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Journal Article

Study of the Sliding Door Shaking Problem and Optimization Based on the Application of Euler’s Spiral

2018-10-03
Abstract This study focuses on the sudden shaking phenomenon of a sliding door passing through a corner. This phenomenon requires attention because shaking during movement can lead to a harsh operation feeling and a short service life. An experiment based on a test setup was conducted, and the sudden change in the acceleration of a sliding door panel was measured. Based on multi-body dynamics (MBD) analysis and a rigid-flexible coupled model of the sliding door system, the cause of the sudden shaking was determined to be the discontinuous curvature of the middle rail trajectory. A transition curve was proposed as the solution for the discontinuous curvature, and Euler’s spiral was applied in the redesign of the middle rail trajectory. Verified by simulations, the results exhibit considerable improvement in sliding door movement stability, with large reductions in the maximum center of mass (CM) acceleration and guide roller impact force.
Journal Article

Study of Temperature Distribution and Parametric Optimization during FSW of AA6082 Using Statistical Approaches

2019-02-01
Abstract In this article, Al-Mg-Si-Mn alloy (AA6082) is butt joined by employing friction stir welding (FSW). The mechanical and metallurgical properties of joints are analyzed by conducting tensile and microhardness testing, respectively. To measure the temperature at different locations, eight thermocouples (L-shaped k-type) are placed at equal distance from the centerline. Least square method attempts to calculate the temperature at the centerline of joints. The process parameters are also optimized using Taguchi’s five-level experimental design. The optimum process parameters are determined, employing ultimate tensile strength (UTS) as a response parameter. A statistical test “analysis of variance” is used to check the adequacy of the model. It has been observed that rotational speed and feed rate are the predominant factors for UTS and microhardness.
Journal Article

Response of Austempering Heat Treatment on Microstructure and Mechanical Property in Different Zones of As-Welded Ductile Iron (DI)

2018-05-08
Abstract Sound ductile iron (DI) welded joints were performed using developed coated electrode and optimized welding parameters including post weld heat treatment (PWHT).Weldments consisting of weld metal, partially melted zone (PMZ), heat affected zone (HAZ) and base metal were austenitized at 900 °C for 2 hour and austempered at 300 °C and 350 °C for three different holding time (1.5 hour, 2 hour and 2.5 hour). In as-weld condition, microstructures of weld metal and PMZ show ledeburitic carbide and alloyed pearlite, but differ with their amount. Whereas microstructure of HAZ shows pearlite with some ledeburitic carbide and base metal shows only ferrite.
Journal Article

Residual Stresses and Plastic Deformation in Self-Pierce Riveting of Dissimilar Aluminum-to-Magnesium Alloys

2018-05-08
Abstract In this work, the complex relationship between deformation history and residual stresses in a magnesium-to-aluminum self-pierce riveted (SPR) joint is elucidated using numerical and experimental approaches. Non-linear finite element (FE) simulations incorporating strain rate and temperature effects were performed to model the deformation in the SPR process. In order to accurately capture the deformation, a stress triaxiality-based damage material model was employed to capture the sheet piercing from the rivet. Strong visual comparison between the physical cross-section of the SPR joint and the simulation was achieved. To aid in understanding of the role of deformation in the riveting process and to validate the modeling approach, several experimental measurements were conducted. To quantify the plastic deformation from the piercing of the rivet, micro hardness mapping was performed on a cross-section of the SPR joint.
Journal Article

Parameter Sensitivity and Process Time Reduction for Friction Element Welding of 6061-T6 Aluminum to 1500 MPa Press-Hardened Steel

2018-12-14
Abstract Conventional fusion joining techniques pervasive in the automotive industry are unable to effectively join aluminum and steel. To solve this problem, a technique termed friction element welding (FEW) has been developed, which is able to join any nonferrous top sheet material to a base steel layer, independent of the base layer strength. FEW works on the same principles as friction welding, as a steel element is pushed and rotated against a nonferrous top sheet to create frictional energy which softens and flows the material around the fastener shaft and under the fastener head, exposing the steel below. The element then contacts the steel and bonds through traditional friction welding. FEW is a four-step process (penetration, cleaning, welding, compression), with two to four parameters (endload, spindle speed, displacement transition, time transition) controlling each step.
Journal Article

Optimization of WEDM Cutting Parameters on Surface Roughness of 2379 Steel Using Taguchi Method

2018-04-07
Abstract Surface roughness is one of the important aspects in producing quality die. Wire Electrical Discharge Machine (WEDM) is commonly used in tool and die fabrication, since the die material is usually difficult to cut using traditional metal removal processes. Selection of optimal WEDM cutting parameters is crucial to obtain quality die finish. In this study, 2379 steel which equivalent to SKD 11 is selected as the die material. Four main WEDM cutting parameters, namely, pulse duration (A), pulse interval (B), servo voltage (C), ignition pulse current (D), were experimentally evaluated for both main cut and multiple trim cuts using Taguchi Method. Taguchi’s L9 orthogonal array is employed for experimental design and analysis of variance (ANOVA) was used in recognizing levels of significance of WEDM cutting parameters.
Journal Article

Numerical Prediction of Various Failure Modes in Spotweld Steel Material

2018-05-11
Abstract Crash simulation is targeted mainly carried out by the collision regulations FMVSS simulation to identify problems in vehicle structures. A modern car structure consist of several thousand weld-type connections, and failure in these connections plays an important role for the crashworthiness of the vehicle. Therefore accurate modeling of these connections is important for the automotive industry in order to improve Vehicle collision characteristics. In pursuit of this key requirement, we introduced a proper methodology for the development detailed weld model to study structural response of the weld when the applied load range is beyond the yield strength. Three-dimensional finite element (FE) models of spot welded joints are developed using the LS-Dyna FE code. In this process the force estimation model of spot welds is explained. The results from this paper shows good agreement between the simulations and the tests.
Journal Article

Mixture Distributions in Autonomous Decision-Making for Industry 4.0

2019-05-29
Abstract Industry 4.0 is expected to revolutionize product development and, in particular, manufacturing systems. Cyber-physical production systems and digital twins of the product and process already provide the means to predict possible future states of the final product given the current production parameters. With the advent of further data integration coupled with the need for autonomous decision-making, methods are needed to make decisions in real time and in an environment of uncertainty in both the possible outcomes and in the stakeholders’ preferences over them. This article proposes a method of autonomous decision-making in data-intensive environments, such as a cyber-physical assembly system. Theoretical results in group decision-making and utility maximization using mixture distributions are presented. This allows us to perform calculations on expected utility accurately and efficiently through closed-form expressions, which are also provided.
Journal Article

Machining Quality Analysis of Powertrain Components Using Plane Strain Finite Element Cutting Models

2018-05-07
Abstract Finite Element Analysis (FEA) of metal cutting is largely the domain of research organizations. Despite significant advances towards accurately modelling metal machining processes, industrial adoption of these advances has been limited. Academic studies, which mainly focused on orthogonal cutting, fail to address this discrepancy. This paper bridges the gap between simplistic orthogonal cutting models and the complex components typical in the manufacturing sector. This paper outlines how to utilize results from orthogonal cutting simulations to predict industrially relevant performance measures efficiently. In this approach, using 2D FEA cutting models a range of feed, speed and rake angles are simulated. Cutting force coefficients are then fit to the predicted cutting forces. Using these coefficients, forces for 3D cutting geometries are calculated.
Journal Article

Joint Mechanism and Prediction of Strength for a Radial Knurling Connection of Assembled Camshaft Using a Subsequent Modeling Approach

2018-06-25
Abstract Knurling joint applied in assembled camshaft has developed rapidly in recent years, which have exhibited great advantages against conventional joint methods in the aspects of automation, joint precision, thermal damage, noise, and near net shape forming. Both quality of assembly process and joint strength are the key requirements for manufacturing a reliable assembled camshaft. In this article, a finite element predictive approach including three subsequent models (knurling, press-fit and torsion strength) has been established. Johnson-Cook material model has been used to simulate the severe plastic deformation of the material. The residual stress field calculated from the knurling process was transferred as initial condition to the press-fit model to predict the press-fit load. The predicted press-fit load, torque strength and displacement of cam profile before failure were calculated.
Journal Article

Investigation of Residual Stresses in Cold-Formed Steel Sections with Nonlinear Strain-Hardened Material Model

2018-09-17
Abstract In this article, forming residual stresses in cold-formed small-radius corner sections are analytically predicted with the consideration of the shift in the neutral axis and the nonlinear strain-hardened material model. The predicted forming stress results in the transverse direction show a trend of increased compressive residual stress in the outer surface and reduced tensile residual stress in the inner surface as the corner radius-to-thickness ratio increases in small-radius bends. In the longitudinal direction, there is no significant change in the residual stress values observed in the inner and outer surfaces with respect to an increase in corner radius-to-thickness ratios. But a considerable decrease in compressive residual stress and an increase in tensile stress values are observed in the midsection areas with an increase in the corner radius-to-thickness ratio.
Journal Article

Influence of the Friction Coefficient in Self-Pierce Riveting Simulations: A Statistical Analysis

2018-05-08
Abstract In this work, optimal modeling parameters for self-pierce riveting (SPR) were determined using a factorial design of experiments (DOE). In particular, we show statistically how each of the calibrating parameters used in modeling the SPR process through nonlinear finite element modeling can drastically change the geometry of the joint. The results of this study indicate that the degree of interlock, which is a key feature of a sound joint, is largely influenced by the friction between the die and bottom sheet as well as the friction between the rivet and top sheet. Furthermore, this numerical study also helped elucidate the role of friction in SPR and sheds light on how coatings with diverse friction coefficients can affect material deformation and ultimately structural integrity of the joint.
Journal Article

Improving Hole Expansion Ratio by Parameter Adjustment in Abrasive Water Jet Operations for DP800

2018-09-17
Abstract The use of Abrasive Water Jet (AWJ) cutting technology can improve the edge stretchability in sheet metal forming. The advances in technology have allowed significant increases in working speeds and pressures, reducing the AWJ operation cost. The main objective of this work was to determine the effect of selected AWJ cutting parameters on the Hole Expansion Ratio (HER) for a DP800 (Dual-Phase) Advanced High-Strength Steel (AHSS) with s0 = 1.2 mm by using a fractional factorial design of experiments for the Hole Expansion Tests (HET). Additionally, the surface roughness and residual stresses were measured on the holes looking for a possible relation between them and the measured HER. A deep drawing quality steel DC06 with s0 = 1.0 mm was used for reference. The fracture occurrence was captured by high-speed cameras and by Acoustic Emissions (AE) in order to compare both methods.
Journal Article

Impact of Dynamic Characteristics of Wheel-Rail Coupling on Rail Corrugation

2019-07-02
Abstract To gain a better understanding of the characteristics of corrugation, including the development and propagation of corrugation, and impact of vehicle and track dynamics, a computational model was established, taking into account the nonlinearity of vehicle-track coupling. The model assumes a fixed train speed of 300 km/h and accounts for vertical interaction force components and rail wear effect. Site measurements were used to validate the numerical model. Computational results show that (1) Wheel polygonalisation corresponding to excitation frequency of 545-572 Hz was mainly attributed to track irregularity and uneven stiffness of under-rail supports, which in turn leads to vibration modes of the bogie and axle system in the frequency range of 500-600 Hz, aggregating wheel wear. (2) The peak response frequency of rail of the non-ballasted track coincides with the excitation frequency of wheel-rail coupling; the resonance results in larger wear amplitude of the rail.
Journal Article

Evaluation of Weldability and Mechanical Properties in Resistance Spot Welding of Ultrahigh-Strength TRIP1100 Steel

2018-12-14
Abstract To use steel in the automotive industry, it is essential to characterize its weldability and weldable current range. The resistance spot welding of ultrahigh-strength transformation-induced plasticity steel (TRIP1100 steel), which is a candidate for application in an autobody, is studied here. Identifying the weld lobe and the best welding parameters and studying the microstructure and mechanical properties of the spot welds of TRIP steel were done using metallurgical techniques, tensile-shear and cross-tension tests, and fractography and microhardness testing. A partial fracture analysis (stepwise tensile test) showed a crack initiated at the tip of the notch. The best range for welding current was found to be 10-12 kA. The diameter of the weld nugget increased up to 5√t; however, it was found that at least 15% increase in the diameter of the weld nugget can result in a more favorable failure. The ductility ratio was found to be less than 0.5 for ultrahigh-strength steel.
Journal Article

Erosion Wear Response of Linz-Donawitz Slag Coatings: Parametric Appraisal and Prediction Using Imperialist Competitive Algorithm and Neural Computation

2019-03-14
Abstract Slag, generated from basic oxygen furnace (BOF) or Linz-Donawitz (LD) converter, is one of the recyclable wastes in an integrated steel plant. The present work aims at utilization of waste LD slag to develop surface coatings by plasma spraying technique. This study reveals that LD slag can be gainfully used as a cost-effective wear-resistant coating material. A prediction model based on an artificial neural network (ANN) is also proposed to predict the erosion performance of these coatings. The 2.27% error shows that ANN successfully predicts the erosion wear rate of the coatings both within and beyond the experimental domain. In addition to it, a novel optimization algorithm called imperialist competitive algorithm (ICA) is used to obtain minimum erosion wear rate of 12.12 mg/kg.
Journal Article

Effect of Welding Parameters on the Microstructure and Tensile Properties of Friction Stir-Welded DP600 Steel

2019-07-02
Abstract The aim of this study was to investigate the effect of friction stir welding (FSW) parameters on the microstructure and tensile properties of dual-phase (DP) steels. In this regard, DP600 steel sheets were joined using FSW under different tool rotational (ω) and transverse speeds (v). Optical microstructure of the stir zone exhibited a mixture of bainite, Widmanstatten ferrite, grain boundary ferrite, and ferrite-carbide (FC) aggregate, which resulted in a hardness increase compared to the base metal (BM). The fraction of bainite and Widmanstatten ferrite in the stir zone increased with increasing the welding heat input. Formation of a softened zone in the subcritical area of the heat-affected zone (HAZ) resulted in the reduction of ultimate tensile strength and total elongation compared to those for the BM, while the yield strength was only marginally affected.
Journal Article

Determination of Influence of Parameters on Undercarriage Shock Absorber

2018-12-31
Abstract The simple oleo pneumatic (shock absorber) model was developed using the available computational fluid dynamics (CFD) program to understand how various parameters influence the performance of the undercarriage shock absorber. The study is divided into two parts: first part is focused on the influence of orifice geometry and the second part of the study is focused on the other parameters including chamber geometry. Both the studies are carried out using design of experiments (DOE) for the same output characteristics (response). In this study, the impacts on the flow behavior due to the orifice shapes are also studied. The results and the other outcomes are shown in the form of DOE parameters such as main effect plots and interaction plots.
Journal Article

Classification of Contact Forces in Human-Robot Collaborative Manufacturing Environments

2018-04-02
Abstract This paper presents a machine learning application of the force/torque sensor in a human-robot collaborative manufacturing scenario. The purpose is to simplify the programming for physical interactions between the human operators and industrial robots in a hybrid manufacturing cell which combines several robotic applications, such as parts manipulation, assembly, sealing and painting, etc. A multiclass classifier using Light Gradient Boosting Machine (LightGBM) is first introduced in a robotic application for discriminating five different contact states w.r.t. the force/torque data. A systematic approach to train machine-learning based classifiers is presented, thus opens a door for enabling LightGBM with robotic data process. The total task time is reduced largely because force transitions can be detected on-the-fly. Experiments on an ABB force sensor and an industrial robot demonstrate the feasibility of the proposed method.
Journal Article

Carbon Fiber/Epoxy Mold with Embedded Carbon Fiber Resistor Heater - Case Study

2018-04-07
Abstract The paper presents a complete description of the design and manufacturing of a Carbon Fiber/epoxy mold with an embedded Carbon Fiber resistor heater, and the mold performances in terms of its surface temperature distribution and thermal deformations resulting from the heating. The mold was designed for manufacturing aileron skins from Vacuum Bag Only prepreg cured at 135°C. The glass transition temperature of the used resin-hardener system was about 175°C. To ensure homogenous temperature of the mold working surface in the course of curing, the Carbon Fiber heater was embedded in a layer of a highly heat-conductive cristobalite/epoxy composite, forming the core of the mold shell. Because the cristobalite/epoxy composite displayed much higher thermal expansion than CF/epoxy did, thermal stresses could arise due to this discrepancy in the course of heating.
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