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Carbon neutrality has become a significant target. One essential parameter regarding energy consumption and emissions is the mass of vehicles. Lightweight design improves the result of vehicle life cycle assessment (LCA), increases efficiency, and can be a step towards sustainability and CO2 neutrality. Weight reduction through structural optimization is a challenging task. Typical design development procedures have to be overcome. Instead of just a facelift or the creation of a derivative of the predecessor design, completely alternative design creation methods have to be applied. Automated structural optimization is one tool for exploring completely new design approaches. Different methods are available and weight reduction is the focus of topology optimization. This paper describes a fatigue life homogenization method that enables the weight reduction of vehicle parts. The applied CAE process combines fatigue life prediction and topology optimization.

Collisions between opened doors and approaching vehicles such as bicycles are common occurrences in urban areas around the world. For example, in Chicago, 20% of all bicycle accidents involve collisions with doors, which occur over 300 times a year. In addition, there are concerns about a further rise in accidents due to the recent increase in home delivery services and bicycle commuting during the COVID-19 pandemic. Some advanced driver assistance systems (ADAS) that are designed to help prevent this type of accident have already been introduced. These systems detect approaching vehicles with sensors and alert the person opening the door via LED lights or a buzzer when the door is opened. The occupant must understand the meaning of the alert and stop opening the door quickly to prevent an accident. However, if the occupant is an elderly person or a child, it is difficult to stop opening the door quickly.

This paper describes a method for assisting pedestrians to cross a road. As motorization develops, pedestrian protection techniques are becoming more and more important. Advanced driving assistance systems (ADAS) are improving rapidly to provide even greater safety. However, since the accident risk of pedestrians remains high, the development of an advanced walking assistance system for pedestrian protection may be an effective means of reducing pedestrian accidents. Crossing a road is one of the highest risk events, and is a complex phenomenon that consists of many dynamically changing elements such as vehicles, traffic signals, bicycles, and the like. A road crossing assistance system requires three items: real-time situational recognition, a robust decision-making function, and reliable information transmission. Edge devices equipped with autonomous systems are one means of achieving these requirements.

This paper describes the development of a simplified fracture finite element (FE) model for resistance spot welds (RSW) of ultra-high-strength steel (UHSS) that can be incorporated into large-scale vehicle FE model. It is known that the RSW of UHSS generates two types of fracture modes: heat-affected zone (HAZ) and nugget zone fractures. Lap shear and peeling coupon tests using UHSS sheets found that the different RSW fracture modes occurred at different nugget diameters. To analyze this phenomenon, detailed simulated coupon tests were carried out using solid hexahedral elements. The analytical results revealed that RSW fractures are defined by both the application of plastic strain on the elements and the stress triaxiality state of the elements. A detailed model incorporating a new fracture criteria model recreated the different UHSS RSW fracture modes and achieved a close correlation with the coupon test results.

The research described in this paper focused on improving occupant ride comfort and road holding by suppressing sprung and unsprung vibration using a semi-active suspension system. It has been reported that occupants tend to perceive vertical vibrations in a frequency range between 4 and 8 Hz as uncomfortable (described below as the “mid-frequency range”). Previous research into semi-active suspension system has focused on reducing vibration in this mid-frequency range, as well as close to the sprung resonance frequency of between 1 and 2 Hz. Skyhook damper (SH) control is a typical ride comfort control used to damp vibration close to the sprung resonance frequency. However, since SH control is not capable of damping vibration in the mid-frequency range, the shock absorbers are configured with a lower damping factor. This helps to achieve a good balance between reducing vibration close to the sprung mass resonance and in the mid-frequency range.

1 Structural parts, such as the center pillar, are a multi-layer structure. They are a combination of high-strength panels and high-toughness panels, to control the deformation mode during a crash. If we can make this multi-layered structure as one panel, consisting of different hardness within it, we will be able to make a lightweight part. In this study, we have developed a method to fabricate a ‘lightweight center pillar’ with the following processes. First, the whole panel is hardened by quenching within the hot stamp process. Next, certain areas of the panel are softened by partial tempering. We have found that the temperature zone for softening is between A1 and A3, and it is easy to perform a rapid and accurate tempering by utilizing induction heating around the Curie temperature between A1 and A3 transformation temperature.

In the last decade, extensive efforts have been made to understand the physics of submarining and its consequences in terms of abdominal injuries. For that purpose, 27 Post Mortem Human Subject (PMHS) tests were performed in well controlled conditions on a sled and response corridors were provided to assess the biofidelity of dummies or human body models. All these efforts were based on the 50th percentile male. In parallel, efforts were initiated to transfer the understanding of submarining and the prediction criteria to the THOR dummies. Both the biofidelity targets and the criteria were scaled down from the 50th percentile male to the 5th percentile THOR female. The objective of this project was to run a set of reference PMHS tests in order to check the biofidelity of the THOR F05 in terms of submarining. Three series of tests were performed on nine PMHS, the first one was designed to avoid submarining, the second and third ones were designed to result in submarining.

Petit et al. 2015 and Lebarbé et al. 2016 reported on two studies where the injury mechanism and threshold of the sacroiliac joint were investigated in two slightly oblique crash test conditions from 18 Post Mortem Human Subjects (PMHS) tests. They concluded that the sacroiliac joint fractures were associated with pubic rami fractures. These latter being reported to occur first in the time history. Therefore it was recommended not to define a criterion specific for the sacroiliac joint. In 2012, injury risk curves were published for the WorldSID dummy by Petitjean et al. For the pelvis, dummy and PMHS paired tests from six configurations were used (n = 55). All of these configurations were pure lateral impacts. In addition, the sacroiliac joint and femur neck loads were not recorded, and the dummy used was the first production version (WorldSID revision 1). Since that time, the WorldSID was updated several times, including changes in the pelvis area.

The new P710 hybrid transaxle for a mid-size 2.5-liter class vehicle was developed based on the Toyota New Global Architecture (TNGA) design philosophy to achieve a range of desired performance objects. A smaller and lighter transaxle with low mechanical loss was realized by incorporating a new gear train structure and a downsized motor. The noise of the P710 transaxle was also reduced by adopting a new damper structure.

The renewed platform of the upcoming flagship front-engine, rear-wheel drive (FR) vehicles demands high levels of driving performance, fuel efficiency and noise-vibration performance. The newly developed driveline system must balance these conflicting performance attributes by adopting new technologies. This article focuses on several technologies that were needed in order to meet the demand for noise-vibration performance and fuel efficiency. For noise-vibration performance, this article will focus on propeller shaft low frequency noise (booming noise). This noise level is determined by the propeller shaft’s excitation force and the sensitivity of differential mounting system. In regards to the propeller shaft’s excitation force, the contribution of the axial excitation force was clarified. This excitation force was decreased by adopting a double offset joint (DOJ) as the propeller shaft’s second joint and low stiffness rubber couplings as the first and third joints.

The aim of this study was to investigate the sacroiliac joint injury mechanism. Two test configurations were selected from full scale car crashes conducted with the WorldSID 50th dummy resulting in high sacroiliac joint loads and low pubic symphysis force, i.e. severe conditions for the sacroiliac joint. The two test conditions were reproduced in laboratory using a 150-155 kg guided probe propelled respectively at 8 m/s and 7.5 m/s and with different shapes and orientations for the plate impacting the pelvis. Nine Post Mortem Human Subject (PMHS) were tested in each of the two configurations (eighteen PMHS in total). In order to get information on the time of fracture, eleven strain gauges were glued on the pelvic bone of each PMHS. Results - In the first configuration, five PMHS out of nine sustained AIS2+ pelvic injuries. All five presented sacroiliac joint injuries associated with pubic area injuries.

Torque loss reduction at differential gear unit is important to improve the fuel economy of automobiles. One effective way is to decrease the viscosity of lubricants as it results in less churning loss. However, this option creates a higher potential for thin oil films, which could damage the mechanical parts. At tapered roller bearings, in particular, wear at the large end face of rollers and its counterpart, known as bearing bottom wear is one of major failure modes. To understand the wear mechanism, wear at the rolling contact surface of rollers and its counterpart, known as bearing side wear, was also observed to confirm the wear impact on the tapered roller bearings. Because gear oils are also required to avoid seizure under extreme pressure, the combination of a phosphorus anti-wear agent and a sulfurous extreme pressure agent are formulated.

Vehicles equipped with in-wheel motors (IWMs) are capable of independent control of the driving force at each wheel. These vehicles can also control the motion of the sprung mass by driving force distribution using the suspension reaction force generated by IWM drive. However, one disadvantage of IWMs is an increase in unsprung mass. This has the effect of increasing vibrations in the 4 to 8 Hz range, which is reported to be uncomfortable to vehicle occupants, thereby reducing ride comfort. This research aimed to improve ride comfort through driving force control. Skyhook damper control is a typical ride comfort control method. Although this control is generally capable of reducing vibration around the resonance frequency of the sprung mass, it also has the trade-off effect of worsening vibration in the targeted mid-frequency 4 to 8 Hz range. This research aimed to improve mid-frequency vibration by identifying the cause of this adverse effect through the equations of motion.

A dynamics model considering series rigidity was constructed to examine suspension friction, which has a major effect on ride comfort on paved roads. The friction characteristics of the bushings, ball joints, and shock absorbers are expressed with series elastic elements such as arm rigidity and the spring constant of the oil seals. It was confirmed that the calculated values for the overall spring constant and damping coefficient of the suspension virtually matched values measured in a 4-post shaker test. In addition, the results of analysis using this dynamics model confirmed that the degree of friction affects both the damping coefficient and the spring constant of the suspension, especially when the series rigidity is high. Also highly rigid friction has an adverse effect on sprung motion in frequency ranges above 15 Hz. After suspension enhancements were adopted based on these findings, 4-post shaker tests confirmed that sprung motion above 2 Hz improved..

A new concept of an electromagnetic torque converter for hybrid electric vehicles is proposed. The electromagnetic torque converter, which is an electric system comprised of a set of double rotors and a stator, works as a high-efficiency transmission in the driving conditions of low gear ratio including a vehicle moving-off and as a starting device for an internal combustion engine. Moreover, it can be used for an electric vehicle driving as well as for a regenerative braking. In this concept, a high-efficiency drivetrain system for hybrid electric vehicles is constructed by replacing a fluid-type torque converter with the electromagnetic torque converter in the automatic transmission of a conventional vehicle. In this paper, we present the newly developed electromagnetic torque converter with a compact structure that enables mounting on a vehicle, and we evaluate its transmission efficiency by experiment.

With the goal of improving drivability, this research aimed to clarify the mechanism of vehicle longitudinal acceleration, focusing on tip-in acceleration. Conventional typical analysis methods include experimental modal and model-based analysis. However, since the former requires the measurement of impulses and other input forces while the vehicle is stopped, measurement under actual driving conditions is difficult. The latter requires characteristic values such as the stiffness and damping coefficients to be identified in advance, which cannot be achieved either easily or precisely. Therefore, this paper proposes a new experiment-based analysis method. This method enables the acquisition of engine torque and transmission torque/force by measuring only the acceleration values of some components under driving conditions.

It is important for vehicle concept planning to estimate fuel economy and the influence of vehicle vibration using virtual engine specifications and a virtual vehicle frame. In our former study, we showed the 1D physical power plant model with electrical starter, battery that can predict combustion transient torque, combustion heat energy and fuel efficiency. The simulation result agreed with measured data. For idling stop system, the noise and vibration during start up is important factor for salability of the vehicle. In this paper, as an application of the 1D physical power plant model (engine model), we will show the result of analysis that is starter shaft resonance and the effect on the engine mount vibration of restarting from idle stop. First, an engine model for 3.5L 6cyl NA engine was developed by energy-based model using VHDL-AMS. Here, VHDL-AMS is modeling language registered in IEC international standard (IEC61691-6) to realize multi physics on 1D simulation.

Current vehicle acoustic performance prediction methods, CAE (computer aided engineering) or physical testing, have some difficulty predicting interior sound in the mid-frequency range (300 to 1000 Hz). It is in this frequency range where the overall acoustic performance becomes sensitive to not only the contributions of structure-borne sources, which can be studied using traditional finite element analysis (FEA) methods, but also the contribution of airborne noise sources which increase proportional to frequency. It is in this higher frequency range (>1000 Hz) that physical testing and statistical CAE methods are traditionally used for performance studies. This paper will discuss a study that was undertaken to test the capability of a finite element modeling method that can accurately simulate air-borne noise phenomena in the mid-frequency range.

According to the U.S. National Highway Traffic Safety Administration, 743 pedal cyclists were killed and 48,000 were injured in motor vehicle crashes in 2013. As a novel active safety equipment to mitigate bicyclist crashes, bicyclist Pre-Collision Systems (PCSs) are being developed by many vehicle manufacturers. Therefore, developing equipment for evaluating bicyclist PCS is essential. This paper describes the development of a bicycle carrier for carrying the surrogate bicyclist in bicyclist PCS testing. An analysis on the United States national crash databases and videos from TASI 110 car naturalistic driving database was conducted to determine a set of most common crash scenarios, the motion speed and profile of bicycles. The bicycle carrier was designed to carry or pull the surrogate bicyclist for bicycle PCS evaluation. The carrier is a platform with a 4 wheel differential driving system.

The unsteady aerodynamic loads produced due to vehicle dynamic motions affect vehicle dynamic performance attributes such as straight-line stability or handling characteristics. To improve these dynamic performances, understanding the detailed mechanisms by which unsteady aerodynamic loads are caused during dynamic motions and the effects of unsteady aerodynamic loads on vehicle dynamic performance are needed. This paper describes the numerical study of unsteady aerodynamics of a 1/4 scale car model in dynamic pitching motion to clarify the detailed mechanisms by which unsteady aerodynamic loads are caused during the motion. Vortical structures around front wheelhouse and front under side of the body are analyzed by introducing schematic views to understand the mechanisms of unsteady flow fields. Furthermore, effects of aerodynamic devices devised based on the analyses on unsteady aerodynamics are discussed.