Vehicle cybersecurity vulnerabilities could impact a vehicle's safe operation. Therefore, engineers should ensure that systems are designed free of unreasonable risks to motor vehicle safety, including those that may result due to existence of potential cybersecurity vulnerabilities. The automotive industry is making vehicle cybersecurity an organizational priority.
This 2-day foundational-level course builds on geometric dimensioning and tolerancing fundamentals and teaches an introduction of how to inspect GD&T requirements. The course offers an explanation of the geometric symbols, rules, and concepts, the datum system, and how to inspect GD&T requirements using tools from the four categories of inspection tools (CMM; comparison instruments and fixed gages; hand tools and open set up; and production gaging systems).
Thermal management of battery packs is essential to keep the cell temperatures within safe operating limits at all times and, hence, ensure the healthy functioning of an EV. The life cycle of a cell is largely influenced by its operating temperature, maintaining the cell temperature in its optimum range improves its longevity by decreasing its capacity fade rate and in turn extending the life of an EV. Liquid cooling techniques have proven to be cost-effective compared to other techniques such as air cooling, PCM-based in terms of performance in the given volumetric constraints. The battery thermal management solution being presented employs a tabbed type liquid cooling technology that achieves low-temperature differentials for an in-house designed battery pack consisting of 320 LFP cells (Size: 32700) with a total voltage and capacity of 27V and 240Ah respectively. Thermal design of the battery pack considers maximum dissipation when continuously operating at 1C-rate conditions.
Slot liners are commonly used in electric motors to electrically insulate the motor windings from the laminated core. However, thermal conductivity of materials commonly used as slot liners is very low compared to other components in the motor thus creating a barrier for heat transfer. This thermal barrier affects overall motor performance and efficiency. Also, slot liners typically lack intimate contact with the laminated core resulting in air gaps which further increase thermal resistance in the system. Slot liners are traditionally made from high temperature films/papers that are cut and slid into slots of motors. The proposed work looks at developing an injection moldable slot liner to minimize air gaps. Additionally, use of TECI materials further lowers thermal resistance. A thermal finite element model has been developed to evaluate effects of slot liner thermal properties and air gaps on temperature distribution within the motor.
Performance evaluation of martensitic press-hardened steels by VDA 238-100 three-point bend testing has become commonplace. Significant influences on bending performance exist from both surface considerations related to both decarburization and substrate-coating interaction and base martensitic steel considerations such as structural heterogeneity, i.e., banding, prior austenite grain size, titanium nitride (TiN) dispersion, mobile hydrogen, and the extent of martensite tempering as result auto-tempering upon quenching or paint baking during vehicle manufacturing. Deconvolution of such effects is challenging in practice, but it is increasingly accepted that surface considerations play an outsized role in bending performance. For specified surface conditions, however, the base steel microstructure can greatly influence bending performance and associated crash ductility to meet safety and mass-efficiency targets.
The importance of true fracture strain was initially highlighted in the context of local versus global formability considerations used in material selection among advanced high strength steels (AHSSs) of similar tensile strength. Inspired by the relative studies, a precedent work had compared the discrepant fracture strain results from the digital image correlation (DIC) and the optical measurement techniques. This work further investigated various factors, such as the measurement techniques, the effective strain formula, and the fracture surface morphology, which could affect the true fracture strain measurement and derivation results, and subsequently the calibration of the Generalized Incremental Stress State dependent damage Model (GISSMO) used in crash simulations. In the meantime, explanations and discussions on the possible mechanisms behind these effects were also presented.
A low carbon, lean alloyed chemistry was selected for the development of high strength dual phase (DP) steels with enhanced global and local formability. Optimized best process conditions including clean steel practices, choice of suitable casting powder, hot rolling and continuous anneal set points resulted in excellent mechanical properties and formability characteristics of DP steels. The enhanced balance of strength and formability is attributed to the optimization of the microstructure through refinement, uniformity and balancing microconstituents mechanical response and guaranteeing outstanding internal cleanliness. In this contribution, production strategy and formability characterization of DP steels with tensile strengths of 780 MPa and above relevant to automotive body structure applications will be discussed.
Limited room temperature formability hinders the wide-spread use of high strength aluminum alloys in structural body-in-white parts. Stamping or extrusion at warm temperatures or from softer tempers are the current solutions. In this work, our approach is to start with age- and work-hardened sheets from 7xxx, 6xxx, and 5xxx family of alloys and improve their formability using local thermomechanical processing only in the regions demanding highest ductility in the forming processes. The processes used were friction stir processing (FSP) and roller bending-unbending. In both the methods sheets were locally deformed and heated simultaneously without any change in the final sheet geometry or chemistry. Initial results indicated significant deformation in the processed zones with minimal sheet distortion. FSP also resulted in dynamically recrystallized, fine grained (d <5 µm) microstructures in the processed regions with textures significantly different from the base material.
Plane strain test specimens used for the constitutive characterization of automotive sheets are typically limited to low strains levels due to the onset of necking and fracture at the specimen edges in uniaxial tension. In contrast, notched plane strain tensile tests for fracture characterization are commonly used for the calibration of stress-state dependent fracture models and possess strong stress and strain gradients to avoid failure in uniaxial tension at the edges. Inverse finite-element analysis can be used to exploit the stress gradients in the notch test to calibrate the local arc of the anisotropic yield surface from uniaxial-to-plane strain tension. However, the principal stress directions across the width are not constant due to the notch geometry and can be influenced by the tensile properties in the other directions leading to non-unique solutions in the inverse analysis.