scholarly journals Experimental and Numerical Characterization of the Cyclic Thermomechanical Behavior of a High Temperature Forming Tool Alloy

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Sean B. Leen ◽  
Aditya Deshpande ◽  
Thomas H. Hyde
Keyword(s):  
High Temperature ◽  
Life Prediction ◽  
Material Constant ◽  
Superplastic Forming ◽  
Material Model ◽  
Fatigue Tests ◽  
Material Behavior ◽  
Future Application ◽  
Rate Dependent ◽  
Numerical Characterization

This paper describes high temperature cyclic and creep relaxation testing and modeling of a high nickel-chromium material (XN40F) for application to the life prediction of superplastic forming (SPF) tools. An experimental test program to characterize the high temperature cyclic elastic-plastic-creep behavior of the material over a range of temperatures between 20°C and 900°C is described. The objective of the material testing is the development of a high temperature material model for cyclic analyses and life prediction of SPF dies for SPF of titanium aerospace components. A two-layer viscoplasticity model, which combines both creep and combined isotropic-kinematic plasticity, is chosen to represent the material behavior. The process of material constant identification for this model is presented, and the predicted results are compared with the rate-dependent (isothermal) experimental results. The temperature-dependent material model is furthermore applied to simulative thermomechanical fatigue tests, designed to represent the temperature and stress-strain cycling associated with the most damaging phase of the die cycle. The model is shown to give good correlation with the test data, thus vindicating future application of the material model in thermomechanical analyses of SPF dies for distortion and life prediction.

Experimental and Numerical Characterisation of the Cyclic Thermo-Mechanical Behaviour of a High Temperature Forming Tool Alloy

2009 ◽  
Author(s):  
Aditya Deshpande ◽  
Sean B. Leen ◽  
Thomas H. Hyde
Keyword(s):  
High Temperature ◽  
Life Prediction ◽  
Creep Behaviour ◽  
Material Constant ◽  
Superplastic Forming ◽  
Material Model ◽  
Future Application ◽  
Temperature Dependent ◽  
Rate Dependent ◽  
Nickel Chromium

This paper describes high temperature cyclic and creep relaxation testing and modelling of a high nickel-chromium material (XN40F) for application to the life prediction of superplastic forming (SPF) tools. An experimental test programme to characterise the high temperature cyclic elastic-plastic-creep behaviour of the material over a range of temperatures between 20°C and 900°C is described. The objective of the material testing is the development of a high temperature material model for cyclic analyses and life prediction of superplastic forming (SPF) dies for SPF of titanium aerospace components. A two-layer visco-plasticity model which combines both creep and combined isotropic-kinematic plasticity is chosen to represent the material behaviour. The process of material constant identification for this model is presented and the predicted results are compared with the rate-dependent (isothermal) experimental results. The temperature-dependent material model is furthermore applied to simulative thermo-mechanical fatigue (TMF) tests, designed to represent the temperature and stress-strain cycling associated with the most damaging phase of the die cycle. The model is shown to give good correlation with the test data, thus vindicating future application of the material model in thermo-mechanical analyses of SPF dies, for distortion and life prediction.

A Microstructure-Level Material Model for Simulating the Machining of Carbon Nanotube Reinforced Polymer Composites

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Ashutosh Dikshit ◽  
Johnson Samuel ◽  
Richard E. DeVor ◽  
Shiv G. Kapoor
Keyword(s):  
Carbon Nanotube ◽  
Weight Fraction ◽  
Material Model ◽  
Material Behavior ◽  
Compression Tests ◽  
Linear Elastic ◽  
Rate Dependent ◽  
Wide Range ◽  
Parametrization Scheme ◽  
Fraction Length

A continuum-based microstructure-level material model for simulation of polycarbonate carbon nanotube (CNT) composite machining has been developed wherein polycarbonate and CNT phases are modeled separately. A parametrization scheme is developed to characterize the microstructure of composites having different loadings of carbon nanotubes. The Mulliken and Boyce constitutive model [2006, “Mechanics of the Rate Dependent Elastic Plastic Deformation of Glassy Polymers from Low to High Strair Rates,” Int. J. Solids Struct., 43(5), pp. 1331–1356] for polycarbonate has been modified and implemented to capture thermal effects. The CNT phase is modeled as a linear elastic material. Dynamic mechanical analyzer tests are conducted on the polycarbonate phase to capture the changes in material behavior with temperature and strain rate. Compression tests are performed over a wide range of strain rates for model validation. The model predictions for yield stress are seen to be within 10% of the experimental results for all the materials tested. The model is used to study the effect of weight fraction, length, and orientation of CNTs on the mechanical behavior of the composites.

Finite Element Modelling and Experimental Testing of Thermomechanical Behaviour and Failure of Titanium Superplastic Forming Dies

2010 ◽  
Vol 433 ◽  
pp. 247-256 ◽  
Author(s):  
Sean B. Leen ◽  
Aditya A. Deshpande ◽  
Thomas H. Hyde
Keyword(s):  
High Temperature ◽  
Life Prediction ◽  
Experimental Testing ◽  
Creep Behaviour ◽  
Strain Range ◽  
Superplastic Forming ◽  
Nickel Chromium ◽  
Thermomechanical Behaviour ◽  
And Diffusion ◽  
Plastic Creep

This paper describes high temperature cyclic and creep relaxation testing and modelling of a high nickel-chromium material (XN40F) for application to life prediction of superplastic forming (SPF) tools. An experimental test programme to (i) characterise the high temperature cyclic elastic-plastic-creep behaviour of the material over a range of temperatures between 20oC and 900oC, including cyclic controlled strain-range tests at different strain-rates and creep relaxation tests, and (ii) identify the material constants relevant to thermo-mechanical fatigue (TMF) life prediction, is described. The objective of the material testing is the development of high temperature material and failure models for cyclic analyses and life prediction of SPF and diffusion bonding (DB) dies for titanium aerospace components.

Thickness Optimization of SPF for Titanium Alloy Negative Angle Parts

2011 ◽  
Vol 328-330 ◽  
pp. 1395-1402
Author(s):  
Zong Ke Shao ◽  
Zhong Guo Huang ◽  
Shun Yao Jin ◽  
Qing Hua Yuan ◽  
Yu Zhou
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Thickness Distribution ◽  
Superplastic Forming ◽  
Material Model ◽  
Minimum Thickness ◽  
Forming Technology ◽  
Forming Characteristics ◽  
Material Forming ◽  
High Temperature Tensile

With the Superplastic forming technology, the problem that the forming of the complex titanium alloy parts is difficult has been solved. The high temperature forming characteristics of the titanium alloy material and the establishment of the constitutive model of material that will be used as the material model of the simulation of the material forming (the minimum thickness is larger than 0.8 mm) about the negative Angle parts are based on high-temperature tensile test. The influence of the thickness of the parts is analyzed from three different SPF schemes, which are simulated by the MSC.MARC software. The results demonstrate the parts taking advantage of two-stage SPF, which is consisted of concave die SPF method and convex die SPF method can meet the requirement of minimum thickness and improve the thickness distribution on the die draft sides. Furthermore, the thickness distribution of the parts is more uniform with the convex die SPF method.

scholarly journals High-Temperature Low Cycle Fatigue Life Prediction and Experimental Research of Pre-Tightened Bolts

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 828 ◽  
Author(s):  
Qingmin Yu ◽  
Honglei Zhou ◽  
Xudong Yu ◽  
Xiangjin Yang
Keyword(s):  
High Temperature ◽  
Fatigue Life ◽  
Life Prediction ◽  
Low Cycle Fatigue ◽  
Equivalent Stress ◽  
Fatigue Tests ◽  
Fatigue Life Prediction ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Fatigue Model

Bolted connections are widely used in various mechanical structures due to their superior fastening properties. However, vibration and fatigue loads in the structure are likely to cause fatigue failure of the bolted joints, especially those under high temperature, such as in aero-engines. This paper mainly studies the low-cycle fatigue life of the pre-tightened bolts working at a high temperature. A novel test fixture is designed for fatigue tests, and low cycle fatigue tests of pre-tightened bolts are conducted at the temperatures of 550 °C and 650 °C, respectively. Furthermore, a new low cycle fatigue model that is based on the Von Mises equivalent stress/strain criterion is proposed. Meanwhile, the proposed model is used to predict the high-temperature low cycle fatigue life of pre-tightened bolts according to the stress/strain results obtained by finite element analysis. There is good agreement between the experimental results and those obtained by theoretical prediction, which validates the accuracy of the proposed fatigue model. Research results will provide a theoretical basis for the low cycle fatigue life prediction of pre-tightened bolts.

scholarly journals An Efficient Approach for Identifying Constitutive Parameters of the Modified Oyane Ductile Fracture Criterion at High Temperature

2013 ◽  
Vol 2013 ◽  
pp. 1-4 ◽  
Author(s):  
Sergei Alexandrov ◽  
Yusof Mustafa ◽  
Mohd Yazid Yahya
Keyword(s):  
High Temperature ◽  
Ductile Fracture ◽  
Computational Models ◽  
Fracture Criterion ◽  
Fracture Initiation ◽  
Material Model ◽  
Material Behavior ◽  
Ductile Fracture Criterion ◽  
Path Dependent ◽  
Constitutive Parameters

The paper presents the theoretical part of a method for identifying constitutive parameters involved in the modified Oyane ductile fracture criterion at high temperature. Quite a general rigid viscoplastic model is adopted to describe material behavior. The ductile fracture criterion is in general path-dependent and involves stresses. Therefore, the identification of constitutive parameters of this criterion is a difficult task which usually includes experimental research and numerical simulation. The latter requires a precisely specified material model and boundary conditions. It is shown in the present paper that for a wide class of material models usually used to describe the behavior of materials at high temperatures, the criterion is significantly simplified when the site of fracture initiation is located on traction free surfaces. In particular, this reduced criterion does not involve stresses. Since there are well established experimental procedures to determine the input data for the reduced criterion, the result obtained can be considered as a theoretical basis for the efficient method for identifying constitutive parameters of the modified Oyane ductile fracture criterion at high temperature. The final expression can also be used in computational models to increase the accuracy of predictions.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

scholarly journals Aluminide Thermal Barrier Coating for High Temperature Performance of MAR 247 Nickel Based Superalloy

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 48
Author(s):  
Mateusz Kopec ◽  
Dominik Kukla ◽  
Xin Yuan ◽  
Wojciech Rejmer ◽  
Zbigniew L. Kowalewski ◽  
...  
Keyword(s):  
High Temperature ◽  
Stress Amplitude ◽  
Aluminide Coating ◽  
Chemical Vapor ◽  
Fatigue Tests ◽  
Protective Atmosphere ◽  
X Ray ◽  
Nickel Based Superalloy ◽  
Barrier Coating ◽  
Aluminide Layer

In this paper, mechanical properties of the as-received and aluminide layer coated MAR 247 nickel based superalloy were examined through creep and fatigue tests. The aluminide layer of 20 µm was obtained through the chemical vapor deposition (CVD) process in the hydrogen protective atmosphere for 8 h at the temperature of 1040 °C and internal pressure of 150 mbar. A microstructure of the layer was characterized using the scanning electron microscopy (SEM) and X-ray Energy Dispersive Spectroscopy (EDS). It was found that aluminide coating improve the high temperature fatigue performance of MAR247 nickel based superalloy at 900 °C significantly. The coated MAR 247 nickel based superalloy was characterized by the stress amplitude response ranging from 350 MPa to 520 MPa, which is twice as large as that for the uncoated alloy.

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