The increasing awareness on the harmful effects on the environment of traditional Internal Combustion Engines (ICE) is driving the industry toward cleaner powertrain technologies such as battery-driven Electric Vehicles. Nonetheless, the high energy density of Li-Ion batteries can cause strong exothermic reactions under certain conditions that can lead to catastrophic results, called Thermal Runaway (TR). Hence, a strong effort is being placed on understanding this phenomena and increase battery safety. Specifically, the vented gases and their ignition can cause the propagation of this phenomenon to adjancent batteries in a pack. In this work, Computational Fluid Dynamics (CFD) are employed to predict this venting process in a LG18650 cylindrical battery. The ejection of the generated gases was considered to analyze its dispersion in the surrounding volume through a Reynolds-Averaged Navier-Stokes (RANS) approach.
Churning loss is an important energy loss term for rolling bearings at high speed condition. However, it is quite challenging to accurately calculate the churning loss. A CFD study based on unsteady Reynolds-Averaged-Navier-Stokes that resolves the gas-liquid interface was performed to examine the unsteady multiphase flow in a roller/ball bearing. In this study, the rotating motion of the cage, races, rollers/balls about the shaft as well as self-rotation of rollers/balls about their own axis were accounted to accurately predict the oil distribution in various parts of the bearings. A novel meshing strategy is presented to resolve thin gaps between the roller/balls and the races/cage while preserving the shape of balls/rollers, races and cage. Seven and five rotational speeds of the shaft have been examined for roller bearing and ball bearing respectively.
In the field of automotive aerodynamics, there's a consistent need for tools that effectively manage both rapid design changes and comprehensive simulations. The recent GPU code update to the PowerFLOW, Lattice Boltzmann simulation tool is an attempt to meet this need. An important feature of this update is the inclusion of the Sliding Mesh rotating reference frame, which improves rim modeling accuracy. This modification provides a clearer depiction of vehicle aerodynamics, aiming for balanced and efficient designs. The updated GPU solver has been tested with two main resolutions. First, a low-resolution aerodynamics scheme which can assist designers and stylists in their initial stages of design. This setup aims to offer a rapid iterative design process. In addition, for more detailed analysis, full-scale resolution simulation setups are possible with the NVIDIA A100's 80GB memory capacity.
The passive pre-chamber is valued for its jet ignition and is widely used in the field of gasoline direct injection (GDI) for small passenger cars, which can improve the performance of lean combustion. However, the scavenging and ignition combustion stability of the engine at low speed is a shortcoming that has not been overcome. Simply changing the structural design to increase the fluidity of MC and PC may lead to a reduction in jet ignition performance, which in turn will affect engine dynamics. This investigation is based on a non-uniformly nozzles distributed passive pre-chamber, which is adjusted according to the working fluid exchange between PC and MC. The advantages and disadvantages of the ignition mode of PC and SI in the target engine speed range are compared through optical experiments on a small single cylinder GDI engine. The results show that with the increase of λ from 1.0 to 1.6, the promotion effect of PCJI on load performance gradually decreases.
An advanced multi-layer material model has been developed to simulate the complex behavior in case-carburized gears where hardness dependent strength and elastic-plastic behavior is characterized. Also, an advanced fatigue model has been calibrated to material fatigue tests over a wide range of conditions and implemented in FEMFAT software for root bending fatigue life prediction in differential gears. An FEA model of a differential is setup to simulate the rolling contact and transient stresses occurring within the differential gears. Gear root bending fatigue life is predicted using the calculated stresses and the FEMFAT fatigue model. A specialized rig test is set up and used to measure the fatigue life of the differential over a range of load conditions. Root bending fatigue life predictions are shown to correlate very well with the measured fatigue life in the rig test.
Considering that the 315 V battery may be damaged in actual use of the vehicle or the battery cannot be charged and discharged normally in a low temperature environment, this paper proposes a new "voltage control" mode and analyzes the working state of the entire vehicle under the abnormal condition of the high-voltage battery of the micro-mixing system. In order to ensure that the vehicle can still run like a traditional car under such circumstances, the paper also proposes a new "voltage control" mode. At this time, the generator is no longer in the conventional torque control mode, but in the voltage control mode. At this time, the control variable of the controller is "voltage", the working mode switching of the motor is controlled by HCU, the target voltage command is issued by HCU, the value of the target voltage can be calibrated through actual test, and the motor responds to the target voltage in real time during the system operation.
Side doors are pivotal components of any vehicle, not only for their aesthetic and safety aspects but also due to their direct interaction with customers. Therefore, ensuring good structural performance of side doors is crucial, especially under various loading conditions during vehicle use. Among the vital performance criteria for door design, torsional stiffness plays an important role in ensuring an adequate life cycle. This paper focuses on investigating the impact of several door structural parameters on the torsional stiffness of side doors. These parameters include the positioning of the latch, the number of hinge mounting points on doors (single or double bolt), and the design of inner panel with or without Tailor Welded Blank (TWB) construction.
A lot of parts about 20,000 to 40,000 are composed of a car. When developing new car, design, manufacturing, cost, quality control and etc. are reviewed for these parts. In order to develop parts with low price and high quality, various factors such as design, manufacturing and cost need to optimize specifications for each part in development stage. In particular, this optimization is most effective when it is done at the design stage. A comprehensive review should be made based on various information such as design, manufacturing and cost for each component to optimize these specifications. However, the information is managed separately by each development department, so access to the information is limited. In addition, there are many inefficiencies in generating, searching, analyzing and processing the information.
Mo free 1.6GPa bolt was developed for The Variable Compression Turbo (VC-Turbo) engine, which is effective for environmental friendliness and improving fuel efficiency and output. Mo contributes not only to the improvement of temper softening resistance, but also the improvement of delayed fracture resistance by precipitating fine carbides during high-temperature tempering and effecting as trap sites for hydrogen, so the main issue is to achieve both high strength and delayed fracture resistance. Therefore, developed steel is added Si to improve tempering softening resistance and achieve a microstructure superior to delayed fracture resistance to achieve both high strength and delayed fracture resistance. The delayed fracture test was done by Hc/He method. Hc means the limit of the diffusible hydrogen contents without causing delayed fracture under tightening, and He means diffusible hydrogen contents entering under the hydrogen charging condition equivalent to actual environment.
Abstract: Rubber mount as an important element can reduce the vibration transmitted by the engine to the frame. And under small and medium deformation conditions, Mooney-Rivlin model can well describe the mechanical properties of the rubber mount. The accurate parameters of Mooney-Rivlin model is the basis of describing the mechanical properties of the mount. First, taking powertrain rubber mount as the research object, the influence of preload on the static characteristics of the mount is studied by the preload test rig. Second, Particle swarm optimization-Backpropagation neural network (PSO-BPNN) model and Backpropagation neural network (BPNN) model was established. After the number and step length of hidden layer neurons were determined, the prediction accuracy of the two models is compared.
Unlike conventional heat shrink tubes or enclosure systems which only seals wires and splices on the outside, a novel Acrylate based sealing technology developed and introduced by Eurotech is a very low viscosity fluid formulated to be applied to the splices either in droplets or by dipping, utilizes fast capillary-wicking action and quick self-cure inside the wires to form a robust, cost effective, flexible, impenetrable seal to prevent moisture damage of wire harnesses and associated components. This technology is an enabler of new wire harness architectures currently limited by the shortcomings of conventional sealing products such as heat shrink tubes which come up short when the splice configurations or geometries become too complex or difficult for sealing from the outside.
Fiber-reinforced plastics (FRPs), produced through injection molding, are increasingly preferred over steel in automotive applications due to their lightweight, moldability, and excellent physical properties. However, the expanding use of FRPs in diverse automotive components presents a critical challenge: deformation stability. The occurrence of warping significantly compromises the initial product quality due to challenges in component mounting and interference with surrounding parts. Consequently, addressing warping in fiber-reinforced plastic-based injection parts is paramount for achieving high-quality parts. In this study, we present a comprehensive approach to address warpage issues in injection-molded components using FRPs. We employed a systematic Design of Experiments (DOE) methodology to optimize materials, processes, and equipment, with a focus on reducing warpage, particularly for the exterior part of a delivery EV.
The inverter of the Electrical Driven Compressor (EDC) is subjected to high thermal loads which are resulting from external temperature exposure and from compressor solicitations from the vehicle thermal loop (refrigerant nature, flow rate, compression rate, initial temperature). An incorrect thermal management of the inverter might lead to a significant decrease of efficiency which degrades the performance of the product, huge decrease in the product lifetime (electronics components failure) and even worse, might lead to a Hazardous Thermal Event. The need of the Automotive market to drastically decrease project development time, requires decreasing design and simulation activities lead time without degrading the design robustness, which is one additional complexity and challenge for the R&D team.
The study focuses on understanding the air and oil flow characteristics within a ball bearing during high-speed rotation, with a particular emphasis on optimizing frictional heat dissipation and oil lubrication methods. Computational fluid dynamics (CFD) techniques are employed to analyze the intricate three-dimensional airflow and oil flow patterns induced by the motion of rotating and orbiting balls within the bearing. A significant challenge in conducting three-dimensional CFD studies lies in effectively resolving the extremely thin gaps existing between the balls, races, and cages within the bearing assembly. In this research, we adopt the ball-bearing structured meshing strategy offered by Simerics MP+ to meticulously address these micron-level clearances, while also accommodating the rolling and rotation of individual balls. Furthermore, we investigate the impact of different designs of the lubrication ports to channel oil to other locations compared to the ball bearings.
Optimized Tapered Roller Bearing Powerloss Equal to Deep Groove Ball Bearings in Real-World Electric Vehicle Intermediate Shaft Tests One often reported roadblock to consumer acceptance of electric vehicles is driving range, which is a function of powertrain efficiency and vehicle mass. Electric vehicle gearbox design often is based on multiple parallel shafts, which creates significant packaging constraints. Industry perception holds that DGBB are more efficient than TRB, and standard spin-loss testing confirms those beliefs. However, spin-loss efficiency testing does not accurately reproduce typical real-world driving. A more realistic comparison of bearing efficiency is required to properly select bearings during the powertrain design stage. Recently completed testing was focused on recreating application conditions for electric vehicle gearbox intermediate shafts, including bearing loads, speeds and load zones.
The study and application of Topology Optimization (TO) has experienced great maturity in recent years, presenting itself as a highly influential and sought-after design tool in both the automotive and aerospace industries. TO has experienced development from single material topology optimization (SMTO) to multi-material topology optimization (MMTO), where material selection is simultaneously optimized with material existence. Today, MMTO for standard structural optimization responses are well supported. An additional and vital response in the design of structures is that of stress. Stress-driven or stress-controlled optimization techniques for SMTO are well understood and have been well-documented, evidenced by both published works and its availability in multiple commercial solvers. However, its integration into MMTO frameworks has not yet achieved reliable levels of accuracy and flexibility.
Hot-rolled AHSS grades are utilized in automotive parts where high formability is required. However, these grades can fail below their predicted formability limit due to edge cracking. Microstructure and sheared-edge face quality contribute to the initiation of micro-cracks that lead to edge cracking. While it is established that strain incompatibilities between phases and micro-constituents with differing hardness promote edge cracking, microstructural properties governing edge ductility are not fully understood. The edge ductility of eight hot-rolled automotive AHSS grades with tensile strengths of 600 and 800 MPa, achieved with single- or multi-phase microstructures, are being investigated. The experimental and structural single-phase grades include microstructures comprised of ferritic matrices with composite micro-alloyed nano-precipitates and cementite micro-constituents.
Model-based development is being introduced to shorten the development time of vehicle systems. Various model-based tools, including MATLAB/Simulink, have been introduced, and each vehicle part has model assets using different tools. This makes the system complex and reduces simulation efficiency because of the need for interfaces or converters when reusing model assets and combining parts. On the other hand, machine learning, in which neural nets are pre-trained to make inferences in real-time, is being applied to automatic driving and other applications, such as object recognition. This study constructed a system in which inputs and outputs given to a model are trained by neural nets, and the trained neural nets are combined on UML. A previous UML integration proposal is integrated C/C++ codes which are automatically generated from models. For this reason, the previous proposal had limited use of modeling tools with automatic code generation capabilities.
As part of the development of its new powertrain consisting of two electric motors, a combustion engine and a gearbox, Renault SAS followed an original approach to achieve an assembly with an optimized, robust, and reliable link between the main electric motor and the gearbox. The running operation optimization as well as the high reliability is achieved by processing the following topics: filtration of vibrations and operating jolts; solving of tribological problems specific to splined connections, such as fretting corrosion and abrasive tooth wear; avoidance of potential seizure of elements with cyclic relative slippage under load; and eventually, control of wear and tear on the sealing and damping O-rings, which must accept oscillating translational movements at the same time as torque transfer. The aim of this article is to retrace the main steps taken to achieve the desired reliability and performance targets for this type of product.