Drawing Thin-Walled Tubing With a Moving Mandrel Through a Single Stationary Die

1944 ◽  
Vol 11 (4) ◽  
pp. A199-A210
Author(s):  
G. Sachs ◽  
J. D. Lubahn ◽  
D. P. Tracy
Keyword(s):  
Flow Stress ◽  
Cold Working ◽  
Fundamental Equation ◽  
Strain Curve ◽  
Cold Drawing ◽  
Stress Strain Curve ◽  
Hot Drawing ◽  
Thin Walled ◽  
Fundamental Equations ◽  
Algebraic Solutions

Abstract The fundamental equations for the drawing of tubing with a moving mandrel have been solved for the simplified cases of both cold-drawing and hot-drawing of thin-walled tubing through a stationary die. For the solution of the fundamental equation, a method of successive improvement can be used for any contour of the tools and any shape of the stress-strain curve. Algebraic solutions were developed for tapered tools and for a metal exhibiting a constant flow stress in cold-working, and for a metal with the flow stress depending exponentially upon the strain rate in hot-working. The effects of the die and punch contours and the friction coefficients between the metal and the die and punch, respectively, on the stresses in the metal, the draw forces, and the limits of drawing were determined. The calculations reveal that, with a small die angle and high friction on the mandrel, the process resembles extrusion rather than drawing, the limit being determined by the strength of the die rather than by the tensile strength of the metal.

Fracture Assessment of Pipes Having Multiple Flaws Based on Ramberg–Osgood-Type Stress–Strain Relationships

2011 ◽  
Author(s):  
Hideo Machida ◽  
Tetsuya Hamanaka ◽  
Yoshiaki Takahashi ◽  
Katsumasa Miyazaki ◽  
Fuminori Iwamatsu ◽  
...  
Keyword(s):  
Flow Stress ◽  
Stress Concentration ◽  
Fracture Strength ◽  
Strain Curve ◽  
Assessment Method ◽  
Experimental Results ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Strain Relationship ◽  
Fracture Assessment

This paper describes a fracture assessment method for a pipe having multiple circumferential flaws. According to Fitness-for-Service (FFS) codes for nuclear facilities published by the Japanese Society of Mechanical Engineers (JSME), the fracture strength of a high-ductility pipe having a circumferential flaw is evaluated using the limit load assessment method assuming the elastic–perfectly-plastic stress–strain relationship. In this assessment, flow stress is used as a proportional stress. However, previous experimental results [1, 2, 3] show that a crack penetrates before the entire flawed pipe section reaches the flow stress. Therefore, stress concentration at a flaw was evaluated on the basis of the Dugdale model [4], and the fracture strength of the crack-ligament was evaluated. This model can predict test results with high accuracy when the ligament fracture strength is assumed to be tensile strength. Based on this examination, a fracture assessment method for pipes having multiple flaws was developed considering the stress concentration in the crack-ligament by using the realistic stress–strain relationship (Ramberg–Osgood-type stress–strain curve). The fracture strength of a multiple-flawed pipe estimated by the developed method was compared with previous experimental results. When the stress concentration in the crack-ligament was taken into consideration, the fracture strength estimated using the Ramberg–Osgood-type stress–strain curve was in good agreement with experimental results, confirming the validity of the proposed method.

Research on the High Temperature Constitutive Model of 300M Ultrahigh Strength Steel

2016 ◽  
Vol 836-837 ◽  
pp. 484-492
Author(s):  
Hui Ping Zhang ◽  
Na Zhao ◽  
Xu Shi ◽  
Xiao Lei Zhang ◽  
Yi Ren
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Strain Rate ◽  
Thermal Deformation ◽  
Strain Curve ◽  
Peak Stress ◽  
Stress Strain Curve ◽  
Ultrahigh Strength ◽  
Ultrahigh Strength Steel ◽  
300M Steel

300M ultrahigh strength steel has good mechanical properties. It has been widely used in the force bearing components of aircraft. In this paper, By using Gleeble1-500D thermal simulator, we studied the change regularity of stress-strain curve of 300M steel using hot compression deformation when temperature is from 800°C to1100°C, strain rate is from 0.001 S-1to 1 S-1 and the strain is 0.7.The experimental results showed that when the strain rate is constant, the flow stress and the peak stress decrease with the increase of deformation temperature. When the deformation temperature is constant, the flow stress and peak stress increase with the increase of strain rate. From the test, we got the true stress-strain curve, calculated the thermal deformation constants such as the deformation activation energy of 300M ultrahigh strength steel. Eventually, we built the thermal deformation constitutive model in hyperbolic sine form of 300M steel.

Folding and Deployment of a New Thin-Walled Tube Flexible Hinge

2014 ◽  
Vol 635-637 ◽  
pp. 365-369 ◽  
Author(s):  
Hui Yang ◽  
Rong Qiang Liu ◽  
Hong Wei Guo ◽  
Jian Guo Tao
Keyword(s):  
Finite Element Analysis ◽  
Strain Curve ◽  
Tension Test ◽  
Slot Width ◽  
Stress Strain Curve ◽  
Element Analysis ◽  
Flexible Hinge ◽  
Thin Walled Tube ◽  
Thin Walled ◽  
Explicit Solver

A new thin-walled tube flexible hinge with six slots is proposed. The slot geometry is parameterized in terms of slot width, length and distance between two adjacent slots. The experiment for tension test of the thin-walled tube hinge with six-slots is conducted by INSTRON and the tensile stress-strain curve is measured. Finite element analysis to investigate the quasi-static folding and deployment of the new hinges by ABAQUS/Explicit solver are employed to perform a series of parameter studies for the slots longitude lengthl0, the slot widthwand the distancedbetween two adjacent slots.

scholarly journals High Strain Rate Behavior of Ultrafine Grained AA2519 Processed via Multi Axial Cryogenic Forging

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 115 ◽  
Author(s):  
Amin Azimi ◽  
Gbadebo Moses Owolabi ◽  
Hamid Fallahdoost ◽  
Nikhil Kumar ◽  
Grant Warner
Keyword(s):  
Plastic Deformation ◽  
Flow Stress ◽  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Strain Curve ◽  
Thermal Softening ◽  
Stress Strain Curve ◽  
Ultrafine Grained ◽  
Cryogenic Forging

The present work deals with studies on the dynamic behavior of ultrafine grained AA2519 alloy synthesized via cryogenic forging (CF) and room temperature forging (RTF) techniques. A split-Hopkinson pressure bar was used to perform high strain rate tests on the processed samples and the microstructures of the samples were characterized before and after impact tests. Electron backscatter diffraction (EBSD) maps demonstrated a significant grain size refinement from ~740 nm to ~250 nm as a result of cryogenic plastic deformation showing higher dislocation densities and stored strains in the CF sample when compared to the RTF sample. This microstructure modification caused the increase of dynamic flow stress in this alloy. In addition, the aluminum matrix of the CF alloy is more densely populated with fragmented particles than the RTF alloy due to the heavier plastic deformation applied to the cryogenically forged alloy. The results obtained from the stress–strain curve for the RTF sample showed intense thermomechanical instabilities in the RTF sample which led to a severe thermal softening and the subsequent sharp drop in the flow stress. However, no significant decrease was observed in the stress–strain curve of the CF alloys with ultrafine grains which means that thermal softening would probably not be the most effective failure mechanism. Furthermore, higher level of sensitivity of CF alloys to strain rates was observed which is ascribed to transition of rate-controlling plastic deformation mechanisms. In the post-mortem microstructure investigation, deformed and transformed adiabatic shear bands (ASBs) were identified on the RTF alloy when the strain rate is over 4000 s−1 at which it had experienced a significant thermal softening. On the other hand, circular path and aligned split arcs are the various shapes of the deformed ASB seen at no earlier than 4500 s−1 in the CF alloys. This is associated with the crack failure caused by grain boundary sliding.

scholarly journals Constitutive Model of 30CrMoA Steel with Strain Correction

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1214
Author(s):  
Song Zhang ◽  
Xuedao Shu ◽  
Jitai Wang ◽  
Yingxiang Xia
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
High Speed ◽  
Strain Curve ◽  
Material Constant ◽  
Test Machine ◽  
Experimental Stress ◽  
High Speed Train ◽  
Stress Strain Curve ◽  
Stress Strain

It is necessary to establish a constitutive model of 30CrMoA steel to optimize the forming shape and mechanical properties of high-speed train axles. The experimental stress–strain curve of 30CrMoA steel was obtained by an isothermal compression test on a Gleeble-3500 thermal simulation test machine under temperature of 1273~1423 K and strain rate of 0.01~10 s−1. Considering the effect of strain on the material constant, an empirical constitutive model was proposed with strain correction for 30CrMoA steel. In addition, the material constant in the constitutive model is determined by linear regression analysis of the experimental stress–strain curve. Comparing the theoretical value and experimental value of flow stress, the correlation R is 0.9828 and the average relative error (ARRE) is 4.652%. The constitutive model of 30CrMoA steel with strain correction can reasonably predict the flow stress under various conditions. The results provide an effective numerical tool for further study on accurate near-net forming of high-speed train axles.

Activation Volumes in the Yield Strength Anomaly Domain of Ni3(Al,Ta).

1994 ◽  
Vol 364 ◽  
Author(s):  
P. Spätig ◽  
J. Bonneville ◽  
J.-L. Martin
Keyword(s):  
Shear Stress ◽  
Flow Stress ◽  
Yield Strength ◽  
Activation Volume ◽  
Strain Curve ◽  
Rate Sensitivity ◽  
Effective Activation ◽  
Stress Strain Curve ◽  
Controlling Mechanism ◽  
Critical Resolved Shear Stress

AbstractNi3(Al,Ta) single crystals have been deformed in compression in the temperature range of the flow stress anomaly (293–780K). The strain-rate sensitivity (SRS) of the flow stress has been characterised by using a technique of repeated stress relaxations that allows for the measurement of the true (or effective) activation volume (Veff). When measured at the conventional critical resolved shear stress (CRSS), Veff exhibits as a function of temperature a sharp discontinuity close to 470K. When the temperature is held constant (420K), the discontinuity of Veff occurs along the stress-strain curve at approximately 3% strain; the stress for both discontinuities is approximately the same. These results suggest a change in the rate controlling mechanism that is dependent on stress as much or more than temperature.

Dynamic Constitutive Equations and Behaviour of Brass at High Strain Rates

1995 ◽  
Vol 209 (4) ◽  
pp. 287-293 ◽  
Author(s):  
L-Y Li ◽  
T C K Molyneaux
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Yield Stress ◽  
Constitutive Equations ◽  
High Strain ◽  
Strain Curve ◽  
Strain Rates ◽  
Stress Strain Curve ◽  
High Strain Rates ◽  
Stress Strain

This paper presents an experimental study of the mechanical properties of brass at high strain rates. The brass tested is the copperzinc alpha-beta and beta two-phase alloy in the cold-worked state. Experiments were conducted using an extended tension split Hopkinson bar apparatus. It is found that, at lower strain rates, the stress-strain curve is smooth, exhibiting no well-defined yield stress, but at higher strain rates the stress-strain curve not only shows a well-defined yield stress but also displays a very pronounced drop in stress at yield. The flow stress is found to increase with increasing strain rate, but the increase is more significant for the yield stress than for the flow stress, showing that the yield stress is more sensitive to the strain rate than the flow stress away from the yield point. Based on the experimental results, empirical strain-rate-dependent constitutive equations are recommended. The suggested constitutive equations provide a reasonable estimate of the strain-rate-sensitive behaviour of materials.

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