Showing papers in "SAE transactions in 1995"

A new model comparing impact responses of the homogeneous and inhomogeneous human brain

Abstract: We have developed a totally new three-dimensional human head model in which the gray matter, white matter, vehicles and parasagittal bridging veins were included. This study is a continuation of the modeling efforts of the two-dimensional porcine brain models by Zhou et al. (1994) and three-dimensional human head model by Ruan et al. (1994). The paper presents some preliminary simulation results of the new three-dimensional model for a direct frontal impact and an indirect sagittal plane rotational impact ro delineate differences between the homogeneous and inhomogeneous brain models, and to study the mechanism of the subdural hematoma. Language: en

Ignition and early soot formation in a DI diesel engine using multiple 2-D imaging diagnostics

Abstract: Combined optical imaging diagnostics in the fuel jet of a direct-injection diesel engine to study the ignition and early soot formation processes. A diesel engine of the ``heavy-duty`` size class was operated at a representative medium speed (1200 rpm) operating condition. Two fuels were used, a 42.5 cetane number mixture of the diesel reference fuels and a new low-sooting fuel. Combustion and soot formation are almost identical for both fuels. Ignition and early combustion were studied by imaging the natural chemiluminescence using a calibrated intensified video camera. Early soot development was investigated via luminosity imaging and simultaneous planar imaging of laser-induced incandescence (LII) and elastic scattering. The latter provide relative soot concentrations and particle size distributions. Data show that ignition occurs at multiple points across the downstream region of all the fuel jets prior to first apparent heat release well before any soot luminosity occurs. Quantitative vapor-fuel/air mixture images in the leading portion of the jet are also presented and discussed with respect to the early combustion data. The first soot occurs at random locations, and shortly thereafter, small soot particles develop throughout the cross section of the leading portion of the jet. Data indicate that this soot arises frommore » the fuel-rich premixed burn. Then, significantly larger soot particles appear around the periphery of the jet, presumably from the initial diffusion combustion. By the end of the premixed burn, the soot has developed a distribution pattern of a higher concentration toward the front of the jet and a lower concentration upstream, with the larger-sized soot particles being generally confined to the periphery of the jet.« less

Human Head and Neck Kinematics After Low Velocity Rear-End Impacts - Understanding “Whiplash”

Abstract: This paper reports findings from an analysis of kinematic responses to a test series of fourteen rear end impacts including a higher range of impact related delta-V (5.8-10.9 kph or 3.6-6.8 mph) than was previously studied. The resulting head, neck and torso kinematics from a total of eighteen human and four Hybrid III anthropometric test device exposures were recorded using a variety of improved electronic and high speed film based data collection methods. All but one of the observations from the earlier study were confirmed, some of the earlier observations and unanswered questions were able to be refined or corrected and biomechanically rational explanation of human head, neck, torso, seatback and head restraint interaction during rear end collisions can now be offered along with comments suggesting a proposed mechanism of injury related to the often referred to, but ill defined 'whiplash' syndrome. Language: en

The effect of TDC temperature and density on the liquid-phase fuel penetration in a D.I. Diesel engine

Abstract: A parametric study of the liquid-phase fuel penetration of evaporating Diesel fuel jets has been conducted in a directinjection Diesel engine using laser elastic-scatter imaging. The experiments were conducted in an optically accessible Diesel engine of the ``heavy-duty`` size class at a representative medium speed (1200 rpm) operating condition. The density and temperature at TDC were varied systematically by adjusting the intake temperature and pressure. At all operating conditions the measurements show that initially the liquid fuel penetrates almost linearly with increasing crank angle until reaching a maximum length. Then, the liquid-fuel penetration length remains fairly constant although fuel injection continues. At a TDC density of 16.6 kg/m{sup 3} and a temperature of about 1000 K the maximum penetration length is approximately 23 mm. However, it varies significantly as TDC conditions are changed, with the liquid-length being less at higher temperatures and at higher densities. The corresponding apparent heat release rate plots are presented and the results of the liquid-phase fuel penetration are discussed with respect to the ignition delay and premixed bum fraction.

Human Volunteer Head-Neck Response in Frontal Flexion: a New Analysis

Abstract: The objective of this paper is to investigate the difference in T1 instrumentation mount response in the -15G-sub-x human volunteer experiments and the PMHS experiments, based new film analyses to develop a method to correct for observed differences in T1 instrumentation mount rotation earlier and to define a new set of easy to measure neck performance requirements for frontal impact expressed relative to the corrected origin of the first thoracic vertebral body (T1). As in the earlier analyses the head motions will be presented with a two-pivot head-neck mechanical linkage mechanism. Language: en

Dynamic Characteristics of the Human Cervical Spine

Abstract: This paper presents the experimental dynamic tolerance and the force-deformation response corridor of the human cervical spine under compression loading. Twenty human cadaver head-neck complexes were tested using a crown impact to the head at speeds from 2.5 m/s to 8 m/s. The cervical spine was evaluated for pre-alignment by using the concept of the stiffest axis. Mid cervical column (C3 to C5) vertebral body wedge, burst, and vertical fractures were produced in compression. Posterior ligament tears in the lower column occurred under flexion. Anterior longitudinal ligament tears and spinous process fractures occurred under extension. Mean values were: force at failure, 3326 N; deformation at failure, 18 mm; and stiffness, 555 N/mm. The deformation at failure parameter was associated with the least variance and should describe the most accurate tolerance measure for the population as a whole. (A) For the covering abstract of the conference see IRRD 882980.

The iowa driving simulator : an implementation and application overview

Abstract: This paper gives an overview of the Iowa Driving Simulator (IDS) designed to create high fidelity, operator-in-the-loop vehicle simulation and realistic cueing feedback to the driver. The paper refers to a number of human factors issues that are currently being investigated. Focus is on two specific applications of the IDS: a study of Automated Highway Systems (AHS) and vehicle virtual prototyping on a virtual proving ground.

Computational analysis of head impact response under car crash loadings

Abstract: A computational procedure for estimating damage on the soft tissue of the brain, by replicating transitional and rotational dynamic loads experienced during actual crash testing has been described. Data from 3-2-2-2 array of accelerometers located within the dummy headpart are used to extract a complete 6 DOF characterization of the headpart translational and rotational velocity and momentum field. These data are used as input to a finite element model of the brain to compute Cumulative Strain Damage Measure values in response to dynamic loads applied using actual crash test data.