Airbag Modeling Using Initial Metric Methodology

Tanavde, Anand S.; Khandelwal, Himanshu; Lasry, David; Ni, X.; Haug, E.; Schlosser, J.E.; Balakrishnan, Pradeep

doi:10.4271/950875

Cited by 12 publications

(6 citation statements)

References 5 publications

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“…The airbag mesh strain field was referenced to the unfolded mesh throughout the deployment sequence using the Initial Metric Method (Tanavde et al, 1995). Inflation behavior was defined by a mass inflow function with isothermal expansion.…”

Section: Methodsmentioning

confidence: 99%

Thoracic Injury Metrics With Side Air Bag: Stationary and Dynamic Occupants

Hallman

Yoganandan

Pintar

2010

Traffic Injury Prevention

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Objective Injury risk from side airbag deployment has been assessed using stationary out-of-position occupant test protocols. However, stationary conditions may not always represent real world environments. Therefore, the objective of the present study was to evaluate the effects of torso side airbag deployment on close-proximity occupants, comparing a stationary test protocol with dynamic sled conditions. Methods Chest compression and viscous metrics were quantified from sled tests utilizing post-mortem human specimens and computational simulations with three boundary conditions: rigid wall, ideal airbag interaction, and close-proximity airbag deployment. PMHS metrics were quantified from chestband contour reconstructions. The parametric effect of ΔV on close-proximity occupant was examined with the computational model. Results PMHS injuries suggested close-proximity occupants may sustain visceral trauma, which was not observed in occupants subjected to rigid wall or ideal airbag boundary conditions. Peak injury metrics were also elevated with close-proximity occupant relative to other boundary conditions. The computational model indicated decreasing influence of airbag on compression metrics with increasing ΔV. Airbag influence on viscous metric was greatest with close-proximity occupant at ΔV = 7.0 m/s, at which the response magnitude was greater than linear summation of metrics resulting from rigid impact and stationary close-proximity interaction. Conclusions These results suggest that stationary close-proximity occupants may not represent the only scenario of side airbag deployment harmful to the thoracoabdominal region. The sensitivity of the viscous metric and implications for visceral trauma are also discussed.

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Section: Methodsmentioning

confidence: 99%

Thoracic Injury Metrics With Side Air Bag: Stationary and Dynamic Occupants

Hallman

Yoganandan

Pintar

2010

Traffic Injury Prevention

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“…The IMM first builds the folding model of a simple geometry (such as a cube or cuboid) and subsequently modifies the folding model with a mapping relationship between the real inflatable geometry (such as a cylinder) and the simple geometry. Tanavde et al 14 proposed this method and applied it to fold modeling of passenger airbags. Zhang et al 15 wrote an automatic fold modeling program using the IMM and successfully established a folding model for a cylindrical airbag.…”

Section: Introductionmentioning

confidence: 99%

Modeling inflatable fabric with undevelopable surfaces by motion folding method

Zhao

He²,

Sun

et al. 2019

Journal of Engineered Fibers and Fabrics

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At present, most space inflatable structures are composed of flexible inflatable fabrics with complex undevelopable surfaces. It is difficult to establish a multi-dimensional folding model for this type of structure. To solve this key technical problem, the motion folding method is proposed in this study. First, a finite element model with an original three-dimensional surface was flattened with a fluid structure interaction algorithm. Second, the flattened surface was folded based on the prescribed motion of the node groups, and the final folding model was obtained. The fold modeling process of this methodology was consistent with the actual folding processes. Because the mapping relationship between the original finite element model and the final folding model was unchanged, the initial stress was used to modify the model errors during folding process of motion folding method. The folding model of an inflatable aerodynamic decelerator, which could not be established using existing folding methods, was established by using motion folding method. The folding model of the inflatable aerodynamic decelerator showed that the motion folding method could achieve multi-dimensional folding and a high spatial compression rate. The stability and regularity of the inflatable aerodynamic decelerator numerical inflation process and the consistency of the inflated and design shapes indicated the reliability, applicability, and feasibility of the motion folding method. The study results could provide a reference for modeling complex inflatable fabrics and promote the numerical study of inflatable fabrics.

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“…The IMM first establishes the folding model of a simple geometry (such as cube or cuboid) and then corrects the folding model by mapping the relation between the simple geometry and the real inflatable geometry (such as a cylinder). Tanavde et al (1995) proposed this method for the first time and applied it to the inflation deployment of passenger airbags. Zhang et al (2005) and Bai et al (2002) wrote an automatic fold modeling program using IMM and successfully applied it to cylindrical airbags.…”

Section: Introductionmentioning

confidence: 99%

Segmentation mapping and folding method of surfaces of revolution and its applications

Zhao

Xue

et al. 2019

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Purpose The purpose of this study was to develop a new folding method for modeling complicated folded fabric with surfaces of revolution. Design/methodology/approach Irregular wrinkles and mesh distortions easily appear in the fold modeling of a complex curved surface. Aimed at this key technical problem, the segmentation mapping folding method (SMFM) is proposed in this paper. First, high-precision flattened planes were obtained by using segmentation mapping techniques. Second, the segmented planes were transformed into a folded and continuous geometric model by using matrix transformations. Finally, initial stress was used to modify the geometric folding errors, which ensured agreement with the inflated flexible fabric’s geometry and the original design. Findings Compared with the traditional folding method, SMFM has the advantages of good finite-element mesh quality, large radial compression rate, regular folds, etc. The surface area error and the volume error of the inflated single torus established by SMFM were only 1.2 per cent, showing that SMFM has high modeling accuracy. The numerical results of an inflatable re-entry vehicle are presented to demonstrate the reliability, feasibility and applicability of SMFM. Moreover, the stress modification reduced the problems of stress concentration and mesh distortions, improving the accuracy and stability of the numerical calculations. Originality/value In this paper, for the first time, a folding method for modeling complicated folded fabric is proposed. This methodology can be used to model the multidimensional compression and regular folds of complex surfaces of revolution that cannot be flattened and to improve the accuracy and stability of the numerical calculations.

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Airbag Modeling Using Initial Metric Methodology

Cited by 12 publications

References 5 publications

Thoracic Injury Metrics With Side Air Bag: Stationary and Dynamic Occupants

Thoracic Injury Metrics With Side Air Bag: Stationary and Dynamic Occupants

Modeling inflatable fabric with undevelopable surfaces by motion folding method

Segmentation mapping and folding method of surfaces of revolution and its applications

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