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Abstract Based on the characteristics of high strength and modulus of carbon fiber-reinforced composite (CFRP), in this article, the CFRP material was used to replace the steel material of the automobile’s B-pillar inner and outer plates, and the three-stage optimization design of the lamination structure was carried out. Firstly, this article used the principle of equal stiffness replacement to determine the thickness of the carbon fiber B-pillar inner and outer plates, and the structural design of the replaced B-pillar was also carried out. Secondly, on the basis of the vehicle collision model, the B-pillar subsystem model was extracted, and the material replacement and collision simulation were carried out.

Abstract The present study aims to join the dissimilar materials such as Dual-Phase (DP) 600 Steel and AA6082-T6 Aluminum (Al) alloy via the friction stir welding (FSW) process with a reduced intermetallic compound (IMC) layer. The five different tool tilt angles of 0°, 0.5°, 1°, 1.5°, and 2° were selected to fabricate the joints. The weld characteristics such as tensile strength, hardness, macrostructure, and microstructure were analyzed. The weld interface was studied by employing an optical microscope and scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) techniques. The joint produced with a 0.5° tilt angle has achieved the highest ultimate tensile strength (UTS) of 240 MPa. The IMCs were identified as Fe2Al8 and FeAl2 from the joint interface studies.

Abstract Vaporizing foil actuator welding (VFAW) created nominally solid-state spot welds between high-strength DP980 steel and 6022 T4 aluminum. The effects of varying the impact velocity and angle between the Al flyer and target steel sheets on the structure and properties of the joints were evaluated using photonic Doppler velocimetry (PDV), scanning electron microscopy (SEM), fractography, and energy-dispersive spectroscopy (EDS) analysis. The incident angle and velocity of the flyer plate were quantified using PDV, and their relations to the structure and properties of the joint were assessed with microscopy and strength testing. Impact velocity and average impact angle increase with the increasing standoff. Lower impact angles and higher impact velocities promoted interfacial failure due to increased melting, higher intermetallic thickness, and lower wave amplitude and wavelength.

Abstract Direct welding of coated steels to aluminum alloys is challenging due to high energy requirements, decreased weldability, and unstable weld quality. The present study reports the application of a new design approach in vaporizing foil actuator welding (VFAW), where an asymmetric preform shape on the target sheet generated the requisite standoff, enabling direct spot welding of a typical automotive aluminum alloy (6022 T4) and two different zinc-coated steels, galvanized high-strength low-alloy 350 and galvannealed dual-phase 590. The use of the new approach enabled for the first time the ability to spot weld through coating without any preweld surface preparation. Characterization using lap-shear and peel testing revealed strong joints for both the weld pairs (AA 6022 T4-HSLA 350 and AA 6022 T4-DP 590). The weld interface characterized by scanning electron microscopy (SEM) revealed a hierarchical structure and the presence of a typical wavy region.

Abstract The causes of failure due to cracking in the resistance spot welding of the advanced high-strength steels dual-phase 590 (DP590) were investigated using scanning electron microscopy (SEM), optical microscopy, and the tensile-shear test. The results showed that by increasing the current amount, the formation of the melting zone occurred in the heat-affected zone, leading to the cracking in this area, reducing the tensile strength and decreasing the mechanical properties; the initiation and growth of cracking and failure in this region also happened. In the heat-affected zone, by increasing the current amount with the softening phenomenon, the recrystallized coarse grains also occurred, eventually resulting in the loss of mechanical properties. The results of the tensile-shear test also indicated that by increasing the current up to 12 kA, the strength was raised, but the ductility was reduced.

Abstract Raceway Brinell damage is one major cause of wheel bearing (hub unit) noise during driving. Original Equipment Manufacturer (OEM) customers have asked continuously for its improvement to the wheel bearing supply base. Generally, raceway Brinelling in a wheel hub unit is a consequence of metallic yielding from high external loading in a severe environment usually involving a side impact to the wheel and tire. Thus, increasing the yielding strength of steel can lead to higher resistance to Brinell damage. Both the outer ring and hub based on Generation 3 (Gen. 3) wheel unit are typically manufactured using by AISI 1055 bearing quality steel (BQS); these components undergo controlled cooling to establish the core properties then case hardening via induction hardening (IH). This paper presents a modified grade of steel and its IH design that targets longer life and improves Brinell resistance developed by ILJIN AMRC (Advanced Materials Research Center).

Abstract Surface roughness is one of the important aspects in producing quality die. Wire Electrical Discharge Machine (WEDM) is commonly used in tool and die fabrication, since the die material is usually difficult to cut using traditional metal removal processes. Selection of optimal WEDM cutting parameters is crucial to obtain quality die finish. In this study, 2379 steel which equivalent to SKD 11 is selected as the die material. Four main WEDM cutting parameters, namely, pulse duration (A), pulse interval (B), servo voltage (C), ignition pulse current (D), were experimentally evaluated for both main cut and multiple trim cuts using Taguchi Method. Taguchi’s L9 orthogonal array is employed for experimental design and analysis of variance (ANOVA) was used in recognizing levels of significance of WEDM cutting parameters.

Abstract Current End-of-Life Vehicle (ELV) recycling processes are mainly based on mechanical separation techniques. These methods are designed to recycle those metals with the highest contribution in the vehicle weight such as steel, aluminum, and copper. However, a conventional vehicle uses around 50 different types of metals, some of them considered critical by the European Commission. The lack of specific recycling processes makes that these metals become downcycled in steel or aluminum or, in the worst case, end in landfills. With the aim to define several ecodesign recommendations from a raw material point of view, it is proposed to apply a thermodynamic methodology based on exergy analysis. This methodology uses an indicator called thermodynamic rarity to assess metal sustainability. It takes into account the quality of mineral commodities used in a vehicle as a function of their relative abundance in Nature and the energy intensity required to extract and process them.

Abstract New analytical structural stress solutions for a rigid inclusion in a finite square thin plate with clamping edges under opening loading conditions are developed. The new solutions are used to derive new analytical structural stress and stress intensity factor solutions for similar and dissimilar spot welds in cross-tension specimens. Three-dimensional finite element analyses are conducted to obtain the stress intensity factor solutions for similar spot welds and dissimilar magnesium/steel spot welds in cross-tension specimens of equal thickness with different ratios of half-specimen width-to-weld radius. A comparison of the analytical and computational solutions indicates that the analytical stress intensity factor solutions for similar spot welds in cross-tension specimens of equal thickness are accurate for large ratios of half-specimen width-to-weld radius.

Abstract With increased consumer demand for fuel efficient vehicles as well as more stringent greenhouse gas regulations and/or Corporate Average Fuel Economy (CAFE) standards from governments around the globe, the automotive industry, including the OEM (Original Equipment Manufacturers) and suppliers, is working diligently to innovate in all areas of vehicle design. In addition to improving aerodynamics, enhancing internal combustion engines and transmission technologies, and developing alternative fuel vehicles, mass reduction has been identified as an important strategy in future vehicle development. In this article, the development, analysis, and experiment of multi-cornered structures are presented. To achieve mass reduction, two non-traditional multi-cornered structures, with twelve- and sixteen-cornered cross-sections, were developed separately by using computer simulations.

Abstract Automotive-grade high-strength steels are galvanized for improved corrosion resistance. However, selective oxidation of alloying elements during annealing heat-treatment may influence the subsequent zinc (Zn) coating quality. The formation of internal and external oxides depends on the alloy composition, especially the Si/Mn ratio, and the oxygen potential of the annealing atmosphere. In this work, a dual-phase (DP) steel was intercritically annealed with varied fuel-to-air ratios in a direct-fired furnace and then galvanized in a Zn bath with 0.2 wt% Al. The type of internal and external oxides and the interfacial structures between the steel substrate, the Al-Fe-Zn inhibition layer, and the Zn coating were examined by using site-specific focused ion beam (FIB) and transmission electron microscopy (TEM).

Abstract Reducing a vehicle’s weight is an efficient method to reduce energy consumption. Aluminum alloy is the best material for lightweight automobiles. However, the poor formability of aluminum means that it is difficult to develop stamping dies. This study designs a suitable forming tool for aluminum fenders. A simulation and an experiment are used to analyze the formability of aluminum fenders. A theoretical calculation, experimental testing, and sampling comparison are used to verify the design. The material properties of steel and aluminum are firstly studied and compared. The results show that a traditional S-type blank die face design is not suitable for aluminum because of its low tensile strength and the potential for elongation. A relatively flat trapezoid blank die face design is proposed to smooth the variation. However, a flat die face for a trapezoidal blank limits stretching, so another design is essential to improve the formability.

Abstract In this article, forming residual stresses in cold-formed small-radius corner sections are analytically predicted with the consideration of the shift in the neutral axis and the nonlinear strain-hardened material model. The predicted forming stress results in the transverse direction show a trend of increased compressive residual stress in the outer surface and reduced tensile residual stress in the inner surface as the corner radius-to-thickness ratio increases in small-radius bends. In the longitudinal direction, there is no significant change in the residual stress values observed in the inner and outer surfaces with respect to an increase in corner radius-to-thickness ratios. But a considerable decrease in compressive residual stress and an increase in tensile stress values are observed in the midsection areas with an increase in the corner radius-to-thickness ratio.

Abstract The use of Abrasive Water Jet (AWJ) cutting technology can improve the edge stretchability in sheet metal forming. The advances in technology have allowed significant increases in working speeds and pressures, reducing the AWJ operation cost. The main objective of this work was to determine the effect of selected AWJ cutting parameters on the Hole Expansion Ratio (HER) for a DP800 (Dual-Phase) Advanced High-Strength Steel (AHSS) with s0 = 1.2 mm by using a fractional factorial design of experiments for the Hole Expansion Tests (HET). Additionally, the surface roughness and residual stresses were measured on the holes looking for a possible relation between them and the measured HER. A deep drawing quality steel DC06 with s0 = 1.0 mm was used for reference. The fracture occurrence was captured by high-speed cameras and by Acoustic Emissions (AE) in order to compare both methods.

Abstract This article presents the application of the Enhanced Sequence Diagram (ESD) for the analysis of the functionality of a system with shape-changing aspects in the context of its multiple operational modes, considering an active real spoiler as a case study. The article provides new insights on the ESD support for model-based capture and articulation of functional requirements across multiple operation modes of the same system, with appropriate detail on attributes and metrics, and the alignment of these attributes and metrics in line with the concept of time through scope lines. The article also provides a comprehensive argument and discussion, exemplified based on the case study, for the support that the ESD provides for early systems functional and architecture analysis, within the context of a broader model-based Failure Mode Analysis methodology.

Abstract Identifying and eliminating failure scenarios is critical in the development of autonomous vehicle (AV) systems. However, finding such failures through real-world vehicle-level testing is a difficult task as system disengagements and accidents are rare occurrences. Simulation approaches have been proposed to supplement vehicle-level testing and reduce the costs associated with operating large fleets of autonomous test vehicles. While one can run more vehicles in simulation than in the real world, applying traditional Monte Carlo sampling techniques to find failures still yields an unguided search and a large waste of computing resources. A more directed method than random sampling is needed to identify failure scenarios in a computationally efficient manner. Adaptive Stress Testing (AST) is a method that uses reinforcement learning (RL) paradigms to efficiently find failure scenarios in stochastic sequential decision-making systems.

Abstract TOC

Abstract Reducing the weight of automotive components is one of the most achievable solutions for lowering the transport carbon footprint. This is the reason for the rapid increase over the last few years in the replacement of conventional alloys (i.e., steel and cast iron) with low-density materials (i.e., aluminum alloys, composites) and in the redesign of components shape in order to remove the unnecessary material (e.g., related to the introduction of additive manufacturing or high-strength materials). Despite this general trend, the use of higher-density metals and massive geometries is still predominant in the production of structural components, especially for heavy vehicles and safety-relevant parts. Aim of the present review is to summarize how this current situation can be overcome. The analysis started with an investigation about the materials that can be used for the production of structural parts, the potential reduction of the component weight and its costs.

Abstract Heat-affected zone (HAZ) softening occurs during the laser welding of many Advanced High-Strength Steels (AHSS) that are used for body-in-white (BIW) of automobiles, leading to degradation in the mechanical properties of the welded joints. The microstructure and mechanical properties of dissimilar laser-welded AHSS comprising of as-received 22MnB5 with dual-phase (DP) steels (DP600, DP800, and DP 1000) were investigated in this study. Welds were made at welding speeds ranging from 1 m/min to 3 m/min. Irrespective of welding speed, the DP600-22MnB5 joints fractured in the base metal (BM) of 22MnB5 during tensile tests. Likewise, welded joints of DP800-22MnB5 and DP1000-22MnB5 made at 1 m/min and 2 m/min failed in the BM; however, at 3 m/min the failure location of these joints shifted to the fusion zone (FZ). The fractured surfaces of all the welded combinations were characterized by optical and scanning electron microscopy (SEM).

Abstract Powder metallurgy is a widely used manufacturing methodology in the gearbox industry. Noise and vibration is a common cause for concern in the gearbox industry due to the continuous contact between gear teeth at high rotational frequencies. Despite this, limited research has been performed investigating the modal properties of powder metal products. This work investigates the damping ratios of a copper-infiltrated steel powder metal ring and a hot-rolled steel ring both experimentally and computationally. Negligible difference was observed between the damping ratios of the powder metal and hot-rolled steel rings. Two proportional damping models were investigated to predict the damping ratios of the powder metal ring. It was found that the Caughey damping model was the most accurate, generating damping ratios within 2.36% for a frequency bandwidth of up to 4000 Hz.