Ratcheting Assessment of a Fixed Tube Sheet Heat Exchanger Subject to In Phase Pressure and Temperature Cycles

2010 ◽  
Author(s):  
Donald Mackenzie ◽  
Khosrow Behseta ◽  
Robert Hamilton
Keyword(s):  
Heat Exchanger ◽  
Strain Hardening ◽  
Sheet Thickness ◽  
Tube Sheet ◽  
Plastic Response ◽  
Hardening Material ◽  
Elastic Plastic ◽  
Perfectly Plastic ◽  
Inelastic Analysis ◽  
Plastic Shakedown

An investigation of the cyclic elastic-plastic response of an Olefin plant heat exchanger subject to cyclic thermal and pressure loading is presented. The heat exchanger configuration is non-standard as the tube-sheet thickness is considerably less than that required by conventional design by formula rules. Ratchetting assessment is performed using the elastic stress analysis and stress categorization procedure, which indicates that shakedown occurs under the specified loading. The cyclic elastic-plastic response of the heat exchanger is also modeled by inelastic analysis, assuming both elastic perfectly plastic and a strain hardening material models. In the elastic-perfect plastic analysis, the vessel exhibits incremental plastic strain accumulation for 10 full load cycles, with no indication that the configuration will adapt to steady state elastic or plastic action; i.e. elastic shakedown or plastic shakedown. However, the strain increments are small and would not lead to the development of a global plastic collapse or gross plastic deformation during the specified life of the vessel. The strain hardening analysis indicates that the actual vessel will adapt to plastic shakedown after 6 load cycles.

scholarly journals Ratcheting Assessment of a Fixed Tube Sheet Heat Exchanger Subject to In Phase Pressure and Temperature Cycles

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Khosrow Behseta ◽  
Donald Mackenzie ◽  
Robert Hamilton
Keyword(s):  
Heat Exchanger ◽  
Plastic Material ◽  
Sheet Thickness ◽  
Peak Stress ◽  
Material Model ◽  
Tube Sheet ◽  
Hardening Material ◽  
Perfectly Plastic ◽  
Inelastic Analysis ◽  
Plastic Shakedown

An investigation of the cyclic elastic-plastic response of an Olefin plant heat exchanger subject to cyclic thermal and pressure loading is presented. Design by analysis procedures for assessment of shakedown and ratcheting are considered, based on elastic and inelastic analysis methods. The heat exchanger tube sheet thickness is nonstandard as it is considerably less than that required by conventional design by formula rules. Ratcheting assessment performed using elastic stress analysis and stress linearization indicates that shakedown occurs under the specified loading when the nonlinear component of the through thickness stress is categorized as peak stress. In practice, the presence of the peak stress will cause local reverse plasticity or plastic shakedown in the component. In nonlinear analysis with an elastic–perfectly plastic material model the vessel exhibits incremental plastic strain accumulation for 10 full load cycles, with no indication that the configuration will adapt to steady state elastic or plastic action, i.e., elastic shakedown or plastic shakedown. However, the strain increments are small and would not lead to the development of a global plastic collapse or gross plastic deformation during the specified life of the vessel. Cyclic analysis based on a strain hardening material model indicates that the vessel will adapt to plastic shakedown after 6 load cycles. This indicates that the stress categorization and linearization assumptions made in the elastic analysis are valid for this configuration.

A Compressible Elastic, Perfectly Plastic Wedge

1958 ◽  
Vol 25 (2) ◽  
pp. 239-242
Author(s):  
D. R. Bland ◽  
P. M. Naghdi
Keyword(s):  
Plane Strain ◽  
Yield Criterion ◽  
The State ◽  
Hardening Material ◽  
Included Angle ◽  
Elastic Plastic ◽  
Numerical Example ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

Abstract This paper is concerned with a compressible elastic-plastic wedge of an included angle β < π/2 in the state of plane strain. The solution, deduced for an isotropic nonwork-hardening material, employs Tresca’s yield criterion and the associated flow rules. By means of a numerical example the solution is compared with that of an incompressible elastic-plastic wedge in one case (β = π/4) for various positions of the elastic-plastic boundary.

Continuous Strength Method for Aluminium Alloy Structures

2013 ◽  
Vol 742 ◽  
pp. 70-75 ◽  
Author(s):  
Mei Ni Su ◽  
Ben Young ◽  
Leroy Gardner
Keyword(s):  
Aluminium Alloy ◽  
Strain Hardening ◽  
Plastic Material ◽  
Design Method ◽  
Material Model ◽  
Hardening Material ◽  
Perfectly Plastic ◽  
Base Curve ◽  
Current Design ◽  
Elastic Perfectly Plastic

Aluminium alloys are nonlinear metallic materials with continuous stress-strain curves that are not well represented by the simplified elastic, perfectly plastic material model used in many current design specifications. Departing from current practice, the continuous strength method (CSM) is a recently proposed design approach for non-slender aluminium alloy structures with consideration of strain hardening. The CSM is deformation based and employs a base curve to define a continuous relationship between cross-section slenderness and deformation capacity. This paper explains the background and the two key components - (1) the base curve and (2) the strain hardening material model of the continuous strength method. More than 500 test results are used to verify the continuous strength methodas an accurate and consistent design method for aluminium alloy structures.

Evaluating Plastic Loads in Torispherical Heads Using a New Criterion of Collapse

2006 ◽  
Author(s):  
Duncan Camilleri ◽  
Donald Mackenzie ◽  
Robert Hamilton
Keyword(s):  
Pressure Vessels ◽  
Plastic Collapse ◽  
Total Work ◽  
Medium Thickness ◽  
Material Models ◽  
Hardening Material ◽  
Perfectly Plastic ◽  
Inelastic Analysis ◽  
Elastic Perfectly Plastic ◽  
New Criterion

In ASME Design by Analysis, the plastic load of pressure vessels is established using the Twice Elastic Slope criterion of plastic collapse. This is based on a characteristic load-deformation plot obtained by inelastic analysis. This study investigates an alternative plastic criteria based on plastic work dissipation where the ratio of plastic to total work is monitored. Two sample analyses of medium thickness torispherical pressure vessels are presented. Elastic-perfectly plastic and strain hardening material models are considered in both small and large deformation analyses. The calculated plastic loads are assessed in comparison with experimental results from the literature.

Lower Bound Methods in Elastic-Plastic Shakedown Analysis

2010 ◽  
Author(s):  
Wolf Reinhardt ◽  
Reza Adibi-Asl
Keyword(s):  
Lower Bound ◽  
Plastic Material ◽  
Shakedown Analysis ◽  
Elastic Plastic ◽  
Perfectly Plastic ◽  
Efficient Calculation ◽  
Asme Code ◽  
Elastic Shakedown ◽  
Plastic Shakedown

Several methods were proposed in recent years that allow the efficient calculation of elastic and elastic-plastic shakedown limits. This paper establishes a uniform framework for such methods that are based on perfectly-plastic material behavour, and demonstrates the connection to Melan’s theorem of elastic shakedown. The paper discusses implications for simplified methods of establishing shakedown, such as those used in the ASME Code. The framework allows a clearer assessment of the limitations of such simplified approaches. Application examples are given.

Ductile Tearing Instability of a Center-Cracked Panel of an Elastic-Plastic Strain Hardening Material

1981 ◽  
Vol 103 (1) ◽  
pp. 46-54 ◽  
Author(s):  
Akram Zahoor ◽  
Paul C. Paris
Keyword(s):  
Plastic Strain ◽  
Strain Hardening ◽  
Plane Strain ◽  
Plane Stress ◽  
Hardening Material ◽  
Ductile Tearing ◽  
Elastic Plastic ◽  
Linear Elastic ◽  
Tearing Instability ◽  
Crack Stability

An analysis for crack instability in an elastic-plastic strain hardening material is presented which utilizes the J-integral and the tearing modulus parameter, T. A center-cracked panel of finite dimensions with Ramberg-Osgood material representation is analyzed for plane stress as well as plane strain. The analysis is applicable in the entire range of elastic-plastic loading from linear elastic to full yield. Crack instability is strongly influenced by the elastic compliance of the system, the conditions of plane stress or plane strain, and the hardening characteristics of the material. Numerical results indicate that if crack stability is ensured in a plane strain situation, then under the same circumstances a geometrically identical but plane stress panel will be stable.

Using Nonlinear Kinematic Hardening Material Models for Elastic-Plastic Ratcheting Analysis

2015 ◽  
Author(s):  
Tim Gilman ◽  
Bill Weitze ◽  
Jürgen Rudolph ◽  
Adrian Willuweit ◽  
Arturs Kalnins
Keyword(s):  
Material Model ◽  
Pressure Vessels ◽  
Growth Strain ◽  
Temperature Dependent ◽  
Material Models ◽  
Hardening Material ◽  
Material Parameters ◽  
Elastic Plastic ◽  
Material Data ◽  
Inelastic Analysis

Applicable design codes for power plant components and pressure vessels demand for a design check against progressive plastic deformation. In the simplest case, this demand is satisfied by compliance with shakedown rules in connection with elastic analyses. The possible non-compliance implicates the requirement of ratcheting analyses on elastic-plastic basis. In this case, criteria are specified on maximum allowable accumulated growth strain without clear guidance on what material models for cyclic plasticity are to be used. This is a considerable gap and a challenge for the practicing CAE (Computer Aided Engineering) engineer. As a follow-up to two independent previous papers PVP2013-98150 ASME [1] and PVP2014-28772 [2] it is the aim of this paper to close this gap by giving further detailed recommendation on the appropriate application of the nonlinear kinematic material model of Chaboche on an engineering scale and based on implementations already available within commercial finite element codes such as ANSYS® and ABAQUS®. Consistency of temperature-dependent runs in ANSYS® and ABAQUS® is to be checked. All three papers together constitute a comprehensive guideline for elasto-plastic ratcheting analysis. The following issues are examined and/or referenced: • Application of monotonic or cyclic material data for ratcheting analysis based on the Chaboche material model • Discussion of using monotonic and cyclic data for assessment of the (non-stabilized) cyclic deformation behavior • Number of backstress terms to be applied for consistent ratcheting results • Consideration of the temperature dependency of the relevant material parameters • Consistency of temperature-dependent runs in ANSYS® and ABAQUS® • Identification of material parameters dependent on the number of backstress terms • Identification of material data for different types of material (carbon steel, austenitic stainless steel) including the appropriate determination of the elastic limit • Quantification of conservatism of simple elastic-perfectly plastic behavior • Application of engineering versus true stress-strain data • Visual checks of data input consistency • Appropriate type of allowable accumulated growth strain. This way, a more accurate inelastic analysis methodology for direct practical application to real world examples in the framework of the design code conforming elasto-plastic ratcheting check is proposed.

Plastic Response Estimation in Repeated Elastic Analyses for Strain Hardening Material Model

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
S. L. Mahmood ◽  
R. Adibi-Asl ◽  
C. G. Daley
Keyword(s):  
Strain Hardening ◽  
Strain Energy ◽  
Plastic Material ◽  
Limit Load ◽  
Material Model ◽  
Element Analysis ◽  
Hardening Material ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

Simplified limit analysis techniques have already been employed for limit load estimation on the basis of linear elastic finite element analysis (FEA) assuming elastic-perfectly-plastic material model. Due to strain hardening, a component or a structure can store supplementary strain energy and hence carries additional load. In this paper, an iterative elastic modulus adjustment scheme is developed in context of strain hardening material model utilizing the “strain energy density” theory. The proposed algorithm is then programmed into repeated elastic FEA and results from the numerical examples are compared with inelastic FEA results.

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