Characteristic Verification and Parameter Optimization of Airbags Cushion System for Airborne Vehicle

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.

Current state and influencing factors in airbag management among emergency department nurses:A multicenter study

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.

Data Mining Based Research of Development Direction of Waist Protection Equipment

[Objectives]To explore the trend of brands towards the design of waist protection products through data mining,and to provide reference for the design concept of the contour of waist protection pillow.[Methods]The structural design information of all waist protection equipment was collected from the national Internet platform,and the data were classified and a database was established.IBM SPSS 26.0 and MATLAB 2018a were used to analyze the data and tabulate them in Tableau 2022.4.After the association rules were clarified,the data were imported into Cinema 4D R21 to create the concept contour of waist protection pillow.[Results]The average and standard deviation of the single airbag design were the highest in all groups,with an average of 0.511 and a standard deviation of 0.502.The average and standard deviation of the upper and lower dual airbags were the lowest in all groups,with an average of 0.015 and a standard deviation of 0.120;the correlation coefficient between single airbag and 120°arc stretching was 0.325,which was positively correlated with each other(P<0.01);the correlation coefficient between multiple airbags and 360°encircling fitting was 0.501,which was positively correlated with each other and had the highest correlation degree(P<0.01).[Conclusions]The single airbag design is well recognized by companies,and has received the highest attention among all brand products.While focusing on single airbag design,most brands will consider the need to add 120°arc stretching elements in product design.At the time of focusing on multiple airbag design,some brands believe that 360°encircling fitting elements need to be added to the product,and the correlation between the two is the highest among all groups.

Simulation and optimization for airdrop adaptability of overweight equipment

Airbag buffer process was analyzed with the aid of aerodynamic and thermodynamic methods.Based on the current structure of the airbag,the terminal velocity was too high.Therefore,the research on the diameter and height of the airbag was done and the feasible design area was found.With the optimized structure parameters,the airbag buffer experiment under normal conditions was conducted.Furthermore,the residual height and internal pressure of the airbag as well as the terminal velocity and acceleration of the airdrop were obtained.The experiment results show that the optimized airbag is feasible for 20 t cargo airdrop.

Optimization of Vehicle Side Curtain Airbag Module Based on Computer Aided Engineering

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.

Multi-objective Optimization Design of Vented Cylindrical Airbag Cushioning System for Unmanned Aerial Vehicle

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.

Establishment and Validation for the Theoretical Model of the Vehicle Airbag

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.

Experimental Research on Permeability of Airbag Fabrics at High Pressure Differential

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.

Design and Occupant-Protection Performance Analysis of a New Tubular Driver Airbag

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,

Designing for Ripped-up Edge in Full Airbag

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.

Design and experiment of a novel pneumatic soft arm based on a deployable origami exoskeleton

Soft arms have shown great application potential because of their flexibility and compliance in unstructured environments.However,soft arms made from soft materials exhibit limited cargo-loading capacity,which restricts their ability to manipulate objects.In this research,a novel soft arm was developed by coupling a rigid origami exoskeleton with soft airbags.The joint module of the soft arm was composed of a deployable origami exoskeleton and three soft airbags.The motion and load performance of the soft arm of the eight-joint module was tested.The developed soft arm withstood at least 5 kg of load during extension,contraction,and bending motions;exhibited bistable characteristics in both fully contracted and fully extended states;and achieved a bending angle of more than 240°and a contraction ratio of more than 300%.In addition,the high extension,contraction,bending,and torsional stiffnesses of the soft arm were experimentally demonstrated.A kinematic-based trajectory planning of the soft arm was performed to evaluate its error in repetitive motion.This work will provide new design ideas and methods for flexible manipulation applications of soft arms.

A numerical study of passenger side airbag deployment based on arbitrary Lagrangian-eulerian method

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.

Airbag Mapped Mesh Auto-Flattening Method

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.

A hierarchical updating method for finite element model of airbag buffer system under landing impact

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.

Dynamic PIV Measurement of a Compressible Flow Issuing from an Airbag Inflator Nozzle

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.

Design of the Airbag Inflation System Applicable to Conventional and Autonomous Vehicles

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.