverberation time is evaluated and discussed. In accordance with the obtained results the values are, in general, in accordance the actual standards.

Development of a virtual biomechanical manikin used in vibrations studies in occupied spaces

In this paper is developed and applied a virtual biomechanical manikin used in occupied spaces. This multi-nodal numerical model is applied in the vibrations of the different sections of the human body, under transient conditions. The integration of second order equations systems, based in Newton equation, after being converted in a first order equation system, is solved through the Runge-Kutta-Fehlberg method with error control. This multi-nodal numerical model will be used, in this work, in the study of the vibrations that a standing person is subjected when stimuli are applied to the feet. The influence of various types of stimuli is analyzed, with periodic irregularities, in the dynamic response of the vibrations in different sections of the human body. The signals of the stimuli, the displacement of some sections of the body and the power spectrum of the same signals will be presented. In the study the influence of the floor vibration in the human body sections is analyzed and presented.

The influence of different air flows introduced on the thermal comfort of car passengers during the cooling period – Numerical Study

In this article the effects of different airflow rates introduced by the ventilation system are investigating by numerical simulation over the thermal comfort of the driver in a regular vehicle. The 3D LDV (Laser Doppler Velocimetry) measurement for the diffusers velocity field was imposed as boundary condition at the inlets of the investigated domain. Also, the flow rate discharged by each diffuser was measured for the first three positions of the air conditioning system. In the numerical model which was previously validated we imposed the boundary conditions from the experimental sessions. Thermal comfort was assessed by calculation of the equivalent temperature on the surface of a virtual manikin on the driver place and by the determination of the maps of Predicted Mean Vote (PMV) and the Draft rate indices. A first conclusion is that the results of the three flowrates may assure the comfort of the front passengers and a draft sensations and uncomfortable state for the rear passengers.

Investigation of Thermal Sensation in a Railway Vehicle during Cooling Period

The paper presents an investigation of local thermal comfort of passengers in a railway vehicle. The railway vehicle model includes five different parts called modules, and each module had different properties such as passenger capacity and seating arrangement. A virtual manikin model was developed and added to the numerical model which includes convection and radiation heat transfer between the human body and the environment. The numerical simulation was conducted according to the EN 14750-1 standard describing the thermal comfort conditions for different climatic zones. Two different cases were performed for steady-state conditions. Meanwhile, measurements were taken in a railway vehicle cabin to validate the numerical simulation, and the numerical results were in good agreement with the experimental data. It is observed that the local heat transfer characteristics of the human body have significant importance for the design of an effective heating, ventilation, and air conditioning (HVAC) system because each module had different heat transfer and air flow characteristics. It is also shown that the thermal sensation (TSENS) index helps railway vehicle HVAC researchers to determine the reasons for discomfort zones of each occupant. Another important result is that using a single air flow channel did not meet the thermal comfort demands of all passengers in this railway vehicle. Therefore, multiple air flow channel design configurations should be considered and developed for these vehicles. Local thermal comfort models allow HVAC systems to achieve better comfort conditions with energy saving. The numerical model can be used for effective module design, including seating arrangements, to achieve better thermal comfort conditions.

Investigation of transient and heterogeneous micro-climate around a human body in an enclosed personalized work environment

Heterogeneous distribution of indoor environmental quality is known to have a great impact on human health, comfort, and productivity. A personalized work environment, that creates a localized and independent environment with capsules or partitions, is being developed worldwide to provide workers with a space that enables undisturbed concentration on studying and working. However, the minimized interior space of a personalized work environment can immediately cause adverse health impacts for occupant if the air quality and thermal environment in the personalized work environment is not controlled appropriately. Particularly, constant breathing can sharply increase the CO2 concentrations in an interior space with an insufficient ventilation rate. In order to design a healthy and comfortable indoor environment, especially in a personalized work environment, it is important to predict precisely and comprehensively the transient and heterogeneous structure of the indoor environment formed around a human body. With this background, we have developed an in silico human model that integrates a computational human model (virtual manikin combined with thermoregulation models) and respiratory model (virtual airway) for estimating indoor environmental quality, targeting the microclimate around a human body and breathing zone with high accuracy. In this study, we report the applicability of a comprehensive in silico human model to estimate the environmental quality in a personalized work environment. A coupled analysis of heat and contaminant transfer with computational fluid dynamics was conducted targeting the space around the in silico human model installed in a virtual personalized work environment. The informative data including human thermal comfort and breathing air quality were obtained, potentially forming the basis for the development of a digital twin of the personalized work environment and contributing to the design of a healthy, comfortable, and productive personalized work environment.

Development of vehicle undercarriage with roadster body using topological optimization

Nowadays the key task of designer is to reduce the mass of the automobile. This requirement is dictated by increasing demands for efficiency and dynamics of vehicle. On the other hand, the constantly increasing requirements for comfort and safety of the automobile, as well as the degree of automation of the driver's work lead to the use of a large number of additional systems, which increases the weight of the vehicle. In addition, the use of alternative power plants leads to the appearance of non-standard layout schemes. The number of manufactured models is increasing to satisfy all consumer groups. Simultaneously, the time period for R&D is reduced. In these conditions, we consider that it is effective to use methods of topological optimization of the undercarriage at the stage of the choice of the power circuit and the concept of the undercarriage. The article deals with the process of topological optimization of the vehicle undercarriage with roadster body. The car was developed at the Bauman MSTU. The process of developing of vehicle layout and design of driver position using a virtual manikin are shown. The process of preparing the design space for a computational model for optimizing is considered. A description of the finite element model for optimizing the undercarriage is given. There are considered two groups of calculation cases: operational and emergency. The optimization problem is formulated, the objective function and constraints are given. When performing calculations, the OptiStruct software was used. The results of optimization of the undercarriage for several loading regimes are presented. The analysis of the obtained topology is carried out.

Preliminary research on virtual thermal comfort of automobile occupants

Numerical simulation of climate conditions in automotive industry for the study of thermal comfort had become more and more prominent in the last years compared with the classical approach which consists in wind tunnel measurements and field testing, the main advantages being the reduction of vehicle development time and costs. The study presented in this paper is a part of a project intended to evaluate different strategies of cabin ventilation for improving the thermal comfort inside vehicles. A virtual thermal manikin consisting of 24 parts was introduced on the driver seat in a vehicle. A heat load calculated for summer condition in the city of Cluj-Napoca, Romania was imposed as boundary condition. The purpose of this study was to elaborate a virtual thermal manikin suitable for our research, introduction of the manikin inside the vehicle and to examine his influence inside the automobile. The thermal comfort of the virtual manikin was evaluated in terms of temperature and air velocity.

室内熱・空気環境に起因する健康リスクの総合評価を可能とする数値人体モデルの開発 (第2報)呼吸モデルを組み込んだVirtual Manikinによる呼吸域・気道内空気質予測

室内熱・空気環境に起因する健康リスクの総合評価を可能とする数値人体モデルの開発 (第2報)呼吸モデルを組み込んだVirtual Manikinによる呼吸域・気道内空気質予測

Comparison of training in department of anesthesiology for flexible fibreoptic intubation with application of virtual reality simulator and high-fidelity manikin

Objective To compare the efficacy and efficiency of simulation-based training of flexible fibreoptic intubation in novices with virtual reality simulator. Methods A total of 46 anaesthesia residents in their first stage of training in anaesthesiology with no experience in flexible fibreoptic intubation at Peking University People' s Hospital were enrolled in the study, and were divided into 2 groups randomly, which were virtual reality simulator group(group S, n=23)and manikin group(group M, n=23). The group S was then trained for 25 times on simulator, while the group M did the same processes on manikin. After training, participants in both groups had their performance assessed with the fibrescope evaluated through the oral route using a simulation manikin, who were instructed to attempt to advance the fibrescope 5 consecutive times to view the carina in the shortest amount of time. The time required to view the carina of each practice during training in both groups were recorded as pooled data to construct group learning curves with the application of SPSS 20.0. By using repeated measures analysis of variance and T-test, the procedure time and global rating scale(GRS)of fibreoptic bronchoscope manipulation ability were compared between groups, so did the participant’s confidence between before and after the training both within-subjects and between-subjects. Results The plateaus in the learning curves were achieved after 19(15, 26)practice sessions in group S and 24(19, 31)in group M, respectively. There was no significant difference in the procedure time[(13.7±6.6)s and(11.9±4.1)s]and GRS [(3.9±0.4)vs.(3.7±0.3)]between groups. There were significant increases in participant’s confidences in both groups after training [group S:(1.8±0.5)vs.(3.9±0.6), t=10.928, P=0.000; group M:(2.0±0.7)vs.(3.9±0.5), t=15.306, P=0.000], but there was no significant difference between groups. Conclusion The simulation-based training of flexible fibreoptic intubation in novices with virtual reality simulator is more efficient than the one with manikin, but the similar effects can be achieved in both modalities, after adequate trainings. In the related training a balance between time cost and economic cost should be considered and the appropriate teaching methods and forms should be taken. Key words: Standardized training for medicine residents; Simulation-based training; Flexible fibreoptic intubation; Virtual reality simulators; Learning curves

Investigation of transient cooling of an automobile cabin with a virtual manikin under solar radiation

The aim of the paper is to present a three dimensional transient cooling analysis of an automobile cabin with a virtual manikin under solar radiation. In the numerical simulations the velocity and the temperature distributions in the automobile cabin as well as around the human body surfaces were computed during transient cooling period. The surface-to-surface radiation model was used for calculations of radiation heat transfer between the interior surfaces of the automobile cabin and a solar load model that can be used to calculate radiation effects from the sun's rays that enter from the glazing surfaces of the cabin was used for solar radiation effects. Inhomogeneous air flow and non-uniform temperature distributions were obtained in the automobile cabin and, especially in ten minutes of cooling period, high temperature gradients were computed and measured and high temperature values were obtained for the surfaces which were more affected from the sunlight. Validations of the numerical results were performed by comparing numerical data with the experimental data presented in this study. It is shown that the numerical results were good agreement with the experimental data.

An Air Distribution Index for Assessing the Thermal Comfort and Air Quality in Uniform and Nonuniform Thermal Environments

This study introduces a new Air Distribution Index ( ADI)New to assess the ventilation performance in uniform and nonuniform thermal environments. The index comprises parameters for assessing the indoor thermal comfort and air quality in occupied spaces. The thermal comfort assessment was carried out using a virtual thermal manikin that is adjusted by a model of human thermoregulation and coupled with a psychological comfort model. The virtual manikin was used in a computational fluid dynamics (CFD) code to simulate tests in an environmental chamber that were largely conducted under thermally neutral conditions with mixing ventilation (MV) or displacement ventilation (DV) systems. Eight human subjects were used in the study that included measurement of their skin temperature, local and overall thermal sensation votes during their exposure to the MV and DV systems. The results from CFD predictions were compared with measurements in the test chamber. The predicted ( ADI)New parameters, such as the thermal comfort, the ventilation effectiveness for both heat and contaminant removals as well as the local mean age of air, were compared with measured values in the chamber and found to be in good agreement. The results demonstrate that ( ADI)New is a useful index for evaluating the performance of a ventilation system under uniform thermal environment and can also be applied to nonuniform environment.

Three dimensional numerical analysis of temperature distribution in an automobile cabin

In this study, 3-D numerical analysis of temperature distribution in the automobile cabin were performed by using computational fluid dynamics method. For this purpose, a 3-D automobile cabin including window and outer surfaces was modeled by using the real dimensions of a car. To evaluate the results of numerical analysis according to thermal comfort, a virtual manikin divided into 17 parts with real dimensions and physiological shape was added to the model of the automobile cabin. Temperature distributions of the automobile cabin were obtained from the results of the 3-D steady and transient numerical analyses for standard heating and cooling period. Validations of the results were achieved by comparing to the results of the experimental studies performed simultaneously with the numerical analyses.

The effects of using different type of inlet vents on the thermal characteristics of the automobile cabin and the human body during cooling period

A three-dimensional (3-D) transient numerical analysis was performed inside an automobile cabin during cooling period. A three-dimensional vehicle cabin including glazing surfaces was modelled by using the real dimensions of a car. A virtual manikin with real dimensions and physiological shape was added to the model of the vehicle cabin, and it was assumed that the manikin surfaces were subjected to constant temperature. The virtual manikin was divided into 17 parts in standing posture to evaluate the local heat transfer characteristics of the human body during transient cooling period. We considered three different cases that the cooling capacity of the automobile cabin was same for all cases. Three-dimensional fluid flow, temperature distribution and heat transfer characteristics inside the automobile cabin were calculated with different type of inlet vents. Comparisons of the numerical results were presented and discussed.

A Numeric Model to Simulate Solar Individual Ultraviolet Exposure

Exposure to solar ultraviolet (UV) light is the main causative factor for skin cancer. UV exposure depends on environmental and individual factors. Individual exposure data remain scarce and development of alternative assessment methods is greatly needed. We developed a model simulating human exposure to solar UV. The model predicts the dose and distribution of UV exposure received on the basis of ground irradiation and morphological data. Standard 3D computer graphics techniques were adapted to develop a rendering engine that estimates the solar exposure of a virtual manikin depicted as a triangle mesh surface. The amount of solar energy received by each triangle was calculated, taking into account reflected, direct and diffuse radiation, and shading from other body parts. Dosimetric measurements (n = 54) were conducted in field conditions using a foam manikin as surrogate for an exposed individual. Dosimetric results were compared to the model predictions. The model predicted exposure to solar UV adequately. The symmetric mean absolute percentage error was 13%. Half of the predictions were within 17% range of the measurements. This model provides a tool to assess outdoor occupational and recreational UV exposures, without necessitating time-consuming individual dosimetry, with numerous potential uses in skin cancer prevention and research.

Infection-Risk Assessment of Bioaerosols by Coupling Numerical Analysis of Unsteady CFD with Epidemiological Model : Part2: CFD Simulation of Exposure Concentration by Multi-Nesting Method Connecting Building Space, Virtual Manikin, and Bronchial Airway

Infection-Risk Assessment of Bioaerosols by Coupling Numerical Analysis of Unsteady CFD with Epidemiological Model : Part2: CFD Simulation of Exposure Concentration by Multi-Nesting Method Connecting Building Space, Virtual Manikin, and Bronchial Airway

Transient numerical analysis of airflow and heat transfer in a vehicle cabin during heating period

This paper describes a three-dimensional transient numerical analysis to determine the airflow and heat transfer characteristics inside the vehicle cabin during a heating period. A three-dimensional vehicle cabin including glazed surfaces and pertinent physical and thermal properties of the enclosure was modelled by using the real dimensions of a car. A virtual manikin was added to the model of the vehicle cabin to determine the heat transfer between the human body and the vehicle cabin ambient. The analysis takes into account all the possible thermal load of the cabin. Governing equations were solved by an implicit, time marching finite volume numerical scheme under varying inlet boundary conditions of the vehicle air conditioning system. The results of numerical calculations were in good agreement with the available experimental and theoretical data in the literature.

Evaluation of Heat Transfer Characteristics in an Automobile Cabin with a Virtual Manikin During Heating Period

In this study, a three-dimensional transient numerical analysis was performed inside the automobile cabin during heating period. A three-dimensional vehicle cabin including glazing surfaces was modeled by using the real dimensions of a car. A virtual manikin with real dimensions and physiological shape was added to the model of the vehicle cabin. It was assumed that the manikin surfaces were subjected to either constant heat flux or constant temperature. Three-dimensional fluid flow, temperature distribution, and heat transfer characteristics inside the cabin were calculated. Experimental measurements were also conducted. Comparisons of the results were presented and discussed. The results of numerical calculations were in good agreement with the experimental and theoretical data in the literature.

Robust design of car packaging in virtual environment

This paper presents a statistical methodology to improve the car packaging setup in the first phase of a new mini-car design. An original procedure for comfort assessment using virtual manikins is formulated. The Robust Design approach enables to identify the optimal level for the main design factors of the new car packaging. The optimal solution is the most insensitive to anthropometric variability. The case study of a new mini-car packaging setup is exploited. The experimental results in virtual environment are obtained using the virtual manikin Jack by UGS. On the base of adequate comfort indexes, the proposed methodology allows defining a car packaging which is, on average, more comfortable than that obtainable as initial setting by applying the Enhanced SAE Packaging Guidelines and the Posture Prediction algorithms proposed by the UMTRI (UMI-USA).

Thermal comfort evaluation with virtual manikin methods

Computational fluid dynamics has become an important tool in the prediction of thermal comfort in occupied spaces. Despite its ability to predict temperature and velocity fields, it is more difficult to evaluate the degree of thermal comfort experienced by an occupant. This article describes the construction of a new numerical thermal manikin, with new comfort evaluation methods based on data from thermal manikin measurements as well as subjective results from several hundred experiments. The level of thermal comfort is highly dependent on the local environment. Human beings respond differently to local heat transfer in different parts of their bodies. It is suggested for that reason that local results from manikins should be presented in new clothing independent comfort zone diagrams. The research presented in here is intended to be used to evaluate system solutions that provide improved thermal climate in many different everyday situations, e.g. all types of buildings and vehicles.