Rear Passenger Research Articles

Rear passenger restraint in frontal NCAP tests compared to the right-front passenger

Objective This study compared kinematic and biomechanic responses of the 5th female Hybrid III in the right-rear and right-front passenger seats in frontal NCAP tests with 2015–16 MY vehicles. It focused on the lap-shoulder belt restraint of the rear passenger. Methods Eleven frontal NCAP tests were conducted by NHTSA at 56 km/h with a lap-shoulder belted 5th Hybrid III dummy in the right-rear and right-front seats. The right-front passenger had pretensioning and load limiting belts and advanced airbags with inflatable knee bolster. The rear passenger had seatbelts without pretensioning or load limiting. The kinematic and biomechanical responses of the 5th Hybrid III dummy in the rear and front were analyzed. The tests included onboard video cameras covering the rear and front passenger. Lap and shoulder belt loads were measured. The responses were compared for the two seating positions and restraint systems. Results Only one of 11 vehicles had favorable restraint of the right-rear passenger. All vehicles passed criteria for the right-front passenger. The right-rear passenger HIC15 was 888 ± 314 (779 IARV) significantly higher than 242 ± 72 in the right-front passenger (t = 6.36, p < 0.001). The right rear Nij was 1.16 ± 0.19 (1.00 IARV) significantly higher than 0.46 ± 0.11 in the right-front (t = 9.18, p < 0.001) and the rear chest deflection was 46.1 ± 9.8 mm (42 mm IARV) significantly higher than 20.8 ± 5.6 mm in the right-front (t = 7.12, p < 0.001). The shoulder belt load was 8,771 ± 2,088 N on the right-rear passenger significantly higher than 3,564 ± 911 N on the right-front (t = 7.28, p < 0.001). Three of the 11 crash tests involved submarining by the right-rear passenger at 76.0 ± 7.2 ms. Two tests with submarining involved the seatbelt buckle lifting by shoulder belt load pulling the lap belt onto the abdomen. One test involved compressing the front of the seat cushion with the H-point dropping, the pelvis rotating rearward and the lap belt sliding onto the abdomen. Conclusions Restraining loads on the rear passenger were significantly higher than on the right-front passenger in 2015–16 MY vehicle NCAP tests. The HIC15 was 3.7-times higher in the rear passenger than the front. The Nij was 2.5-times higher and chest deflection was 2.2-times higher. The dummy responses were significantly higher in the rear seat compared to the front seat because of greater restraining loads, submarining and a hardware failure in NCAP tests. The lack of pretensioning, load limiting and airbags involved higher injury risks in the rear passenger compared to the right-front passenger.

Effects of seatback angle, seat rotation, and impact speed on injury risk of occupants in highly automated vehicles in frontal crashes

Objective The objective of this study is to examine the effects of seatback angle, seat rotation, and impact speed on occupant kinematics and injury risk in highly automated vehicles. Methods The study utilized the Global Human Body Models Consortium midsize male (M50-OS+B) simplified occupant model in a simplified vehicle model (SVM) to simulate frontal crashes. The M50-OS+B model was gravity-settled and belted into the driver and left rear passenger seat. To investigate the effects of seatback angle, seat rotation, and impact speed on occupant kinematics and injury risk in frontal crashes, a design of experiments (DOE) was conducted. The DOE incorporated four seatback angles (13°, 23°, 45°, and 57.5° about vertical), four seat rotation angles (0°, 25°, 45°, and 90°), three impact speeds (25, 35, and 45 kph), and four frontal crash type configurations. All four seatback angles were used with 0° seat rotation, whereas 13° seatback angle was used with the remaining seat rotation configurations because of cabin fit considerations. Injury risks were estimated for the head, neck, shoulder, thorax, pelvis, and lower extremities for both occupants for each simulation (n=588). Results Statistically significant differences between all the groups within each independent variable category were observed based on the analysis of variance. HIC-based head injury risk and chest injury risk decreased and femur force for the driver and tibia force for the passenger increased with an increase in seatback angles. The head injury risk increased with seat rotation. All the injury risks increased with an increase in impact speed. The driver airbag was able to safeguard the driver from head injuries for all seat rotations except at 90° of seat rotation. Conclusion This is the first vehicle modeling study that collectively looked at the effects of seatback angle, seat rotation, and impact speed along with the interaction of occupants on the risk of injury in frontal crashes. The rear passenger experienced higher seatbelt loads than the driver. More reclined seats decreased head and chest injury risk, but increased driver femur injury risk and rear passenger tibia injury risk. Results underscore the necessity for additional anti-submarining mechanisms and driver airbag designs adapted for the anticipated occupant positions.

Demographic and injury trends for car crash casualties hospitalized in Level I Trauma centers over two decades: data from the National Trauma Registry

BackgroundDuring the past two decades, there have been many changes in automotive and medical technologies, road infrastructure, trauma systems, and demographic changes which may have influenced injury outcomes. The aim of this study was to examine injury trends among traffic casualties, specifically private car occupants, hospitalized in Level I Trauma Centers (TC).MethodsA retrospective cohort study was performed based on data from the Israel National Trauma Registry. The data included occupants of private cars hospitalized in all six Level I TC due to a traffic collision related injury between January 1, 1998 and December 31, 2019. Demographic, injury and hospitalization characteristics and in-hospital mortality were analyzed. Chi-squared (X2) test, multivariable logistic regression models and Spearman’s rank correlation were used to analyze injury data and trends.ResultsDuring the study period, 21,173 private car occupants (14,078 drivers, 4,527 front passengers, and 2,568 rear passengers) were hospitalized due to a traffic crash. The percentage of females hospitalized due to a car crash increased from 37.7% in 1998 to 53.7% in 2019. Over a twofold increase in hospitalizations among older adult drivers (ages 65+) was observed, from 6.5% in 1998 to 15.7% in 2018 and 12.6% in 2019. While no increase was observed for severe traumatic brain injury, a statistically significant increase in severe abdominal and thoracic injuries was observed among the non-Jewish population along with a constant decrease in in-hospital mortality.ConclusionsThis study provides interesting findings regarding injury and demographic trends among car occupants during the past two decades. Mortality among private car occupant casualties decreased during the study period, however an increase in serious abdominal and thoracic injuries was identified. The results should be used to design and implement policies and interventions for reducing injury and disability among car occupants.

Effects of Adaptive Cruise Control System on Traffic Flow and Safety Considering Various Combinations of Front Truck and Rear Passenger Car Situations

Existing studies on the heterogeneity in traffic flow have considered either conventional car–truck or conventional vehicle–automated vehicle combinations. Nevertheless, these assumptions are not realistic as there will be possible combinations of cars–trucks and conventional–automated vehicles in the future. This study aims to investigate heterogeneous traffic flow with or without an adaptive cruise control (ACC) system for the pair of a front truck and a rear passenger car. Vissim microscopic traffic simulation software and the HighD dataset were applied. The major findings include the following. (1) The greater the penetration rate of ACC vehicles in the same speed interval, the smaller the space headway of the rear car. (2) Both conventional and ACC cars accelerate or decelerate frequently when their speeds exceed that of the front truck in the car-following state. In the free-flow state, a conventional car keeps a constant speed or accelerates, while an ACC car mainly adopts an acceleration strategy. (3) The variation of speed differences and space headways is smallest when both the front truck and rear car have ACC. (4) The probability of conflicts between the front truck and rear car pair decreases with the increase of market penetration of ACC vehicles. Compared to conventional cars, the rear car equipped with ACC exhibits a lower probability of conflicts. Statistical tests further confirmed the significant differences between any two of the four combinations based on the ACC equipment.

Trends and characteristics of severe road traffic injuries in children: a nationwide cohort study in Japan.

The purpose of this study was to evaluate temporal trends of characteristics of severe road traffic injuries in children and identify factors associated with mortality using a nationwide database in Japan. We performed a retrospective analysis of Japan Trauma Data Bank (JTDB) from 2004 to 2018. We included patients with traffic injuries under the age of 18 who were hospitalized. The primary outcome was in-hospital mortality. We evaluated trends in characteristics and assessed factors associated with in-hospital mortality using a logistic regression analysis. A total of 4706 patients were analyzed. The most common mechanism of injury was bicycle crash (34.4%), followed by pedestrian (28.3%), and motorcycle crash (21.3%). The overall in-hospital mortality was 11.2%. We found decreasing trends in motorcycle crash and in-hospital mortality and increasing trends in rear passenger seats in cars over the 15-year period. The following factors were associated with in-hospital mortality: car crash (aOR 1.69, 95%CI 1.18-2.40), pedestrian (aOR 1.50, 95%CI 1.13-1.99), motorcycle crash (aOR 1.42, 95%CI 1.03-1.95) [bicycle crash as a reference]; concomitant injuries to head/neck (aOR 5.06, 95%CI 3.81-6.79), thorax (aOR 2.34, 95%CI 1.92-2.87), abdomen (aOR 1.74, 95%CI 1.29-2.33), pelvis/lower-extremity (aOR 1.57, 95%CI 1.23-2.00), spine (aOR 3.01, 95%CI 2.02-4.43); and 5-year increase in time period (aOR 0.80, 95%CI 0.70-0.91). We found decreasing trends in motorcycle crash and in-hospital mortality, increasing trends in rear passenger seats in cars over the 15-year period, and factors associated with in-hospital mortality such as type of mechanisms and concomitant injuries. Strengthening child road safety measures, particularly for rear passenger seats in vehicles, is imperative to enhance our dedication to injury prevention.

Bus Cabin Noise Predictions of Large HVAC System using Total Noise Method

HVAC system design has an accountability towards acoustic comfort of passengers of a vehicle. Owing to larger cabin volume of a bus, multiple air blowers have to be installed to ensure comfort of passengers. Such multiple blowers produce significant flow induced noise inside the cabin. For commercial success, it becomes essential to predict intensity of such a flow induced noise at very early stages in product development. Conventionally sliding mesh based CFD approach is deployed to predict flow and turbulence noise around each blower. However due to complexity, this method becomes computationally intensive resulting in cost and time inefficiency. Hence it is desirable to innovate around an alternative rapid, reliable prediction method, which ensures quick turnaround of prediction. This paper describes a unique innovative approach developed around a multiscale method where flow induced noise generated by a single blower in motion is predicted using commercial Lattice Boltzmann CFD software with a digitally scaled down HVAC system in an anechoic digital wind tunnel. These CFD predictions are used to replace all blowers with virtual stationary speakers inside digital cabin to emulate noise emanated by a large HVAC unit. Authors named this method as total Noise Multiscale Approach, in the paper. With the total multiscale approach, overall sound pressure level predicted inside the bus cabin at rear passenger ear levels are comparable with the physical test measurements and has shown fair correlation. Using this multiscale total noise method, computational cost and turnaround time has significantly reduced compared to the flow conventional resolving approach for cabin with all the blowers. This predictive total noise method found useful in designing and planning countermeasures during product development.

Integrated Module Antenna for Automotive UWB Application

In this paper, an integrated module antenna for automotive UWB application is proposed. The target applications of the proposed antenna are for UWB localization and rear passenger detection. The purpose of this work is to design an antenna with a wide and narrow beamwidth that can be attached to the exterior/interior of a vehicle for simultaneous UWB localization and a rear passenger detection sensor with a single-module substrate in a limited space. For UWB localization, the wide beam coverage is required so the antenna receives the signal from any incident angle in horizontal plane. Meanwhile, the rear passenger detection sensor requires a relatively narrower beamwidth than the localization antenna for accurate detection within the vehicle. To integrate two different antennas into a single compact module substrate, modified ground stubs and parasitic radiators are applied. The size of the entire antenna structure is 35 mm × 65 mm × 1.156 mm. The proposed antenna designed on the multi-layered FR-4 substrate with a dielectric constant of 4.3. The bandwidth of the monopole is 6.14~8.24 GHz, and the patch array is 6.95~8.47 GHz. The isolation between the monopole and the patch array is less than −23 dBi in the target band. The performance of the proposed antenna is verified with simulation and measurement. In addition, a simulation of the proposed antenna with the real vehicle model is also conducted to verify the feasibility on actual vehicle. Based on this work, the proposed antenna can be applied to multi-function antenna for automotive application with low cost.

Analysis of injury patterns and contributory factors among three-wheeler occupants admitted to Teaching Hospital Karapitiya following road traffic accidents

<strong><em>Introduction:</em></strong><em> </em>Increasing morbidity and mortality following road traffic accidents (RTA) is a major health and economic burden in developing countries. Among the increased number of registered vehicles in Sri Lanka 15% are three-wheelers and they are responsible for 11% of the road fatalities in the year 2021 with high impact incidence. The objectives in this study were to determine different patterns, nature, and mechanisms of the injuries, contributory factors, safety measures, and crash characteristics among the occupants of three-wheelers who are admitted following road traffic accidents to a tertiary care hospital in Southern Sri Lanka. <strong><em>Methodology:</em></strong> Data on socio-demographic profile, mechanisms of causation of injuries, affected region and severity of injuries, and contributory factors for the collision were retrieved from Medico-Legal Examination Forms of the patients admitted following three-wheeler accidents to the teaching hospital Karapitiya from 2019 to 2021. The data were analyzed using the SPSS IBM Version 22. <strong><em>Results:</em></strong> Rear-seat passengers (64%) were mostly injured than drivers. A bi-fold pattern of prevalence was observed at the time of incidents. The commonest incident was impacts with moving vehicles (41%) and most injuries were sustained by impacts of objects inside the vehicle (48%). The commonest injury seen was abrasion (69%) and the majority were seen over upper limbs (51%). There was no significant difference in the injury pattern between drivers and rear passengers. (11%) of the three-wheel drivers in this study did not possess a driving license and (24%) of them were drunk at the time of the accidents. <strong><em>Conclusion:</em></strong> High vehicular instability, lack of safety measures, reckless driving, and unnecessary vehicular modifications increase the number of three-wheel accidents. Replacing more crash-worthy four-wheel light vehicles and enforcement of legal limits are recommended.

Role of pathogen-laden expiratory droplet dispersion and natural ventilation explaining a COVID-19 outbreak in a coach bus

The influencing mechanism of droplet transmissions inside crowded and poorly ventilated buses on infection risks of respiratory diseases is still unclear. Based on experiments of one-infecting-seven COVID-19 outbreak with an index patient at bus rear, we conducted CFD simulations to investigate integrated effects of initial droplet diameters(tracer gas, 5 μm, 50 μm and 100 μm), natural air change rates per hour(ACH = 0.62, 2.27 and 5.66 h−1 related to bus speeds) and relative humidity(RH = 35% and 95%) on pathogen-laden droplet dispersion and infection risks. Outdoor pressure difference around bus surfaces introduces natural ventilation airflow entering from bus-rear skylight and leaving from the front one. When ACH = 0.62 h−1(idling state), the 30-min-exposure infection risk(TIR) of tracer gas is 15.3%(bus rear) - 11.1%(bus front), and decreases to 3.1%(bus rear)-1.3%(bus front) under ACH = 5.66 h−1(high bus speed).The TIR of large droplets(i.e., 100 μm/50 μm) is almost independent of ACH, with a peak value(∼3.1%) near the index patient, because over 99.5%/97.0% of droplets deposit locally due to gravity. Moreover, 5 μm droplets can disperse further with the increasing ventilation. However, TIR for 5 μm droplets at ACH = 5.66 h−1 stays relatively small for rear passengers(maximum 0.4%), and is even smaller in the bus middle and front(<0.1%). This study verifies that differing from general rooms, most 5 μm droplets deposit on the route through the long-and-narrow bus space with large-area surfaces(L∼11.4 m). Therefore, tracer gas can only simulate fine droplet with little deposition but cannot replace 5–100 μm droplet dispersion in coach buses.

PENGARUH SISTEM DOUBLE BLOWER TERHADAP KINERJA PENDINGINAN AC KENDARAAN PENUMPANG

Cooling using air conditioning in passenger vehicles is very important for the user's comfort. The study aims to get the effect of double blowers on the cooling performance of passenger vehicles. The research was conducted using laboratory-scale equipment.&#x0D; The wind speed of the blower varied by 3.1; 3.5 and 3.7 m/s. To measure wind speed using a digital anemometer. Cabin room temperature is measured using type K thermocouples for 4 measurement points, namely the left rear passenger seat (point 1), the right rear passenger seat (point 2), then the front passenger seat (point 3), and the driver's position (point 4).&#x0D; Measurement times varied by 5, 10, 15 and 20 minutes. Visualizing airflow using the smoke method and recorded with a camera. In this study showed that the double blower system affects the cooling performance of passenger vehicle air conditioners

The Influence of Seat Occlusion on Driver’s Binaural Signal in Automobile based on FEM-RTM Simulation

Automotive environment is increasingly becoming an indispensable listening space in our daily life. Affected by the seat occlusions on sound propagation between the front-row and rear-row space, the speech communication between front and rear passengers in automobile is a well-known problem. However, this issue has been paid less attention. To this issue, the numerical simulation is a common, low-cost and high-efficiency technical approach. However, it is a well-known limitation on the effective frequencies to common numerical methods. To extend the region of effective frequencies, a combined approach of the finite element method (FEM) for low-frequency and the ray-tracing method (RTM) for high-frequency (i.e., FEM-RTM) was adopted in current work. The full-bandwidth binaural room impulse responses for a listener in driver’s seat were simulated with the speaker at mid-right seats, and both conditions with seats and without seats were taken into account. Result showed that the seats occlusions mainly affected the left ear (i.e., contralateral ear). The seat occlusions reduced the early decay time, speech transmission index and magnitude spectrum for left ear considerably. The inter-aural correlation coefficient under condition without seats was lower than that under condition with seats.

An Isolated Dextrogastria Simulating Diaphragmatic Rupture in a Post-Traumatic Context

We report a case of isolated dextrogastria discovered in imaging a 34-years-old woman who was in the emergency department for vomiting and fluctuating right chest pain following a road accident. It was a collusion between 2 motorcycles, the patient being a rear passenger, performing a whiplash mechanism with a brief initial loss of consciousness. The day after the accident, she complained of left cervical swelling, painful with dysphagia to solids. Physical examination revealed bilateral palpebral oedema. There was a decrease in right vesicular murmurs with symmetrical tympanism towards the base of the lung. The rest of the examination was normal. The chest x-ray showed digestive loops above the liver that appeared to be located in the right intra-thoracic, suggesting in this context a diaphragmatic rupture. The OGDT and the thoraco-abdominal CT made possible to correct the diagnosis of type II dextrogastria by showing the stomach and part of the colon located on the right, above the liver, under the diaphragmatic dome which is disembowelled, pushing back the lung homolateral up. There was also a deviation of the ipsilateral thoracic esophagus in continuity with the stomach. The liver, in the right quasi-lateral position, is forced downward, extending to the lower edge of the ipsilateral flank. The other viscera kept their usual topographies. KEY WORDS: Dextrogastria, Isolated dextrogastria, Chest pain, Dysphagia.

차량용 공기 순환 장치가 후석 승객의 온열 쾌적성에 미치는 영향에 관한 연구

Recently, automotive industry in Southeast Asia and India has enlarged and lifestyle has been changed, with time spending in an automotive showing a gradual increase. Accordingly, thermal comfort that passengers feel inside the cabin of an automotive is more important than other region. Current air-conditioning system is dependent on the cool-down performance of an HVAC located inside the front instrument panel that supplies cold air from the front cabin to the rear cabin. Therefore, front seat passengers and rear seat passengers can feel thermal comfort quite differently because of solar radiation through windows, air flow velocities, and blowing air path in the cabin. In this study, to increase thermal comfort for rear passengers, especially those in 2nd row and 3rd row seats, an air-circulator was developed. The air-circulator was subjected to computational fluid analysis to find the appropriate airflow volume, air distribution rate, and air direction for passengers in 2nd row and 3rd row seats. Air-conditioning system cool-down performance, PMV, and subjective evaluation of thermal comfort of vehicle experiments were also carried out. As the result, roof top mounted air-circulator was optimized by computational analysis and experimental study. It was a quite good solution for improving cabin thermal comfort for passengers in 2nd row and 3rd row seats with cost effectiveness and a compact package.

Measurement analysis of braking forces and braking coefficient at different loads of a passenger vehicle

This paper presented an analysis of the braking force efficiency, i.e. its intensity in the case. It presented an analysis of the efficiency of braking forces, i.e. their intensity in the case when the load of a passenger vehicle was gradually changing. The change in the load of the vehicle was done by varying the number of passengers in it from one to five which is a feature of a higher number of M1 category vehicle. By increasing in the number of passengers the weight of the vehicle varied by approximately 75kg per passenger. The experimental test was performed in the technical inspection station, i.e. on standard rollers for the brake system testing. The test results shown that the relative difference of braking forces occurred on the front axle during intensive braking and that the braking coefficient was the lowest of about 69.94% in the case when only the driver was in the vehicle. It increased with increasing load, i.e. the number of passengers in the vehicle up to 85.91% and then dropped by increasing the rear passenger behind the driver and front passenger to 80.43% which can affect the stability of the vehicle when braking in the event of a dangerous traffic situation.

Parametric Study of Factors Affecting Lateral Stability of a Public Transportation Vehicle

The availability of public transport is one of the solutions to traffic congestion in Jakarta. Focusing on angkot, one of the public transport types in Jakarta, this study discusses a model and simulations to investigate several factors that affect its lateral stability. Those factors include rear tire inflation pressure, passenger configuration, velocity, and downhill inclination angle. The results show that the stability of an angkot is proportional to the rear tires cornering stiffness. It also has an indirect relationship with the passenger configuration within the angkot. Moreover, the stability of an angkot decreases as its velocity and the angle of the inclined road increase. In general, this study is expected to have a contribution to the development of public transport in Jakarta, especially angkot.

Literature review on hydrostatic vaginal and anorectal injuries caused by personal watercraft

IntroductionThe use of personal watercrafts (PWCs) has increased in popularity, size and engine power over time. Hydrostatic injuries when the passenger falls into water and the pelvic floor is directly hurt by the water jet remain rarely reported in literature but potentially lethal. Perineal, gynaecological and rectosigmoid regions present significant points of anatomical weakness to the force vector of the water. Biomechanical aspects on water-associated injuries on PWC may include disruption of the perineal soft tissues, inefficient anal sphincter and hydrodynamic insufflation.MethodsThis is a study involving a literature review from 1972 to 2020 using suitable search terms to identify all hydrostatic PWC injuries following PRISMA guidelines. Data were extracted from suitable articles on mechanism of injury, injuries sustained, treatment and outcomes.ResultsThirty-two patients with major perineal, gynaecological and/or digestive injuries due to hydrostatic PWC traumas were identified. Major risk factors were female gender (84.4%), young age (25.5 years), being a rear passenger and wearing a standard swimsuit (100%). The injuries were digestive tract only (81.3%), gynaecological only (46.9%) or combined (28.1%). The interdisciplinary surgical management must include a vaginal and anal exploration under general anaesthesia and an exploratory surgery. Vaginal repair (41.9%) may be associated with a transanal anorectal suturing for lacerations of the intraperitoneal rectum (40.6%). A defunctioning stoma was performed in 62.5% and consisted of a loop sigmoidostomy (43.5%) or Hartmann’s procedure (34.8%) depending on laceration complexity.ConclusionsPWC-related hydrostatic injuries are still rare but associated with a mortality rate of 6.3% which rises to 25% if initial haemodynamic instability was present. Expert guidelines such as adding an automated engine shut-off switch for the rear passenger and wearing a protective and safety clothing should be more widely respected.

The influence of different air flows introduced on the thermal comfort of car passengers during the cooling period – Numerical Study

In this article the effects of different airflow rates introduced by the ventilation system are investigating by numerical simulation over the thermal comfort of the driver in a regular vehicle. The 3D LDV (Laser Doppler Velocimetry) measurement for the diffusers velocity field was imposed as boundary condition at the inlets of the investigated domain. Also, the flow rate discharged by each diffuser was measured for the first three positions of the air conditioning system. In the numerical model which was previously validated we imposed the boundary conditions from the experimental sessions. Thermal comfort was assessed by calculation of the equivalent temperature on the surface of a virtual manikin on the driver place and by the determination of the maps of Predicted Mean Vote (PMV) and the Draft rate indices. A first conclusion is that the results of the three flowrates may assure the comfort of the front passengers and a draft sensations and uncomfortable state for the rear passengers.

Buckle Up! A Nudge for Car Occupant Safety

The seatbelt remains one of the most effective solutions in reducing vehicle occupants' injuries in road crashes. Nevertheless, achieving a high compliance rate in Malaysia, where the situation of not buckling up is glaringly evident among rear passengers, still poses a great challenge. On another note, despite manufacturers' countermeasure to introduce the Seatbelt Reminder (SBR) system, some users still find ways to flout the system by using fake clips.

Analysis and Optimization of Driveline Bushing for Lateral Ride Vibration under Shock Excitation

Ride comfort is increasingly important for automobile companies due to the increasing concern of the demands of customers. Response to shock at low speed, such as single or consecutive pulse excitations from humps, are one of the greatest assessing indices of vehicle ride related to the ride comfort. This paper aims to study the effect of driveline bushing on ride vibration when the vehicle experiences shock excitation and to improve the ride quality by optimizing the bushing parameters. A vehicle level multibody dynamic model with a differential-subframe subsystem is developed and calibrated against field test data. The sensitivities of the bushing stiffness and damping coefficients are analyzed and the most influential bushing parameters on the seat rail vibration are identified. The relationship between the bushing parameters and the ride vibration is developed by a 5-level response surface design. The fitted response functions are validated and adopted as the optimization objectives. The optimized results, including the acceleration, the running r.m.s. acceleration, the jerk, the running r.m.s. jerk, the VDV and the comfort, are compared with those of the baseline vehicle. Results show that the optimized bushings significantly decrease the vibration at the driver and the rear passenger seats by approximately 50% in the lateral direction. A considerable improvement has been achieved in ride comfort that the weighted vibration at seats is reduced to a level below the median perception threshold of human being in the lateral direction.

An evaluation of occupant dynamics during moderate-to-high speed side impacts.

The present study examined trends in occupant dynamics during side impact testing in vehicle models over the past decade. "Moderate-to-high" speed side impacts (delta-V ≥15 km/h) were analyzed. The Insurance Institute for Highway Safety (IIHS) side impact crash data was examined (N = 126). The test procedure involved a moving deformable barrier (MDB) impacting the sides of stationary vehicles at 50.0 km/h. Instrumented 5th-percentile female SID IIs dummies were positioned in the driver and left rear passenger seats. Occupant head, neck, shoulder, torso, spine, and pelvis/femur responses (times histories, peaks, and time-to-peak values) were evaluated and compared to injury assessment reference values (IARVs). The effects of delta-V, vehicle model year, vehicle body type, and occupant seating position on dynamic responses were examined. The vehicle lateral delta-Vs ranged from 15.9 to 34.5 km/h. The MY2018-2020 demonstrated lower peak dynamics than MY2010-2013, for the driver head acceleration (53.7 ± 11.3g vs 46.4 ± 11.6g), shoulder lateral forces (1.7 ± 0.7 kN vs 1.5 ± 0.2 kN), average rib deflection (29.8 ± 8.3 mm vs 28.4 ± 6.2 mm), spine accelerations at T4 (51.4 ± 23.4g vs 39.6 ± 5.9g) and T12 (56.3 ± 18.5g vs 45.2 ± 9.6g), iliac forces (1.9 ± 1.0 kN vs 1.2 ± 0.9 kN), and acetabular forces (1.9 ± 0.8 kN vs 1.3 ± 0.5 kN). The driver indicated statistically higher dynamic responses than the left rear passenger. Higher wheelbase vehicles generally showed lower occupant loading than the smaller vehicles. In conclusion, a reduction in occupant loading and risks for injury was observed in vehicle models over the past decade. This provides further insight into injury mechanisms, occupant dynamics simulations, and seat/restraint design.