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We are in the context of the analysis of carbon fiber reinforced plastics (CFRP) high-pressure vessel (COPV - Composite Overwrapped Pressure Vessel) manufactured by filament winding (FW). Classically, the parameters of material models are identified based on flat laminate coupons with specific predetermined fiber orientations, and based on standards like the ones of ASTM relevant for flat coupons. CFRP manufactured by FW has a unique and complex laminate structure, which presents curvatures and ply interlacements. In practice, it is important to use coupons produced with the final manufacturing process for the parameter identification of the material models; if classical coupons produced by e.g. ply lamination are used, the effect of FW structure cannot be accounted for, and cannot be introduced in the material models. It is therefore essential to develop an approach to create representative flat coupons based on the FW process.

To help ensure that engine components are as reliable as customers need them to be, we have thus far evaluated them by establishing development target values based on market requirements, having engineers design parts to meet these requirements, then performing durability tests. These durability requirements are calculated to provide a margin of safety for use in the marketplace. However, depending on the part, these evaluation criteria can be overly aggressive against how it is used in the market, having led to a decrease in development efficiency as engine systems become more advanced. Therefore, in this study, we focused on the subject of high-cycle fatigue, which affects numerous components and is highly scalable, and built up a process for estimating the life span of components that would enable us to conduct appropriate evaluations that reflect how parts are truly used in the market.

The piston and piston ring are used in a severe contact environment in engine durability tests, which causes severe wear to the piston ring groove, leading to significant development costs for countermeasures. Conventionally, in order to ensure functional feasibility through wear on the piston top ring groove (hereinafter “ring groove”), only functional evaluations through actual engine durability testing were performed, and there was an issue in determining the limit value for the actual amount of wear itself. Because of this, the mechanism that may cause wear on the ring groove was clarified through past research, but this resulted in judgment criteria with some leeway from the perspective of functional assurance. To establish judgment criteria, it was necessary to understand both functional effect from ring groove wear and the mechanism behind it.

In recent years, an increase in vehicle weight due to the electrification of automobiles, specifically EVs, has increased the input loads on anti-vibration rubber parts. Moreover, the characteristics of these loads have also changed due to the rotational drive of electric motors, regenerative braking, and other factors. When designing a vehicle, in advance it is necessary to set specifications that take into account the spring characteristics and durability of the anti-vibration rubber parts in order to meet functional requirements. In this study, the hyperelastic and fatigue characteristics (S-N diagram and Haigh diagram) of Rubbers which is widely used for anti-vibration rubber parts, were experimentally obtained, and structural and fatigue analyses using FEM (Finite Element Method) were conducted in conjunction with spring and fatigue tests of anti-vibration rubber parts to determine the correlation between their spring and fatigue characteristics.

Fretting is a phenomenon in which a fatigue crack is initiated by a small relative slip between two objects, resulting in crack propagation and fracture at stresses far below the fatigue limit [1, 2]. Since the mechanism behind fretting is complex and covers multiple disciplines, it is not easy to develop a consistent evaluation method. In the field of engine development, fretting events can also pose an issue due to the complexity of the mechanism [3]. In particular, it has been a challenge to help predict changes in the presence and severity of fretting events, as the engine temperature fluctuates with operating conditions. As one method for evaluating fretting, Sato, et al. have made predictions using analytical models based on the finite element method (FEM) [4, 5]. However, their predictions did not take into account temperature fluctuations in the system, and they were unable to predict events in which the occurrence of fretting fatigue changed with temperature fluctuations.

Model-based Development (MBD) has been employed for engine development to reconcile the contradictory relationship between numerous functions and systems at a high level and in a short span of time. However, in actuality, as engines have become more advanced, it has become challenging to even satisfy the requirements of individual components. Moreover, reconciling multiple contradictory functions like engine power and strength and durability performance, as well as coordinating many related systems, requires an even higher level of skill. Such harmonization techniques require total optimization studies that cover a wide range of designs, and which requires several years of examination with current development processes. Multi-objective Design Exploration (MODE) methods [1] using parametric models [2] and surrogate models [3] are being used to shorten the development period and achieve more balanced designs.

Recent automobile engines are equipped with many devices that are driven by oil pressure. Generally, engine oil is used for oil pressure, and in addition to its conventional functions of lubrication and cooling, etc., it also plays an important role in accurately driving such devices. One of the factors that can interfere with the characteristics of engine oil is air contamination. Excessive air contamination can cause issues with driving devices. Although there are various factors that contribute to air contamination, this paper focuses on, and attempts to help predict, the air generated by engine oil falling and colliding with the surface of the oil in the oil pan as it returns from the top to the bottom of the engine. Using the particle method as the prediction method, the coupled Moving Particle Simulation (MPS) and Discrete Element Method (DEM) calculations were used to represent the generation of air.

This paper contributes to the Committee on Commonized Aerodynamics Automotive Testing Standards (CAATS) initiative, established by the late Gary Elfstrom. It is collaboratively compiled by automotive wind tunnel users and operators within the Subsonic Aerodynamic Testing Association (SATA). Its specific focus lies in automotive wind tunnel test techniques, encompassing both those relevant to passenger car and race car development. It is part of the comprehensive CAATS series, which addresses not only test techniques but also wind tunnel calibration, uncertainty analysis, and wind tunnel correction methods. The core objective of this paper is to furnish comprehensive guidelines for wind tunnel testing and associated techniques. It begins by elucidating the initial wind tunnel setup and vehicle arrangement within it.

Powertrain development requires an efficient development process with no rework and model-based development (MBD). In addition, to performance design that achieves low CO2 emissions is also required. Furthermore, it also demands fuel economy performance considering real-world usage conditions, and in North America, the EPA (U.S. Environmental Protection Agency) 5-cycle, which evaluates performance in a combination of various environments, is applied. This evaluation mode necessitates predicting performance while considering engine heat flow. Particularly, simulation technology that considers behavior based on engine temperature for Hybrid Electric Vehicle (HEV) is necessary. Additionally, in the development trend of vehicle aerodynamic improvement, variable devices like Active Grille Shutter (AGS) are utilized to contribute to reducing CO2 emissions.

The challenges concerning noise, vibration, and harshness (NVH) performance in the vehicle cabin have been significantly changed by the powertrain shift from a conventional drive unit with an internal-combustion engine (ICE) to electric drive units (eAxles). However, there is few research regarding the impact of electrification on NVH considering the influence of the context such as multi-stimuli and traffic rules during a real-life driving. In this study, the authors conducted test drives using EVs and ICEVs on public roads in Europe and conducted a statistical analysis of the difference in driver impression of NVH performance based on interviews during actual driving. The impression data were categorized into clusters corresponding to related phenomena or features based on driver comments. Furthermore, the vehicles data (vehicle speed, acceleration, GPS information, etc.) were recorded to associate the driver impressions with the vehicle’s conditions when the comments were made.

Emission regulations are becoming more stringent, as global temperature continues to rise due to the increasing greenhouse gases in the atmosphere. Battery electric vehicles (BEV), which have zero tailpipe emissions, are expected to become widespread to solve this problem. As the powertrain of BEV is more efficient than conventional powered vehicles, the proportion of energy loss during driving due to aerodynamic drag becomes greater. Therefore, reducing aerodynamic drag for improved energy efficiency is important to extend the pure electric range. At Honda, Computational Fluid Dynamics (CFD) and wind tunnel testing are used to optimize vehicle shape and reduce aerodynamic drag. Highly accurate CFD is essential to efficiently guide the development process towards reducing aerodynamic drag. Specifically, the prediction accuracy for the exterior shape, underfloor devices, tires, and wheels must meet development requirements.

Honda developed a new model plug-in hybrid (hereafter PHEV) system for use in new 2023 models. This system has a high degree of commonality with the 2022 model year e:HEV system. It is optimized as a PHEV system not only for long range EV Drive mode but also for Hybrid Drive mode and Engine Drive mode, and it realizes a refined, exhilarating driving experience. In terms of environmental performance, it has an all-electric range 12% higher than the previous model PHEV, and its fuel economy is improved by 14%. Its battery thermal management system that is shared with the air conditioning system provides the greatest yield of battery power and charging performance with a high market inclusion rate for driving loads and environmental conditions.

With the promotion of electrification of powertrains, development using the simulation model is being promoted to achieve highly efficient development of the powertrains. Since the hybrid powertrain includes many subsystems, the complexity of the development process bloats the development scale. To proceed with large-scale development efficiently, it is necessary to utilize simulation. Furthermore, to maximize efficiency, improvement in development speed is required. In this study, we selected the real-time technology for 1D engine model that is suitable for the concurrent development aiming at increasing the development speed. The real-time technology achieved a high prediction accuracy, a lower modeling workload, and reliable real-time computation speed. And as a practical application of this technology, we conducted collaborative development of engine and transmission using the real-time engine model.

A 3.5-L natural aspiration engine was developed to enhance the environmental performance of V6 engines to be used in Honda’s North American market. This engine changes from the single overhead cam architecture for the cylinder head found in the previous engine to a double overhead cam architecture and adopted variable timing control intake and exhaust variable cylinder management for the valve system. This increased the degree of freedom in setting valve timing across the operating range compared to the past, increased the intake air volume in the high-load range, and realized reduction of pumping loss under low and medium load. The intake port, combustion chamber, and piston shape related to combustion have been newly designed to enhance in-cylinder flow. In addition, while following the cooling structure of previous engine, water channels were installed between the exhaust valves and between the cylinder bores to enhance the cooling performance of the combustion chamber.

The implementation of enablers on a luxury sport utility vehicle is used to illustrate the development process for reduction of road noise. The vehicle in this case study was launched into production with two tuned mass dampers for reduction of low frequency road noise content which was amplified by frame modes. Additionally, resonators were integrated into the wheels (rims) to address the dominant cavity resonance frequencies. The results of this successful production implementation are illustrated herein. An RNC (road noise cancellation) system was integrated into the case vehicle to assess its performance relative to the passive enablers listed above. This production representative (embedded software solution) RNC system utilized the vehicle’s existing audio system for creation of active noise to cancel noise content which was predicted using accelerometers mounted to the vehicle chassis.

In this paper, a newly developed Active Noise Control (ANC) system is introduced, that effectively reduces road noise, which becomes a major issue with electrified vehicles, and that enhances vehicle interior sound levels matching seamless acceleration by electric drive. Conventionally, reducing road noise using ANC requires numerous sensors and speakers, as well as a processor with high computing power. Therefore, the increase in system cost and the complexity of the system are obstacles to its spread. To overcome these issues, this system is developed based on four concepts. The first is a modular system configuration with unified interface to apply to various vehicle types and grades. The second is the integration and optimal placement of noise source reference sensors to achieve both reduction in number of parts and noise reduction performance.

Honda has developed a new hybrid system targeting the C and D segments that aims for the latest environmental performance, high fuel economy, and enhanced acceleration feeling in driving. The new engine to be applied to this new hybrid system has been developed with the goal of expanding the high thermal efficiency range, realizing the latest environmental performance, and high quietness. The new engine has adopted the Atkinson cycle and cooled exhaust gas recirculation (EGR) carried over from the previous model [1], and employed an in-cylinder direct fuel injection system with fuel injection pressure of 35 MPa. The combustion chamber and ports have been newly designed to match the fuel system changes. By realizing high-speed combustion, the engine realized a high compression ratio with the mechanical compression ratio of 13.9.

With the objective of further enhancing the engine performance of the Acura brand and the environmental performance of the Honda brand in relation to the North American market, where there is a need for powertrains with driving force margin for SUVs and pickup trucks, Honda has developed a 3.0 L turbocharged engine and a 3.5 L naturally aspirated engine. Both engines adopt the same newly developed valvetrain structure and share main engine geometries. These newly developed engines are equipped with a compact new valvetrain structure combining Hydraulic Lash Adjusters and roller rocker arms with a valve-lifter based Variable Cylinder Management system which has an internalized switching mechanism. This newly developed valvetrain made it possible to incorporate dual overhead cam structure without enlarging the cylinder head shape relative to the single overhead cam structure.

In recent years, emission regulations have become stricter as part of the shift toward decarbonization. Particularly in Europe, the PN (Particulate Number) regulation has grown stricter, and further enhancement of PN filtration efficiency of GPF (Gasoline Particulate Filter) is required. However, as PN filtration efficiency is enhanced, pressure drop increases. There is a trade-off between PN filtration efficiency and pressure drop. In particular, coated GPF (cGPF) tends to deteriorate this trade-off relationship compared to uncoated GPF because of the coating of the catalyst. On the other hand, cGPFs have three-way performance, which can reduce the number of catalyst converters in the exhaust system. Therefore, we tried to establish a high performance cGPF by enhancing the trade-off relationship between PN filtration efficiency and pressure drop.

Injury assessment by using a whole-body pedestrian dummy is one of the ways to investigate pedestrian safety performance of vehicles. The authors’ group has improved the biofidelity of the lower limb and the pelvis of the mid-sized male pedestrian dummy (POLAR III) by modifying those components. This study aims to evaluate the biofidelity of the whole-body response of the modified dummy in full-scale impact tests. The pelvis, the thigh and the leg of POLAR III have been modified in a past study by optimizing their compliance by means of the installation of plastic and rubber parts, which were used for the tests. The generic buck developed for the assessment of pedestrian dummy whole-body impact response and specified in SAE J3093 was used for this study. The buck representing the geometry of a small family car is comprised of six parts: lower bumper, bumper, grille, hood edge, hood and windshield.