The electrochemical pseudo-two dimensional (P2D) model is one of the most promising approaches that provide suitable physical depth at reasonable computational costs for the simulation of lithium-ion batteries. The parameterization of the P2D model plays an important role as it decides about the acceptance and application range of subsequent simulation studies. Electrical impedance spectroscopy (EIS) is commonly applied to characterize the batteries and to obtain the exchange current density and the electrode diffusion coefficient of a given electrode material. EIS measurements performed with frequencies ranging from 1 MHz down to 10mHz typically do not cover clearly isolated solid state diffusion processes of lithium-ions in positive or negative electrode materials. To extend the frequency range down to 10µHz, the distribution relaxation times (DRT) is a sound analysis method.
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: Vehicle weight reduction is a popular research topic in automobile industry to achieve high efficiency and cost-effectiveness vehicles. Self-piercing rivets (SPR) are one of important joining approaches in light weight vehicle design. Numerical simulation of the riveting process could significantly boost design efficiency by reducing trial-and-error experiments. The traditional Finite Element Method (FEM) with element erosion cannot capture the large plastic deformation and complex failure behaviors in SPR process. Smoothed Particle Galerkin Method (SPG) is a genuine meshless method which is established basing on Galerkin weak form. SPG method uses a novel bond-based failure mechanism to keep the conservation of mass and momentum during material failure process. In this study, a combined FEM and Smoothed Particle Galerkin (SPG) approach was utilized to join sheet Aluminum 5754 and Cast aluminum Aural-2 using a full three-dimensional (3D) model in LS-DYNA/explicit.
Automotive body structures are being increasingly made in multi-material system consisting of steel, aluminum (Al) and fiber-reinforced plastics (FRP). Therefore, many joining tech-niques such as self-piercing riveting (SPR) and adhesive bonding have been developed. On the other hand, OEMs want to minimize the number of joining techniques to reduce the manufacturing complexity. Amount all joining methods, resistance Spot welding (RSW) is the most advanced and cost-effective one for body-in-white. However, RSW cannot be applied for joining dissimilar materials. Therefore, a novel Rivet Resistance Spot Welding method (RRSW) was developed in which Al or FRP Components can be directly welded to steel structures with existing welding systems. RRSW uses rivet-like steel elements as a welding adapter which are formed into Al or FRP components dur-ing their forming process. After that, they are welded to the steel components by RSW. This paper shows at first the results on Steel – Al RRSW.
The microstructure and mechanical properties of the Al-Si-Mg alloy with bulk and lattice structure produced by Laser-powder bed fusion additive manufacturing were systematically investigated. And then, the microstructure behavior of Al-Si-Mg alloys according to As-built and heat treatment was closely analyzed. Firstly, through grain size analysis, the cause of mechanical properties higher than casting materials and similar to forging materials could be analyzed. Secondly, mechanical changes according to the Mg2Si reinforced phase and cell-wall morphology after heat treatment were investigated. The Al-Si-Mg bulk and lattice structures are composed of a cell structure consisting of α-Al and eutectic Si. With heat treatment, needle-shape Mg2Si precipitates in the α-Al matrix. Simultaneously, collapse of the cell-wall morphology occurs.
Vibrations constitute a pivotal factor affecting passenger comfort and overall vehicle performance in both Conventional Internal Combustion Engine (ICE) vehicles and Electric Vehicles (EVs). These vibrations emanate from various sources, including vehicle design and construction, road conditions, and driving patterns, thereby leading to passenger discomfort and fatigue. In the pursuit of mitigating these issues, natural fibers, known for their exceptional damping properties, have emerged as innovative materials for integration into the automotive industry. Notably, these natural fiber-based materials offer a cost-effective alternative to traditional materials for vibration reduction. This research focuses on evaluating natural fibers mainly hemp, banana and cotton fibers for their damping characteristics when applied to a steel plate commonly used in the automotive sector.
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.
Options for CNVII emission legislation are being widely investigated in a national program organized by China Vehicle Emission Control Center (VECC) since early 2020. It is foreseen that this possibly last legislation in China will have more stringent emission requirements compared to CNVI, including further reduction of nitrogen oxide (NOx), inclusion of nitrous oxide (N2O) and sub-23 nm particle number (PN) and etc. This study investigates the technical feasibility to fulfill a CNVII emission legislation scenario, based on a modified CNVI 8 L engine operating under both cold and hot World Harmonized Transient Cycle (WHTC) and Low Load Cycle (LLC). Methods to address the challenges are discussed and validated, including a twin dosing system, electric heater, hybrid concept of combining Copper (Cu-), Iron (Fe-) and Vanadium (V-) SCR technologies, high filtration DPF and optimization of engine calibration and urea dosing strategies.
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.
Austenitic stainless steel (1.4837Nb) is widely used for turbo housing and other components which are subjected to elevated temperature conditions. Due to assembly constraints, geometry limitation, and particularly high temperatures, thermomechanical fatigue (TMF) issue is commonly seen in the service of the components. Therefore, it is critical to understand the TMF behavior of the steel. In the present study, a series of fatigue tests including isothermal low cycle fatigue (LCF) test at elevated temperatures up to 1000°C, in-phase and out-of-phase TMF tests in different temperature ranges have been conducted. Both creep and oxidation are active in these conditions, and their contributions to the damage of the steel are evaluated. A Chaboche viscoplasticity model for constitutive simulation, and a DTMF damage model for life prediction are developed and validated at specimen level.
Aluminum alloy has become an indispensable part of the automotive industry because of its excellent mechanical properties such as lightweight, high strength, high reliability, maintainability, and low cost. Aluminum alloy is used in automobiles, such as engine blocks, cylinder heads, intake manifolds, brake components, and fuel tanks. Fatigue and fracture are the main reasons for its engineering failure. Surface strengthening techniques, such as ultrasonic shot peening (USP), are often used to improve the fatigue resistance of aluminum alloys. This article expounds on the working principle of ultrasonic shot peening and elucidates the influence of USP process parameters on the surface characteristics of aluminum alloy. Experimental results observed the effects of USP parameters on surface properties such as surface roughness, microhardness, and surface morphology.
The design of lightweight vehicle structure has become a common method for automotive manufacturers to increase fuel efficiency and decrease carbon emission of their products. By using aluminum instead of steel, manufacturers can reduce the weight of a vehicle while still maintaining the required strength and stiffness. Body panels are an area in which automotive designers are using aluminum to lightweight their vehicles. Resistance Spot Welding (RSW) is used extensively to join steel body panels but presents challenges for aluminum. When compared to steel, RSW of aluminum requires frequent electrode cleaning, higher energy usage, and more controlled welding parameters, which has driven up the cost of manufacturing. Due to the increased cost associated with RSW of aluminum, Refill Friction Stir Spot Welding (RFSSW) is being considered as an alternative to RSW for joining aluminum body panels.
As data science technologies are being widely applied on various industries, an importance of data itself increased. A typical manufacturer company has a vast data of products as 3D format but a common problem was that building a database from the 3D data costs much and it is hard to update the database after building by new products developed. In this paper, an automated database building method using CATIA and future probabilities are suggested. An aluminum wheel part was used as an example. An automated logic for extracting design shape features was used and data mining process deployed based on the extracted data. CNN and Auto-Encoder models were used for wheel weight regression and searching similarity in z-space. By using the method of this paper, establishing and analyzing database efficiently were possible with low cost.
Fracture characterization of automotive metals under simple shear deformation is critical for the calibration of advanced fracture models employed in forming and crash simulations. Great strides in shear fracture characterization have been made over the past decade with several novel geometries proposed. However, in-plane shear tests of high ductility materials have proved challenging since the edge fails first in uniaxial tension before the shear fracture limit is reached in the center of the sample. Although through-thickness machining is undesirable, particularly for extrusions and castings, it appears required to promote higher strains within the shear zone to avoid edge cracking in materials where the shear fracture limit significantly exceeds that of uniaxial tension. The objective of the present study is to adapt existing in-plane shear geometries, which have otherwise been successful for many automotive materials, to have a local shear zone with a reduced thickness.
High cycle fatigue (HCF) S-N curves of steels are often requested by customers for direct evaluation of the products' durability or as an input to their CAE for design purpose. It has been found that the existing models for S-N data resulting HCF test might have difficulties in properly depicting the entire spectrum of fatigue lives. To overcome these difficulties, a new equation has been developed based on the relationship between the behaviors of short and long fatigue lives. The new equation was applied to model S-N data resulting from recent HCF testing of several steels and was compared with the 3 existing popular models. The comparison in the preliminary validations indicated that the new equation has high potential for application in more accurate S-N data modeling and fatigue limit prediction.
At the dawn of battery electric vehicles (BEVs), protection of automotive battery systems as well as passengers, especially from severe side impact, has become one of the latest and most challenging topics in the BEV crashworthiness designs. Accordingly, two material-selection concepts are being justified by the automotive industry: either heavy-gauge extruded aluminum alloys or light-gauge advanced high-strength steels (AHSSs) shall be the optimal materials to fabricate the reinforcement structures to satisfy both the safety and lightweight requirements. In the meantime, such a justification also motivated an ongoing C-STARTM (Cliffs Steel Tube as Reinforcement) Protection project, in which the all-AHSS(s) reinforcement beams, essentially a series of modularized steel tube assemblies, were demonstrated both experimentally and virtually to be more cost-efficient, sustainable, design-flexible, and manufacturable than the equivalent extruded aluminum alloy beams.
Upcoming, increasingly stringent greenhouse gas as well as emission limits demand for powertrain electrification throughout all vehicle applications. Increasing complexity of electrified powertrain architectures require an overall system approach combining modular component technology with integration and industrialization requirements when heading for further significant efficiency optimization. At the same time focus on reduced development time, product cost and minimized additional investment demand reuse of current production, machining, and assembly facilities as far as possible. Up to date additive manufacturing (AM) is an established prototype component, as well as tooling technology in the powertrain development process, accelerating procurement time and cost, as well as allowing to validate a significantly increased number of variants. The production applications of optimized, dedicated AM-based component design however are still limited.
This research focuses on the commercial 6111 aluminum alloy as the subject of investigation. By designing tensile specimens with the same characteristic dimensions but varying fillet radii, the effects of fillet radius on the tensile properties and stress concentration effects of the aluminum alloy were studied through tensile testing and digital image correlation techniques. The results demonstrate that with an increase in fillet radius, the failure strength and stress distribution of the aluminum alloy specimens have both undergone alteration. This phenomenon can be attributed to the reduction of stress concentration at the fillet due to the larger fillet radius. Further verification through digital image correlation reaffirms that samples with a fillet radius of 10mm exhibit notable stress concentration effects at the fillet, while specimens with a fillet radius increased to 40mm display uniform plastic deformation across the parallel section.