Elasto-plastic and creep behaviour of axially loaded, shouldered tubes

1980 ◽  
Vol 15 (1) ◽  
pp. 21-29 ◽  
Author(s):  
R J Dawson ◽  
H Fessler ◽  
T H Hyde ◽  
J J Webster
Keyword(s):  
Finite Element ◽  
Creep Behaviour ◽  
Equivalent Stress ◽  
Strain Curve ◽  
Equivalent Strain ◽  
Uniaxial Tensile ◽  
Plastic Strain Increment ◽  
Axially Loaded ◽  
Initial Strains ◽  
Creep Strains

This paper compares the finite element predictions of elasto-plastic and creep behaviour with experimental data for axially loaded, shouldered tube models. Four shouldered tube models were made of a lead alloy and tested at 61°C, using strain gauges to measure the elasto-plastic and creep strains in the plain tube and fillet regions of the models. Instantaneous stress-strain and creep data were obtained from strain-gauged, uniaxial tensile specimens. The finite element solutions are based on the incremental Prandtl-Reuss equations. The elasto-plastic iterative solutions use a ‘negative gradient’ from the calculated point to the equivalent stress-equivalent strain curve to get the next estimate of the plastic strain increment. A time incremental method is used to obtain the creep solutions. Tests with the mean tube stress below, at and above the yield stress showed very good agreement between prediction and measurement of initial strains in the fillets. Differences between predictions and measurements of creep strains are attributable to cast-to-cast variations.

scholarly journals Exploring Strong Spinning Formation Mechanisms of GH3030 Superalloy Tapered Rotary Part with Wall Thickness Gradient

2019 ◽  
Vol 37 (4) ◽  
pp. 785-793
Author(s):  
Xuedao Shu ◽  
Zewei Cen ◽  
Yu Wang ◽  
Zixuan Li ◽  
Ying Zhu
Keyword(s):  
Finite Element ◽  
Stress Field ◽  
Wall Thickness ◽  
Equivalent Stress ◽  
Strain Curve ◽  
Element Model ◽  
Equivalent Strain ◽  
Formation Mechanisms ◽  
Distribution Law ◽  
Metal Casing

In order to effectively control the deformation of tapered spinning parts with gradually changing wall thickness, the precise forming of such sheet metal casing parts can be realized. This paper uses experiments to establish the true stress-strain curve equations of GH3030 superalloy at normal temperature. Based on the equations, it establishes the finite element model of the strong spinning forming of a GH3030 superalloy tapered rotary part with wall thickness gradient. The equivalent stress field for the strong spinning forming is used to combine the finite element simulation with experiments. The strong spinning forming is simulated, and the distribution characteristics of the equivalent stress field and the equivalent strain field for the strong spinning forming are analyzed in some detail, and their distribution law is obtained. The strong spinning forming mechanisms for the GH3030 superalloy tapered rotary part with wall thickness gradient is clarified. The experimental and simulation results are verified with the conical flange plane degree.

Determining the Anisotropy Coefficients of an Ultra Fine Grained Al6082 Alloy Subjected to ECAP

2007 ◽  
Vol 537-538 ◽  
pp. 215-222
Author(s):  
György Krállics ◽  
Arpad Fodor
Keyword(s):  
Constitutive Equation ◽  
Yield Stress ◽  
Continuum Mechanics ◽  
Equivalent Stress ◽  
Strain Curve ◽  
Equivalent Strain ◽  
Rigid Plastic ◽  
Fine Grained ◽  
Anisotropy Coefficients

Bulk Al6082 alloy is subjected to ECAP using route Bc. This paper focuses on the determination of the anisotropy coefficients and equivalent stress-equivalent strain curve using continuum mechanics equations. Assuming the material to be rigid-plastic, the parameters of the constitutive equation are determined with the aid of measuring the deformation and the uniaxial yield stress during upsetting tests in three perpendicular directions.

Fatigue Life of Thread Connection for Casing Drilling under Tension and Torsion

2008 ◽  
Vol 33-37 ◽  
pp. 255-260
Author(s):  
Feng Hui Wang ◽  
Qiong Wu ◽  
Ying Xi Wu ◽  
Sheng Yin Song
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Failure ◽  
Equivalent Stress ◽  
Equivalent Strain ◽  
Test Machine ◽  
Proportional Loading ◽  
Thread Connection ◽  
Good Agreement ◽  
Casing Drilling

Casing drilling technique which has been dramatically developing is a revolution in petroleum industry and has aroused great concerns. The fatigue failure of casing thread connection is a critical issue for using. Therefore, to study the fatigue failure of casing connection is an important issue for understand the life of casing drilling. For the notched element, how to estimate the life and which parameter (equivalent stress, equivalent strain ,or the strain in the root )represent the damage under fatigue condition is still a problem. The purpose of this paper is to investigate the fatigue life of notch element under multiaxial stresses and to find out the damage parameter so as to predict the life of notch element. First specimen were machined with the same notch geometer dimension as the casing thread connection, fatigue tests with tension and torsion loading were carried out by fatigue test machine , for stress levels designed to obtain S-N lifetime curve. The stress and strain for the connections subjected to proportional loading were analyzed by elastic-plastic finite element method. The stress-strain state for notched specimens subjected to constant amplitude proportional multiaxial loadings was also calculated and analyzed by the finite element model. Take the equivalent stress, equivalent strain and the strain by FEM in the root into the prediction model, the strain by FEM has a good agreement with the experiment.But the results from the equivalent stress and equivalent strain also in good agreement with the experiment and is thought to be a simple prediction way.

Thermal ratchetting of axially loaded tubes operating in the creep range

1982 ◽  
Vol 17 (4) ◽  
pp. 243-251 ◽  
Author(s):  
T H Hyde ◽  
J J Webster ◽  
H Fessler
Keyword(s):  
Finite Element ◽  
Creep Behaviour ◽  
Practical Interest ◽  
Model Material ◽  
Strain Gauges ◽  
Lead Alloy ◽  
Temperature Variations ◽  
Finite Element Calculations ◽  
Cyclic Temperature ◽  
Axially Loaded

Finite element predictions of ratchetting and creep behaviour are compared with experimental data for axially loaded tubes subjected to axisymmetric cyclic temperature variations. Eleven tubes made of a lead alloy model material which creeps at ambient temperature were tested. Strain gauges were used to measure the ratchet and creep strains. In the finite element calculations it was assumed that no plasticity-creep interactions occur. Reasonably good predictions of ratchet strains were obtained, particularly in the range of most practical interest. Some of the discrepancies between ratchet and creep results can be accounted for by considering the results from a small number of uniaxial plasticity-creep interaction tests.

Strain-Induced Martensite Formation of AISI 304L Steel Sheet: Experiments and Modeling

2016 ◽  
Vol 869 ◽  
pp. 490-496 ◽  
Author(s):  
D.C.T. Costa ◽  
M.C. Cardoso ◽  
Gláucio S. da Fonseca ◽  
Luciano Pessanha Moreira ◽  
M. Martiny ◽  
...  
Keyword(s):  
Finite Element ◽  
Strain Rate ◽  
Phenomenological Model ◽  
Steel Sheet ◽  
Strain Curve ◽  
Temperature Deformation ◽  
Uniaxial Tensile ◽  
Aisi 304L ◽  
Strain Induced Martensite ◽  
304L Steel

Metastable austenitic stainless steels are prone to strain-induced martensite transformation (SIMT) during deformation at room temperature, as in the case of sheet metal forming processes. The SIMT is influenced by the chemical composition, grain size, temperature, deformation mode or stress state and strain-rate. In this work, interrupted and continuous uniaxial tensile tests were performed in AISI 304L sheet to evaluate the SIMT as a function of strain and strain-rate effects. The SIMT was evaluated by feritscope and temperature in-situ measurements and both XRD and optical microscopy techniques. The SIMT kinetics was also investigated by means of thermo-mechanical finite element simulations using a phenomenological model. In the small strain range, the yield stress increases with the strain-rate whereas in the large strain domain a cross-effect in the stress-strain curve is observed given that the SIMT is inhibited due to the specimen heat generation. A very good correlation between XRD and feritscope measurements was found from the interrupted uniaxial tensile testing. The finite element numerical simulations allowed to identify the parameters of a phenomenological model which describes the SIMT kinetics of AISI 304L steel sheet as a function of plastic-strain, strain-rate and temperature effects.

scholarly journals A Simple and Efficient Method for Obtaining the Whole-Range Uniaxial Tensile Properties of Pipeline Steel

Metals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 555
Author(s):  
Lingzhen Kong ◽  
Lingbo Su ◽  
Xiayi Zhou ◽  
Liqiong Chen ◽  
Jie Chen ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Pipeline Steel ◽  
True Strain ◽  
Strain Curve ◽  
Element Model ◽  
True Stress ◽  
Material Behavior ◽  
Uniaxial Tensile ◽  
Output Data

To obtain the whole-range true stress-true strain curves of API X65, a method is proposed based on the equal proportion principle and digital images. The tensile elongation was obtained by tracing the gauge points on the specimen surface, and the true strain and true stress of API X65 were calculated according to the formulae. The obtained true stress-true strain curves were validated by a 3-D finite element model. The true stress-true strain curve was set as the input data, while the engineering stress-engineering strain curve was set as the output data. The output data of the finite element model was the same as that of the experiment test. The findings imply that the proposed method could acquire reliable, whole-range true stress-true stain curves. These curves, which depict the material behavior of pipeline steel from initial elongation to fracture, could provide basic data for pipeline defect tolerance limit analysis and fracture assessment.

Numerical modeling of the effects hydration and number of hydrogen bonds on the mechanical properties of the tropocollagen molecule

2020 ◽  
Vol 234 (3) ◽  
pp. 299-306 ◽  
Author(s):  
Marouane El Mouss ◽  
Amna Rekik ◽  
Said Zellagui ◽  
Tarek Merzouki ◽  
Ridha Hambli
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Hydrogen Bonds ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Strain Curve ◽  
Collagen Molecule ◽  
Uniaxial Tensile ◽  
Type I ◽  
Two Parameters

Bone aging involves structural and molecular modifications, especially at the level of type I tropocollagen. This macromolecule shows two main age-related alterations, which are the decrease of both molecular diameter (due to the loss of hydration) and number of hydrogen bonds. In this work, it is proposed to investigate the influence of these two parameters (molecular diameter and number of hydrogen bonds) on the mechanical behavior of tropocollagen using finite element method. To this end, a novel three-dimensional finite element model of collagen molecule accounting for hydrogen bonds was developed. Then, a numerical design of experiments for the diameter of tropocollagen and variations in the number of hydrogen bonds has been established. The mechanical properties (“load–strain” curve and apparent Young’s modulus) of the collagen molecule were obtained by employing the proposed model to uniaxial tensile tests. The parametric study demonstrates that the mechanical properties of tropocollagen are slightly affected by the rate of hydration but considerably affected by variation of the number of hydrogen bonds. Finally, a fitted analytical function was deduced from the above results showing effects of the two parameters (hydration rate and hydrogen bonds) on the apparent Young’s modulus of tropocollagen. This study could be useful to understand the influence of structural age modifications of tropocollagen on the macroscopic mechanical properties of bone.

Chip Prediction in Finite Element Modeling of the Chip Formation Process during Cutting Ti-6Al-4V Alloy

2011 ◽  
Vol 418-420 ◽  
pp. 1148-1153
Author(s):  
Yu Gang Ye
Keyword(s):  
Finite Element ◽  
Titanium Alloy ◽  
Strain Rate ◽  
Equivalent Stress ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Equivalent Strain ◽  
Forming Process ◽  
Serrated Chip ◽  
Equivalent Strain Rate

Based on the theory of adiabatic shearing, the forming process of a serrated chip during cutting Ti-6Al-4V titanium alloy was analyzed by comparing the results of the finite element (FE) calculations with the cutting experiments. The results show that the equivalent stress, equivalent strain and equivalent strain rate within a ribbon chip varied a little, but they varied a lot within a serrated chip. Moreover, the effect of cutting speed on equivalent strain rate is greater than on the equivalent stress and equivalent strain within a serrated chip. It can also be found from the results that there are small gaps between the simulation results and experimental results for the chip thickness and sawtooth height, while there is a big gap for saw-tooth pitch. This means that the simulation model has its limitations for accurate simulation of micro-geometric shape of a chip during cutting the Ti-6Al-4V titanium alloy, and further research remains to be done.

Two Dimensional Quasi-Steady Molecular Statics Nanocutting Simulation for Cutting Copper Material with Point Defect

2011 ◽  
Vol 264-265 ◽  
pp. 1357-1363
Author(s):  
Zone Ching Lin ◽  
Jia Rong Ye
Keyword(s):  
Point Defect ◽  
Copper Atom ◽  
Equivalent Stress ◽  
Strain Curve ◽  
Equivalent Strain ◽  
Two Dimensional ◽  
Molecular Statics ◽  
One Step ◽  
Copper Material ◽  
The Relationship

This article presents a quasi-steady molecular statics nanocutting simulation model for simulating orthogonal two dimension cutting copper materials with different point defects by using diamond cutters. The analyses of cutting action, cutting force, equivalent strain and equivalent stress are taken during nanocutting copper material with point defect. The two dimensional quasisteady molecular statics nanocutting model first assumes the trajectory of each atom of copper workpiece being cut whenever the diamond cutter goes forward one step. It then uses the Hooke- Jeeves search method to solve the force equilibrium equation of the Morse force in X and Y directions when each copper atom moves a small distance, so as to find the new movement position of each copper atom. Then, the displacement of the acquired new position of each atom combined with the concept of shape function of finite element method are employed to calculate the equivalent strain of the copper workpiece during nanocutting . By using the relationship equation of the flow stress-strain curve, the equivalent stress of the copper workpiece during cutting can also be calculated

scholarly journals Investigation on Ultra-high Temperature Forging Process Based on DEFORM-3D Simulation

2021 ◽  
Author(s):  
Wu Yong-qiang ◽  
Wang Kai-kun
Keyword(s):  
High Temperature ◽  
Equivalent Stress ◽  
Strain Curve ◽  
Green Manufacturing ◽  
Equivalent Strain ◽  
Temperature Fields ◽  
Forging Process ◽  
Reheating Process ◽  
Deform 3D ◽  
Ultra High Temperature

Abstract Green manufacturing and forming technology is becoming increasingly important in modern industry. In this study, a new forging technology with the ultra-high temperature demoulding is introduced, in which conventional reheating process could be avoided. The DEFORM-3D software simulated the forging process and the temperature fields were obtained. The traditional forging process was simulated when the initial forging temperature was 1220℃. The highest temperature of the ingot in the new forging technology was about 200℃ higher than that of the traditional forging process. We cut the ingot longitudinally along the centerline. Nine points on the axis of the cutting plane and nine points on the radial direction were selected. The equivalent stress and the equivalent strain of these points were compared respectively under the two forging processes by using the particle tracking method. The variation laws of the equivalent stress and the equivalent strain with the reduction were obtained. According to the variation laws, the typical points which were easy to crack under two different forging processes were found. Based on the flow stress-strain curve calculated by the software JMatPro®, the new forging technology could avoid hot cracking.

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