The quest for sustainability and reduction of human impact on the planet has led to discussions about environmental efficiency in the manufacture and use of automotive vehicles. The advancement of ...environmental and government laws has encouraged the automotive industry to seek constant improvements in safety, fuel economy and reduction of greenhouse gas emissions. To achieve these goals, reducing the weight of vehicles has been considered a relevant strategy, with several research and development efforts in search of high-tech materials and innovative design. The assessment of the life cycle of vehicles, from the extraction of raw materials to the end of their useful life, is essential for estimating environmental impacts. In this context, this paper focuses on the life cycle analysis of vehicles with new generation steel structures (Body in White Solution) compared to current steels (Body in White Baseline), aiming at reducing greenhouse gas emissions by reducing of the thickness of the steel plates, maintaining the mechanical properties necessary to guarantee the safety of the vehicle. The methodology of this study was divided into the evaluation of Body in White (BIW) mass in current steels (Baseline) and in advanced high resistance steels (Solution); detailing the vehicular life cycle from the extraction of materials to its end of life; in the estimation of greenhouse gas emissions through simulation and in the comparison of vehicle emissions with BIW in current steels and in advanced high resistance steels. As a result, it was possible to observe that, in the comparison of the CO2 footprint, modeled in the Eco Audit, there is a 15% reduction in emissions in the CO2 footprint for the BIW solution, as well as a 7% reduction in the Ceq total, in the on-site test and a saving of 260.40 L in fuel consumption, that is, the reduction in vehicle weight plays a significant role in reducing CO2 emissions, providing a mitigation factor for global warming.
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•There is a 15% reduction in emissions in the CO2 footprint for the BIW solution.•There is a 7% reduction in the Ceq total, in the on-site test.•Reduction in vehicle weight plays a significant role in reducing CO2 emissions.•Providing a mitigation factor for global warming.•There is a fuel economy of 260.4 L over the vehicle's life cycle.
•An all-aluminum vehicle body was used as an example and the finite element model of the body-in-white was established in ANSA.•The bending stiffness, torsional stiffness and modal characteristics of ...the body were calculated, analyzed and optimized, based on the sensitivity analysis of thickness of the vehicle body structure.•The body structure was optimized according to the body structure optimization, the quality was reduced by 9.2% to achieve lightweight goal.
The intensity analysis was proposed for a certain all-aluminum vehicle body-in-white, and an optimistic method of the vehicle body was carried out based on lightweight target. The finite element model of vehicle body-in-white was established, and the flexural rigidity and torsional rigidity of the vehicle body are calculated according to the actual operating conditions of the vehicle. The flexural rigidity and torsional rigidity of the vehicle body are calculated, and the main opening deformation of the vehicle body under these two working conditions was studied. Finally, based on the thickness of the body panel, the structural sensitivity analysis of the vehicle body was carried out. According to the sensitivity analysis data, the optimization variable is determined with lightweight as the target, and the vehicle body structure is optimized. The results showed that the static and dynamic performance indexes of the white body were higher than the standards of similar motorcycle type at home and abroad, the bending stiffness of the structurally improved basic model after sensitivity optimization was reduced by 2.1% compared with before optimization, but still much higher than the target reference value (122,000 N/mm). And the quality of the vehicle body was reduced, which met the lightweight requirements of optimized design after the optimization of the thickness of the improved basic model.
•The dynamics of a passenger car is studied through experimental tests.•Three configurations changing shock absorber effects are investigated.•Shock absorbers behave as viscous dampers, so the system ...is non-proportionally damped.•Damping matrices are identified directly from experimental data.•The spatial damping identification through Layer Method is based on inverse FRFs.
This paper investigates the effects of the shock absorbers of a passenger body in white car on identified modal properties and damping matrices. The authors propose an experimental approach to evaluate the changes induced by localised dissipations on damping matrices and modal behaviour. The shock absorbers behave as localised viscous dampers; therefore, the global system results non-proportionally damped. The chassis dynamics is studied through experimental tests, e.g. roving hammer modal analysis. The chassis is tested in three different configurations to include or exclude the shock absorbers effects on the dynamic behaviour.
A new approach to damping matrix identification is presented and applied to the chassis experimental data. The system viscous and hysteretic damping matrices are identified from the experimental data based on the inverse frequency response functions method combined with original physical and topological constraints able to describe the system mechanical properties. The effects of the suspension system on the first flexible modes are evaluated comparing the modal properties of the three experimental sets of mode shapes. A numerical method is developed to attenuate noise and to reduce the incompleteness of experimental data. Finally, the influence of localised dampers, their identification and spatial distribution are discussed.
The remarkly high degree of automation within body-in-white production, with high quality requirements and the increasing demand for product-flexible production form a conflict of objectives. The ...most significant challenges in making the operating resources of body-in-white manufacturing more flexible arise with the the development of model-flexible geometry fixtures, with the geometric and qualitative requirements being most significant in the production of vehicle doors. For the efficient design of model-flexible fixtures specific methods and software tools for part alignment, clamp point grouping and fixture design have been developed.
The production of pure steel and steel-aluminum (Al) bi-material body-in-white (BIW) in the same assembly line requires the use of joining techniques with high flexibility, and this is not currently ...possible with state-of-the-art mechanical joining techniques. This work therefore developed a hybrid joining technique, rivet resistance spot welding (RRSW). In this process, a special FEM-optimized rivet clamps the Al sheet on both sides, with one flat and one nearly flat surface. It functions as an adapter to weld the Al part with the other steel parts and separates the steel and Al parts to avoid contact corrosion. Experiments demonstrated that, with optimized rivet geometry and proper welding parameters, RRSW created steel-Al combinations in BIW that were of at least equal strength to, and usually stronger, than self-piercing riveting (SPR). RRSW’s corrosion resistance was also superior to SPR’s. To verify the sample level development, a steel roof was redesigned to use Al, and this was then welded to the adjacent steel parts using fully-automated spot welding unit. Using the same welding conditions as for the steel roof the RRSW quality was good. The same welding system can thus be used both for pure steel and for steel-Al multi-material BIW assembly. RRSW is therefore a flexible and economical joining method and a viable alternative to SPR.
The increasing change of production leads to differences between the current shop floor and the state of planning. This difference causes significant challenges for production planners while ...integrating new products into existing production systems. To tackle this issue, this paper presents a concept for the automated creation of a digital twin of a body-in-white production system based on current resources, products as well as process information from the cyber-physical system. The paper focuses on the different data sources and information in cyber-physical systems necessary for integration planning. Furthermore, major parts of the concept are evaluated in a real body-in-white production system. The resulting digital twin enables faster product integration and Industry 4.0 concepts.
The load-bearing capacity of hybrid riv-bonded aluminum-magnesium lap joints under shear-tensile loading was studied with particular focus on their static strength and fatigue performance. Sheets of ...1.5 mm-thick EN AW-6016-T4 aluminum alloy were joined with sheets of 2 mm-thick AZ91 magnesium alloy using two high-strength steel rivets and epoxy-based adhesive. Local deformation-induced fracture of the comparatively inductile magnesium alloy sheet at the rivet holes during riveting at room temperature was intentionally tolerated. The lap joints were heat-treated to peak-age the aluminum alloy (condition T4 → T6) and to cure the adhesive between the sheets. Characteristic cross-section features and hardness maps were measured for assessing the quality of the joints and thus for proving the general capability of the riv-bonding process. The fracture behavior of the inductile magnesium alloy sheet determined the static strength as well as the fatigue performance at load ratios of 0.1 and 0.5. Both, load amplitude and mean load, influenced the site of fatigue crack initiation and the path of crack propagation. Local fracture of the inductile magnesium alloy sheet at the rivet hole is tolerable, if riv-bonded lap joints are just exposed to cyclic loading with low amplitudes.
Lightweight designs of new-energy vehicles can reduce energy consumption, thereby improving driving mileage. In this study, a lightweight design of a newly developed multi-material electric bus body ...structure is examined in combination with analytical target cascading (ATC). By proposing an ATC-based two-level optimization strategy, the original lightweight design problem is decomposed into the system level and three subsystem levels. The system-level optimization model is related to mass minimization with all the structural modal frequency constraints, while each subsystem-level optimization model is related to the sub-structural performance objective with sub-structure mass constraints. To enhance the interaction between two-level systems, each subsystem-level objective is reformulated as a penalty-based function coordinated with the system-level objective. To guarantee the accuracy of the model-based analysis, a finite element model is validated through experimental modal test. A sequential quadratic programming algorithm is used to address the defined optimization problem for effective convergence. Compared with the initial design, the total mass is reduced by 49 kg, and the torsional stiffness is increased by 17.5%. In addition, the obtained design is also validated through strength analysis.
The assembly process of car body in white (BIW) in body shop is a very important link in the whole vehicle manufacturing process. Hundreds of stamping parts must be located and joined on the correct ...location of the platform, and the related accuracy influence the performance and quality of the cars. To guarantee the BIW manufacturing accuracy, the dimension control is a critical task in each automobile production line. In Comparison to traditional offline dimension control, this article proposed an event-triggered feedforward predictive control method to realize real-time inline dimension control during BIW assembly process. Experiments based on the actual production data from BMW Brilliance Automotive Ltd. demonstrate this control strategy can significantly improve the final products key point pass rate and decrease the fixture adjustment frequency.
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