Simulation Study On Protective Property Of Hip-protected Airbag In Sideway Fall

Hip fracture caused by falls is one of the most deadly injury to the old.And as the largest developing country,China is faced with grave problem of population aging.Thus the study on fall prevent and pretection is of great importance.With the development of fall detection technology,it has been possible to detect the fall event before the man impact the floor,making it possible to trigger the hip-protected system to protect the hip from heavy hurt.The hip-protected system for sideway falls protect the aged from falls by triggerring a airbag deployment.Based on the hip-protected system,this article mainly introduce our jobs on how the the hip-protected airbag protected and how some factors influence the hip-protected performance of the airbag as follows:(1)A 3D geometric model of human hip is accomplished by importing the 2D CT images of the hip,and a finite element model of the airbag is completed with the FEA software ANSYS.(2)The prototype of the hip-protected airbag system is introduced,and the structure of the inflating mechanism is described.The velocity and accelation of the hip is measured and analyzed as it is impacting the floor with a few expriments.(3)By set the airbag size 0.2m×0.2m,the thickness 0.5mm,the initial pressure0.138 MPa and the velocity of sideway falls 2.0m/s,the hip-protected’s good performance is confirmed,with decreasing the peak impact force of the hip by 70%and the absorption of energy by 83.8%.(4)Summarize how the the factors of size,initial pressure,thickness affected the airbag’s hip-protected performance from peak impact force and energy absorption angles as follows:1)The peak impact force and the energy absorption of the hip on the optimized initial pressure grows stronger as the size decreases.And if the size is 0.1m×0.1m or less,the lest peak impack force is larger than 4630 N,which is much bigger than the average threshold force that cause the hip fracture.2)At the condition that the airbag is inflated full,keep the factors of size and thickness,as the initial pressure arise,the peak impact force and the the energyabsorption of the hip decreases firstly and then increases.For the airbags with sizes of 0.1m×0.1m,0.2m×0.2m,0.3m×0.3m and 0.4m×0.4m,their optimized initial pressure for least peak impack force are 0.911 MPa,0.176 MPa,0.121 MPa and0.157 MPa,and their optimized initial pressure for least energy absorption of the hip are 0.827 MPa,0.176 MPa,0.11 MPa,0.175 MPa.3)Keep the factors of size and initial pressure of the airbag and make sure the airbag material is strong enough,as the thickness grows thinner,the peak impact force and the the energy absorption of the hip decreases,which is linear with the thickness.