bluuebunny/crossref_metadata_2025_split huggingface dataset:
The study on the relationship between the friction characteristic and the formability of the automotive steel sheet during the stamping process
Authors: Kim J Y , Yoon S C , Hyun J S , Lee M.-G. 
Published: November 2020

Abstract
This study aims to analyse the formability characteristics by friction characteristics of automotive steel sheets to improve sheet forming during the stamping process. During the stamping operation, the steel sheet is pushed into the tool surface, a complex phenomenon occurs, and many parameters interact. Therefore, automotive steel researchers want to optimize the friction of automotive steel sheets to improve the forming process, such as drawing ratio limit, dome height limit, cup drawing test, etc. In addition, in this study, the finite element method is used in combination with a numerical solution to present the friction behavior of high strength steel sheets in automobiles, taking into account the operating deformation mechanism during the formability test.
Crystal Plasticity Simulation of the AZ31B Alloy Sheet under Uniaxial Deformation Considering Grain Boundary Sliding
Authors: Li Zihan , Li Dayong , Tang Weiqin , Wang Huamiao , Peng Yinghong 
Published: November 2020

Abstract
The aim of present work is to develop a crystal plasticity modeling approach to integrate slip, dynamic recrystallization (DRX) and grain boundary sliding (GBS) for simulating the deformation and texture evolution of magnesium alloys deformed at the high temperature. A GBS model is developed to evaluate strain and grains’ rotation induced by GBS, and implemented into the polycrystal plasticity framework VPSC. The VPSC-DRX-GBS model can well reproduce the stress-strain curves and texture evolution. The calculated GBS contribution ratio in tension is obviously higher than in compression due to easier cavity nucleation on grain boundaries under tensile creep-aging conditions. The significantly different texture development in tension and compression deformation due to GBS is well reproduced by the proposed model.
Effects of Lubrication and Temperature on the Tribological Behavior of a Magnesium Alloy under Contact Sliding
Authors: Wu C H , Zhang L C , Qu P L , Li S Q , Jiang Z L , Wang Y 
Published: November 2020

Abstract
This paper aims to experimentally investigate the effects of lubrication and temperature on the tribology behavior of a magnesium alloy, AZ31B, sliding against 86CrMoV7. The effects of lubricant additives, including oil film improver and extreme pressure (phosphorous donors), on the friction coefficient and surface morphology in the sliding zone were studied. It was found that the relatively lower surface hardness of the material significantly affects the wear of the materials in the sliding zone. The lubricant with oil film improver and extreme pressure can reduce friction. Temperature rise brings about lower friction due to the lubricant additives.
Nondestructive detection of the interfacial failure of steel-polymer sandwich composites during forming process
Authors: Yang Jewook , Han Sungjin , Yu Woong-Ryul 
Published: November 2020

Abstract
Steel-polymer composites have low density, high specific flexural stiffness and vibration damping properties over other metal materials. However, the weak interfaces between steel and polymer sheet are the typical locations where the failure occurs. Furthermore, interfacial failure is a fatal reason of the degradation of mechanical properties. Therefore, predicting interfacial failure of the final product is an important technology in commercialization of steel-polymer composites. In this study, we built forming limit diagram (FLD) based on two different failure modes: failure of the bottom skin steel and interfacial failure between the skin steel and core polymer. Acoustic emission (AE) technique was conducted to observe the interfacial failure moment. Peak frequency was found to be the key feature to distinguish interfacial failure. Peak frequency band that indicates interfacial failure was from 300 kHz to 500 kHz. This peak frequency band made it possible to build FLD considering the interfacial failure.
Formability simulation of steel-polymer sandwiched composites considering the adhesion strength
Authors: Han S , Yang J , Yu W-R 
Published: November 2020

Abstract
Developed to increase the energy efficiency of automobiles, steel-polymer sandwiched composites are attracting attention due to their lightweight and multi-functionality and are being actively researched recently. In order to apply those composites to industrial fields, their formability must be investigated in order to prevent the degradation of mechanical properties of the composites during the forming process in various shapes. Therefore, experimental studies have recently been conducted to evaluate the formability of the composites. However, there are few studies to predict the formability of the composites considering the mechanical properties of core polymer and interfacial properties. In this study, formability tests were carried out for evaluating the forming limit diagram of the composites. Also, the formability test of the composites was simulated considering the viscoplastic properties of the core polymer using Arruda-Boyce model and the interfacial properties using the cohesive zone model. Finally, the effect of the interfacial adhesion on the formability of the composites was investigated, from which an optimal condition was explored for the interfacial adhesion strengths that can ensure the formability of the composites for specific applications.
Fuzzy modelling of surface scratching in contact sliding
Authors: Li Wei , Zhang Liangchi , Chen Xinping , Wu Chuhan , Cui Zhenxiang , Niu Chao 
Published: November 2020

Abstract
This paper presents a fuzzy modelling technique for the prediction of surface scratching problems encountered in sheet metal forming processes involving contact sliding. To generalize the contact conditions with die-sheet interactions in such processes, ball-on-disk sliding investigations, including modelling and experiment, were carried out with various ball diameters to mimic the die-contact radii effect and a range of contact loads to simulate the effect of contact stress variation experienced in forming processes. Because die-contact radius, surface roughness and contact stress changes cannot be exactly defined in a practical production process, in the modelling of the ball-on-disk configuration, ball diameter, normal load, surface roughness, sliding cycles and extent of scratching depth in a metal sheet surface were treated as fuzzy variables for the prediction. Based on the comparison between predictions with the relevant experimental measurements, it can be seen that the fuzzy modelling technique developed in this paper can predict very well the surface scratching.
Numerical analysis of the bulge test in temperature for the EN AW 6061-T6 sheet
Authors: Boyer A , Germain L , Laurent H , Neto D M , Oliveira M C 
Published: November 2020

Abstract
The equibiaxial expansion test allows the evaluation of the mechanical behaviour of materials on a large strain range. In this context, a bulge test device was developed which enables a fast heating stage, a uniform heating of the specimen, and the control of the temperature during the expansion phase. Although during the test, the temperature is uniform at the pole of the cap, the contact with the tools imposes a gradient along its radius. Therefore, a thermo-mechanical model of the bulge test was built in order to improve knowledge about the influence of the temperature gradient in the evaluation of the hardening behaviour at the pole of the cap. Numerical simulations of the bulge test were performed considering both isothermal and anisothermal conditions. The anisothermal conditions considered reproduce the temperature gradient observed experimentally. This enables the analysis of the impact of the thermal gradient in the stress versus strain evolution at the pole of the cap and the comparison with experimental results.
Development of inline closed-loop vibration control in progressive die stamping using finite element simulation
Authors: Steinlehner F , Ott M , Budnick D , Weinschenk A , Laumann S , Worswick M , Volk W 
Published: November 2020

Abstract
Modern progressive dies are increasingly equipped with integrated sensors and actuators, thus enabling an improvement of the manufacturing process and an inline monitoring of the component quality. The design of the tooling is determined at an early stage and is largely based on the desired product and the specific production stages such as blanking, forming and punching. Nevertheless, malfunctions such as strip vibrations cannot always be foreseen and may occur during operation time, which may lead to reduced component quality and in the worst case to component collision or a damage of the tooling. Therefore, complex reworking or a reduction of the stroke rate and thus lower output quantity are often necessary for a reliable and stable process. Strip vibrations are often caused by the highly dynamic transportation of the strip in the tool and can have various causes. Among others, passive tooling components such as spring-loaded, hard stop limited strip lifter can be the cause of such vibrations. Strip lifter are always necessary when three-dimensional components are produced and have to be lifted out of the die for the feeding phase. The feeding phase takes place between two strokes of the stamping process. This work is aiming for a control strategy to suppress strip vibrations in various progressive die stamping processes based on closed-loop controlled active strip lifter. These strip lifter combine the spring-loaded passive standard strip lifter with an additional PID-controlled actuator. Taking the dynamics of the flexible strip during operation into account, a Finite Element Analysis (FEA) model of a progressive die tooling system is created. For the design of the control algorithm, the FEA model is connected to an environment for model-based design in a co-simulation. This approach allows modelling the influence of arbitrary control parameter settings on the movement curve of the strip, aiming for an increased stroke rate.
Axial formation and cross-section distortion control for stretch bending based on batch simulations
Authors: Lu Kaijun , Luo Jianxi , Zou Tianxia , Li Dayong , Peng Yinghong 
Published: November 2020

Abstract
Stretch bending is a widely used to form long parts with a definite cross-section shape. The forming path is an effective way to eliminate the defects such as springback, distortion when the material and the die shape are determined. In this study, the stretch bending path is represented by a curve function of bending angle and stretch length. To simplify the path optimization problem, the path is represented by 4 parameters, including a newly introduced parameter of total stretch. Based on the batch simulation results, it is found that the axial springback and cross section distortion are primarily controlled by total stretch, bending angle and pre-stretch proportion. When the total stretch is determined, the different distribution schemes for pre-stretch, bending stretch and post-stretch in total stretch have a similar effect on forming quality except the schemes with extremely large proportions of pre-stretch. In most cases, with the total stretch length in growth, the axial springback decreases dramatically at first and then stays constant while the section distortion continues to rise, indicating that the optimal forming path is around the elbow point in the relationship curve of total stretch and springback angle. The optimal path is verified by experiments. It is shown that for a workpiece with determined material and die shape, the optimal path to minimize axial rebound and section distortion simultaneously does exit and the study provide an effective way to obtain it.
Springback and end flare compensation in flexible roll forming
Authors: Abeyrathna B , Ghanei S , Rolfe B , Taube R , Weiss M 
Published: November 2020

Abstract
Flexible roll forming enables the forming of complex automotive components from Advanced High Strength Steels (AHSS) and Ultra High Strength Steel (UHSS) but common shape defects such as end flare and springback occur and need to be compensated. In flexible roll forming a pre-cut blank is fed through a set of rolls which are computer numerically controlled (CNC) to follow the 3D contour of the part. The company, dataM Sheet Metal Solutions, have established a new 3D flexible roll forming facility at Deakin University which allows the manufacture of flexible roll formed prototypes.
In this study, Deakin’s flexible roll forming facility is employed to implement an approach to overcome springback and end flare defects in a flexible roll formed automotive component of variable width. To do this, the flexible roll forming process is simulated using the commercial software package Copra FEA. Non-uniform springback due to end flare is observed and a variable overbending approach developed and implemented to overcome this defect. Experimental validation is performed on Deakin’s flexible roll forming facility and the results suggest that the flexible overbending approach can be used to control final shape in flexibly roll formed components.
Deformation characteristics in 3D free-bending forming of complex spiral tubes
Authors: Abd El-Aty A , Wei W , Guo X , Wang H , Tao J , Chen H , Qin Y 
Published: November 2020

Abstract
Free-bending is a novel bending technology suitable for tube and profile bending. It can achieve accurate bending of tubes or profiles with different bending radii without die. In current study, a new theoretical analysis of a spiral tube formed by 3D free-bending is proposed to reveal the relationship between the spiral tube and the parameters of free-bending forming technology. The results obtained from the proposed theoretical analysis were compared with those achieved from FE modelling and experimentation. The maximum error of forming was less than 7%, which verified the accuracy and the reliability of the proposed theoretical model. The forming limits of the spiral tubes based on 3D free-bending were explored. It was noticed that the spiral diameter was mainly influenced by the eccentricity and the distance between the center of the bending die and the front end of the guide mechanism in the Z–direction (distance A). Furthermore, the spiral diameter is inversely proportional to the eccentricity, and directly proportional to the distance A. In addition, the screw pitch is mainly influenced, and directly proportional to the spiral diameter and the single spiral circle swing angle of the spherical bearing.
A simple device to measure bend limit of sheet metals
Authors: Deole A , Etxebarria N , Mendiguren J , Ilinich A , Weiss M 
Published: November 2020

Abstract
The analysis of bend fracture limits of sheet metals is important for the automotive industry. For high and mid-ductility materials, current methods are often unreliable due to the difficultly of detecting the initiation of a crack on the outer surface of the bend. Sophisticated techniques that rely on the strain evolution in the material are capable to detect the cracks and establish the bend limits using digital image correlation (DIC) strain measurement systems. However, these techniques are complex and sometimes impractical for industrial use. This study uses a simplified bend test technique that uses optical image processing to detect crack initiation to then determine the bend limits of aluminum alloys using a modified angled line method (MALM). The findings of this study indicate that the optical method is inconsistent in detecting the crack initiation and likely to result in a large deviation in detected the bend limits.
Crystal plasticity as complementary modelling technique for improved simulations results of anisotropic sheet metal behaviour in forming processes
Authors: Hirsiger Sebastian , Berisha Bekim , Hippke Holger , Hora Pavel 
Published: November 2020

Abstract
The accuracy of the simulation results in terms of metal sheet forming strongly depends on the capability of modelling the anisotropic material behaviour. In addition, predictive capabilities of the models are strongly influenced by the way how the constitutive model parameters are calibrated. Macroscopic models lean towards to become more complex in order to map the material behaviour more precisely. As consequence the amount and complexity of the experiments is increasing as well. In addition, it is well known that, some of the experiments, for example the equibiaxial compression test, are difficult to perform and therefore, a reasonable coupling of crystal plasticity (CP) modelling and macroscopic models is proposed. It is worth to mention that, in the domain of CP, arbitrary load cases are possible and therefore, any stress ratio of the yield criterion can be used for calibration. Prediction of anisotropic material behaviour of AA6016-T4 and DC05 sheets based on CP simulations were previously presented and compared with the macroscopic Yld2000-2d model. Their data set is now used for the calibration of the parameters of the macroscopic model, where in contrast to the classical procedure, the exponent of the yield locus is defined as a fitting parameter. The strain distributions predicted by the models have been compared with DIC-measurements of Nakajima samples. The predictive capabilities of the CP-based fitting procedure, compared to the classical fitting, are highlighted. Additionally, a comparison of the strain distribution prediction between all model variants is performed on a cruciform shaped deep drawing part. It underlines the importance of the correct prediction of the yield normal, as it is given by the crystal plasticity computation.
On the design of an air-cooling system of an IC engine block made from sheet metal
Authors: Date Prashant P , Dhonde Shubham P 
Published: November 2020

Abstract
The cast and machined automotive cylinder block and the cylinder head serve to locate and hold the combustion cylinders in place, provide for cooling channels for the combustion cylinders and damp out vibrations, besides housing allied components needed for combustion. In the present work, the authors attempt to redesign the cooling system of the engine block for manufacture from sheet metal, and reduce its weight. It is proposed to have an air-cooling system around each of the combustion cylinders using a finned cooling cylinder rotating concentric with respect to the combustion cylinder with a coolant occupying the annular gap between the combustion cylinder and the cooling cylinder. The peculiar design enables hotter air to enter the combustion cylinder thereby increasing the expected thermal efficiency and power output, besides enhancing the quality of air-fuel mixing. Manufacture of the engine block from sheet metal involves embossing flow channels into thin sheets for the coolant, or machining such channels in thick sheets, folding them over, brazing the flat surfaces between channels and brazing the fin to the periphery of the cooling cylinder.
A new technique for characterising mechanical properties of materials under hot stamping conditions
Authors: Zhang R , Lin J , Shi Z , Shao Z 
Published: November 2020

Abstract
In order to characterise mechanical properties of materials (e.g. formability) under hot stamping conditions, significant efforts have been made to the development of the biaxial tensile testing method using cruciform specimens. However, no method for necking strain determination and no cruciform specimen design have been widely accepted. In this study, a new technique for characterising mechanical behaviour of materials under hot stamping conditions has been proposed. It includes two main parts: 1) a novel spatio-temporal method for determining necking and fracture strains, and 2) a cruciform specimen design for formability evaluation using biaxial testing method. In the first part, the theoretical base of the novel spatio-temporal method has been discussed, and the method has been validated by applying to uniaxial tensile tests on AA6082 specimens. The method has also been compared with several existing popular methods, in the determination of limit strain at onset of localised necking. It is found that the novel method has greater simplicity, stability and accuracy for the determination of localised necking strain. In the second part, a proposed cruciform specimen of AA5754 has been tested under the equi-biaxial tension, and both the necking initiation location and the strain path at the location where necking initiates, have been analysed. Furthermore, the novel spatio-temporal method has been applied to the biaxial tensile test for the determination of necking and fracture strains. The results show that the designed cruciform specimen enables to initiate fracture at the centre of the specimen and realisation of linear strain path under equi-biaxial tension.
Forming limit of sheet metal in cylindrical deep drawing with a conical die
Authors: Xin Luo , Evsyukov C A , Zhongqi Yu 
Published: November 2020

Abstract
It is well-known that the use of a conical die in cylindrical deep drawing can enhance the formability compared with conventional process. The most commonly observed failure mode in the process is fracture near the punch corner or wrinkling in the flange region. In order to obtain the limiting drawing ratio (LDR), a cylindrical deep drawing including only the conical die and flat punch is discussed based on numerical simulation in the paper. A finite element model for the deep drawing with a conical die is developed, and the accuracy of the model is verified by experiments results. The investigation shows that in the cylindrical deep drawing with a conical die, the types of failure above, which can obtain for thinner sheet materials, are obviously related to the sheet thickness and the conical angle, and the optimum conical angle is also found.
Experimental Analysis of Warping Defects in Chain-die Forming Variable-width Profiles
Authors: Liang Zhenye , Zou Tianxia , Li Dayong , Xiao Hua , Shi Lei , Ding Shichao , Peng Yinghong 
Published: November 2020

Abstract
Chain-Die forming is an emerging gradual forming technology suitable to fabricate advanced high strength steel (AHSS) products. In this paper, a variable-width product was designed, and the feasibilities of chain-die forming were investigated with experiments. The results show that chain-die forming is capable of manufacturing AHSS variable-width products with good precision. However, warping defects were found in the chain-die formed variable-width products. Meanwhile, web-warping and flange-warping show a similar trend for the designed variable-width profile, and the maximum deviation of warping was quantitatively analyzed. The occurrences of warping defects are ascribed to the insufficient tensile or compressive deformation, and both web area and flange area of hat profile tend to rotate to compensate for the geometrically necessary longitudinal strain.