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Current numerical simulation practice does not capture the seat mounted Side Airbag (SAB) breaking out through the seat tear seam and its correct early deployment characteristics. A late SAB breakout negatively impacts full SAB deployment and occupant coverage. An early breakout enhances timely SAB positioning and coverage, providing early cushioning to the occupant from the intruding barrier. This paper presents a numerical modeling process capable of predicting and enhancing seat tear seam breakout time and early SAB deployment kinematics. The critical phases used in the development of SAB breakout modeling process are as follows: Phase 1: Physical Tear Seam and Seat Trim coupon tests to characterize physical material properties for the numerical material model development; Phase 2: Numerical Modeling of the Tear Seam and Seat Trim breakout and, Phase 3: Numerical prediction of SAB breakout through a candidate seat tear seam.

This paper presents a systematic study to assess maturity of Corpuscular Particle Method (CPM) to accurately predict airbag deployment kinematics and its overall responses. The study was performed in three phases: (1) a correlation assessment of CPM predicted inflator characteristics to closed tank tests; (2) a correlation assessment of CPM predicted airbag deployment kinematics, airbag pressure, reaction force from a static deployment of a Driver Airbag (DAB) and (3) a correlation prediction of the impactor force by CPM versus impactor force from physical drop tower tests. These studies were repeated using the Uniform Pressure Method (UPM), to compare the numerical methods for their accuracy in predicting the physical test, computational cost, and applicability. Results from the study suggest that CPM satisfies the fundamental energy laws, and accurately captures the realistic airbag deployment kinematics, especially during the early deployment stage, unlike UPM.

This article discusses steps to predictively estimate the responses of Anthropomorphic Test Device (ATD) in a side impact event, based on a Side Airbag (SAB) Force-Deformation (F-D) characteristics derived from the linear impactor test. A critical load management challenge that has been used to assess this predictive response process is the oblique pole impact test - part of the FMVSS 214 protocol. In this scenario, the ATD is assumed to have a free travel until it is stopped by the crushed and stacked up door against the rigid pole. Three critical energy management paths involved to manage the kinetic energy of the ATD at impact are assumed at the onset, namely, the door trim crush, ATD torso loading and most important efficient energy management of the SAB at a controlled force level. The SAB energy management is assumed critical and tied with the final response of the test ATD.

NHTSA issued the FMVSS 226 ruling in 2011. It established test procedures to evaluate countermeasures that can minimize the likelihood of a complete or partial ejection of vehicle occupants through the side windows during rollover or side impact events. One of the countermeasures that may be used for compliance of this safety ruling is the Side Airbag Inflatable Curtain (SABIC). This paper discusses how three key phases of the optimization strategy in the Design for Six Sigma (DFSS), namely, Identify; Optimize and Verify (I_OV), were implemented in CAE to develop an optimized concept SABIC with respect to the FMVSS 226 test requirements. The simulated SABIC is intended for a generic SUV and potentially also for a generic Truck type vehicle. The improved performance included: minimization of the test results variability and the optimization of the ejection mitigation performance of the SABIC.

This paper discusses steps for identifying, evaluating and recommending a quantifiable design metric or metrics for Side Airbag (SAB) development. Three functionally related and desirable attributes of a SAB are assumed at the onset, namely, effective SAB coverage, load distribution and efficient energy management at a controlled force level. The third attribute however contradicts the “banana shaped” force-displacement response that characterizes the ineffective energy management reality of most production SAB. In this study, an estimated ATD to SAB interaction energy is used to size and recommend desired force-deformation characteristic of a robust energy management SAB. The study was conducted in the following three phases and corresponding objectives: Phase 1 is a SAB assessment metric identification and estimation, using a uniform block attached to a horizontal impact machine.

This paper discusses the simulation based methodology for designing and developing a deployable vehicle door interior trim, an Active Side Bolster (ASB), and its interaction (in FEA simulation) with an ATD in side impact crash test modes like FMVSS2141 Oblique Pole, IIHS2 and LINCAP. The FEA models, especially with the complexity of the full vehicle structure, the ATDs3 and the airbags, require extensive correlation using vehicle tests. A methodology is outlined here to ensure that the model results could be used to generate FEA ATD assessments without a significant numerical contamination of the results. These correlated FEA models for side impact vehicle tests and ATDs were used to simulate various side impact crash test conditions; such as IIHS barrier, the FMVSS-214 Oblique Pole and LINCAP. The ATD responses from the baseline vehicle FEA models and those modified with the addition of an ASB in the door shows improvement in assessment values due to the introduction of the ASB.

The Insurance Institute for Highway Safety (IIHS) has begun a new side impact crashworthiness evaluation of vehicles, using tests that represent impacts from large trucks and sport utility vehicles. This test protocol, intended as consumer information rating of vehicles, adds new challenges to current side impact crashworthiness development in both the vehicle structure and dummy responses. Available tests data seem to indicate that safety enhancement features that work for current US-SID and Euro-SID may not work for the SID-IIs dummy that is used in the IIHS test protocol, but may in fact deteriorate dummy response. This may partly be explained by the fact that the SID-IIs is not a scaled down dummy of either the US-SID or the Euro-SID. This paper presents and discusses the results from sled tests conducted to investigate countermeasures that will help improve the response of the SID-IIs in the Insurance Institute's side impact test.

A three-step vehicle development process for crashworthiness in the frontal impact test mode is proposed in this paper. The three steps are: (a) System identification, (b) Initial Component Sizing and (c) Detailed Analyses, System Integration and Optimization, which suggests the use of FEA methods to do detailed analyses, system integration and design optimization as applicable in the later part of the process when more vehicle details are known. This paper discusses this process and the results achieved. Limitations inherent in this approach are also identified and discussed. The emphasis is on the development of the structural aspects of a vehicle for a high star rate performance in the NHTSA NCAP impact test mode.

In the continuing automotive design trends towards greater lightness, the energy absorption capacity and low deformability of the knee bolster system in a front end collision, must not be compromised for light material guages. In order to minimize knee injury to both the driver and the front seat passenger, it is necessary to have a knee bolster system that absorbs as much of the impact energy as possible. Moreover, in order to minimize chest injury to the driver, the driver side knee bolster must not come in contact with the steering column during impact. In a study conducted by us, a simplified approach was used to evaluate the energy absorption capacity and the deformations of the knee bolster system under frontal impact. The analysis was performed using a nonlinear dynamic finite element computer code, DYNA3D, developed at the Lawrence Livermore National Laboratory.