Airbag Impact Attenuation and Deflation Modelling

Andrews, Steven (2004). Airbag Impact Attenuation and Deflation Modelling Honours Thesis, School of Engineering, The University of Queensland.

       
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Author Andrews, Steven
Thesis Title Airbag Impact Attenuation and Deflation Modelling
School, Centre or Institute School of Engineering
Institution The University of Queensland
Publication date 2004
Thesis type Honours Thesis
Supervisor Not known
Total pages 92
Language eng
Subjects 0913 Mechanical Engineering
Formatted abstract
To help in design efforts of a full airbag impact actuation system for the Mars Gravity Biosatellite Program a simple MATLAB simulation has been written to give a better understanding of  airbag impact dynamics. This simulation was then compared with a series of tests to determine the  influence of vent radius on the behaviour of the system.

A MATLAB simulation was constructed to model the behavior of a simple airbag impact attenuation  system. The model consisted of a simple spherical airbag being squeezed under a virtual mass of  75kg, simplified airbag volume equations during the compression and ideal gas assumptions to reduce  the complexity of the code. The simulations investigate the effect from varying parameters such as  the burst pressure, vent radius, initial velocity and initial airbag pressures on the pressure and  deceleration behaviour of the system. Venting was the most important aspect of the simulation and  while mathematical manipulations could give formulas for venting, the actual venting rates were
dependant on the discharge coefficient which can only be determined experimentally.

Impact attenuation tests on airbags with 15mm, 17.5mm, 20mm and 25mm radius vents were conducted.  For this a test rig and airbag were constructed, with the test rig constructed into a flat circular  plate of mild steel 3mm thick, with a smaller plate at the centre welded to a vertical support column. The airbag was made from sailcloth Nylon coated in a polyurethane sealant. The airbag was  constructed from six ‘orange peel’ sections sewn together using a three line prayer seam. The seams  were sealed using a liquid silicone sealant.

It was found that the discharge coefficient varied with the vent size and relationships were  obtained correlating both the pressure and decelerations of the test rig with the simulations.

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Keyword Deflation Modelling

Document type: Thesis
Collection: UQ Theses (non-RHD) - UQ staff and students only
 
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Created: Thu, 13 Nov 2014, 14:34:09 EST by Asma Asrar Qureshi on behalf of Scholarly Communication and Digitisation Service