Car Body Parts Research Articles

Study on prediction in far-field aerodynamic noise of long-marshalling high-speed train.

It is still difficult to conduct numerical calculation of the aerodynamic noise of full-scale, long-marshalling, high-speed trains. Based on the Lighthill acoustic analogy theory, the aerodynamic sound source of the high-speed train is equivalent to countless micro-vibrating sound sources. An acoustic radiation model of the dipole sound source of high-speed trains is established, and a method to predict the aerodynamic noise in the far field of long-marshalling high-speed trains is proposed. By this method, combined with numerical simulation technology, the flow field, noise source, and far-field noise characteristics of high-speed trains with different marshalling numbers are studied. The improved delayed detached eddy simulation method is used for flow field calculation, to obtain aerodynamic noise source information regarding the surface of high-speed trains. The numerical calculation method is verified by wind tunnel testing. The results show that the flow field and noise source characteristics of high-speed trains with different marshalling numbers are similar. The greater the length of the train body, the longer the trailing distance of the train wake, and the stronger of a surface noise source the tail car becomes. The spatial distribution characteristics of aerodynamic noise in the far field of high-speed trains do not change significantly with the length of the train body, but the magnitude of the sound pressure level will increase with the increase in length of the train body. The middle car body parts of high-speed trains with different marshalling numbers have similar noise distributions and sound pressure levels. Based on the noise calculation results of the 3-marshalling high-speed train, the far-field noise of the 5-marshalling and 8-marshalling train models is predicted and found to be in good agreement with the far-field noise of the actual train model. The differences in average sound pressure level are 1.01 dBA and 1.74 dBA, respectively.

Rule and optimization-based selection of car body parts for the application of tailor rolled blank technology

The majority of parts in modern car bodies is manufactured from sheet metal. Rarely these parts are fully stressed due to design space restrictions and complex requirements. The usage of tailor rolled blanks (TRB) enables the reduction of sheet thickness in areas less loaded and thus reduces part weight. Technically most sheet metal parts are potentially suited for the application of TRB. Economic circumstances like the additional flexible rolling process and technology-specific nesting constraints limit the application to a subset of parts. The search for the best candidate parts taking mass and cost into account is currently challenging. This article presents an optimization strategy for the selection of the parts in a vehicle structure that are best suited for the application of TRB. As a first step, a priori preferencing is performed to select parts based on engineering rules. Using a reduced number of candidate parts, high quality metamodels are trained to perform multiobjective optimizations of all possible combinations of remaining parts, revealing the most efficient part selection under consideration of mass and cost.

Solving a multi-dimensional matching problem for grouping clamping points on car body parts

Modern car body production is faced by an increasing number of car models as well as individualizing options, which leads to the need for more adaptable assembly equipment, e.g. grippers and fixtures that can switch between models in a matter of seconds. Based on known clamping positions, automated jigs consisting of several clamps can already adapt to different part geometries.To enable an efficient flexible jig, exactly one clamp must be assigned to each clamping point of each model taking into account different optimization criteria. Therefore, clamping points need to be grouped across all different models in the planning phase. Grouping of clamping points e.g. in order to minimize adaptation time or tooling costs is usually performed manually.In this paper, the grouping optimization problem is formalized, and a mathematical algorithm is introduced to solve this multi-dimensional matching. The envisaged approach uses a greedy algorithm to get an initial solution, which is optimised to a technically feasible solution considering economical aspects. To conclude, a short evaluation of the achieved results - especially in comparison with expert based grouping - is given.

Examining the superplastic behavior of (Al-Si-Mg)/SiC metal matrix nanocomposites

Aluminum alloy (Al-Si-Mg) is widely used material in aircrafts, ships, and automotive industries. Applications of formed aluminum components specifically found in automobile body parts. Superplasticity is the immensely recommended industrial process for forming the complex shapes and structures. This work focused to fabricate Al-Si-Mg / 0.5 wt% SiC metal matrix nanocomposites (MMNCs) by sonication assisted casting process. The scanning electron microscopic analysis was conducted to confirm the particle distribution and its uniformity in the matrix. The fabricated MMNCs were subjected to hot rolling process to analyze the superplastic behavior of the MMNCs. Rolled MMNCs indicates the refined grain structure. Tensile behavior of the composite was analyzed at three different temperatures. As the temperature increased the tensile strength of the composites tends to reduce. Rolled MMNC sample was subjected to blow forming type of superplastic operation. Blow formed components showed reasonable superplastic elongation.

自動車用エンジン部品のアルミダイカスト鋳造工程の最適化

Looking at recent applications of aluminum die castings, automotive parts account for about 90% of the production volume. Application to parts with high functional requirements, such as automobile undercarriage and body parts, is increasing. However, there are few reports published in Japan on the application of quality engineering to the casting field. There are still unclear points regarding the reduction of internal defects that improve casting quality. In addition, there are no examples of systematic research on casting conditions for stabilization of casting quality with respect to the three elements of productivity indices: high quality(Q),cost reduction(C),and high productivity(D).Therefore ,in this study ,an ideal function was set up using casting weight as a characteristic value ,which can be easily measured .We propose the application of a function evaluation method to evaluate the characteristic value of casting condition that affects casting weight.

AN EFFICIENT QUALITY CONTROL SYSTEM BY MACHINE LEARNING FOR SURFACE DEFECTS

Quality control plays a crucial role to meet the high and accurate quality of production in many manufacturing industries. The high quality products may become unreliable due to surface defects. Generally, quality control is more important in automotive industry such as in the field of car-body parts manufacturing. The exterior appearance of the car body should be smooth surfaces and edges with flawless nature. In order to build such flawless body parts, surface defect detection system is taken into account. In this paper, an Automated Defect Detection (ADD) system is presented. The design of the ADD system consists of two steps. The first step is considered as a classification system where the given image is classified into defected or non-defected using Gabor expansion with Principal Component Analysis (PCA). The next step is segmentation where the region of defect is identified using local thresholding. The evaluation is performed on raw alloy steel surface and machined surfaces of steel and cast iron. Results prove that the ADD system classify the input image into defect/no defect with 100% accuracy by a simple nearest neighbor classifier and with 94.5% detection accuracy for the segmentation system.

Pulse spray gas metal arc welding of advanced high strength S650MC automotive steel

With an increasing demand for safer and greener vehicles, mild steel and high strength steel are being replaced by much stronger advanced high strength steels of thinner gauges. However, the welding process of advanced high strength steels is not developed at the same pace. The performance of these welded automotive structural components depends largely on the external and internal quality of weldment. Gas metal arc welding (GMAW) is one of the most common methods used in the automotive industry to join car body parts of dissimilar high strength steels. It is also recognized for its versatility and speed. In this work, after a review of GMAW process and issues in welding of advanced high strength steels, a welding experiment is carried out with varying heat input by using spray and pulse-spray transfer GMAW method with filler wires of three different strength levels. The experiment results, including macro-microstructure, mechanical properties, and microhardness of weld samples, are investigated in detail. Very good weldability of S650MC is demonstrated through the weld joint efficiency > 90%; no crack in bending of weld joints, or fracture of tensile test sample within weld joint or heat affected zone (HAZ), or softening of the HAZ. Pulse spray is superior because of thinner HAZ width and finer microstructure on account of lower heat input. The impact of filler wire strength on weldability is insignificant. However, high strength filler wire (ER100SG) may be chosen as per standard welding practice of matching strength.

SplineLearner: Generative learning system of design constraints for models represented using B-spline surfaces

Product design involves a computer-aided design (CAD) model with its design (dimensional) parameters. A generative design (GD) system can then be utilized to generate new designs by modifying these parameters. There is a need for a GD system to determine the visual validity of a design that is obtained after parametric modification. In this context, this paper introduces an approach to learn visual (i.e., design) constraints of a CAD model (represented using B-spline surfaces) by means of user feedbacks. A deformation technique (utilizing modification and limit curves) for B-spline surfaces is first introduced, which involves a few design (deformation) parameters. Via a generative learning process, the proposed system, SplineLearner, generates random designs, which are shown to user(s) for visual validity classifications. In a machine learning step, a mathematical model is computed that can perform prediction for a design to be valid or not. The mathematical model is also integrated into SplineLearner (after some user interactions) to prevent imbalances between the numbers of valid and invalid designs. As a proof of concept, B-spline surface models of a car body parts (hood, roof, side and trunk) are utilized, and two user studies are conducted to demonstrate the efficacy of the proposed method.

Resistance Spot Welding of Transformation- Induced Plasticity Steel RAK 40/70

The paper deals with the analysis of the influence of the parameters of resistance spot welding. Resistance spot welding is high-efficiency process for joining metallic materials. The application of resistance spot welding is still the most used joining method for joining the car body parts. The influence of the parameters of resistance spot welding was determined by an experiment. The optimal parameters for achieving the highest load-bearing capacity of joints for the material TRIP40 / 70 with a defined thickness of 0.77 mm were determined. The results of resistance spot welding joints reached the values of load-bearing capacity from 6300N to 9000 N. The exact values parts of the experiment are shown in the paper.

Analysis of Tool Geometry for the Stamping Process of Large-Size Car Body Components Using a 3D Optical Measurement System.

The paper presents a method for checking the geometry of stamped car body parts using a 3D optical measurement system. The analysis focuses on the first forming operation due to the deformation and material flow associated with stall thresholds. An essential element of the analysis is determining the actual gap occurring between the forming surfaces based on the die and punch geometry used in the first stamping operation. The geometry of car body elements at individual production stages was analyzed using an optical laser scanner. The control carried out in this way allowed one to correctly position the tools (punch and die), thus introducing the correction of technological parameters, having a fundamental influence on the specific features of the final product. This type of approach has not been used before to calibrate the technological line and setting of shaping tools. The influence of the manufactured product geometry in intermediate operations on the final geometry features was not investigated.

Determination and calculation of quantitative values of the parameters of a complex criterion for making decisions about the type of repair of a car body part

Approaches for determining and calculating the quantitative values of the parameters of a complex criterion for making decisions about the type of repair of a car body part are described. Keywords: types of repairs, types and combinations of types of damage, normative labor intensity, body section, complex criterion, quantitative values of parameters, expert, mathematical model, objective function

Resistance Spot Weldability of Aluminum Alloy with 6 wt.% Magnesium

To ensure safety and reduce the weight of vehicles, studies are being actively conducted on different aluminum alloys that have strength higher than conventional aluminum alloys. The development of high-performance aluminum alloys through magnesium content control is underway. Research on manufacturing techniques, such as, welding for application to the car body parts of these materials is required. In this study, the resistance spot weldability of an aluminum alloy with 6 wt.% magnesium (Al-6Mg) was evaluated and compared with the commercial aluminum alloy 5052, 6061 (Al5052, Al6061). The suitable welding range of the Al-6Mg was found to have a welding current of 24 kA to 28 kA, and a similar level of Al6061. The welding heat input was almost the same for the three materials, which resulted in no difference in the diameter of the nuggets. There was no significant difference of the porosity ratio between Al-6Mg and Al5052; however, the porosity ratio of Al6061 was higher. The alloy with the highest tensile shear strength, hardness and energy absorption of a welded joint was Al-6Mg. The low porosity ratio and high hardness of the Al-6Mg alloy caused the relatively high tensile shear strength and energy absorption of the welded joint.

A Method for Calculating the Parameters of a Unit for Thermoradiation Treatment of Polymer Coatings in the Restoration of Car Body Parts

A Method for Calculating the Parameters of a Unit for Thermoradiation Treatment of Polymer Coatings in the Restoration of Car Body Parts

Material Characterization and Modeling for Finite Element Simulation of Press Hardening with AISI\xa0420C

The process of press hardening is gaining importance in view of the increasing demand for weight reduction combined with higher crash safety in cars. An alternative to the established manganese-boron steel 22MnB5 is hot-formed martensitic chromium steels such as AISI 420C. Strengths of 1850 MPa and elongations of 12% are possible, exceeding those of 22MnB5. In industrial manufacturing, FE-simulation is commonly used in order to design car body parts cost-efficiently. Therefore, the characterization and the modeling of AISI 420C regarding flow stress, phase transformations as well as failure behavior are presented in this paper. Temperature-depended flow curves are determined, showing the low flow stress and hardening behavior at temperatures around 1000 °C. Cooling experiments are carried out, and a continuous cooling diagram is generated. Observed phases are martensite and retained austenite for industrial relevant cooling rates above 10 K/s. In addition, tests to investigate temperature-dependent forming limit curves are performed. As expected, the highest forming limit is reached at 1050 °C and decreases with falling temperature. Finally, a simulation model of a press-hardening process chain is set up based on the material behavior characterized earlier and compared to experimental values. The forming force, phase transformation and forming limit could be calculated with good agreement to the experiment.

A Mathematical Model of Thermal Irradiation Processing of Polymer Coatings during Restoration of Automobile Body Parts

A Mathematical Model of Thermal Irradiation Processing of Polymer Coatings during Restoration of Automobile Body Parts

Improving the tensile and flexural properties of reinforced epoxy composites by using cobalt filled and carbon/glass fiber

In this paper, the study concentrates on the flexural and tensile characteristics of the cobalt filler and fiber-reinforced epoxy composites used in the car body parts. Glass fiber (GF) and carbon fiber (CF) filled with the epoxy compound were prepared by hand lay-up varying the percentage of weight (wt.%) of cobalt from (0.4 to 1.0 wt.%). GF tensile and flexural strength were available at approximately 96.9 MPa and 120 MPa, respectively, while tensile and flexural strength of the reinforced CF was combined found in 194.82 MPa and 393.34 MPa. A 55.64% increase in flexural and tensile strength of the specimen was obtained compared to pure epoxy which represents a significant improvement. The use of a 0.6 wt.% Cobalt (Co) filler content for the combination of GF and CF epoxy reinforces positive results in the strength test. In addition, Field Emission Scanning Electron Microscopy (SEM) was done to investigate the microstructural characterization, the performance of GF and CF epoxy reinforced composite.

Bending behavior of a hot stamped complex phase steel with tailored properties by local carburization

Concerning lightweight design, hot stamping of boron-manganese steels has developed to a state-of-the-art process for manufacturing safety-relevant car body parts in the last two decades. To further improve passenger safety, the idea of components with tailored properties has become even more important. Normally, these process variants aim to bring in so-called soft zones, where a fully martensitic microstructure is prevented to significantly improve ductility. The growing importance of battery electric vehicles and their special requirements call for alternative processes. Especially the battery and its housing are often referred to as a no deformation zone. Concerning this matter, the new process of tailored carburization can be advantageous, since it aims to locally improve strength rather than ductility. Regarding the field of application as a safety-relevant component, the crash behavior is of high interest. In recent years, the three-point bending test has prevailed as a suitable comparative test to estimate crash performance. Within this work, the influence of various carburization parameters on the bending behavior is analyzed. The results reveal that the additional carburization improves punch force at the cost of the bending angle. By analyzing locally carburized samples it is shown, that especially the carburization of the tensile loaded side within the deformation zone is crucial for local strengthening under bending load.

Virtual die spotting: Advanced setup for coupling of forming and structure simulation

Shorter product life cycles and increasing product variety in the automotive industry are leading to increasing pressure on manufacturing of stamping dies for car body parts. A high amount of manual rework is needed to meet product quality, which is one of the main drivers for long production time and high cost. The long-term goal is to meet quality requirements directly after machining of the active tool surfaces to reduce the manual rework needed to a bare minimum. This can only be achieved by taking elastic deformations of tools and press into account during the virtual die making process.To predict the deflection at the active surfaces during the forming process, a conventional forming simulation with rigid tools is coupled with a structure simulation using elastic tools and press. For the accurate representation of the deflection behaviour of the real press, substitute models of moving bolster and ram are used, which are based on press measurement data.In this paper, different press deformation characteristics are presented, and the viability of the universal FE substitute model is evaluated. Further, advanced settings for the coupled FE simulation are discussed and the simulation results are validated with experimentally determined data.

Variance based sensitivity analysis of deep drawing processes based on neural networks using Sobol indices

Today’s deep drawing of car body parts is operated increasingly closer to the process limits, making it more challenging to ensure a high robustness of the process. Disturbances like varying material properties or changing tribological conditions may negatively affect the process, leading to deteriorated product properties and a loss of productivity. In the past, several approaches using different combinations of sensors and actuators to build up a control system have been investigated to fulfil the need of a more robust process. Hence, a thorough process analysis comes to be beneficial to evaluate the expediency of a control system and to make a reasonable preselection of sensors in order to avoid unnecessary costs. This paper presents a method using variant simulations to evaluate the expediency of a control system, including the necessary sensors. The influence of disturbances in the process is evaluated by a numerical sensitivity analysis under consideration of interaction effects. These higher order effects are calculated by Monte Carlo integration. Potential measurands are determined by the maximum achievable observability of not directly measurable quality criteria of a part. For this purpose, different modelling approaches of the observability are considered and compared with regard to their goodness-of-fit.

Research on stress intensity factor and fatigue crack propagation rate of the general-purpose gondola car body

In order to study the crack propagation characteristics of key parts of the general-purpose gondola car body, according to the structural characteristics and crack statistics results of the car body, the floor along the cross bearer weld was taken as the research object. The stress intensity factors under different conditions of the floor were studied, based on linear elastic fracture mechanics and finite element analysis. In addition, the crack propagation rates of the floor were studied by the Paris formula. These research results will provide a reference not only for formulating maintenance procedures for the general-purpose gondola car body, but also for evaluating the safety and reliability of wagon bodies.