An Approximate Model to Calculate Foldover and Strains During Cold Upsetting of Cylinders Part I: Formulation and Evaluation of the Foldover Model

1990 ◽  
Vol 112 (3) ◽  
pp. 260-266 ◽  
Author(s):  
O. M. Ettouney ◽  
K. A. Stelson
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Approximate Model ◽  
Ring Test ◽  
Forming Limit ◽  
Cold Upsetting ◽  
Element Analysis ◽  
Forming Limit Diagrams ◽  
Volume Equations ◽  
Friction Calibration

In this paper, a new approximate model to calculate foldover of a cylinder undergoing nonuniform compression test (simple upsetting) is presented. The model is formulated using constant-volume equations and workpiece geometry. In addition to foldover, the model can be used to calculate equatorial-axial strains. This eliminates the need for inscribing grids (when determining forming-limit diagrams) on the cylinder’s free surface to find these strains. Combined with friction-calibration curves (prepared using finite-element analysis) that relate foldover to friction, the model enables one to estimate the friction coefficient. This eliminates the need for a separate test (e.g., the ring test) to determine friction or evaluate type of lubrication to be used. When compared to finite-element results and experiments, the new model showed excellent results in calculating foldover, strains, and friction coefficient.

An Approximate Model to Calculate Foldover and Strains During Cold Upsetting of Cylinders Part II: Use of the Foldover Model to Estimate Friction

1990 ◽  
Vol 112 (3) ◽  
pp. 267-271 ◽  
Author(s):  
O. M. Ettouney ◽  
K. A. Stelson
Keyword(s):  
Finite Element Analysis ◽  
Approximate Model ◽  
Ring Test ◽  
Internal Diameter ◽  
Cold Upsetting ◽  
Element Analysis ◽  
New Approach ◽  
The Finite Element Analysis ◽  
Friction Calibration ◽  
Good Agreement

This paper addresses an approach to calculate the friction coefficient during nonuniform compression of cylinders. The approach combines new friction-calibration curves (prepared using the finite-element analysis) that relate friction to workpiece shape and the foldover model from Part I. Foldover in upsetting is used in the same way that the change in internal diameter is used in the ring test to determine friction. However, the new approach has the advantage that measurements are taken directly from the workpiece. Comparisons of friction values calculated from the ring test and the new approach showed good agreement.

Determination of Friction Coefficient by Employing the Ring Compression Test

2000 ◽  
Vol 123 (3) ◽  
pp. 338-348 ◽  
Author(s):  
Hasan Sofuoglu ◽  
Hasan Gedikli ◽  
Jahan Rasty
Keyword(s):  
Finite Element ◽  
Friction Coefficient ◽  
Material Properties ◽  
Rate Sensitivity ◽  
Compression Tests ◽  
Element Analysis ◽  
Test Conditions ◽  
Calibration Curves ◽  
Ring Compression ◽  
Friction Calibration

The main objective of this research was to investigate the effect of material properties, strain-rate sensitivity, and barreling on the behavior of friction calibration curves. The compression tests were conducted to obtain the necessary material properties for the finite element analysis. A series of ring compression tests were then conducted in order to determine the magnitude of the friction coefficient, μ. The experiments were first conducted for the modeling materials, namely, white and black plasticine and later on, for aluminum, copper, bronze, and brass. The experiments were then simulated via an elastic-plastic finite element code (ABAQUS). Contrary to the results available in the literature, where the same friction calibration curves are recommended for all types of materials and test conditions, the results of this investigation showed that friction calibration curves are indeed affected by the material properties and test conditions.

Prediction of Forming Limit Diagrams for Aluminum Alloy Sheet Using Finite Element Analysis

2006 ◽  
Author(s):  
Bing Li ◽  
Tim J. Nye
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Aluminum Alloy ◽  
Sheet Thickness ◽  
Alloy Sheet ◽  
Forming Limit ◽  
Aluminum Alloy Sheet ◽  
Element Analysis ◽  
Anisotropic Parameter ◽  
Forming Limit Diagrams

Prediction of forming limit diagram (FLD) for aluminum alloy sheet using finite element analysis without implementing pre-defined geometrical imperfections or material imperfections was studied. The limit strains of the FLD were determined by applying a new proposed localization criterion in the dome stretching test. The elements just outside the necking area, where their major and minor principal strains have no simultaneous change after localized necking happens, were chosen as the reference elements for measurement of limit strains. Simulations were carried out for various strain paths ranging from balanced biaxial stretching to uniaxial stretching. The effects of material properties, sheet thickness, anisotropic parameter and friction coefficient at the sheet punch interface on the locus of FLD were investigated. It was found that the material yield stress and average anisotropic parameter value has almost no effect on forming limits; larger strain-hardening exponent and higher sheet thickness result in higher level of forming limit strains; the friction coefficient has little influence on the locus of FLD but does affect the strain path taken during the deformation. The predicted FLD of AA 5182-O was compared with an experimentally determined FLD and very good agreement has been achieved. It was demonstrated that forming limit diagrams can be predicted by the finite element method without requiring any assumed geometric or material imperfections in the numerical model.

3D Coupled Thermomechanical Finite Element Analysis of Ultrasonic Consolidation

2007 ◽  
Vol 539-543 ◽  
pp. 2651-2656 ◽  
Author(s):  
C.J. Huang ◽  
E. Ghassemieh
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Friction Coefficient ◽  
Stress Field ◽  
Ultrasonic Wave ◽  
Ultrasonic Vibration ◽  
Softening Effect ◽  
Element Analysis ◽  
Consolidation Process ◽  
Ultrasonic Consolidation

A 3-D coupled temperature-displacement finite element analysis is performed to study an ultrasonic consolidation process. Results show that ultrasonic wave is effective in causing deformation in aluminum foils. Ultrasonic vibration leads to an oscillating stress field. The oscillation of stress in substrate lags behind the ultrasonic vibration by about 0.1 cycle of ultrasonic wave. The upper foil, which is in contact with the substrate, has the most severe deformation. The substrate undergoes little deformation. Apparent material softening by ultrasonic wave, which is of great concern for decades, is successfully simulated. The higher the friction coefficient, the more obvious the apparent material softening effect.

Simulation of Thermo-Mechanical Models for Hot Formed Parts by Numerical Experiments

2014 ◽  
Vol 663 ◽  
pp. 668-674
Author(s):  
Azman Senin ◽  
Zulkifli Mohd Nopiah ◽  
Muhammad Jamhuri Jamaludin ◽  
Ahmad Zakaria
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Prediction Accuracy ◽  
Research Work ◽  
Deformation Characteristic ◽  
Element Model ◽  
Forming Limit ◽  
Prototype Model ◽  
New Production ◽  
Element Analysis

The Finite-Element Analysis (FEA) is a prediction methodology that facilitates product designers produced the part design with manufacturing focused. With the similar advantages, manufacturing engineers are capable of build the first actual car model from the new production Draw Die. This approach has eliminated the requirement to manufacture the prototype model from soft tool parts and soft tool press die. However, the prediction accuracy of FEA is a major topic of research work in automotive sector's practitioners and academia as current accuracy level is anticipated at 60%. The objective of works is to assess the prediction accuracy on deformation results from mass production stamped parts. The Finite-element model is developed from the CAD data of the production tools. Subsequently, finite-element model for production tools is discretized with shell elements to avoid computation errors in the simulation process. The sheet blank material with 1.5 mm and 2.0 mm thickness is discredited by shell (2D modeling) and solid elements (3D modeling) respectively. The input parameters for the simulation model for both elements are attained from the actual setup at Press Machine and Production Tool. The analysis of deformation and plastic strain are performed for various setup parameters. Finally, the deformation characteristic such as Forming Limit Diagram (FLD) and thinning are compared for all simulated models.

Effect of temperature and punch speed on forming limit strains of AA5182 alloy in warm forming and improvement in failure prediction in finite element analysis

2017 ◽  
Vol 52 (4) ◽  
pp. 258-273 ◽  
Author(s):  
D Raja Satish ◽  
D Ravi Kumar ◽  
Marion Merklein
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Strain Rate ◽  
Deep Drawing ◽  
Failure Prediction ◽  
Forming Limit ◽  
Element Analysis ◽  
Working Temperature ◽  
Warm Working ◽  
Punch Speed

Formability of AA5182-O aluminum alloy sheets in the warm working temperature range has been studied. Forming limit strains of sheets of two different thicknesses have been determined experimentally in different modes of deformation (biaxial tension, plane strain and tension–compression) by varying temperature and punch speed. A correlation has been established for plane strain intercept of the forming limit diagram (FLD0) with temperature, punch speed and thickness from the experimental results. This correlation has been used to plot the forming limit diagrams for failure prediction in the finite element analysis of warm deep drawing of cylindrical cups. The effect of strain and strain rate on material flow behavior has been incorporated using a strain rate–sensitive power hardening law in which the strain hardening exponent and strain rate sensitivity index have been experimentally determined. The predictions from simulations have been validated by warm deep drawing experiments. Large improvement in accuracy of failure prediction has been observed using the FLDs plotted based on the developed correlation when compared to the existing method of calculating FLD0 using only strain hardening coefficient and thickness. The results clearly indicate the importance of incorporating temperature and punch speed in failure prediction of Al alloys using FLDs in the warm working temperature range.

Study on Wrinkles during Rotary-Draw Bending Forming

2019 ◽  
Vol 943 ◽  
pp. 43-47
Author(s):  
Xia Zhu ◽  
Keiji Ogi ◽  
Nagatoshi Okabe
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Friction Coefficient ◽  
General Purpose ◽  
Straight Tube ◽  
Tube Material ◽  
Rotary Draw Bending ◽  
Element Analysis ◽  
Draw Bending ◽  
Wrinkle Generation

The purpose of this research is to determine the state inside the material using finite-element analysis and to improve the performance of a rotary-draw bending forming by clarifying the mechanism of wrinkle generation. An analytical model of rotational drawing was made by using the general-purpose nonlinear finite-element analysis software MSC Marc, and the analytical results were compared with experimental results to verify the validity of the model. Furthermore, the mechanism of wrinkle generation was investigated. With the progress of processing, wrinkles occur not in the R part but in the original tube-side straight-tube part. The coefficient of friction between the tube material and the R portion of the bending mold promotes the occurrence of wrinkles and the growth of the generated wrinkles. Because wrinkles occur even if the friction coefficient between the tube material and bending mold R part is ignored, the generation condition of wrinkles also depends on parameters other than the friction coefficient.

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