Car Body Parts Research Articles

The effect of RSW technological parameters to the properties of aluminium/steel hybrid joints

To reduce fuel consumption and costs, the lightweight construction of car bodies is a very important aspect. This is achieved by using high-strength steel and aluminium alloy base materials. The latest car bodies contain both steel and aluminium alloy, so it is necessary to develop a reliable joining technology between them. Several joining technologies were investigated, such as mechanical joining, adhesive joining, and welding too. Resistance spot welding (RSW) is typically used to join car body parts and can be used for aluminium/steel hybrid joints. During welding, a very brittle intermetallic compound (IMC) is formed, which basically determines the properties of the joint, which is particularly influenced by the thickness and phases of the IMC. EN AW 5754 H22/ DP600 dissimilar joints were made with RSW, using different welding parameters. The joints were tested by shear-tensile tests and the effect of the IMC layer was determined.

Expanding Lightweight Design Potential by Hybrid Joining of Aluminum Sheets with Aluminum Casting Through Compound Sand Casting and Induction Heating

Combining light metals like aluminum to produce lightweight structures offers a high weight‐saving and contributes to a circular economy in automotive car body construction. Compound casting is a promising process for producing car body parts. Difficulties arise in creating metallic continuity between insert and casting. Insert coatings are used to remove the oxide layer and thereby improve the wettability of the melt. This study uses a hybrid joining method to improve the metallic bond between insert and casting. Induction heating differently influences the strength properties of age‐ and nonage‐hardenable inserts. Compression shear tests characterize the metallic bond strength. Microscopic images show the influence of the process variables on the compound quality. Reproducible sound metallic bonding with low scattering is achieved by enhancing the compound casting process through induction and no insert coating. Cast wall thicknesses down to 4 mm contribute to further lightweight potential as they have the same strength level as the reference sample. A decisive factor is the insert temperature in the compound zone. Thereby, insert preheating conditions play a crucial role. Additional heat treatment of hardenable compounds leads to a further increase in metallic bond strength.

A Study on GAN-Based Car Body Part Defect Detection Process and Comparative Analysis of YOLO v7 and YOLO v8 Object Detection Performance

The main purpose of this study is to generate defect images of body parts using a GAN (generative adversarial network) and compare and analyze the performance of the YOLO (You Only Look Once) v7 and v8 object detection models. The goal is to accurately judge good and defective products. Quality control is very important in the automobile industry, and defects in body parts directly affect vehicle safety, so the development of highly accurate defect detection technology is essential. This study ensures data diversity by generating defect images of car body parts using a GAN and through this, compares and analyzes the object detection performance of the YOLO v7 and v8 models to present an optimal solution for detecting defects in car parts. Through experiments, the dataset was expanded by adding fake defect images generated by the GAN. The performance experiments of the YOLO v7 and v8 models based on the data obtained through this approach demonstrated that YOLO v8 effectively identifies objects even with a smaller amount of data. It was confirmed that defects could be detected. The readout of the detection system can be improved through software calibration.

Uncertainty estimates for semantic segmentation: providing enhanced reliability for automated motor claims handling

Deep neural network models for image segmentation can be a powerful tool for the automation of motor claims handling processes in the insurance industry. A crucial aspect is the reliability of the model outputs when facing adverse conditions, such as low quality photos taken by claimants to document damages. We explore the use of a meta-classification model to empirically assess the precision of segments predicted by a model trained for the semantic segmentation of car body parts. Different sets of features correlated with the quality of a segment are compared, and an AUROC score of 0.915 is achieved for distinguishing between high- and low-quality segments. By removing low-quality segments, the average mIoU\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$m{\ extit{IoU}} $$\\end{document} of the segmentation output is improved by 16 percentage points and the number of wrongly predicted segments is reduced by 77%.

Numerical analysis of the dependence of damage on friction during deep drawing of asymmetric geometries

The manufacturing of three-dimensional sheet metal components, such as car body parts, heavily relies on deep drawing. With the increasing demand for lightweight measures in the automotive industry due to CO2 limitation requirements, various methods are currently employed to reduce the weight of deep drawn components. However, these methods often overlook the potential for influencing the stress-strain dependent damage state within the component, even though it can greatly affect its performance in subsequent applications, and thus offers lightweight potentials. Friction between the deep drawing tools and the sheet metal is a key factor influencing the stress-strain state, and hence, represents a lever that can be utilized to manipulate the damage state in the component. This paper focuses on the numerical analysis of the dependence of damage on friction during deep drawing. Therefore, a rectangular geometry with an asymmetrical material flow is numerically investigated. A friction ratio is introduced with different constant friction coefficients for the corner of the tools and the straight sides. The established load paths at a chosen reference point are then considered in the form of selected stress and strain characteristics and the numerically predicted damage state is compared. The results are used to derive a recommended friction ratio that leads to less damage in the corner of the geometry. Afterwards strip drawing tool surfaces are modified to manipulate their friction properties using machine hammer peening. Subsequently, the influence of the structures of the strip drawing tool surfaces is quantified using strip drawing tests. The identified contact normal stress dependent friction coefficients are then implemented in the numerical simulation and the established numerical predicted damage state is examined to gain a more comprehensive understanding of how the friction ratio and the structure of the tool surfaces influence the damage state.

Process strategies for optimizing the cooling behaviour of laser-welded Tailor Welded Blanks made of advanced high strength steels (AHSS)

AHSS with 1000 MPa tensile strength show promising properties for the use in Tailor Welded Blanks (TWBs) to locally strengthen car body parts. Challenges in laser beam welding of the sheets are hardness-drops and -peaks in the heat-affected zone (HAZ) and weld, which cause risks during cold-forming. This happens due to rapid cooling caused by laser welding. A numerical approach aiming for slower cooling rates in the weld region is presented in this article. Laser welded sheets served as reference for setting up a process simulation. Models for pre-heating and a coaxial setup with power split were set up. A correlation between cooling-rate and hardness in the joining zone was established and applied to the modelled strategy. Splitting the power led to a slightly narrower weld seam and experimental pre-heating of the sheets to 600 °C could lower total seam hardening. It achieved a homogenization of the fusion zone.

An Approach to Inline Monitoring of the Electrode State in Resistance Spot Welding

Resistance Spot Welding (RSW) is a key technology for joining car body parts. During the process, the upper and lower electrodes of the welding gun are subject to wear, which affects the electric current flow and thus, the quality of the spot weld. To counteract this effect, the electrode tip is dressed after a predefined number of spot welds. The frequency for tip dressing is based on experience and does currently not directly reflect the actual state of the electrode. This work provides an approach to inline electrode state monitoring to determine the ideal and demand-based point in time for electrode tip dressing based on process data. We avoid costly and time-intensive experimental labeling of electrode states and utilize changes in the dynamic electrical resistance between dressing cycles to represent the electrode wear state. To describe the changes in the dynamic electrical resistance curve, new features such as the peak time delay are calculated and visualized. We evaluate our approach with a real-world data set that stems from a dynamic and complex environment out of a series production line, which, in contrast to laboratory data, ensures a successful application of the proposed methods in an industrial setting.

An assessment of new materials that are light weight for use in automobiles to improve fuel efficiency

Global energy demand is currently contributing to a severe problem of rising fuel prices for automobile users. One solution is to reduce the weight of the car body to improve fuel efficiency and reduce fuel costs. The choice of car body material can achieve this purpose. This paper will present the criteria such as stiffness, strength, and density to determine the suitability of substituting traditional materials, such as mild steel and carbon steel, with new materials High Strength Steel (HSS), aluminum alloys, and Long Fiber Thermoplastic (LFT). A literature review of the research is done to showcase the challenges traditional materials experience and how the development of these three new materials can overcome these challenges. Results from the case study show the feasibility of implementing these new materials in an automobile. More future research should be conducted to overcome the challenges and limitations posed by using these new materials, focusing on the low-cost replacement, manufacturing, and co-joining techniques of car body parts.

Cyber Physical Production Systems for Deep Drawing

Abstract Deep Drawing is an essential manufacturing technology for car body parts. High process stability is a key to reducing scrap and therefore the ecological footprint during production. To deal with an unknown fluctuation of the incoming material properties and uncertainties considering the friction, an adaptive process needs to be implemented. Various approaches have been pursued in the past, but not all of them are suited for industrial series production with high demands for equipment durability, cost efficiency, and flexibility. For this reason, a new concept for cyber-physical production systems (CPPS) in deep drawing is presented, linking the data from the simulation, tool, press, material, and finished part quality. Two common application scenarios are distinguished. First, these are large outer parts with a complex geometry and high value, typically produced with tandem presses. Second, smaller structural parts from high-strength steel for the body in white (BIW) are usually produced through a transfer or progressive die. Non-destructive material testing, supplier material certificates, and data measured directly in the forming tool are considered regarding the input. The servo curve and blank holder force (BHF) operate as control instances. Within the two application scenarios, a reactive and a preventive solution are characterized. As a first step toward the implementation of the CPPS, material inflow, and force sensors are installed and tested in an industrially relevant deep drawing tool.

Accuracy of stretch flange formability prediction by considering strain gradient for actual car body parts

The effect of the strain gradient on the stretch flange deformation limit of steel sheets was investigated by hole expansion tests under various forming conditions and by FEM forming simulations. The hole expansion ratio was changed by changing the initial hole diameter and punch shapes. This study clarified the fact that deformation limit strain increases, as it does not depend on the initial hole diameter or punch shape, and thus the strain gradient increases. The deformation limit thickness strain of the stretch flange portion could be changed by changing the strain gradient. These results suggest that the formability of the stretch flange deformation area should be determined from not only the maximum principal strain but also the strain gradient. Then, the accuracy of stretch flange formability prediction by considering the strain gradient for actual car body parts in mass production was investigated. The maximum principal strain and the strain gradient of the parts were calculated by FEM or measured in the press part. These results suggest that the formability of the stretch flange deformation area for actual car body parts could not be predicted by not only the maximum principal strain or the thickness reduction, but also the conventional FLD. This investigation verified the accuracy of stretch flange formability prediction by considering the strain gradient for actual car body parts.

Numerical Investigation of the Corrosion and Fatigue Behavior of Clinched Joints

AbstractThe application area of clinched joints is steadily increasing. They are vastly used in the automotive industry to join car body parts. Clinched components are often exposed to different environmental conditions as well as cyclic mechanical loading. Those environments are common originators of multiple corrosion and material fatigue phenomena. It is thus important to include possible environmental factors into the design of the joining process, to ensure full functionality of the clinched joint during its service life. In order to estimate material failure in such joints, several experimental and numerical tools are available. However, the literature provides little knowledge about the combined influence of corrosion and high‐cycle fatigue on the service life of clinched joints. In this work, a modeling framework is given that combines the effects of corrosion products formation on the fatigue life of clinched EN AW‐6014/HCT590X+Z joints by means of numerical simulations.

Study on the physicomechanical, fracture-deformation, interface-adhesion, and water-absorption properties of twill fabric cotton-bamboo/epoxy composites

Natural fibre reinforced composites are being used in a variety of industries. Epoxy matrix composites reinforced with woven bamboo-cotton fibre has been fabricated via., hand lay-up technique and compression moulding technique. In the fabrication of the composite panels, the number of layers varied from 8 to 14 according to the weight of the fabric. The tensile, bending, impact, compression, water-absorption, and ILS properties for the developed composites have been tested or examined. SEM characterization was being used to examine the fractured morphology and assess interface-strength of the developed composites. It was found that increasing the number of fibre layers improved the composites' physico-mechanical properties. Due to the micro-voids, detachment, and hydrophilic nature of natural fibres, the cotton/bamboo twill fabric reinforced composites absorb the most water. In addition, the results have demonstrated that the fibre matrix debonding, which was actually the result of a weak-bonding amid the fibre and matrix, was the cause of the escalated water absorption behavior. Hence, the fabricated composites are suitable for the applications of moderate load bearing, including automobile body parts and structural components that require sufficient strength.

Exploring Properties of Short Randomly Oriented Rattan Fiber Reinforced Epoxy Composite for Automotive Application

ABSTRACT The acrylic acid treated rattan fiber reinforced epoxy (RF/Epoxy) composite has been fabricated by taking various weight percentages (5, 10, 15, 20, and 25 wt%) of fibers using hand layup followed by compression molding technique. The optimum fiber loading has been determined by regression analysis and it is found that 18 wt% of rattan fiber gives maximum tensile strength. The interaction of rattan fiber with epoxy matrix has been studied by Fourier transform infrared spectroscopy and X-ray diffraction. Scanning electron microscope (SEM) has been used to study the morphology of chemically modified rattan fiber and RF/Epoxy composite. The mechanical, thermal, and dynamic mechanical thermal properties of 18 wt% RF/Epoxy composite have been studied as per ASTM standards. From the results, it is observed that RF/Epoxy composite gives best properties at optimum (18 wt%) fiber loading. The maximum tensile strength and flexural strength of the composite are found to be 47.5 and 121 MPa, respectively, which is better in comparison to other natural fiber composites used for manufacturing different automobile body parts. Hence, it can be concluded that 18 wt% RF/Epoxy composite can be considered as a potential candidate for automotive body parts.

Study of Transition Areas in Press-Hardened Steels in a Combined Tool for Hot and Cold Forming.

Press-hardening, also known as hot stamping, is a manufacturing process for producing car body parts that must meet the high demands of their mechanical properties and safety parameters. Moreover, these components often require different mechanical properties in different parts of the component. This work presents the press-hardening process in a special combined tool where one half of the tool is heated and the other half is cooled. The cooled part has been 3D printed due to the complexity of the internal cooling channels. The aim of this work is to investigate the variation of the microstructures in the sheet metal and the mechanical properties in relation to the cooling process in the tool and to determine the transition area where these properties cross over. Two steels were chosen for the experiment. The most commonly used steel 22MnB5, and an experimental high-strength steel with 0.2% C alloyed with manganese and aluminium. A temperature of 425 °C was set in the heated part of the tool, and different holding times in the tool were tested. In the heated part of the tool, a bainitic structure with a fraction of ferrite and retained austenite was formed, while in the quenched part of the tool, a martensitic transformation was promoted due to rapid cooling. In addition to microscopic analyses, mechanical tests and hardness measurements were also performed.

The TRANSIT project: innovation towards train pass-by noise source characterisation and separation tools

In TRANSIT, experimental methods are developed to separate and characterise noise sources on moving trains. Improved microphone array techniques allow quantification of sound power and directivity. Source separation methods based on the Pass-By Analysis method, Advanced Transfer Path Analysis and the TWINS model are also developed. For trains at standstill, new test methods are developed to quantify noise transmission paths from sources to the standard microphone positions accounting for installation effects. Several measurement campaigns are used to demonstrate and verify these methods. In addition, innovative materials and methods are investigated for improved sound comfort in trains. Approaches considered include optimal sound absorption at the source, attenuation along ducts for air conditioning systems and innovative meta-structure designs for the car-body parts.

Intelligent Detection and Classification of Surface Defects on Cold-Rolled Galvanized Steel Strips Using a Data-Driven Faulty Model With Attention Mechanism

Abstract In the production of cold-rolled galvanized steel strips used for stamping car body parts, the in-situ and real-time defect detection is crucial for quality control, in which various types of defects inevitably occur. It is challenging to improve the accuracy of defect detection and classification by appropriate means to assist the manual screening process better. Defects under actual production conditions are often not prominent enough in defect characteristics, and there may be a significant similarity between different defect categories. To eliminate this weakness, we propose a data-driven deep learning approach named steel surface faulty detection attention net (SSFDANet) that uses images of the galvanized steel surfaces as input to identify whether the product is qualified and automatic classification of defect types instantaneously. This method can shorten product inspection time and improve the production line automation efficiency. In addition, the attention mechanism is utilized to enhance the performance of SSFDANet. Compared with the baseline ResNet, SSFDANet achieves a noticeable improvement in classification accuracy on test data. The well-trained model can successfully show an improved performance than the baseline models on the multiple types of faulty. Enhanced by SSFDANet with high classification accuracy, the defect rate of products is significantly reduced, and the production speed of the production line is significantly improved. Future prospective studies that are inspired by this article are also discussed.

Research of Mechanical Properties of the Aluminium Alloy Amag 6000 Under the Plane Stress State Conditions

Today's demands directly encourage to utilize the light alloy materials in industrial production. In the automotive industry, there is an increasing tendency to reduce the total weight of the car and thus also the weight of the individual car-body parts. A correct description of the material deformation behaviour with respect to the different stress states is very necessary for the own possibility to use these materials in the production. This paper describes a measurement of the mechanical properties and deformation behaviour of aluminium alloy Amag 6000 under the plane strain conditions. Thus these properties are monitored and evaluated by means of the plain strain tensile test. In this case, the plane strain is achieved by the shape concept of the testing specimen, which is loaded by the uniaxial tensile stress state using a standard testing device. The determined mechanical properties and the resulting stress-strain curves of the material under the plain stress state can be further used at defining material models for a more accurate description of the material deformation process during the sheet metal forming process.

Influence of Friction on the Formability of Fe-Zn-Coated IF Steels for Car Body Parts

This paper presents the formability results of galvanized Zn-Fe-based interstitial-free (IF) “galvanneal” steel sheets with different degrees of alloying. The Fe content of the Zn-Fe coatings was determined by titration method and the phase composition of the coatings was determined by raster electron microscopy with EDX analyzer. A deterioration of the adhesion of the Fe-Zn coating to the substrate was observed in the pre-alloyed coating. The applied modes of annealing and smooth rolling after the surface galvanization resulted in a change in the surface microgeometry parameters Ra and Pc. The suitability of the surface microgeometry of the used Zn-Fe-coated sheets was assessed using control diagrams and the capability indexes Cpk with respect to the defined specifications. The coefficient of friction was determined by dry friction cup test, and using Anticorit lubricant and microtene film as lubricants. With increasing Fe content in the coating, a slight increase in friction coefficient values was observed—a slight deterioration in formability. The results obtained indicate that for car body surface parts, the Fe content of the Zn-Fe coating should range from 7% to 12%.

Analysis of multi-thickness plates by successive forging

The demand of lightweight vehicles is increasing due to environmental issues. To fulfill this demand, tailored blanks are utilized in the production of vehicles. Tailored blanks have been used in car body part such as center pillar and roof rails for the purpose of weight reduction where thickness distribution is being optimized. Tailored blanks are commonly produced by welding and rolling. Tailor-rolled blanks produced by rolling process has continuous thickness transition as compared to tailor-welded blanks and hence stress concentration is reduced. However, the rolling process utilized in the production of tailor-rolled blanks are not commonly available. Hence successive forging process was developed to control the thickness distribution by mean of presses. In this study, successive forging was utilized to control the thickness distribution of a plate by using upper and lower punches. The stroke is constant while the punch was designed to has three different thicknesses to achieve different thickness reduction. The feeding interval was varied for 10 mm and 17 mm. The thickness distribution, material flow and forging load for both feeding interval were analysed and compared with the conventional forging process using finite element analysis.

Mechanical, fatigue and DMA behaviour of high content cellulosic corn husk fibre and orange peel biochar epoxy biocomposite: A greener material for cleaner production

In this study a high toughness biocomposite cleaner production material for advanced engineering applications was developed. The prime objective of this research activity was to understand how the additions of high cellulose content corn husk fibre and sustainable orange peel biochar on static and dynamic mechanical properties of the epoxy based clear production composite material. The fibre and biochar was prepared from agriculture waste and treated prior to biocomposite preparation. The composites were prepared using hand layup process and post cured. According to the results, the composite with 2 vol% orange peel biochar along with 40 vol% of high content cellulosic corn husk fibre exhibited a highest storage modulus and the lowest loss factor. The presence of cellulose content on fibre offered high toughening effect and reduced the extreme brittleness of epoxy. In addition to this the composite has maximum mechanical properties with 166, 191 MPa of tensile and flexural strength, 6.64 J of impact toughness, 91 of shore-D hardness and 28,554 of fatigue life counts. The scanning electron microscope images revealed highly adhered fibre-epoxy matrix interface. Being high load-bearing capacity and biodegradability these composites could be a choice in the manufacturing of automobile body parts, sporting goods and aircraft.