The application of high performance steels in combination with rolled profiles, hydro-formed or tailored tubes (TT) can create a stiffer and safer vehicle structure. However, it presents some ...challenges regarding the joining process, once accessibility to both sides of the surface to be joined is limited. The Single-Sided Spot Welding (SSSW) is an alternative to Resistance Spot Welding (RSW), as it only requires access to just one side of the joint to weld it. In order to validate SSSW as a robust and reliable welding process for automotive manufacturing, this work encompassed experiments comparing SSSW and RSW under manufacturing conditions and tolerance problems, such as sheets and electrode misalignment, gaps or shunt current conditions, using DX54D steel sheets, and steel profiles made of press-hardened 22MnB5 and S355J2 + N. The experimental parameters in this study were current, electrode force, geometry and misalignment angle. The performed tests were lap shear tensile strength, analyses of weld nugget quality and the measurement of spot diameters by chisel testing. The obtained results show that SSSW can meet RSW requirements regarding mechanical properties and quality standards, overcoming the set manufacturing tolerance issues, without reducing the spot diameter and with similar mechanical properties of RSW joints.
Duplex stainless steel is an ideal candidate in the automotive sector leading to a significant weight reduction and enhancement in product safety. In the present work, two major influencing process ...parameters i.e. welding current and welding time have been considered to investigate the mechanical and metallurgical performance of resistance spot welded duplex stainless steel. Other important process parameters, such as electrode force, squeeze time and hold time have been kept constant throughout the process. Results show that tensile shear strength (TSS) increases with an increase in welding current as well as welding time due to more amount of heat generation at interface. However, excessive value of both results in the expulsion of weld material which significantly alters the nugget diameter and cause decrease in TSS. Moreover, the failure mode is changed from interfacial failure (IF) mode to pull-out failure (PF) mode at the higher value of welding current and time. Microstructural observation reveals that the fusion zone (FZ) is consisted of columnar grain structure, whereas heat affected zone (HAZ) contains equiaxed grain structure. Furthermore, the phase balance of austenite and ferrite is completely disturbed in the FZ and HAZ.
The recent increase in electric vehicle (EV) growth influencing the need for dedicated EV platform development work among vehicle manufacturers. The EV Platform is an aggregation of sheet metal ...components, battery pack and electric powertrain components. The platform architecture influences design, development and integration of battery pack into vehicle and the lead time for new product development and Time to Market (TTM). This article discusses the evolution of conventional Body in White (BIW) to flexible modular skateboard platforms in EV segments and how it influences the battery pack integration. It discusses the benefits and challenges in the platform workstream and how automakers are preparing for a shift from conventional Internal Combustion Engine (ICE) derivative platform to native EV platform to take advantages in policy decisions and scale benefits on the overall EV ecosystem.
The paper proposes and metrologically characterizes a gap and flushness optical measurement system based on machine vision. The system is developed for an operator-free application as a plug-and-play ...feature for articulated robotic arms. The system is designed for use in Stop-and-Go quality control point of vehicle assembly process. Non-contact measurement system that consists of an ultraviolet line laser with a sensitive camera and complemented with an advanced machine vision measurement algorithm is developed. The system is directly calibrated according to state-of-the-art literature and the measurement uncertainty within the laboratory conditions is derived according to Guide to the Expression of Uncertainty in Measurement. Measurements on the real vehicle body is done to elicit the difference. The expanded uncertainty achieved by the system is 0.221 mm and 0.177 mm for gap and flushness respectively, significantly smaller than the sole resolution of the most adopted manual feeler gauge verification method.
PURPOSE: The purpose of this paper is to take steps towards a life cycle assessment that is able to account for changes over time in resource flows and environmental impacts. The majority of life ...cycle inventory (LCI) studies assume that computation parameters are constants or fixed functions of time. This assumption limits the opportunities to account for temporal effects because it precludes consideration of the dynamics of the product system. METHODS: System dynamics methods are used in a consequential, fleet-based LCI that accounts for some aspects of the dynamics of the wider system. The LCI model compares the life-cycle energy consumption of car body-in-whites (BIWs) in Australia made from steel and aluminium. It incorporates two dynamic processes: the flow of BIWs into and out of the fleet, and the recycling of aluminium from end-of-life BIWs back into new BIW production. The dynamical model computes both product-based and fleet-based estimates. RESULTS AND DISCUSSION: The product-based computations suggest that an aluminium BIW consumes less energy than a steel BIW over a single life cycle. The fleet-based computations suggest that the energy benefits of aluminium BIWs do not begin to emerge for some time. The substitution of aluminium for steel is a low-leverage intervention that changes the values of a few parameters of the system. The system has a delayed, damped response to this intervention because the large stock of BIWs is a source of high inertia, and the long useful life leads to a slow decay of steel BIWs out of the fleet. The recycling of aluminium back into BIW production is a moderate-leverage intervention that initially strengthens a reinforcing feedback loop, driving a rapid accumulation of energy benefits. Dominance then shifts to a balancing loop, slowing the accumulation of energy benefits. Both interventions result in a measureable reduction in life-cycle energy consumption, but only temporarily divert the underlying growth trend. CONCLUSIONS: The results suggest that product-based LCIs overestimate the short-term energy benefits of aluminium by not accounting for the time required for the stock of preexisting steel components to decay out of the fleet, and underestimate the long-term energy benefits of aluminium components by not accounting for changes in the availability of recycled aluminium. The results also suggest that interventions such as lightweighting and other efficiency measures alone can slow the growth of energy consumption, but are probably inadequate to achieve sustainable energy consumption levels if the fleet is large.
More than 6000 cylindrical joining points connect the individual sheet metal components of a current car body. Due to multi-material design, a large number of these points are currently realized by ...bulk-sheet metal-forming processes, such as clinching or self-pierce riveting. Today, the development and optimization of joining points takes into account tensile, shear and combined tensile-shear strengths of the joint. Although a load-optimized design can be used to increase the utilization of the joining points and to reduce weight and costs, the design of the joining points themselves is not adapted to the actual local load, since their predominant load distributions are hardly known. The aim of this paper is to determine the probability distribution of pure tensile, shear and combined tensile-shear loads at joining points of a body-in-white under realistic global loads. First, a body model is derived from a full vehicle, then the joining points are modeled, and the global loads are applied to the structure. The simulation results are then automatically evaluated. This data-driven approach thus enables an automated determination of the cross-sectional forces at the joining points and their statistical evaluation for load-compliant joint point design in product development.
A missing test methodology that allows for the determination of delayed cracking susceptibility of laser welds of high-strength sheet steel is presented. Unlike other cold crack testing methods, this ...test is based on a self-restraint testing of specimens welded from thin sheet materials without welding consumables and external loading. The potential test procedure with sample geometry, clamping device and documentation of the cracks is described. It is shown that the position of the weld on the specimen is a critical parameter and the susceptibility to cold cracking increases with increasing edge distance. The test methodology in combination with the most critical seam position is successfully used to rank two different steels regarding their susceptibility to delayed cracking. Further investigations are conducted evaluating the cold cracking susceptibility at different energy levels and lubricating conditions. It is proven that the lubrication has a significant influence on the susceptibility to cold cracking. Nevertheless, a narrow but safe process window is found.
It is very important to predict the acoustic radiation of vehicle body for the control of interior noise. Firstly, the kinetic equations of coupled acoustic-structural finite element method are ...explained and the numerical analytical methods of noise transfer function and acoustic panel participation are further obtained. Then the coupled acoustic-structural finite element model of body in white and passenger compartment cavity of a minicar is established and verified by modal test. The passive side of engine mounting points are chosen as the excitation points, and driver’s right ear is the output point of sound pressure response. The noise transfer function is calculated and the critical frequency of vehicle interior noise is obtained. The acoustic panel participation analysis of vehicle roof and floor are conducted, and the key acoustic panels are identified. In order to reduce the noise of critical frequency, the measures, pasting damping material and welding beam, are adopted. The results indicate that, compared with the results of structure improvement of modal method, the vehicle interior noise is controlled more effectively by using the acoustic panel participation analytical method.
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