scholarly journals A Finite Element Study of Thermo-Mechanical Fields and Their Relation to Friction Conditions in Al1050 Ring Compression Tests

2018 ◽  
Vol 2 (4) ◽  
pp. 83 ◽  
Author(s):  
Brigit Mittelman ◽  
Elad Priel ◽  
Nissim Navi
Keyword(s):  
Finite Element ◽  
Flow Stress ◽  
Friction Coefficient ◽  
Computational Models ◽  
Experimental System ◽  
Pure Aluminium ◽  
Compression Tests ◽  
Element Analysis ◽  
Ring Compression ◽  
Flow Stress Data

The most accepted method for determining friction conditions in metal forming is the ring compression test (RCT). At high temperatures, extraction of the friction coefficient, μ, commonly requires numerical analysis due to the coupling between the mechanical and thermal fields. In the current study, compression tests of cylindrical specimens and RCT experiments were conducted on commercially pure aluminium (Al1050) at several temperatures, loading rates, and lubrication conditions. The experiments were used in conjunction with a coupled thermo-mechanical finite element analysis to study the dependence of the friction coefficient on those parameters. It is demonstrated that due to the coupling between friction conditions and material flow stress, both μ and flow stress data should be determined from the cylinder and ring specimens simultaneously and not subsequently. The computed friction conditions are validated using a novel method based on identification of the plastic flow neutral radius. It is shown that, due to heat loss mechanisms, the experimental system preparation stage must be incorporated in the computational analysis. The study also addresses the limitation of the RCT in the presence of high friction conditions. The computational models are finally used to examine the thermo-mechanical fields, which develop during the different processes, with an emphasis on the effect of friction conditions, which were then correlated to the resulting microstructure in the RCTs.

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.

Finite Element Analysis on Plastic Deformation Behaviors of Ti-3Al-2.5V Tubes under Axial Compression

2015 ◽  
Vol 639 ◽  
pp. 551-558 ◽  
Author(s):  
Tao Huang ◽  
Mei Zhan ◽  
Jin Qiang Tan ◽  
Jing Guo ◽  
He Yang
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Flow Stress ◽  
Friction Coefficient ◽  
Axial Compression ◽  
High Performance ◽  
Fe Model ◽  
Deformation Degree ◽  
Element Analysis ◽  
Deformation Behaviors

With the requirement of aviation and aerospace fields for high-strength Ti-3Al-2.5V titanium alloy bent tubes with high-performance, it is great significance to research the plastic deformation of Ti-3Al-2.5V tubes under compression to obtain desired flow stress curves. A finite element (FE) model of axial compression of Ti-3Al-2.5V tubes was established in this study. Using this model, deformation behaviors of Φ12 mm × t0.9 mm Ti-3Al-2.5V tubes with different ratios of thickness to height (t/h) compressed under different frictions were analyzed. It is shown that the non-uniform deformation degree of the tubes increases with the decrease of t/h and the increase of friction coefficient. This means that a large t/h value and small friction can help to attain a uniaxial compression condition to obtain desired flow stress curves. Such compression conditions for the Φ12 mm × t0.9 mm Ti-3Al-2.5V tube is that, t/h is not less than 0.6 and the friction coefficient is not greater than 0.05

scholarly journals Thermo-mechanical forging of 708M40 steel ring samples: experiments and modelling

2021 ◽  
Author(s):  
Steven Hill ◽  
Richard P.Turner
Keyword(s):  
Finite Element ◽  
Experimental Parameter ◽  
Compression Tests ◽  
Molybdenum Disulphide ◽  
Heating Unit ◽  
Modelling Framework ◽  
Process Understanding ◽  
Ring Compression ◽  
Water Based ◽  
Temperature Variable

AbstractA series of ring compression tests using BS970:708M40 alloy steel samples were studied. These tests were conducted using a 2-factor soak-temperature variable, namely 1030 °C and 1300 °C, and a 4-factor lubricant variable consisting of unlubricated samples, synthetic water-based, graphite water-based, and graphite and molybdenum disulphide viscous grease. The lubricant agents were all applied to the tool/billet interface. Process variables such as blow force and heating were controlled with the use of a gravitationally operated drop hammer and an automated programmable induction-heating unit. This matrix of the experimental parameters offered a sound base for exploring dominant factors impacting upon bulk deformation. This deformation was measured using fully calibrated equipment and then systematically recorded. A finite element modelling framework was developed to further improve the thermo-mechanical deformation process understanding, with finite element (FE) predictions validated through experimental measurement. Through the combined experimental and FE work, it was shown that temperature variation in the experimental parameter matrix played a larger role in determining deformation than the lubrication agent. Additionally, the use of synthetic and graphite water-based lubricants does not necessarily produce greater deformation when used in high-temperature forgings due to the lubricants breaking down, evaporating, or inducing rapid billet cooling as a result of the carrier used (water). Graphite-molybdenum disulphate grease far outperforms the other lubricants used in this trial in reducing friction and allowing deformation to occur across a die-face.

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.

Finite Element Analysis for Shock Resistance Evaluation of Cushion-Packaged Multifunction Printer Considering Internal Modules

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Se-Chang Kim ◽  
Dae-Geun Cho ◽  
Tae-Gyu Kim ◽  
Se-Hun Jung ◽  
Ja-Choon Koo ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Shock Acceleration ◽  
External Shocks ◽  
Compression Tests ◽  
Element Analysis ◽  
Dynamic Behaviors ◽  
Shock Resistance ◽  
The Impact ◽  
Multifunction Printer

Failures in IT electronics are often caused by falling or external shocks during transportation. These failures cause customers to mistrust the reliability of the products. Many manufacturers of IT electronics have not only used cushioning materials but also increased the shock resistance of their products for failure prevention. Especially in case of printer products, the design of the packaging and the product robustness are extremely important because of their substantial weight and the fragility of the internal modules. For product design, it is essential to understand the impact failure mechanism of the products. In this study, a compression test, a drop impact test, and a finite element analysis (FEA) were performed to analyze the dynamic behaviors of a packaged multifunction printer (MFP). The mechanical properties of a cushioning material were measured by compression tests. The FE models of the cushion packaging and the MFP included the physical characteristics of the internal modules, and their dynamic behaviors were obtained using the commercial software ls-dyna3d. Simulation results were also compared with drop test results to verify the proposed FE models. The shock resistance of the MFP was assessed by stress analysis and strength evaluation. We also expect our FE models will be useful for evaluating the fragility of the internal modules because the models can numerically estimate the shock acceleration profiles of the internal modules, which are difficult to measure experimentally.

Study on Cylindrical Heatsink Forging Process Considering Friction Condition

2019 ◽  
Vol 823 ◽  
pp. 141-144
Author(s):  
Tung Sheng Yang ◽  
Yong Nan Chen
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Friction Factor ◽  
Testing Machine ◽  
Metal Flow ◽  
Compression Tests ◽  
Stress Strain ◽  
Element Analysis ◽  
Forging Process ◽  
Different Temperatures

The feasibility of forging of AL-1050 alloy of cylindrical heatsink under warm conditions is demonstrated in the present work. The stress-strain curves and friction factor play an important role in the cylindrical heatsink forging. The purpose of forging lubrication is to reduce friction between blank and die, and to decrease resistance of metal flow to die. The stress-strain curves at different temperatures are obtained by compressing tests. The friction factor between 1050 aluminum alloy and die material are determined at different temperatures by ring compression tests with graphite lubricants. The compressing and ring compressing tests are carried out by using the computerized screw universal testing machine. The finite element method is used to investigate the forming characters of the forging process. To verify the prediction of FEM simulation in the cylindrical heatsink forging process, the experimental parameters such as stress-strain curves and fiction factor, are as the input data during analysis. Maximum forging load and effective stress distribution are determined of the heatsink forging, using the finite element analysis. Finally, the cylindrical heatsink parts are formed by the forging machine under the conditions using finite element analysis.

Flow Stress Experimental Determination for Warm-Forming Process

2011 ◽  
Author(s):  
Ting Fai Kong ◽  
Luen Chow Chan ◽  
Tai Chiu Lee
Keyword(s):  
Stainless Steel ◽  
Flow Stress ◽  
Room Temperature ◽  
Warm Forming ◽  
Recrystallization Temperature ◽  
Process Conditions ◽  
Compression Tests ◽  
Forming Process ◽  
Forming Temperature ◽  
Flow Stress Data

Warm forming is a manufacturing process in which a workpiece is formed into a desired shape at a temperature range between room temperature and material recrystallization temperature. Flow stress is expressed as a function of the strain, strain rate, and temperature. Based on such information, engineers can predict deformation behavior of material in the process. The majority of existing studies on flow stress mainly focus on the deformation and microstructure of alloys at temperature higher than their recrystallization temperatures or at room temperature. Not much works have been presented on flow stress at warm-forming temperatures. This study aimed to determine the flow stress of stainless steel AISI 316L and titanium TA2 using specially modified equipment. Comparing with the conventional method, the equipment developed for uniaxial compression tests has be verified to be an economical and feasible solution to accurately obtain flow stress data at warm-forming temperatures. With average strain rates of 0.01, 0.1, and 1 /s, the stainless steel was tested at degree 600, 650, 700, 750, and 800 °C and the titanium was tested at 500, 550, 600, 650, and 700 °C. Both materials softened at increasing temperatures. The overall flow stress of stainless steel was approximately 40 % more sensitive to the temperature compared to that of titanium. In order to increase the efficiency of forming process, it was suggested that the stainless steel should be formed at a higher warm-forming temperature, i.e. 800 °C. These findings are a practical reference that enables the industry to evaluate various process conditions in warm-forming without going through expensive and time consuming tests.

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