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Stress, fatigue, and workload affect worker performance. NSF reported that 61% of respondents state losing concentration at work while 79% occasionally or frequently made errors as a result of being fatigued. Shift work, altered work schedules, long hours of continuous wakefulness, and sleep loss can create sleep and circadian disruptions that degrade waking fundions causing stress and fatigue. Review of the literature has proven void of information that links the combined effects of fatigue, stress, and workload to human performance. This paper will address which occupational factors within stress, fatigue, and workload were identified as occupational contributors to performance changes. The results of this research will be apglied to underlying models and algorithms that will help predict performance changes in control room operators.

Alcohol-based fuels are a viable alternative to fossil fuels for powering vehicles. As a drop-in fuel, an oxygenated fuel blend containing the C8 alcohol 2-ethylhexanol (isomer of octanol), hydrotreated vegetable oil (HVO) and rapeseed methyl ester (RME) can reduce soot and NOx emissions whilst maintaining engine performance. However, fuel injection strategy significantly affects combustion and hence has been investigated with a view to reducing emissions whilst maintaining engine efficiency. In a single cylinder light-duty compression ignition research engine, the effect of different injection strategies (main, main/post, double pre/main, double pre/main/post injection) and EGR levels (0%, 19%) on specifically NOx, soot emissions and particle size distribution was investigated for three different fuels: fossil diesel fuel, HVO and the oxygenated blend. The blend was designed to have diesel-like combustion properties (cetane number of 52) and had an oxygen content of 5.4% by mass. The crank angle used when measuring MFB50, fuel consumption and IMEP was kept constant. The engine efficiencies were similar for all tested fuels and injection strategies. Heat release analysis revealed a strong influence of the cetane number on main and main/post injection strategy. However, when using double pre-injection, the start of combustion was similar for all fuels. Combustion characteristics, particle mass and number were more affected when using double pre-injection rather than post-injection. With 19% EGR and double pre-injection, soot mass increased as agglomerated particle mode increased in the PSD. Further, the in-cylinder temperature and pressure were lower compared to combustion without EGR, leading to a reduction of NOx emissions by a factor of 2.5 while soot emissions increased by a factor of 10. There were just minor differences in NOx emissions with variations in injection strategy. The PSD moved towards smaller particle diameters without EGR. In conclusion, the soot reduction potential of all fuels tested was coupled to the use of double pre-injection and EGR rather than post-injection.

Forthcoming on-highway 2005/2007 European and North American emission regulations will require modern diesel engines to be equipped with Diesel Particulate Filters (DPF) capable of trapping up to 99% of the exhaust particulate matter. Since diesel particulates (soot) accumulate in the filter over time, the overall system needs to be regenerated by attaining the ignition temperature of soot, which in the presence of oxygen is >600 °C. Catalyzed DPFs regenerate at temperatures as low as ∼300 °C. One of the major issues facing OEMs, aftertreatment system manufacturers, and lubricant formulators is the potential effects of the lubricant-derived ash deposits and their impact on a pressure increase across filters, as well as overall filter performance and its service characteristics. In the present study, several lubricant-formulating additive variables, metal detergent type, antiwear additive (ZDP) type and level, the presence of boron as well as the effect of noble metal concentration in catalyzed DPF were examined. The paper explores ramifications of these formulation variables, especially the effects of lubricant chemistry, on DPF balance point temperature, ash deposits distribution and recovery. Findings identify the impact of lubricant derived species on soot combustion, ash type and presence of volatile components within the filter deposits.

Presents results of tests of ultra-low sulfur diesel blended with soy-biodiesel at 5 percent using a Cummins ISB engine with a diesel particulate filter.

Impact of oil-derived ash on the pressure drop of continuous regeneration-type diesel particulate filter (CR-DPF) was investigated through 600hrs running test at maximum power point on a 6.9L diesel engine, which meets the Japanese long-term emission regulations enacted in 1998, using approximately 50ppm sulfur content fuel. Sulfated ash content of test oils were varied as 0.96, 1.31, and 1.70 mass%, respectively. During the running test, the exhaust pressure drop through CR-DPF was measured. And after the test, the ventilation resistance through CR-DPF was also evaluated before and after the baking process, which was applied to eliminate the effect of soot accumulated in CR-DPF. The results revealed that the less sulfated ash in oil gave rise to lower pressure drop across CR-DPF. According to microscope examination of the baked DPF, ash was mainly accumulated on the wall surface of CR-DPF, and that seemed to be related to the magnitude of pressure drop caused by ash. The main component of ash on CR-DPF was CaSO 4 , of which Ca is derived from oil. Metal content in exhaust gas was also analyzed at the engine out. It was found that Ca content at the engine out had increased proportionally with Ca content in oil. Furthermore, when compared at engine out and behind CR-DPF, it was found that over 95% of oil-derived metal in exhaust gas could be trapped by CR-DPF, irrespective of exhaust gas condition (flow rate and temperature) and oil additive formulation. The oil with less sulfated ash can reduce the accumulation of oil-derived ash on DPF, and thus the pressure drop through DPF. Therefore, it will contribute to prolong the maintenance interval of the DPF.

Homogeneous charge combustion and emissions of ethanol ignited by pilot diesel fuel were investigated on a two-cylinder diesel engine. The results show that emissions depend on loads and ethanol volume fraction. At low loads, ethanol has little effects on smoke. With the increase of ethanol, NOx decreases, but CO emissions increase. At high loads, smoke emissions reduce greatly with increasing ethanol, but NOx and total hydrocarbon (THC) emissions increase. With the increase of ethanol, ignition delays, combustion duration shortens. The maximum rates of heat release for the fuel containing 10 vol% ethanol (E10) and 30 vol% ethanol (E30) increase. Brake specific energy consumption (BSEC) of E10 and E30 is improved slightly only at full loads. Compared to smoke emissions obtained on the same engine using ethanol blended diesel fuels, the tendency of smoke reduction is similar to that of homogeneous charge combustion of ethanol at the same operating conditions. But the former is more effective in reducing smoke emissions. When the engine operated at high constant loads, smoke significantly decreases with increasing ethanol and smokeless combustion can be achieved at certain ethanol volume fraction dependent on loads. In the meantime, THC emissions gradually increase. Ignition retards, peak pressure increases first and then decreases again. Indicated mean effective pressures are close to those of diesel (E0), even higher than the latter at some cases. NOx emissions are dependent on loads and ethanol volume fraction, and even are less than those of E0 under certain conditions. The results obtained from an optical diesel engine show that ethanol also shortens combustion duration, decreases flame temperature and KL factor, which indicates that ethanol can suppress soot formation in combustion chamber.

Methyl esters obtained from the most interesting Spanish oleaginous crops for energy use -sunflower and cynara cardunculus- were both used as diesel fuels in this work, pure and in 25% blends with a reference commercial fuel which was also used pure. A stationary engine test bed, together with the appropriate instrumentation for chemical and morphological analysis, allowed to evaluate the effect of these fuels on the engine emissions, particularly in the main particulate matter characteristics, such as soluble organic fraction, origin of adsorbed hydrocarbons, sulphate content, particle number per unit filter surface, and mean particle diameter. Both the consideration of the main thermochemical properties of the tested fuels and the computations of a chemical equilibrium model were helpful for the analysis of the experimental results. These results proved that the use of these vegetable esters provides a significant reduction on particulate emissions, mainly due to reduced soot and sulphate formation. On the contrary, no increases on NOx emissions nor reductions on mean particle size were found.

This research focused on the testing of the original potable water processor aboard Space Station Freedom that was to produce potable water from the humidity condensate and additional water generated by carbon dioxide reduction. Humidity condensate was simulated by an influent water model 'Ersatz'. The humidity condensate was treated with multifiltration (MF) beds that consisted of a train of sorption beds (referred to as 'Unibed') designed to remove specific contaminants. For the complete simulated MF system runs tested for 100 bed volumes (BV) (volume processed/total column volume), 0.6 percent of the TOC was removed by the SAC/IRN 77 (Strong Acid Cation exchange resin), 39.6 percent of the total organic carbon (TOC) was removed by the WBA/IRA 68 (Weak Base Anion exchange resin), 13.2 percent of the TOC was removed by activated carbon adsorption (580-26), and the remaining sorbent media acted as polishing units to remove an additional 1.6 percent of the TOC at steady state. At steady state, 45 percent of the influent TOC passed through the MF bed.

Disinfection and maintenance of an acceptable level of asepsis in spacecraft potable water delivery systems is a formidable task. The major area of research for this project has been to monitor the formation and growth of biofilm, and biofilm attached microorganisms, on stainless steel surfaces (specifically coupons), and the use of ozone for the elimination of these species in a closed loop system. A number of different techniques have been utilized during the course of a typical run. Scraping and sonication of coupon surfaces with subsequent plating as well as epifluorescence microscopy have been utilized to enumerate biofilm protected Pseudomonas aeruginosa. In addition, scanning electron microscopy is the method of choice to examine the integrity of the biofilm. For ozone determinations, the indigo decolorization spectrophotometric method seems most reliable. Both high- and low-nutrient cultured P. aeruginosa organisms were the target species for the ozone disinfection experiments.

This paper presents a high-fidelity electro-thermal model of a half-bridge that consists of IGBTs and anti-parallel diodes. The model calculates and estimates the half-bridge voltages, currents, switching and conduction losses considering the operating temperature and current conditions. Moreover, this model is suitable for varying switching frequency operation. The electro-thermal model can be used as an evaluation tool to analyze the performance of control strategies for traction inverter from efficiency, temperature and component stress point of view. In this paper performance of Direct Torque Model Predictive Control (DTMPC) of an Interior Permanent Magnet Synchronous Motor (IPMSM) is evaluated in comparison with Indirect Field Oriented Control (IFOC) with sinusoidal pulse width modulation (PWM). The inverter model and the MPC are both implemented in C-Mex for rapid execution. The MPC algorithm implemented in this research tracks torque reference while using Maximum-Torque-Per-Ampere (MTPA) strategy and minimizing switching losses. Both control systems are able to follow the speed reference. The MPC shows a decrease in losses compared to IFOC when tested with low-speed and high-speed parts of the WLTC profile.

A new method for determining antioxidant capacity of lubricants was used for monitoring initial antioxidant capacities in various engine oils and antioxidant decay during laboratory and fleet testing of selected oils. The method involves the quantitative determination of antioxidant species present in oil by titration with peroxy radicals formed at a known and constant rate from the decomposition of a free radical initiator at 60 degrees C in the presence of oxygen. A general correlation between initial antioxidant capacities of engine oils and an oil thickening characteristic from Sequence IIIC testing was obtained for engine oils containing conventional additive technologies. Monitoring the decay of antioxidant capacity during laboratory beaker, Sequence IIIC, and long drain fleet testing provided information on lubricant oxidative deterioration in the early period of testing when no other performance characteristics showed appreciable changes. New insights into the nature of engine oils' oxidative deterioration, as a function of antioxidant type and concentration, base oil type, and test or engine severity, were obtained. This was achieved by combining results derived from the new method with those obtained from conventional analysis.

The Penn State microoxidation test has been adapted for use with mineral oil base stocks and fully formulated automotive crank-case oils. Tests under nitrogen and air atmospheres coupled with analyses using gel permeation chromatography and clay column adsorption provide for a semiquantitative analysis of the products by elution time (apparent molecular size). This test procedure allows for primary and secondary oxidation reaction rate studies after substantial quantities of the lubricant have been oxidized. Time-temperature studies can show the effectiveness of base oil quality as well as effects contributed by additives. A general time-temperature equivalence in the range of 200 to 225 degree C has been demonstrated for a series of formulated engine oils. Microoxidation tests have been compared with III-C hot engine tests for a series of ASTM reference oils.

This paper aims to correlate the in-cylinder soot formation and the exhaust particle emissions for different methods of gasoline/ethanol fueling in spark ignition engine. In particular, the engine was fueled with gasoline and ethanol separately and not, in this latter case both blended (E30) and dual fueled (EDF). For E30 the bend was direct injected and for EDF, the ethanol was injected in the combustion chamber and the gasoline into the intake duct. For both the injection configurations, the same percentage of ethanol in gasoline was supplied: 30%v/v. The measurements were carried out at 2000 and 4000 rpm, under full load, and stoichiometric condition, in small single cylinder optical engine. 2D-digital imaging was performed to follow the combustion process with a high spatial and temporal resolution through a full-bore optical piston. The two-color pyrometry was applied for the analysis of the in cylinder soot formation in the combustion chamber. Particle mass concentration was evaluated at the exhaust by means of a smoke meter. The particle size distribution function was measured in the range from 5.6 to 560 nm by an Engine Exhaust Particle Sizer (EEPS). It was observed that the use of ethanol allows the reduction of soot formation and particles emission in DI configuration. However, for E30 the in-cylinder soot formation and emissions are larger than EDF. This result is mainly due to the different contribution of gasoline. Optical analysis shows that in E30 the direct injected gasoline causes wide diffusive flames where soot formation is promoted; whereas for EDF the better evaporation and mixing of gasoline, typical of PFI configuration, results in few, small, and localized diffusive flames producing smaller particle emissions.

In this paper, computation fluid dynamics (CFD) simulations are performed to describe the effect of in-cylinder flow structures on the formation and oxidation of soot in a swirl-supported light-duty diesel engine. The focus of the paper is on the effect of swirl motion and injection pressure on late cycle soot oxidation. The structure of the flow at different swirl numbers is studied to investigate the effect of varying swirl number on the coherent flow structures. These coherent flow structures are studied to understand the mechanism that leads to efficient soot oxidation in late cycle. Effect of varying injection pressure at different swirl numbers and the interaction between spray and swirl motions are discussed. The complexity of diesel combustion, especially when soot and other emissions are of interest, requires using a detailed chemical mechanism to have a correct estimation of temperature and species distribution. In this work, Representative Interactive Flamelets (RIF) method is employed to describe the chemical reactions, ignition, flame propagation and emissions in the engine. The CFD simulations are validated using experimental measurement of light-duty diesel engine at two different loads. A good agreement is achieved between the model results and the pressure, heat release rates and emissions from the experiment. These cases are considered as the base-line for the parameter study cases.

This paper deals with the evaluation of the effect of fuel properties on soot formation in a GDI (gasoline direct injection) engine. Experimental investigation was carried out in an optical 4-stroke small single cylinder engine for twowheel vehicles. The engine displacement was 250 cc. It was equipped with an elongated piston with a wide sapphire window in the head and a quartz cylinder liner. The engine was fuelled with pure gasoline and ethanol, and ethanol/gasoline blends at 20% v/v, 50% v/v and 85% v/v. Optical techniques based on 2D-digital imaging were used to follow the combustion process and soot formation. Spectroscopic measurements were carried out in order to assess the soot evolution. Radical species such as OH and CH, related to fuel quality and to soot formation/oxidation process, were detected. Measurements were carried out at various engine speeds and loads in order to allow optical measurements and to test the engine in real conditions. Regulated gas emissions and opacity were measured at the exhaust by conventional equipment. Moreover, particle emissions were characterized also in terms of number concentration and size distribution using a differential mobility sizer.

In order to meet the requirements in the stringent emission regulations, more and more research work has been focused on homogeneous charge compression ignition (HCCI) and partially premixed combustion (PPC) or partially premixed compression ignition (PCCI) as they have the potential to produce low NOx and soot emissions without adverse effects on engine efficiency. The mixture formation and charge stratification influence the combustion behavior and emissions for PPC/PCCI, significantly. An ultra-high speed burst-mode laser is used to capture the mixture formation process from the start of injection until several CADs after the start of combustion in a single cycle. To the authors' best knowledge, this is the first time that such a high temporal resolution, i.e. 0.2 CAD, PLIF could be accomplished for imaging of the in-cylinder mixing process. The capability of resolving single cycles allows for the influence of cycle-to-cycle variations to be eliminated. This ability to study individual cycles aids the understanding of the mixture formation process as well as the cycle-to-cycle variations. Strong air entrainment at the boundary layer can be clearly observed and followed as the mixing process progresses. The formation of eddies created by the shear force and their rotational motion can be continuously observed during the mixing process. The interaction between two adjacent spray plumes in the recirculation zone is well captured and studied. In addition, the mixing process resulting in the stratified fuel charge being located in the recirculation zone before the SOC while the areas along the original spray axis are leaned out after the end of injection, can be followed in one time sequence. Moreover, the auto-ignition position and early flame development can be studied, from the high-speed chemiluminescence imaging, together with the fuel distribution in the combustion chamber. (Less)

In this paper, a control-oriented soot model was developed for real-time soot prediction and combustion condition optimization in a gasoline Partially Premixed Combustion (PPC) Engine. PPC is a promising combustion concept that achieves high efficiency, low soot and NOx emissions simultaneously. However, soot emissions were found to be significantly increased with high EGR and pilot injection, therefore a predictive soot model is needed for PPC engine control. The sensitivity of soot emissions to injection events and late-cycle heat release was investigated on a multi-cylinder heavy duty gasoline PPC engine, which indicated main impact factors during soot formation and oxidation processes. The Hiroyasu empirical model was modified according to the sensitivity results, which indicated main influences during soot formation and oxidation processes. By introducing additional compensation factors, this model can be used to predict soot emissions under pilot injection. Model parameters were identified using experimental data under a few representative operating points. In order to reduce the cycle-to-cycle variation resulting in the soot estimation noise, a combustion duration calculation method is proposed to estimate CA10 and CA90. This soot model presented in this paper was validated under load-transient operating conditions and agreed with the measurement results with R2 over 0.8 during transient operations, which is sufficient enough for soot prediction as a virtual soot sensor and for control purpose. (Less)

This paper describes a characterisation of the combustion behaviour in an optical Common Rail diesel engine fed by different advanced fuels, via the application of the two-colour pyrometry technique. The acquired images were processed in order to calculate the instantaneous flame temperature and soot volume fraction. For the measurements, a single test point was chosen as representative of the reference four-cylinder engine performance in the European driven cycle ECE+EUDC. The test point was the 1500 rpm and 22 mm 3 /stroke of injected fuel volume, correspondent to the engine point of 1500rpm @ 5 bar of BMEP for the 4-cylinder engine of 1.9L of displacement. As general overview, the flame luminosity from combustion of the fuel injected during pilot injection was always below the threshold of sensitivity of the detection system. As regard the effect of fuel quality on flame evolution, it is confirmed that the presence of oxygen in the fuel reduces the in-cylinder soot loading, but in our experiments, the reduction is observable only for an oxygen content over 15% in weight. Moreover, interesting differences on the effect of fuel oxygen were noted in terms of local soot concentration and global in-cylinder soot loading.

Butanol is an attractive alternative fuel by virtue of its renewable source and low sooting tendency. In this paper, three butanol isomers (n-butanol, isobutanol, and tert-butanol) were induced via port injection respectively and n-heptane was directly injected into the cylinder to investigate reactivity controlled compression ignition in a heavy-duty diesel engine. This work evaluates the potential of applying butanol as low reactivity fuel and the effects of reactivity gradient on combustion and emission characteristics. The experiments were performed from low load to medium-high load. Due to the different reactivities among the butanol isomers, the exhaust gas recirculation rate and the direct injection strategy were varied for a specific butanol isomer and testing load. Particularly, isobutanol/n-heptane can be operated with single direct injection and no exhaust gas recirculation up to medium load due to the high octane rating. As the load increases, all three butanol isomers displayed increased peak cylinder pressure and pressure rise rate. Especially, n-butanol cases yielded a pressure rise rate of 23.4 bar/oCA at medium-high load because of sub-optimal combustion phasing. It constrains the high load limit of n-butanol/n-heptane operation. While tert-butanol cases presented the slowest heat release rate and consequently the lowest pressure rise rates. Extremely low NOx emissions were achieved for all three isomers. Interestingly, tert-butanol/n-heptane operation stands out for showing ignorable engine-out soot mass in the whole testing range. N-butanol cases require the most direct fueling to phasing the combustion properly and displayed the highest soot mass and the highest number of particles in the accumulation mode. Among the isomers, tert-butanol/n-heptane operation achieved the highest gross indicated efficiency (above 52%) in most operating loads.

This paper describes how the number of traffic deaths in Japan was 4,914 for the year 2009. Since the head was the most common site of injury in traffic accidents, traumatic brain injury caused the fatalities in these accidents. The objective of this paper was to quantify micro injuries in the animal brain for the purpose of gaining insight and understanding of human brain injury tolerance. In vitro stress relaxation experiments and in vivo impact experiments were conducted using porcine brain matter. The distribution of the damage ratio of the transverse to longitudinal length of cells, hereafter, referred to as an aspect ratio, in the brain matter under loading were examined in both experiments. In the in vitro stress relaxation experiments, specimens were compressed vertically with a compression velocity of 1 mm/s, and the displacement was held for 140 sec when the compression strain reached the target strain. In the experiments, there were five categories of compression strain: 10, 20, 30, 40, and 50 percent. The aspect ratio of the cell body was 1.5 or less in a no-load condition. On the other hand, the cell body was observed to be greater than 1.5 in the results from the experiments if the compression strain was 30% or more. The results from theses experiments show that a compression strain between 20% and 30% corresponds to the threshold for the extremely deformed cell at the micro level. In the in vivo impact experiments, pigs in an unconscious state were exposed through craniotomy, and their exposed brains were hit with a ram at a low speed of 3.3 m/s and a high speed of 7.2 m/s. The paper revealed that the number of cells in which the aspect ratio was greater than 1.5 increased if the impact is provided under the high speed. At the same time, the results indicated that cell deformation was dependent on the ram velocity in the brain matter. Therefore, the compression strain on the entire brain from the direction of the force applied to the brain may be one criterion for assessing brain damage.

Across the world different regulations are applicable for side impact, each require a different restraint system approach. However it would be much more cost effective to develop one single restraint system suitable for all global requirements. An efficient methodology has been to optimize the restraint system for multiple load cases simultaneously, resulting in a restraint system specification that will ensure that global targets are met. The methodology combines the use of testing and efficient numerical simulation to find a solution in the most effective way. ABSTRACT Across the world different regulations are applicable for frontal impact, each require a different restraint system approach. However it would be much more cost effective to develop one single restraint system suitable for all global requirements. Flexible and reliable development approach has to be used for quick evaluations of various safety system configurations and conditions. An efficient methodology has been developed to optimize the frontal restraint system for multiple load cases simultaneously, Resultant restraint system specification to specification to meet global targets. The methodology combines the use of testing and MADYMO modelling techniques in combination with advanced DoE (Design of Experiments) analysis to find a solution in the most effective way. ABSTRACT In frontal crashes, one of the primary reasons for occupant injuries is hard contact with the vehicle interiors. While restraints like airbags, seat belt pre- tensioners etc. help in preventing direct contact of the upper body region; vehicle interiors play a critical role in controlling the lower body region injuries. Knee injuries can be controlled in various ways as follows:? Avoiding contact with the dashboard by use of buckle pre-tensioners etc • Using restraints like knee airbags • Optimizing the dashboard profile and stiffness at the contact locations All the above options have their own advantages and limitations. This paper explains the effect of dashboard stiffness tuning for controlling knee injuries in a frontal crash. The development methodology and some validation tools are discussed using a case study. ABSTRACT Bumper systems play an important role in energy management during vehicle accidents. Bumpers beams are generally designed to withstand impacts of up to 4 km/h (ECE42, FMVSS-581) and need to withstand low speed 15 km/h offset insurance crash tests to determine damageability and repairability features (RCAR-42) of vehicle design. Globalization of Automotive industry is forcing the designers to propose those designs, which can be introduced, to market quickly and which have lower costs and better quality. This paper presents work a novel design solution of a thermoplastic solitary bumper beam intended to reduce bumper weight and cost, meeting low speed damageability and RCAR impact requirements. A thermoplastic (PC/PBT) solitary beam is proposed that

This paper analyzed rear crashes for the risk of serious injury (AIS 3+) by delta V. Rear impacts were analyzed for occupants sitting in front seats of light vehicles. Data were obtained from the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) for calendar years 1991-2004. Tow-away crashes with \mL15 mph rear delta V account for 67% of rear impacts and 15% of serious injury. Even for crashes \ml30 mph delta V, the risk for serious injury is only 0.24% (less than 1 per 420 exposed occupants). Risks increase for higher delta Vs. Individual cases in the 1997-2004 NASS-CDS electronic database were reviewed for serious injury in crashes with \mL15 mph delta V and \mG35 mph for light vehicles with calendar year \mg1996 to better understand injury mechanisms. Nine cases were available where a front-seat occupant was seriously injured in \mL15 mph rear delta V impact. Most cases involved older occupants, some of whom had stenosis of the cervical spine. These occupants experienced spinal cord injury and paralysis with or without fracture of the cervical spine. Frailty of the cervical spine was a factor in the very low speed crash injuries. There were 28 occupants in 26 crashes with serious injury at delta V \mG35 mph. In 7 of the cases, the most serious injury was to the cervical spine. Intrusion of rear structures was common leading to the front-seat occupant being supported upright or being pushed forward causing serious injury. Intrusion forces were associated with the injury. In the most severe rear crashes, rearward rotation of the seatback was not a factor in the occupant's injury as the early occurrence of intrusion limited seatback rotation. This paper has identified a class of seriously injured occupants in very low speed rear crashes. Advanced age and degeneration of the cervical spinal canal can lead to spinal cord injury and paralysis in crashes otherwise not causing serious injury in normal adults. Yielding seats diminish the risk of cervical injury in frail occupants. Use of stiffer seats would increase the risk of injury in occupants with spinal stenosis. The very high speed crashes involved substantial intrusion, which occurred early in the crash and supported the seatback from rotating rearward. The collision forces and intrusion were associated with injury to front-seat occupants.

This paper provides a preliminary investigation of occupant kinematics for rear seat occupants involved in high-severity rear impacts. The effect of seatbelts equipped with or without a pyrotechnic pretensioner on restraining the rear seat adult occupant was evaluated in the paper. Further, the study examined the result of the occupant's seating alignment by comparing a Nominal Seating Position (NSP) to an occupant whose torso would be rotated forward to be placed in a Moderately Displaced Position (MDP) prior to impact. A series of eight sled tests were performed using a deceleration sled subjected to a delta-V of 30 mph. Instrumented HIII 50th and 5th ATDs were positioned in the outboard, rear seating positions. The study found that pretensioners had little effect on the occupant kinematics of rear seat occupants in either the NSP or the MDP. But, there were marked differences in kinematic evaluations between the occupant seating alignment configurations. HIC 15, HIC 36, Ncf, Nte, Ntf, peak chest acceleration, and peak, resultant pelvis acceleration all increased when the occupant's torso was displaced forward prior to the rear impact.

This paper describes how a decade ago a detailed study of the available National Automotive Sampling System NASS data was conducted on severe rear impacts, with findings that stiffened or rigid seat backs will not substantially mitigate severe and fatal injuries in rear impacts. No field accident study has since been advanced which refutes this finding. Advocates of rigid seat backs often point to specific cases of severe rear impacts in which MAIS 4+ injuries are associated with seat back deformation, coupled with arguments supporting stiffer seatback designs. These arguments are generally based upon laboratory experiments with dummies in normal seating positions. Recent field accident data shows that generally, in collisions where the majority of societal harm is created, yielding seats continue to provide benefits, including those associated with whiplash associated disorders (WAD). This paper reviews the field accident data to identify from actual accident situations the degree to which rigidified or stiffer seats might affect the injury level of real people in severe and extremely severe rear-end crashes. Harm distributions by injury source, damage extent, and velocity change are presented. Individual case studies are reviewed for accident years between 1979 and 2002. Hard copy cases were analyzed to support the findings from the databases. Individual severe injuries were compared with respect to body region and injury contact source. Harm distributions with severity (delta-V) were presented. Pre-impact, out-of-position effects are significant in rear crash injury. The majority of Harm still resides in the lower-severity crashes. Cautions about possible negative net societal effects of stiffer seatbacks remain valid. Recent broad-scale field studies have proven an increased incidence of whiplash injuries related to stiffer seatbacks. Earlier findings are not substantially changed by the more recent data: stiffer seats per se do not reduce the overall incidence of harm due to injury in severe rear crashes.

Methanol is a genuine candidate on the alternative fuel market for internal combustion engines, especially within the heavy-duty transportation sector. Partially premixed combustion (PPC) engine concept, known for its high efficiency and low emission rates, can be promoted further with methanol fuel due to its unique thermo-physical properties. The low stoichiometric air to fuel ratio allows to utilize late injection timings, which reduces the wall-wetting effects, and thus can lead to less unburned hydrocarbons. Moreover, combustion of methanol as an alcohol fuel, is free from soot emissions, which allows to extend the operation range of the engine. However, due to the high latent heat of vaporization, the ignition event requires a high inlet temperature to achieve ignition event. In this paper LES simulations together with experimental measurements on an heavy-duty optical engine are used to study methanol PPC engine. After a successful calibration of the pressure trace in terms of required intake temperature and combustion model, the optical natural luminosity data is used to validate prediction of ignition kernel and vapor penetration length. Moreover, it is shown that the inlet temperature requirement is reduced by 47 K degrees when applying multiple injection strategy. Changing the injection strategy also affects the average temperature of combustion and thus the emissions rates. Additionally, an ignition sequence analysis is performed to identify the mode of combustion and the heat release (HR) distribution depending on the local equivalence ratio, recognizing characteristics of PPC regime. Based on this analysis, a conceptual heat distribution model for PPC engine and other low temperature combustion (LTC) engine concepts is proposed. (Less)

Low temperature combustion concepts used in compression ignition engines have shown to be able to produce simultaneous reduction of oxides of nitrogen and soot as well as generating higher gross indicated efficiencies compared to conventional diesel combustion. This is achieved by a combination of premixing, dilution and optimization of combustion phasing. Low temperature combustion can be complemented by moving away from fossil fuels in order to reduce the net output of CO 2 emissions. Alternative fuels are preferably liquid and of sufficient energy density. As such methanol is proposed as a viable option. This paper reports the results from a simulation based investigation on a heavy-duty multi-cylinder direct injection compression ignition engine with standard compression ratio. The engine was simulated using two different fuels: methanol and gasoline with an octane number of 70. The primary objective of the study was to find the optimal engine settings which maximized the brake efficiency for the engine. A secondary objective was to find the optimal injection strategy and combustion mode that would result if the brake efficiency was targeted. Comparing methanol with gasoline, the brake efficiency was on average 5.5% higher with methanol. This increase stemmed from a reduction of in-cylinder exhaust loss which was due to higher specific heats and favorable combustion phasing. Furthermore there was a significant difference in the optimal injection strategy comparing methanol and gasoline. Due to the higher octane number of methanol, all the fuel could be injected before the start of combustion. Consequently, an injection strategy typical for the low temperature combustion concept partially premixed combustion resulted. The injection strategy with gasoline, on the other hand, was similar to what is typically found in conventional diesel engines.

There is currently no acceptable injury threshold for posterior cruciate ligament (PCL) injuries in frontal crash testing. This paper outlines the approach used to develop an impact protocol to determine PCL response of isolated post mortem human subject (PMHS) lower limbs. The protocol will eventually be used to conduct proximal tibia impacts to PMHS lower limbs for comparison to proximal tibia impacts in the Hybrid III (HIII) midsize male anthropomorphic test device (ATD). This comparison will be done in an effort to relate PMHS tibia subluxation and PCL injury timing to HIII knee slider displacement. Ultimately, a PCL injury threshold will be determined through this relationship.

A large number of measurement techniques have been developed or adapted from other fields to measure various parameters of engine particulates. With the strict limits given by regulations on pollutant emissions, many advanced combustion strategies have been developed towards cleaner combustion. Exhaust gas recirculation (EGR) is widely applied to suppress nitrogen oxide (NOx) and reduce soot emissions. On the other hand, gasoline starts to be utilized in compression ignition engines due to great potential in soot reduction and high engine efficiency. New engine trends raise the need for good sensitivity and suitable accuracy of the PM measurement techniques to detect particulates with smaller size and low particulate mass emissions. In this work, we present a comparison between different measurement techniques for particulate matter (PM) emissions in a compression ignition engine running on gasoline fuel. A wide-range of EGR was used with lambda varied from 3 down to 1. The compared equipment includes AVL smoke meter, AVL Micro Soot Sensor, Pegasor and Cambustion Differential Mobility Spectrometer (DMS). The goal of this paper is to compare the recorded values and show the sensitivity of the instruments to soot properties altering, in both lean and stoichiometric combustion situations. (Less)

Road traffic accidents cause one of the highest numbers of severe injuries. Approximately 1.25 million people die each year as a result of a road traffic crash and between 20 and 50 million more people suffer non-fatal injuries, with many incurring a disability. Nearly half of those dying on the roads are so-called vulnerable road users, namely pedestrians, cyclists and two-wheeler riders including motorcyclists. Those vulnerable road users usually undergo complex kinematics and complex loading caused by the other vehicle impact. Virtual human body biomechanical models play an important role to assess the injuries during impact loading especially for scenarios, where complex dynamical loading is taken into account. The additional benefit of the virtual human models is their scalability so that they can assess the injury risk for the particular subject taking into account the wide spectra of the whole population. The presented work shows the motorcycle rider injury risk analysis during the rear motorcycle accident to a car using the virtual approach by the numerical simulation taking into account the variability of the human body. Several virtual human body models based on the population variability are concerned. Each virtual human body model is generated automatically by the scaling algorithm, coupled to personal protective equipment and sit in the motorcycle. The rear impact to a car is assessed by the numerical simulation. The sensitivity study is processed by evaluating the anthropometry dependent injury risk assessment by the variation of the velocity and the use/non-use of the personal protective equipment. The paper contributes to the field of vehicle safety technology by the virtual approach using scalable virtual biomechanical human body models as a tool for accident reconstruction, personal protective equipment optimization and the injury risk mitigation.

© 2019 SAE International. All Rights Reserved. Natural gas, biogas, and biomethane are attractive fuels for compressed natural gas (CNG) engines because of their beneficial physical and chemical characteristics. This paper examines three combustion modes - homogeneous stoichiometric, homogeneous lean burn, and stratified combustion - in an optical single cylinder engine with a gas direct injection system operating with an injection pressure of 18 bar. The combustion process in each mode was characterized by indicated parameters, recording combustion images, and analysing combustion chemiluminescence emission spectra. Pure methane, which is the main component of CNG (up to 98%) or biomethane (> 98 %), was used as the fuel. Chemiluminescence emission spectrum analysis showed that OH∗ and CN∗ peaks appeared at their characteristic wavelengths in all three combustion modes. The peak of OH∗ and broadband CO 2 ∗ intensities were strongly dependent on the air/fuel ratio conditions in the cylinder. Lower OH∗ and CO 2 ∗ intensities were observed with lean air/fuel mixtures because under these conditions, more air was present, the combustion reactions were slower, and the cylinder pressure was higher. CN∗ was formed by the spark plasma and was detected over a particularly long period when using a dual coil ignition system. The intensities of the OH∗ and CN∗ signals correlated when using this ignition system. Combustion image analysis showed that the flame had a wrinkled boundary in stoichiometric and lean burn modes and was especially distorted in stratified mode. No yellow soot luminescence was observed during homogeneous combustion. However, the emission spectra and combustion images acquired during stratified combustion showed that soot formation occurred due to the presence of fuel-rich areas with inadequate mixing in the cylinder. The difficulty of maintaining stable fuel injection, achieving proper air/fuel mixing, and ensuring stable flame propagation in lean air/fuel mixtures increased cycle-to-cycle variations. However, the homogeneous lean burn and stratified combustion modes achieved significantly lower indicated specific fuel consumption values than stoichiometric combustion.

ILC Dover Inc. was awarded a three-year NRA grant for the development of innovative spacesuit pressure garment technology that will enable safer, more reliable, and effective human exploration of the space frontier. The research focused on the development of a high performance mobility/sizing actuation system for a spacesuit soft upper torso (SUT) pressure garment. This technology has application in two areas (1) repositioning the scye bearings to improve specific joint motion i.e. hammering (Figure 1), hand over hand translation (Figure 2), etc., and (2) as a suit sizing mechanism to allow easier suit entry and more accurate suit fit with fewer torso sizes than the existing EMU. This research was divided into three phases. In phases 1 and 2 SUT actuation technologies were developed and evaluated. In the final phase, which this paper focuses on, a field of previously selected actuation methods was narrowed to one active, pneumatically driven system, and one passive, cable driven system. These systems were developed into fully functioning prototypes which were outfitted to a table top SUT mock-up which was later integrated into a full suit and tested. Both of these systems were shown to be successful in positioning the SUT shoulder joint interface angles in a designated location and holding there until task completion. The control mechanisms used for both the active and passive system was also modeled and developed. The final phase was concluded by collecting video of a manned demonstration of two of the sizing systems in effect. This paper will summarize the findings of this three year research with emphasis on the details of the final phase.

This paper is from the SAE World Congress & Exhibition, held in April 2007 in Detroit, Michigan, USA. Part of the Pedestrian Safety session, this paper reports on a study of pedestrian kinematics with the Polar-II Finite Element Model, used to evaluate the biofidelity of the lower extremity components of the pedestrian dummy. The authors evaluated this biofidelity in lateral impact loading corresponding to a 40 km/h pedestrian-car collision. The authors focused on the bending moment-angle response from a newly developed knee joint, dynamically loaded in four-point valgus bending; this joint was compared against previously published postmortem human subject (PMHS) response values. In addition to the stiffness characteristics of the knee joint, individual ligament forces were also recorded during the bending tests. In another component of the study, lower extremity long bones developed for improved anthropometrical accuracy and deformability were dynamically loaded in latero-medial three-point bending. The final part of the study used a biofidelity rating system to evaluate the modified Polar-II lower extremity components. The authors conclude that the Polar-II Finite Element model accurately replicates the PMHS response under loading conditions similar to a pedestrian-car collision.

This study aimed at determining the influence of impact conditions and occupant mechanical properties on pelvic response in side impact. First, a fracturable pelvis model was developed and validated against dynamic tests on isolated pelvic bones and on whole cadavers. By coupling a fixed cortical bone section thickness within a single subject's pelvis and across the population with a parametric material law for the pelvic bone, this model reproduced the pelvic response and tolerance variation among individuals. Three material laws were also identified to represent fragile, medium and strong pelvic bones for the 50th percentile male. With this model, the influence of impact mass, velocity and surface shape on pelvic response was examined. Results indicated that the shape difference between four main impactors reported in the literature has little effect on the pelvic response. Under iso-energy conditions, the relationship of pelvic loading between different combinations of impact mass and velocity was also determined. Based on this relationship, existing data from different impactor tests were scaled and combined to establish a pelvic response corridor in terms of pelvis loading versus impact energy. The relationship between bone mechanical properties and pelvic response and tolerance was also investigated with this model. Results indicated that changes in the mechanical properties due to ageing affected the pelvic tolerance more than the pelvic mechanical response. Assuming that the ultimate stress of the pelvic bone decreases 0.4% per year from 25 to 80 years old, the pelvic tolerance should be scaled by 0.4% per year while the pelvic loading response should be scaled only by 0.1% per year. Finally, it is to be noted that the model developed in this paper is a "global" model, not a "descriptive" model. Therefore, while it may be a useful tool for the analysis presented in this paper (e.g., overall fracture tolerance, overall effects of age, etc.), it cannot be used for detailed analyses (e.g., fracture locations, number of fractures, etc.).

Dual Sorbent Tubes (DSTs) are currently the primary method for collecting volatile organic compounds in the cabin air of the International Space Station (ISS). Data from groundbased analysis of these archival air samplers provide a major component of the assessment of ISS air quality by the NASA toxicologist. At the 2005 ICES conference data from the positive control DSTs, returned on Soyuz 7S and 8S, were presented. Positive control tubes are dosed, preflight, with known concentrations of representative contaminant compounds and they are launched to ISS in the DST kit as trip controls. Upon return of the DST kit to the ground, results from analysis of the trip (positive) and laboratory control tubes are used to determine the recoveries: concentration of dosed compounds retained in the tube. Results from positive controls, returned on 7S and 8S showed substantial losses of some compounds dosed into the tubes 156 to 240 days prior to the analysis. Low recoveries are expected for spacecraft air contaminants with similar properties to the poorly recovered dosed compounds. It was shown that compound losses in the control tubes were consistent, which led to the generation of acceptable correction factors for spacecraft air contaminants. Correction factors decrease the accuracy of derived compound concentrations and substantial error could arise under some conditions. An investigation into the mechanism for compound loss is necessary before design modifications can be implemented to improve the DST performance. This paper will update results from the DSTs returned on Soyuz 9S and 10S missions during the latter part of 2005. The data acquired from these returned DSTs will be compared to the 7S and 8S data presented last year. Discussion will focus on the reliability of correction factors and identify any trends in the data. This paper will describe the experimental design and plans to identify the compound loss mechanism.

This paper describes how vehicular rear pole impacts are rare and they can be very serious. General accident reconstruction methods, which derive vehicle stiffness values from rear barrier crash tests, over-predict the impact speed for these types of pole impacts. Thirteen pole crash tests were run into the rear ends of four 4-door, front-wheel-drive sedans. Repeated crash testing was used on three of the vehicles. Two 1988 Acura Legends, which have one of the highest stiffness values from FMVSS 301 Rear Compliance crash testing, a 1988 Honda Civic, which has one of the softest rear-end stiffness, and a 1986 Ford Taurus were tested. The repeated crash testing methodology was validated using one of the 1988 Acura Legends and a previously published Ford Taurus test. Residual crush was measured using maximum crush, point-to-point, longitudinal full-width, and longitudinal reduced-width methodologies. Crush was found to be linearly related to impact speed. The crash pulse when compared to barrier testing was longer and exhibited a later peak. Models were developed using linear regression to calculate crush energy or impact speed from the residual crush measurements. Methods were developed to transform rear-end B-values from barrier tests into B-values for use in rear pole impacts. The various models developed were compared using their coefficients of determination, standard deviations, and 95% confidence intervals to determine which models most closely predicted the impact speed. This paper showed that models which used maximum crush had the best correlation.

Diesel oxidation catalyst and particulate filter technologies are well established and their applications are well known. However, there are certain limitations with both technologies due to their inherent technical characteristics. Both technologies get 75-90% reduction of HC and CO. A typical oxidation catalyst can be applied to almost any heavy duty diesel application and achieve 20 to 30% reduction in PM mass but no significant reduction in the number of PM particles. On the other hand, diesel particulate filters are very effective at removing >90% of the particles by mass and >99% by number. Unfortunately, passive DPF technology cannot be applied to all applications since the filter regeneration is limited by engine out NOx to PM ratio as well as exhaust temperature. For this reason, particulate filters can not universally be applied to older “dirtier” engines with high PM emissions. This creates a technology gap for a passive device that can be successfully applied to old, high PM emission engines to achieve significant reduction in both PM mass and PM number. This paper will discuss the development of a passive PM control device referred to as a partial filter technology or PFT. This device combines an oxidation catalyst with a unique filter technology that can reduce PM by up to 77%. The new filter material combines the attributes of a flow through substrate with those of a wall flow filter to collect some but not necessarily all the engine out soot and thus provide PM reduction without leading to filter plugging. Due to the flow through characteristics, excess soot beyond filter capacity is not collected in the PFT and thus the exhaust is able to continue to flow without a significant increase in back pressure. The PFT system also utilizes the NO2:C reaction used by passive diesel particulate filter systems to oxidize a portion of the soot and passively regenerate the filter. In addition, the filter does not accumulate significant amounts of lube oil ash and this may minimize the need for a periodic ash cleaning maintenance. Engine bench emission testing with this system has shown PM reductions ranging from 77% for fresh (degreened) system to 63% for an aged system along with >90% HC and CO reductions. On-road operational data collected on various model year applications over a two year period has shown stable back pressure since installation. In addition, no adverse operational or maintenance issues were noted which can be attributed to the installation of the PFT system. This paper describes the development and testing of this passively regenerating partial filter technology.

The overall perception of a vehicle’s quality is significantly influenced by its interior noise characteristics. Therefore, it is important to strike a balance between “pleasant” and “dynamic” sound that fits the customer requirements with respect to vehicle brand and class [1]. Typically, a significant share of the interior vehicle noise is transferred through structure-borne paths. Hence, the powertrain mounting system plays an important role in designing the interior noise. This paper describes an application of the method of vehicle interior noise simulation (VINS) to achieve a characteristic interior sound. This approach is based on separate measurements (or calculations) of excitations and transfer functions and subsequent calculation of the interior noise in the time domain. The VINS procedure allows for explicit separation (and listening) of the sound field into airborne and structure-borne shares and each share can be further decomposed into its constituent paths and directions. In the vehicle model, which is the basis of the VINS method, the powertrain mounts are represented by frequency dependent transfer functions. In the application discussed in this paper, the influence of mount stiffness on the interior noise is calculated by virtually modifying the characteristics of these transfer functions. Critical noise paths are identified and analytically modified to achieve the desired interior noise characteristics. Finally, engine mounting system hardware changes are conducted and the measured data are compared to the VINS predictions.

This paper describes methods for modeling and characterization of hydraulically damped elastomeric mounts. The objective of the work is to be able to fit models to existing parts, describe modifications to current components and to correctly model and specify hydromounts in virtual prototype vehicles. The model used is physically based and begins with the modeling of the basic mechanical properties of the elastomeric element of the mount. It is shown that it is vital to consider the nonlinear physics of the fluid channel, particularly in relation to the hydromechanical characteristics of the elastomeric element. It is shown that the key to the hydraulic damping phenomenon is the internal resonance of the hydraulic fluid in the damping channel on the volumetric stiffness of the fluid cavity in the elastomer. Furthermore, the importance of orifice losses during the pumping of the hydraulic fluid through the channel is shown. The model has been developed in-house using commercial spreadsheet software and has also been implemented as a FORTRAN-based differential equation model in MSC-ADAMS™ multibody simulation software. Hydraulically damped mounts often include a decoupling device such as a mechanically constrained diaphragm, which can reduce noise transmission for small inputs: it is shown how such devices can be modeled and the concomitant vibration control compromise is considered. The paper emphasizes the importance of using a minimal set of physical parameters to describe the mechanical behavior of the mount and also considers the inverse problem of fitting the parameters to industry standard tests and measurements.

Experiments were conducted with a single cylinder heavy duty research engine, based on the geometry of a Volvo Powertrain D12C production engine. For these tests the engine was configured with a low compression ratio, low swirl, common rail fuel injection system and an eight-orifice nozzle. The combustion process was visualized by video via an inserted endoscope. From the resulting images temperatures were evaluated with the two-color method. In addition, the combustion and emission formation were simulated using the multiple flamelet concept implemented in the commercial CFD code STAR-CD. The models used in this paper are considered state-of-the-art. The purpose of this paper is to demonstrate the possibilities offered by combining several methods in the evaluation of novel engine concepts. Therefore, results from the optical measurements, the CFD simulations and global emission experimental data were compared. Combining the methods shows a great opportunity to understand phenomena associated with new combustion concepts involving long ignition delay, low temperature, and ultra low emissions.

In this paper, we have presented a novel design for a customizable automotive suspension system with independent control of stiffness, damping and ride-height; and demonstrated the concept through a suspension prototype. The major motivation for this design is to avoid the trade-offs, involved in suspension design, which arise from the conflicting requirements of comfort and handling. The objective of this paper is to explore the possible applications of variable stiffness and variable ride-height suspension system to achieve improved vehicle dynamics. The capability of achieving the desired performance depending on user preference, vehicle speed, road conditions and maneuvering inputs using the proposed system is demonstrated. The application of variable stiffness to achieve real-time alteration of pitch and bounce motion centers, and real time alteration of anti-pitch and anti-dive characteristics is discussed. Moreover the possibility of ensuring stability through real-time alteration of understeer-oversteer characteristics is explored. Numerous other applications of variable stiffness are possible as stiffness affects almost every aspect of ride and handling. Since the proposed system is the first system with independent control of ride-height and stiffness, the research area has been virtually unexplored. Hence it is also the objective of this paper to initiate further research in this area and to create a suitable strategy for controlling all the adaptive parameters to get improved performance.

This paper describes recent progress in our program to develop an emissions technology allowing diesel engines to meet the upcoming 2007/2010 regulations for NOx. At the heart of this technology is the ArvinMeritor Diesel Fuel Reformer that reforms the fuel, on-demand, on-board a vehicle. The fuel reformer uses plasma to partially oxidize a mixture of diesel fuel and air creating a highly reducing mixture of Hydrogen and Carbon monoxide. In a previous publication, we have demonstrated that using a reformate rich in H 2 and CO to regenerate a NOx trap is highly advantageous compared to vaporized diesel fuel used conventionally. In this paper we present results and a strategy for performing desulfation of the traps using the fuel reformer. In contrast to vaporized diesel, which requires very high temperatures that fall outside the normal exhaust operating temperatures for diesel engines, desulfation was achieved at temperatures lower by more than 100 °C using the Plasma Fuel Reformer. This is likely to provide substantial durability benefits for the NOx traps, a major hurdle remaining in the commercialization of that technology. A lower temperature that falls within the normal engine operating range also provides an effective desulfation strategy including the possibility of some desulfation occurring simultaneously with regeneration. In this paper, we also present experimental results on the fuel reformer including hydrogen yield, soot production, start-up time and durability. The fuel reformer is capable of reaching up to 90-100% of the theoretically possible hydrogen yield at a range of fuel flow rates when used in conjunction with a downstream catalyst. The soot production is minimal both upstream (

The introduction of a new comfortable car seat or interior is a time consuming and costly process for car and seat manufacturers. The application of numerical models of human and seat could facilitate this process. Vertical vibrations and seat pressure distributions are two objective parameters that have been related to the subjective feeling of (dis)comfort that can be predicted by numerical tools. In this paper, human models suitable for prediction of human behaviour in vertical vibrations and seat pressure distributions are applied in a seat sensitivity study. The objective of this paper is to evaluate the applicability of the human models as design tools for car and seat developers in an early stage of the design process. The sensitivity of the output of the models for variations in seat characteristics for seat developers in the design process of a new comfortable car seat has been studied. The human models proved to be valuable tools for seat developers in an early stage of the design process. The design study shows that human model behaviour in vertical vibrations is sensitive to variations in cushion and suspension stiffness. Seat pressure distributions are sensitive to variations in cushion thickness and cushion stiffness.

lnteraction of the human arm and deploying airbag has been studied in the laboratory using post mortem human subjects (PMHS). These studies have shown how arm position on the steering wheel and proximity to the airbag prior to deployment can influence the risk of forearm bone fractures. Most of these studies used older driver airbag modules that have been supplanted by advanced airbag technology. ln addition, new numerical human body models have been developed to complement, and possibly replace, the human testing needed to evaluate new airbag technology. The objective of this study is to use a finite element-based numerical (MADYMO) model, representing the human arm, to evaluate the effects of advanced driver airbag parameters on the injury potential to the bones of the forearm. The paper shows how the model is correlated to Average Distal Forearm Speed (ADFS) and arm kinematics from two PMHS tests. The PMHS testing employed different offsets (0 and 25mm) between the airbag and forearm in a driving position, using the two arms of the same human subject. The model is then exercised to determine predictive ability for forearm fracture seen with the Omm offset test, but not seen with the 25mm offset. The model accurately predicts fracture in the 0mm offset test, and no fracture in the 25mm offset test using a ADFS criterion of 10.5 m/s. Model elements in the ulna that rapidly exceed an arbitrary 1%o effective strain criteria correspond to fracture locations on the ulna of the Omm offset PMHS test. The model is then exercised to predict fracture using the ADFS criterion for multiple inflator outputs. The paper also discusses issues and recommendations for human model parameters to further increase the robustness of the model.