To ensure the safety of astronauts and equipment during landing,the airbag landing system is commonly utilized to attenuate the impact response of the spacecraft.However,the complex impact dynamics and multi-disciplin...To ensure the safety of astronauts and equipment during landing,the airbag landing system is commonly utilized to attenuate the impact response of the spacecraft.However,the complex impact dynamics and multi-disciplinary coupling pose significant challenges to mission design.This paper first investigates the typical design scheme of the airbag landing system for manned spacecrafts to obtain basic insight.A comprehensive review of the past research works on the airbag landing system is then carried out from three aspects:dynamic modeling,performance optimization,and experimental study.The airbag landing system for spacecraft is a rigid-flexible-gas coupling system,which can be modeled through multi-body dynamics or finite element method.Different venting structures and optimization methods are introduced to improve the cushioning performance.Experimental setups for drop test and airbag test are developed to verify the design feasibility.Finally,this paper proposes key issues in the dynamics analysis and design optimization of the airbag landing system for future study.展开更多
This study presents a Fluid-Structure Interaction(FSI)model to analyze the water landing characteristics of a reentry capsule equipped with airbag cushioning.The model employs the Arbitrary Lagrangian-Eulerian(ALE)met...This study presents a Fluid-Structure Interaction(FSI)model to analyze the water landing characteristics of a reentry capsule equipped with airbag cushioning.The model employs the Arbitrary Lagrangian-Eulerian(ALE)method to simulate the capsule’s impact with water,while the control volume method is used to model the airbag cushioning process.Additionally,both regular and irregular heading waves are incorporated to simulate the landing dynamics of the capsule-airbag system under various sea conditions.The developed FSI model is utilized to investigate the effects of initial velocity,attitude angle,and wave phase on the water landing characteristics of the capsule-airbag system under calm water,regular and irregular wave conditions.Key parameters,such as the impact force on the capsule,as well as the pressure,mass flow rate,and stress distribution within the airbags,are analyzed.The insights gained from this study provide valuable guidance for minimizing damage to personnel and equipment during maritime recovery operations.展开更多
Compared with other kinds of airbags, curtain airbag（CAB） has more complex structures and larger coverage area. The product development process depends on many module tests, sled tests and full size vehicle tests. C...Compared with other kinds of airbags, curtain airbag（CAB） has more complex structures and larger coverage area. The product development process depends on many module tests, sled tests and full size vehicle tests. Computer aided engineering（CAE） technology can replace tests to a great extent, also save test costs and product development time. This paper introduces the way of setting up simulation models and application of static deployment tests and free motion headform（FMH） tests to verify simulation models. In the CAB simulation, uniform pressure airbag models and computational fluid dynamics（CFD） models are all used. The uniform pressure airbag models are not able to simulate the pressure difference among different parts inside the cushion during inflating process. CFD-based CAB models are used to help the curtain airbag optimization design. Based on effective CAE simulation, the optimization analyses related to diffuser tube parameters, inflator mass flow rate and cushion folding patterns are discussed and performed in different cases. The optimization result shows that the proposed techniques are helpful to the parametric optimization design of side curtain airbag module in curtain airbag development process.展开更多
Multi-objective optimization design of the gas-filled bag cushion landing system is investigated.Firstly,the landing process of airbag is decomposed into a adiabatic compression and a release of landing shock energy,a...Multi-objective optimization design of the gas-filled bag cushion landing system is investigated.Firstly,the landing process of airbag is decomposed into a adiabatic compression and a release of landing shock energy,and the differential equation of cylindrical gas-filled bag is presented from a theoretical perspective based on the ideal gas state equation and dynamic equation.Then,the effects of exhaust areas and blasting pressure on buffer characteristics are studied,taking those parameters as design variable for the multiobjective optimization problem,and the solution can be determined by comparing Pareto set,which is gained by NSGA-Ⅱ.Finally,the feasibility of the design scheme is verified by experimental results of the ground test.展开更多
Abstract： The major methods to investigate the airbags cushion system are experimental method, thermodynamic method and finite element method （FEM）. Airbags cushion systems are very complicated and very difficult t...Abstract： The major methods to investigate the airbags cushion system are experimental method, thermodynamic method and finite element method （FEM）. Airbags cushion systems are very complicated and very difficult to be investigated thoroughly by such methods For experimental method, it is nearly impossible to completely analyze and optimize the cushion characteristics of airbags of airborne vehicle because of charge issue, safety concern and time constraint. Thermodynamic method fails to take the non-linear effects of large airbag deformation and varied contact conditions into consideration. For finite element method, the FE model is usually complicated and the calculation takes tens of hours of CPU time. As a result, the optimization of the design based on a nonlinear model is very difficult by traditional iterative approach method. In this paper, a model based on FEM and control volume method is proposed to simulate landing cushion process of airborne vehicle with airbags cushion system in order to analyze and optimize the parameters in airbags cushion system. At first, the performance of airbags cushion system model is verified experimentally. In airdrop test, accelerometers are fixed in 4 test points distributed over engine mount, top, bottom and side armor plate of hull to obtain acceleration curves with time. The simulation results are obtained under the same conditions of the airdrop test and the simulation results agree very well with the experimental results, which indicate the established model is valid for further optimization. To optimize the parameters of airbags, equivalent response model based on Latin Hypercube DOE and radial basis function is employed instead of the complex finite element model. Then the optimal results based on equivalent response model are obtained using simulated annealing algorithm. After optimization, the maximal acceleration of airborne vehicle landing reduces 19.83%, while the energy absorption by airbags increases 7.85%. The performance of the airbags cushion system thus is largely improved through optimization, which indicates the proposed method has the capability of solving the parameter optimization problem of airbags cushion system for airborne vehicle.展开更多
In this paper, we propose an impact finite element （FE） model for an airbag landing buf- fer system. First, an impact FE model has been formulated for a typical airbag landing buffer system. We use the independence ...In this paper, we propose an impact finite element （FE） model for an airbag landing buf- fer system. First, an impact FE model has been formulated for a typical airbag landing buffer system. We use the independence of the structure FE model from the full impact FE model to develop a hierarchical updating scheme for the recovery module FE model and the airbag system FE model. Second, we define impact responses at key points to compare the computational and experimental results to resolve the inconsistency between the experimental data sampling frequency and experi- mental triggering. To determine the typical characteristics of the impact dynamics response of the airbag landing buffer system, we present the impact response confidence factors （IRCFs） to evalu- ate how consistent the computational and experiment results are. An error function is defined between the experimental and computational results at key points of the impact response （KPIR） to serve as a modified objective function. A radial basis function （RBF） is introduced to construct updating variables for a surrogate model for updating the objective function, thereby converting the FE model updating problem to a soluble optimization problem. Finally, the developed method has been validated using an experimental and computational study on the impact dynamics of a classic airbag landing buffer system.展开更多
The current design and optimization of the occupant restraint system（ORS） are based on numerous actual tests and mathematic simulations. These two methods are overly time-consuming and complex for the concept design...The current design and optimization of the occupant restraint system（ORS） are based on numerous actual tests and mathematic simulations. These two methods are overly time-consuming and complex for the concept design phase of the ORS, though they＇re quite effective and accurate. Therefore, a fast and directive method of the design and optimization is needed in the concept design phase of the ORS. Since the airbag system is a crucial part of the ORS, in this paper, a theoretical model for the vehicle airbag is established in order to clarify the interaction between occupants and airbags, and further a fast design and optimization method of airbags in the concept design phase is made based on the proposed theoretical model. First, the theoretical expression of the simplified mechanical relationship between the airbag＇s design parameters and the occupant response is developed based on classical mechanics, then the momentum theorem and the ideal gas state equation are adopted to illustrate the relationship between airbag＇s design parameters and occupant response. By using MATLAB software, the iterative algorithm method and discrete variables are applied to the solution of the proposed theoretical model with a random input in a certain scope. And validations by MADYMO software prove the validity and accuracy of this theoretical model in two principal design parameters, the inflated gas mass and vent diameter, within a regular range. This research contributes to a deeper comprehension of the relation between occupants and airbags, further a fast design and optimization method for airbags＇ principal parameters in the concept design phase, and provides the range of the airbag＇s initial design parameters for the subsequent CAE simulations and actual tests.展开更多
The air permeability of airbag fabrics was measured at high pressure differential up to 200 kPa. It was found that permeability varied with pressure differential nonlinearly. The relationship between air permeability ...The air permeability of airbag fabrics was measured at high pressure differential up to 200 kPa. It was found that permeability varied with pressure differential nonlinearly. The relationship between air permeability and the pressure differential was fitted well with power law curve. The study revealed that the coefficient c and exponent b in the power law equation had a strong correlation with porosity, which was chosen to characterize the airbag fabrics.展开更多
An investigation is reported in which the factors such as air discharge resistance capability, weaving ability, and anti- breakage performance are discussed. These parameters are concerned during weave designing for r...An investigation is reported in which the factors such as air discharge resistance capability, weaving ability, and anti- breakage performance are discussed. These parameters are concerned during weave designing for ripped-up edge of full airbag. Furthermore, two kinds of weave of edge in airbag, rib weave and basket weave,were chosen to analyze the performances of airbag. And the datum relative to the weave which affected the performances of airbag, such as weave form, initial point, were analyzed. In addition, accordingly technical handles are taken on the special loom.展开更多
An airbag is an effective protective device for vehicle occupant safety, but may cause unexpected injury from the excessive energy of ignition when it is deployed, This paper focuses on the design of a new tubular dri...An airbag is an effective protective device for vehicle occupant safety, but may cause unexpected injury from the excessive energy of ignition when it is deployed, This paper focuses on the design of a new tubular driver airhag from the perspective of reducing the dosage of gas generant, Three different dummies were selected for computer simulation to investigate the stiffness and protection performance of the new airhag, Next, a multi-objective optimization of the 50th percentile dummy was conducted, The results show that the static volume of the new airhag is only about 113 of the volume of an ordinary one, and the injury value of each type of dummy can meet legal requirements while reducing the gas dosage by at least 30%, The combined injury index （Pcomb） decreases by 22% and the gas dosage is reduced by 32% after optimization, This study demonstrates that the new tubular driver airbag has great potential for protection in terms of reducing the gas dosage,展开更多
BACKGROUND The emergency department(ED)plays a critical role in establishing artificial airways and implementing mechanical ventilation.Managing airbags in the ED presents a prime opportunity to mitigate the risk of v...BACKGROUND The emergency department(ED)plays a critical role in establishing artificial airways and implementing mechanical ventilation.Managing airbags in the ED presents a prime opportunity to mitigate the risk of ventilator-associated pneumonia.Nonetheless,existing research has largely overlooked the understanding,beliefs,and practical dimensions of airway airbag management among ED nurses,with a predominant focus on intensive care unit nurses.AIM To investigate the current status of ED nurses'knowledge,beliefs,and practical behaviors in airway airbag management and their influencing factors.METHODS A survey was conducted from July 10th to August 10th,2023,using convenience sampling on 520 ED nurses from 15 tertiary hospitals and 5 sary hospitals in Shanghai.Pathway analysis was utilized to analyze the influencing factors.RESULTS The scores for ED nurses'airway airbag management knowledge were 60.26±23.00,belief was 88.65±13.36,and behavior was 75.10±19.84.The main influencing factors of airbag management knowledge included participation in specialized nurse or mechanical ventilation training,department,and work experience in the department.Influencing factors of airbag management belief comprised knowledge,department,and participation in specialized nurse or mechanical ventilation training.Primary influencing factors of airbag management behavior included knowledge,belief,department,participation in specialized nurse or mechanical ventilation training,and professional title.The belief in airbag management among ED nurses acted as a partial mediator between knowledge and behavior,with a total effect value of 0.513,and an indirect effect of 0.085,constituting 16.6%of the total effect.CONCLUSION ED nurses exhibit a positive attitude toward airbag management with relatively standardized practices,yet there remains room for improvement in their knowledge levels.Nursing managers should implement interventions tailored to the characteristics of ED nurses'airbag management knowledge,beliefs,and practices to enhance their airbag management proficiency.展开更多
Aimed at the difficulties in analyzing the buffer characteristics of airbag system by using thermodynamic or experimental method only,the finite element method was used to establish nonlinear models for heavy equipmen...Aimed at the difficulties in analyzing the buffer characteristics of airbag system by using thermodynamic or experimental method only,the finite element method was used to establish nonlinear models for heavy equipment and its airbag system.The models' efficiency and correctness were validated by using on-site experiment data in vehicle airdrop landing.The simulation results agree very well with the experiment results.Then,the environment adaptability of airbag system of heavy equipment under high-altitude condition was studied by using the models.Finally,some solutions were given to solve the overturn problem in the landing.展开更多
A finite element model of vehicle and its airbag landing attenuation system is established and verified experimentally.Two design cases are selected to constrain the airbag design for extreme landing conditions,while ...A finite element model of vehicle and its airbag landing attenuation system is established and verified experimentally.Two design cases are selected to constrain the airbag design for extreme landing conditions,while the height and width of airbag and the area of vent hole are chosen as design variables.The optimization is forced to compromise the design variables between the conflicting requirements of the two extremes.In order to optimize the parameters of airbag,the multi-dimensional response surfaces based on extended Latin hypercube design and radial basis function are employed instead of the complex finite element model.Pareto optimal solution sets based on response surfaces are then obtained by multi-objective genetic algorithm.The results show the optimization method presented in this paper is a practical tool for the optimization of airbag landing attenuation system for heavy airdrop.展开更多
In the criminal cases of driving under the influence(DUI), DNA evidence can be collected from the deployed airbag of the motor vehicle and submitted to the crime lab for touch DNA analysis.The evidence can be acquired...In the criminal cases of driving under the influence(DUI), DNA evidence can be collected from the deployed airbag of the motor vehicle and submitted to the crime lab for touch DNA analysis.The evidence can be acquired when the skin cells are observed on the surface of the airbag in a traffic accident. However, the low quantity or quality of the evidence collected from a crime scene prevents further identification analysis in many cases. In the current study, we reported a case of identifying touch DNA extraction from the shed skin cells from the deployed airbag of a motor vehicle. We managed to collect DNA evidence from the shed skin cells in an airbag using a proper approach of collection and extraction. The 5.87 ng of extracted DNA was sufficient for genotyping and forensic identification, which helped to identify the driver of the car in collision with a pier in the street. In DUI cases and other traffic accidents, therefore, the amount of touch DNA extracted from the deployed airbag can be sufficient for DNA marker genotyping and further analysis.展开更多
In this paper,we propose a pricing model of airbag options with discrete monitoring,time-varying barriers,early exercise opportunities,and other popular features simultaneously.We show that the option value is a visco...In this paper,we propose a pricing model of airbag options with discrete monitoring,time-varying barriers,early exercise opportunities,and other popular features simultaneously.We show that the option value is a viscosity solution of a PDE system.In particular,a closed-form solution is obtained in the classic Black-Scholes economy with no early exercise opportunities.For the general case,we develop a numerical algorithm and conduct an extensive numerical analysis after calibrating the model to the CSI 500 index in China.Greek letters,dynamic hedging,and assessment of investing in airbag options are also studied.展开更多
Presented in this paper is a numerical investigation into the cushioning performance of airbag employed for buffer protection.The cushioning performance,in terms of the peak overload,z-velocity and inner pressure,is d...Presented in this paper is a numerical investigation into the cushioning performance of airbag employed for buffer protection.The cushioning performance,in terms of the peak overload,z-velocity and inner pressure,is described in detail.The influence of the landing angle with the ground,and the chamber configurations on the cushioning performance is analyzed.The results obtained showed that fluctuations were observed in the buffer overload values,inner pressures,and surface stress during the airbag landing process.As the landing angle increased from 0°to 90°,the peak overload experienced by the buffer initially decreased and subsequently increased,reaching its maximum value of 78.13 at 0°.Stress concentration was observed at several critical locations.In addition,the peak overload was minimally influenced by the outer airbag configurations,consistently exhibiting the highest at a landing angle of 0°.Considering variability in landing angles,the horizontal-vertical configuration of the outer airbag is preferable,as it yields the lowest maximum peak overload value of 76.33.展开更多
The passenger side airbags(PAB)are usually larger than the driver airbags.Therefore,the inflator of PAB is more powerful with high mass rate.In this paper,an Arbitrary Lagrangian-Eulerian(ALE)method based computationa...The passenger side airbags(PAB)are usually larger than the driver airbags.Therefore,the inflator of PAB is more powerful with high mass rate.In this paper,an Arbitrary Lagrangian-Eulerian(ALE)method based computational method is developed to simulate the deployment of a PAB.The tank test is used to test the property of the inflator.Through comparison of numerical and experimental results,the ALE method is validated.Based on a failed airbag test,a smaller sub-airbag is placed inside PAB to disperse the gas flow to directions which are less damaging.By applying dynamic relaxation,the initial mesh corresponding to the experimental terms is obtained.The results indicate that the interior pressure and impact force coincide with the test data,and the method in this paper is capable of capturing airbag deploying process of the PAB module accurately.展开更多
Current software cannot easily model an airbag to be flattened without wrinkles. This paper im- proves the modeling efficiency using the initial metric method to design a mapped mesh auto-flattening algo- rithm. The e...Current software cannot easily model an airbag to be flattened without wrinkles. This paper im- proves the modeling efficiency using the initial metric method to design a mapped mesh auto-flattening algo- rithm. The element geometric transformation matrix was obtained using the theory of computer graphics. The algorithm proved to be practical for modeling a passenger-side airbag model. The efficiency and preci- sion of modeling airbags are greatly improved by this method.展开更多
Among many equipment for passenger safety, the air bag system is the most fundamental and effective device for an automobile. The inflator housing is a main part of the curtain-type air bag system, which supplies high...Among many equipment for passenger safety, the air bag system is the most fundamental and effective device for an automobile. The inflator housing is a main part of the curtain-type air bag system, which supplies high-pressure gases in pumping up the air bag-curtain which is increasingly being adapted in deluxe cars for protecting passengers from the danger of side clash. However, flow information on the inflator housing is very limited. In this study, we measure the instantaneous velocity fields of a high-speed compressible flow issuing from the exit nozzle of an inflator housing using a dynamic PIV system. From the velocity field data measured at a high frame-rate, we evaluate the variation of the mass flow rate with time. The dynamic PIV system consists of a high-repetition Nd：YLF laser, a high-speed CMOS camera, and a delay generator. The flow images are taken at 4000 fps with synchronization of the trigger signal for inflator ignition. From the instantaneous velocity field data of flow ejecting from the airbag inflator housing at the initial stage, we can see a flow pattern of broken shock wave front and its downward propagation. The flow ejecting from the inflator housing is found to have very high velocity fluctuations, with the maximum velocity at about 700 m/s. The time duration of the high-speed flow is very short, and there is no perceptible flow after 100 ms.展开更多
The emergency transformation of various aspects of life and business these days requires prompt evaluation of autonomous vehicles.One of the primary reassessments deals with the applicability of the vehicle passive sa...The emergency transformation of various aspects of life and business these days requires prompt evaluation of autonomous vehicles.One of the primary reassessments deals with the applicability of the vehicle passive safety system to the protec-tion of arbitrarily positioned passengers.To mitigate possible risks caused by the simultaneous deployment of several big airbags,a new principle of their operation is required.Herein,the aspirated inflator for a driver airbag is developed that can provide 50L-airbag inflation within 30-40 ms.As a result,about 3/4 of the air is to be entrained into an airbag from the vehicle compartment.The process is initiated by a supersonic pulse jet(1/3 air volume)generated pyrotechnically.Then the Prandtl-Meyer problem formulation enables guiding linear and angular dimensions of the essential parts of the device.Accordingly,a family of experimental models of varied geometry is fabricated and tested to determine their operational effectiveness in a range of motive pressure within~3-7 MPa.Experiments are performed on a specially designed facility equipped with compressed-air tanks and a high-speed valve to mimic the inflator operation with the pyrotechnic gas generator.The aspirated inflator operability is characterized using multivariate measurements of pressure fields,high-speed video-recording of the airbag inflation process,and evaluation of aspiration(entrainment)ratio.The average volume aspiration ratio measured at 300 K is found to reach 2.8 and it’s expected to almost double at 1200 K.展开更多
基金co-supported by the National Natural Science Foundation of China(Nos.11932001,12272003,U224126)。
文摘To ensure the safety of astronauts and equipment during landing,the airbag landing system is commonly utilized to attenuate the impact response of the spacecraft.However,the complex impact dynamics and multi-disciplinary coupling pose significant challenges to mission design.This paper first investigates the typical design scheme of the airbag landing system for manned spacecrafts to obtain basic insight.A comprehensive review of the past research works on the airbag landing system is then carried out from three aspects:dynamic modeling,performance optimization,and experimental study.The airbag landing system for spacecraft is a rigid-flexible-gas coupling system,which can be modeled through multi-body dynamics or finite element method.Different venting structures and optimization methods are introduced to improve the cushioning performance.Experimental setups for drop test and airbag test are developed to verify the design feasibility.Finally,this paper proposes key issues in the dynamics analysis and design optimization of the airbag landing system for future study.
基金supported by the Open Project of Key Laboratory of Aerospace Entry,Descent,Landing,and Ascent(EDLA),CASC,China(No.EDL19092208)the Fundamental Research Funds for the Central Universities,China(No.NZ2024039).
文摘This study presents a Fluid-Structure Interaction(FSI)model to analyze the water landing characteristics of a reentry capsule equipped with airbag cushioning.The model employs the Arbitrary Lagrangian-Eulerian(ALE)method to simulate the capsule’s impact with water,while the control volume method is used to model the airbag cushioning process.Additionally,both regular and irregular heading waves are incorporated to simulate the landing dynamics of the capsule-airbag system under various sea conditions.The developed FSI model is utilized to investigate the effects of initial velocity,attitude angle,and wave phase on the water landing characteristics of the capsule-airbag system under calm water,regular and irregular wave conditions.Key parameters,such as the impact force on the capsule,as well as the pressure,mass flow rate,and stress distribution within the airbags,are analyzed.The insights gained from this study provide valuable guidance for minimizing damage to personnel and equipment during maritime recovery operations.
基金supported by National Hi-tech Research and Development Program of China (863 Program, Grant No. 2006AA110102)
文摘Compared with other kinds of airbags, curtain airbag（CAB） has more complex structures and larger coverage area. The product development process depends on many module tests, sled tests and full size vehicle tests. Computer aided engineering（CAE） technology can replace tests to a great extent, also save test costs and product development time. This paper introduces the way of setting up simulation models and application of static deployment tests and free motion headform（FMH） tests to verify simulation models. In the CAB simulation, uniform pressure airbag models and computational fluid dynamics（CFD） models are all used. The uniform pressure airbag models are not able to simulate the pressure difference among different parts inside the cushion during inflating process. CFD-based CAB models are used to help the curtain airbag optimization design. Based on effective CAE simulation, the optimization analyses related to diffuser tube parameters, inflator mass flow rate and cushion folding patterns are discussed and performed in different cases. The optimization result shows that the proposed techniques are helpful to the parametric optimization design of side curtain airbag module in curtain airbag development process.
文摘Multi-objective optimization design of the gas-filled bag cushion landing system is investigated.Firstly,the landing process of airbag is decomposed into a adiabatic compression and a release of landing shock energy,and the differential equation of cylindrical gas-filled bag is presented from a theoretical perspective based on the ideal gas state equation and dynamic equation.Then,the effects of exhaust areas and blasting pressure on buffer characteristics are studied,taking those parameters as design variable for the multiobjective optimization problem,and the solution can be determined by comparing Pareto set,which is gained by NSGA-Ⅱ.Finally,the feasibility of the design scheme is verified by experimental results of the ground test.
文摘Abstract： The major methods to investigate the airbags cushion system are experimental method, thermodynamic method and finite element method （FEM）. Airbags cushion systems are very complicated and very difficult to be investigated thoroughly by such methods For experimental method, it is nearly impossible to completely analyze and optimize the cushion characteristics of airbags of airborne vehicle because of charge issue, safety concern and time constraint. Thermodynamic method fails to take the non-linear effects of large airbag deformation and varied contact conditions into consideration. For finite element method, the FE model is usually complicated and the calculation takes tens of hours of CPU time. As a result, the optimization of the design based on a nonlinear model is very difficult by traditional iterative approach method. In this paper, a model based on FEM and control volume method is proposed to simulate landing cushion process of airborne vehicle with airbags cushion system in order to analyze and optimize the parameters in airbags cushion system. At first, the performance of airbags cushion system model is verified experimentally. In airdrop test, accelerometers are fixed in 4 test points distributed over engine mount, top, bottom and side armor plate of hull to obtain acceleration curves with time. The simulation results are obtained under the same conditions of the airdrop test and the simulation results agree very well with the experimental results, which indicate the established model is valid for further optimization. To optimize the parameters of airbags, equivalent response model based on Latin Hypercube DOE and radial basis function is employed instead of the complex finite element model. Then the optimal results based on equivalent response model are obtained using simulated annealing algorithm. After optimization, the maximal acceleration of airborne vehicle landing reduces 19.83%, while the energy absorption by airbags increases 7.85%. The performance of the airbags cushion system thus is largely improved through optimization, which indicates the proposed method has the capability of solving the parameter optimization problem of airbags cushion system for airborne vehicle.
基金co-supported by the National Natural Science Foundation of China(No.11472132)the Fundamental Research Funds for Central Universities in China(No.NS2014002)+1 种基金the Research Fund of State Key Laboratory of Mechanics and Control of Mechanical Structures(Nanjing University of Aeronautics and Astronautics)(No.0113Y01)the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions in China
文摘In this paper, we propose an impact finite element （FE） model for an airbag landing buf- fer system. First, an impact FE model has been formulated for a typical airbag landing buffer system. We use the independence of the structure FE model from the full impact FE model to develop a hierarchical updating scheme for the recovery module FE model and the airbag system FE model. Second, we define impact responses at key points to compare the computational and experimental results to resolve the inconsistency between the experimental data sampling frequency and experi- mental triggering. To determine the typical characteristics of the impact dynamics response of the airbag landing buffer system, we present the impact response confidence factors （IRCFs） to evalu- ate how consistent the computational and experiment results are. An error function is defined between the experimental and computational results at key points of the impact response （KPIR） to serve as a modified objective function. A radial basis function （RBF） is introduced to construct updating variables for a surrogate model for updating the objective function, thereby converting the FE model updating problem to a soluble optimization problem. Finally, the developed method has been validated using an experimental and computational study on the impact dynamics of a classic airbag landing buffer system.
基金Supported by National Natural Science Foundation of China(Grant No.51375203)Open Foundation of Zhejiang Province Key Laboratory of Automobile Safety of China(Grant No.LHY1308J00368)Changchun Municipal Science and Technology Planning Project of China(Grant No.12ZX79)
文摘The current design and optimization of the occupant restraint system（ORS） are based on numerous actual tests and mathematic simulations. These two methods are overly time-consuming and complex for the concept design phase of the ORS, though they＇re quite effective and accurate. Therefore, a fast and directive method of the design and optimization is needed in the concept design phase of the ORS. Since the airbag system is a crucial part of the ORS, in this paper, a theoretical model for the vehicle airbag is established in order to clarify the interaction between occupants and airbags, and further a fast design and optimization method of airbags in the concept design phase is made based on the proposed theoretical model. First, the theoretical expression of the simplified mechanical relationship between the airbag＇s design parameters and the occupant response is developed based on classical mechanics, then the momentum theorem and the ideal gas state equation are adopted to illustrate the relationship between airbag＇s design parameters and occupant response. By using MATLAB software, the iterative algorithm method and discrete variables are applied to the solution of the proposed theoretical model with a random input in a certain scope. And validations by MADYMO software prove the validity and accuracy of this theoretical model in two principal design parameters, the inflated gas mass and vent diameter, within a regular range. This research contributes to a deeper comprehension of the relation between occupants and airbags, further a fast design and optimization method for airbags＇ principal parameters in the concept design phase, and provides the range of the airbag＇s initial design parameters for the subsequent CAE simulations and actual tests.
基金This work was supported by the Excellence Young Teachers Program of Ministry of Education,P.R.C
文摘The air permeability of airbag fabrics was measured at high pressure differential up to 200 kPa. It was found that permeability varied with pressure differential nonlinearly. The relationship between air permeability and the pressure differential was fitted well with power law curve. The study revealed that the coefficient c and exponent b in the power law equation had a strong correlation with porosity, which was chosen to characterize the airbag fabrics.
文摘An investigation is reported in which the factors such as air discharge resistance capability, weaving ability, and anti- breakage performance are discussed. These parameters are concerned during weave designing for ripped-up edge of full airbag. Furthermore, two kinds of weave of edge in airbag, rib weave and basket weave,were chosen to analyze the performances of airbag. And the datum relative to the weave which affected the performances of airbag, such as weave form, initial point, were analyzed. In addition, accordingly technical handles are taken on the special loom.
文摘An airbag is an effective protective device for vehicle occupant safety, but may cause unexpected injury from the excessive energy of ignition when it is deployed, This paper focuses on the design of a new tubular driver airhag from the perspective of reducing the dosage of gas generant, Three different dummies were selected for computer simulation to investigate the stiffness and protection performance of the new airhag, Next, a multi-objective optimization of the 50th percentile dummy was conducted, The results show that the static volume of the new airhag is only about 113 of the volume of an ordinary one, and the injury value of each type of dummy can meet legal requirements while reducing the gas dosage by at least 30%, The combined injury index （Pcomb） decreases by 22% and the gas dosage is reduced by 32% after optimization, This study demonstrates that the new tubular driver airbag has great potential for protection in terms of reducing the gas dosage,
文摘BACKGROUND The emergency department(ED)plays a critical role in establishing artificial airways and implementing mechanical ventilation.Managing airbags in the ED presents a prime opportunity to mitigate the risk of ventilator-associated pneumonia.Nonetheless,existing research has largely overlooked the understanding,beliefs,and practical dimensions of airway airbag management among ED nurses,with a predominant focus on intensive care unit nurses.AIM To investigate the current status of ED nurses'knowledge,beliefs,and practical behaviors in airway airbag management and their influencing factors.METHODS A survey was conducted from July 10th to August 10th,2023,using convenience sampling on 520 ED nurses from 15 tertiary hospitals and 5 sary hospitals in Shanghai.Pathway analysis was utilized to analyze the influencing factors.RESULTS The scores for ED nurses'airway airbag management knowledge were 60.26±23.00,belief was 88.65±13.36,and behavior was 75.10±19.84.The main influencing factors of airbag management knowledge included participation in specialized nurse or mechanical ventilation training,department,and work experience in the department.Influencing factors of airbag management belief comprised knowledge,department,and participation in specialized nurse or mechanical ventilation training.Primary influencing factors of airbag management behavior included knowledge,belief,department,participation in specialized nurse or mechanical ventilation training,and professional title.The belief in airbag management among ED nurses acted as a partial mediator between knowledge and behavior,with a total effect value of 0.513,and an indirect effect of 0.085,constituting 16.6%of the total effect.CONCLUSION ED nurses exhibit a positive attitude toward airbag management with relatively standardized practices,yet there remains room for improvement in their knowledge levels.Nursing managers should implement interventions tailored to the characteristics of ED nurses'airbag management knowledge,beliefs,and practices to enhance their airbag management proficiency.
文摘Aimed at the difficulties in analyzing the buffer characteristics of airbag system by using thermodynamic or experimental method only,the finite element method was used to establish nonlinear models for heavy equipment and its airbag system.The models' efficiency and correctness were validated by using on-site experiment data in vehicle airdrop landing.The simulation results agree very well with the experiment results.Then,the environment adaptability of airbag system of heavy equipment under high-altitude condition was studied by using the models.Finally,some solutions were given to solve the overturn problem in the landing.
文摘A finite element model of vehicle and its airbag landing attenuation system is established and verified experimentally.Two design cases are selected to constrain the airbag design for extreme landing conditions,while the height and width of airbag and the area of vent hole are chosen as design variables.The optimization is forced to compromise the design variables between the conflicting requirements of the two extremes.In order to optimize the parameters of airbag,the multi-dimensional response surfaces based on extended Latin hypercube design and radial basis function are employed instead of the complex finite element model.Pareto optimal solution sets based on response surfaces are then obtained by multi-objective genetic algorithm.The results show the optimization method presented in this paper is a practical tool for the optimization of airbag landing attenuation system for heavy airdrop.
基金This research was supported by the National Natural Science Foundation of China
文摘In the criminal cases of driving under the influence(DUI), DNA evidence can be collected from the deployed airbag of the motor vehicle and submitted to the crime lab for touch DNA analysis.The evidence can be acquired when the skin cells are observed on the surface of the airbag in a traffic accident. However, the low quantity or quality of the evidence collected from a crime scene prevents further identification analysis in many cases. In the current study, we reported a case of identifying touch DNA extraction from the shed skin cells from the deployed airbag of a motor vehicle. We managed to collect DNA evidence from the shed skin cells in an airbag using a proper approach of collection and extraction. The 5.87 ng of extracted DNA was sufficient for genotyping and forensic identification, which helped to identify the driver of the car in collision with a pier in the street. In DUI cases and other traffic accidents, therefore, the amount of touch DNA extracted from the deployed airbag can be sufficient for DNA marker genotyping and further analysis.
基金supported by the the National Natural Science Foundation of China(No.11901416)Natural Science Foundation of Jiangsu Province(BK20190812)。
文摘In this paper,we propose a pricing model of airbag options with discrete monitoring,time-varying barriers,early exercise opportunities,and other popular features simultaneously.We show that the option value is a viscosity solution of a PDE system.In particular,a closed-form solution is obtained in the classic Black-Scholes economy with no early exercise opportunities.For the general case,we develop a numerical algorithm and conduct an extensive numerical analysis after calibrating the model to the CSI 500 index in China.Greek letters,dynamic hedging,and assessment of investing in airbag options are also studied.
基金supported by Shanghai Central Government Leading Local and Technology Development Funds(No.YDZX20233100004008).
文摘Presented in this paper is a numerical investigation into the cushioning performance of airbag employed for buffer protection.The cushioning performance,in terms of the peak overload,z-velocity and inner pressure,is described in detail.The influence of the landing angle with the ground,and the chamber configurations on the cushioning performance is analyzed.The results obtained showed that fluctuations were observed in the buffer overload values,inner pressures,and surface stress during the airbag landing process.As the landing angle increased from 0°to 90°,the peak overload experienced by the buffer initially decreased and subsequently increased,reaching its maximum value of 78.13 at 0°.Stress concentration was observed at several critical locations.In addition,the peak overload was minimally influenced by the outer airbag configurations,consistently exhibiting the highest at a landing angle of 0°.Considering variability in landing angles,the horizontal-vertical configuration of the outer airbag is preferable,as it yields the lowest maximum peak overload value of 76.33.
基金supported by the National Basic Research Program of China("973"Project)(Grant Nos.2013CB036101 and 2010CB832704)the National Natural Science Foundation of China(Grant Nos.51221961,51279030 and 51309040)
文摘The passenger side airbags(PAB)are usually larger than the driver airbags.Therefore,the inflator of PAB is more powerful with high mass rate.In this paper,an Arbitrary Lagrangian-Eulerian(ALE)method based computational method is developed to simulate the deployment of a PAB.The tank test is used to test the property of the inflator.Through comparison of numerical and experimental results,the ALE method is validated.Based on a failed airbag test,a smaller sub-airbag is placed inside PAB to disperse the gas flow to directions which are less damaging.By applying dynamic relaxation,the initial mesh corresponding to the experimental terms is obtained.The results indicate that the interior pressure and impact force coincide with the test data,and the method in this paper is capable of capturing airbag deploying process of the PAB module accurately.
文摘Current software cannot easily model an airbag to be flattened without wrinkles. This paper im- proves the modeling efficiency using the initial metric method to design a mapped mesh auto-flattening algo- rithm. The element geometric transformation matrix was obtained using the theory of computer graphics. The algorithm proved to be practical for modeling a passenger-side airbag model. The efficiency and preci- sion of modeling airbags are greatly improved by this method.
文摘Among many equipment for passenger safety, the air bag system is the most fundamental and effective device for an automobile. The inflator housing is a main part of the curtain-type air bag system, which supplies high-pressure gases in pumping up the air bag-curtain which is increasingly being adapted in deluxe cars for protecting passengers from the danger of side clash. However, flow information on the inflator housing is very limited. In this study, we measure the instantaneous velocity fields of a high-speed compressible flow issuing from the exit nozzle of an inflator housing using a dynamic PIV system. From the velocity field data measured at a high frame-rate, we evaluate the variation of the mass flow rate with time. The dynamic PIV system consists of a high-repetition Nd：YLF laser, a high-speed CMOS camera, and a delay generator. The flow images are taken at 4000 fps with synchronization of the trigger signal for inflator ignition. From the instantaneous velocity field data of flow ejecting from the airbag inflator housing at the initial stage, we can see a flow pattern of broken shock wave front and its downward propagation. The flow ejecting from the inflator housing is found to have very high velocity fluctuations, with the maximum velocity at about 700 m/s. The time duration of the high-speed flow is very short, and there is no perceptible flow after 100 ms.
文摘The emergency transformation of various aspects of life and business these days requires prompt evaluation of autonomous vehicles.One of the primary reassessments deals with the applicability of the vehicle passive safety system to the protec-tion of arbitrarily positioned passengers.To mitigate possible risks caused by the simultaneous deployment of several big airbags,a new principle of their operation is required.Herein,the aspirated inflator for a driver airbag is developed that can provide 50L-airbag inflation within 30-40 ms.As a result,about 3/4 of the air is to be entrained into an airbag from the vehicle compartment.The process is initiated by a supersonic pulse jet(1/3 air volume)generated pyrotechnically.Then the Prandtl-Meyer problem formulation enables guiding linear and angular dimensions of the essential parts of the device.Accordingly,a family of experimental models of varied geometry is fabricated and tested to determine their operational effectiveness in a range of motive pressure within~3-7 MPa.Experiments are performed on a specially designed facility equipped with compressed-air tanks and a high-speed valve to mimic the inflator operation with the pyrotechnic gas generator.The aspirated inflator operability is characterized using multivariate measurements of pressure fields,high-speed video-recording of the airbag inflation process,and evaluation of aspiration(entrainment)ratio.The average volume aspiration ratio measured at 300 K is found to reach 2.8 and it’s expected to almost double at 1200 K.
