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There have been multiple studies on the effect of vehicle impact pulses on occupant responses, and studies on the previous and current US NCAP (New Car Assessment Program) vehicle pulses. This paper analyzes 35 mph (56.3 kph) front impact vehicle pulses and occupant responses in US NCAP tests conducted by the NHTSA from 2011 to 2019. Based on the occupant response analysis, a simple generic occupant restraint force-relative displacement model has been created. This generic model captures the fundamental restraint characteristics of the vehicles in the recent years, and together with the vehicle pulse, they provide several occupant response predictors. Furthermore, this paper proposes a new pulse severity metric PSD (Pulse Severity by Displacement) based on the vehicle impact data statistics, and uses the pulse severity to compare with other pulse severity definitions.

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.

Nij, a function of upper neck forces and moment, plays a dominant role in the vehicle's star rating under the new NHTSA NCAP front impact program. This is mainly due to an artifact in the mapping of the Nij into the “risk” value used in the star rating, and the fact that the neck region is not weighted appropriately to reflect its real world significance relative to the other body regions in the NCAP rating. New test data also show that compared with the 50th male driver Nij, the 5th female passenger Nij is significantly more challenging to contain and therefore it is more dominant in the star rating. This paper describes the Hybrid III dummy head and neck impact response and provides a method to determine the external force acting on the head. The force and its acting point on the head are determined from head acceleration, angular acceleration, and the upper neck forces.

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.

A data processing algorithm is presented for determining the spatial orientation and position of a rigid body in impact tests based on an instrumentation scheme consisting of a triaxial angular rate sensor and a trialaxial linear accelerometer. The algorithm adopts the unit quaternion as the main parameterized representation of the spatial orientation, and calculates its time history by solving an ordinary differential equation with the angular rate sensor reading as the input. Two supplemental representations, the Euler angles and the direction cosine matrix, are also used in this work, which provide an intuitive description of the orientation, and convenience in transforming the linear accelerometer output in the instrumentation frame to the global frame. The algorithm has been implemented as a computer program, and a set of example impact tests are included to demonstrate its application.

To mitigate head impact injuries of vehicle occupants in impact accidents, the FMVSS 201 requires padding of vehicle interior so that under the free-moving-head-form impact, the head injury criterion (HIC) is below the limit. More recently, pedestrian head impact on the vehicle bonnet has been a subject being studied and regulated as requirements to the automobile manufacturers. Over the years, the square wave has been considered as the best waveform for head impacts, although it is impractical to achieve. This paper revisits the head impact topic and challenges the optimality of aiming at the square waveform. It studies several different simple waveforms, with the objective to achieve minimal HIC or minimal crush space required in head-form impacts. With that it is found that many other waveforms can be more efficient and more practical than the square wave, especially for the pedestrian impact.

This paper presents an energy relationship between vehicle impact pulses and restraint systems and applies the relationship to formulations of response factors for linear and nonlinear restraints. It also applies the relationship to derive optimal impact pulses that minimize occupant response for linear and nonlinear restraints. The relationship offers a new viewpoint to impact pulse optimization and simplifies the process mathematically. In addition, the effects of different vehicle impact pulses on the occupant responses with nonlinear restraints are studied. Finally, concepts of equivalent pulses and equal intensity pulses are presented for nonlinear restraints.

The paper presents a comparison between the acceleration pulses of vehicle-to-vehicle crash tests with those of different single-vehicle crash tests. The severity of the full frontal rigid barrier test is compared with that of the vehicle- to-vehicle crash test based on average acceleration and time-to-zero-velocity. Based on this a 30mph full frontal rigid barrier test is found equivalent to a 41mph vehicle-to-vehicle crash. A reduced speed of 22mph for full frontal rigid barrier test is found to represent vehicle-to- vehicle crashes with 50%-100% overlap, with each vehicle travelling at 30mph. The paper also presents a comparison of the acceleration pulses from different crash tests based on the pulse shape and the pulse phase cross-correlation. None of the single-vehicle crash tests have been found to resemble vehicle-to-vehicle crashes in terms of the pulse shape and the pulse phase.

A simple spring-mass model of the impact response of the side impact dummy (SID) is established. The spring and mass constants of the model are established through system identification methodology based on data from impact tests. The tests are performed in laboratory with hydraulically driven impactors impacting the chest and pelvis of the SID. The input data to the model consist of measured contact force or impactor velocity time histories, and the output data are accelerations on the rib, spine, and pelvis of the SID. The established model appears to predict the test results with reasonable accuracy. The main purpose of this study, however, is to use this simple model to carry out parametric studies of the response of the dummy with changing impact parameters, the result of which would be useful in understanding vehicle crash tests using the SID.

This paper directs attention to a specific region of the air-bag deployment process. Both experimental and analytical results are presented. Experimental procedures and their results are presented along with a two dimensional unsteady isentropic CFD model and a empirical gas-jet model.