Unifying Monotonic and Hysteresis Material Properties for Notch Plasticity Analysis under Variable Amplitude Loads

2014 ◽  
Vol 891-892 ◽  
pp. 500-505 ◽  
Author(s):  
Xiao Bo Yu ◽  
Qian Chu Liu ◽  
Chris Wallbrink
Keyword(s):  
Strain Amplitude ◽  
Material Properties ◽  
Present Finding ◽  
High Strain ◽  
Cyclic Strain ◽  
Recovery Process ◽  
Material Behaviour ◽  
Variable Amplitude ◽  
Dog Bone ◽  
Conceptual Consideration

This study was performed in support of accurate notch plasticity analysis under variable amplitude loads. Monotonic and cyclic strain-controlled tests were performed on flat dog-bone coupons machined from 6.35mm thick 7075-T651 aluminium alloy plates. The tests with low-high-low strain amplitude transitions revealed both an instant softening following the high strain amplitude cycle and a gradual recovery during the subsequent low strain amplitude cycles. The transition from monotonic-like to hysteresis-like material behaviour was found to be consistent with an overload induced softening and recovery process. A conceptual consideration is thus proposed to unify the characterisation of monotonic and hysteresis material properties. The implications of the present finding on notch plasticity analysis are also discussed.

Uncertainties and Margins in Environmental Fatigue Analysis Rules

2014 ◽  
Author(s):  
C. Faidy
Keyword(s):  
Strain Amplitude ◽  
Material Properties ◽  
Cyclic Strain ◽  
Fatigue Curve ◽  
Fatigue Analysis ◽  
Fatigue Tests ◽  
Pressure Vessels ◽  
Life Assessment ◽  
Combination Rules ◽  
Reduction Factors

During the past 30 years the main rules for fatigue analysis of pressure vessels were based on elastic approaches in order to evaluate cyclic strain amplitude and compare with an S-N fatigue curve for the corresponding material. After review of some rules in different Nuclear and Non-Nuclear Codes, like ASME Boiler & Pressure Vessel Code Section III, French RCC-M and RCC-MRx, European Standards EN 13445, the major conservatisms and uncertainties of different rules are discussed. All these Codes propose simple rules to evaluate the strain amplitude based on elastic approaches and simplified correction factors (Ke and Kν), transient combination rules and damage cumulating procedure. In the other hand, the material properties are based on standard fatigue tests done on the material associated to reduction factors to consider some particular effects like scatter, scale, surface roughness, mean stress or environmental effects to transfer them from small specimen to real structures. Concerned components in this paper are mainly piping systems. No existing Code covers all the aspects of fatigue with similar conservatisms that can affect the in-service inspection programs and the remaining life assessment of the corresponding components. After the review of different rules, key factors that affect the results and predictions will be identified. Some proposals will be issued to progress in the near future. Finally, a first set of recommendation on fatigue analysis will be presented to improve existing codes on harmonized way, associated to material properties needed, as fatigue curves associated to reduction factors.

Fatigue Design Rules in Pressure Vessel Codes Uncertainties and Remaining Open Points

2014 ◽  
Author(s):  
Claude Faidy
Keyword(s):  
Strain Amplitude ◽  
Pressure Vessel ◽  
Material Properties ◽  
Cyclic Strain ◽  
Fatigue Curve ◽  
Fatigue Analysis ◽  
Pressure Vessels ◽  
Life Assessment ◽  
Combination Rules ◽  
Reduction Factors

During the past 30 years the main rules for fatigue analysis of pressure vessels were based on elastic approaches in order to evaluate a cyclic strain amplitude and compare with an S-N fatigue curve for the corresponding material. After review of some rules in different Nuclear and Non Nuclear Codes, like ASME Boiler & Pressure Vessel Code Section III, French RCC-M and RCC-MRx, European Standards EN 13445, the major conservatisms and uncertainties of different rules are discussed. All these Codes propose simple rules to evaluate the strain amplitude based on elastic approaches and simplified correction factors (Ke and Kv), transient combination rules and damage cumulating procedure. In the other hand, the material properties are based on standard fatigue tests done on the material associated to reduction factors to consider some particular effects like scatter, scale, surface roughness, mean stress or environmental effects to transfer them from small specimen to real structures. Concerned components are mainly piping systems. No existing Code covers all the aspects of fatigue with similar conservatisms that can affect the in-service inspection programs and the remaining life assessment of the corresponding components. After the review of different rules, key factors that affect the results and predictions will be identified. Some proposals will be issued to progress in the near future. Finally, a first set of recommendation on fatigue analysis will be presented to improve existing codes on an harmonized way, associated to material properties needed, as fatigue curves associated to reduction factors.

Tension and Compression Behavior of Pre-Stressed Steel Strands at High Strain Rate

2011 ◽  
Vol 82 ◽  
pp. 154-159 ◽  
Author(s):  
Anatoly M. Bragov ◽  
Ezio Cadoni ◽  
Alexandr Yu. Konstantinov ◽  
Andrey K. Lomunov
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
High Strength ◽  
Gauge Length ◽  
Hopkinson Pressure Bar ◽  
Dog Bone ◽  
Tension And Compression ◽  
Set Up

In this paper is described the mechanical characterization at high strain rate of the high strength steel usually adopted for strands. The experimental set-up used for high strain rates testing: in tension and compression was the Split Hopkinson Pressure Bar installed in the Laboratory of Dynamic Investigation of Materials in Nizhny Novgorod. The high strain rate data in tension was obtained with dog-bone shaped specimens of 3mm in diameter and 5mm of gauge length. The specimens were screwed between incident and transmitter bars. The specimens used in compression was a cylinder of 3mm in diameter and 5mm in length. The enhancement of the mechanical properties is quite limited compared the usual reinforcing steels.

Deformation Behavior Prediction of X80 Steel Line Pipe and Implication on High Strain Pipe Specification

2008 ◽  
Author(s):  
Hongyuan Chen ◽  
Lingkang Ji ◽  
Shaotao Gong ◽  
Huilin Gao
Keyword(s):  
Internal Pressure ◽  
Material Properties ◽  
High Strain ◽  
Behavior Prediction ◽  
Buckling Mode ◽  
Line Pipe ◽  
Geometric Imperfection ◽  
China National Petroleum Corporation ◽  
Scale Test ◽  
Pipe Size

The use of strain based design in pipeline technology has been widely discussed during the last decade for pipelines in harsh environment. In such cases pipelines should be designed based on strain criterion. Strain based design poses a number of challenges, particularly on pipe size and material properties. This paper presents preliminary studies on prediction of buckling strain and buckling mode for X80 high-strain line pipe by finite element methods based on full-scale test. The effects of several parameters such as internal pressure, material properties pipe size and geometric imperfection, were investigated to predict the critical strain for 48″ diameter line pipe under compression and pure bending with 12MPa internal pressure. Material parameters of a specification for high strain line pipe were analyzed to promote its application in the 2nd West-East pipeline of China National Petroleum Corporation.

High-Strain-Rate Superplastic Flow Mechanism in ZrO2-30vol% Spinel Two-Phase Composite

2010 ◽  
Vol 433 ◽  
pp. 333-338 ◽  
Author(s):  
Koji Morita ◽  
Keijiro Hiraga ◽  
Byung Nam Kim ◽  
Hidehiro Yoshida
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Flow Behavior ◽  
Recovery Process ◽  
Lattice Diffusion ◽  
Two Phase ◽  
Data Set ◽  
Strain And Strain Rate ◽  
Accommodation Process

High-strain-rate superplasticity (HSRS) can be attained in tetragonal ZrO2-30vol% MgAl2O4 spinel composite. In order to examine the flow behavior of the two-phase composite, the standard rule of the mixture model was employed. The strain rate of the composite can be explained by the isostrain model that is predicted from the data set of Al2O3 doped ZrO2 and spinel polycrystals. For the isostrain model, since the strain and strain rate are the same for ZrO2 and spinel phases, the harder ZrO2 phase carries more of the stress in the composite. In order to preserve homogeneous deformation and material continuity, a concomitant accommodation process within the harder ZrO2 grains is also necessary. For HSRS in the ZrO2-spinel composite, therefore, the rate of deformation may be controlled by the slower dislocation recovery process limited by the lattice diffusion within harder ZrO2 grains rather than within spinel grains.

Effect of high strain amplitude and pre-deformation on damping property of Fe-Mn alloy

2019 ◽  
Vol 770 ◽  
pp. 252-256 ◽  
Author(s):  
Haijun Wang ◽  
Hui Wang ◽  
Ruiqian Zhang ◽  
Rui Liu ◽  
Yu Xu ◽  
...  
Keyword(s):  
Strain Amplitude ◽  
High Strain ◽  
Damping Property ◽  
High Strain Amplitude

Mass Production and Installation of X100 Linepipe for Strain-Based Design Application

2008 ◽  
Author(s):  
Nobuyuki Ishikawa ◽  
Mitsuhiro Okatsu ◽  
Shigeru Endo ◽  
Joe Kondo ◽  
Joe Zhou ◽  
...  
Keyword(s):  
Base Metal ◽  
Material Properties ◽  
Mass Production ◽  
High Strain ◽  
Uniform Elongation ◽  
Accelerated Cooling ◽  
Absorbed Energy ◽  
Strain Capacity ◽  
Weld Properties ◽  
Charpy Absorbed Energy

Continuous efforts have been made for the realization of strain-based design pipeline using high grade linepipe materials. Two demonstrative constructions of the pipelines using X100 linepipe proved sufficient materials properties for strain-based design and high quality field welding with good productivity. In order to verify further applicability of high strain X100 linepipe for long distance transmission, large scale installation of X100 pipeline was accomplished. Mass production of X100 linepipe of about 2,000 metric tons with the size of 42″OD and 14.3mm wall thick was successfully conducted by applying recent developed TMCP process including accelerated cooling and online heat treatment process and UOE pipe forming. Field girth welding was safely completed by the dual tandem pulsed GMAW, and sufficient girth weld properties were demonstrated. This paper will describe material development and mass production results of X100 linepipe for strain-based design which specifying longitudinal tensile properties such as Y/T ratio and uniform elongation. In order to securely specify the shape of stress-strain curve without Luders elongation, material parameter “stress ratio” was introduced for the material specification for compressive strain capacity. Stringent base metal requirements were imposed for base metal material properties in this project. One of the most challenging aspects in developing high strain linepipe is to balance uniform elongation and Charpy absorbed energy. Dual phase microstructure is essential to improve strain capacity, but this may lead to lower Charpy absorbed energy. Therefore, precise control of microstructure by controlling plate manufacturing parameter was required. In addition, on-line heating process subsequently after accelerated cooling enabled increase of Charpy energy without deteriorating uniform elongation. Girth weld properties were closely evaluated using the X100 pipe in as UOE condition and after external coating. All the material properties of base metal and girth weldment of the X100 linepipes used for this project fulfill the stringent requirement for strain-based design consideration to prevent buckling and weld fracture.

High Strain Rate Compressive Properties of Soft Tissue

2003 ◽  
Author(s):  
Caleb R. Van Sligtenhorst ◽  
Duane S. Cronin ◽  
G. Wayne Brodland
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Material Properties ◽  
Fiber Orientation ◽  
Soft Tissues ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Strain Rates ◽  
Post Mortem ◽  
Fresh Tissue

High strain rate material properties and constitutive equations are essential for the development of numerical and physical models to assess the performance of soft materials subject to high rate deformation, with potential applications including protective equipment and vehicle crashworthiness. However, these properties are not available for many soft tissues. This is because specialized testing methods must be employed to obtain the necessary data. Fresh bovine tissue from the semimembranosis muscle was obtained and tested using a polymeric Split Hopkinson Pressure Bar. Samples were tested from 1.4 to 200 hours post mortem to observe the effect of rigor and other possible temporal effects on the material properties. Since this muscle had relatively uniform fiber orientation, it was possible to obtain specimens with fiber directions parallel, perpendicular, and at 45 degrees to the compression axis. The stress-strain curves for the muscle were concave upwards, as is typical of soft tissues at high strain rates. Fiber orientation was determined to have negligible effect at the tested strain rates. The testing revealed that the stiffness of the tissue increased with post mortem time until approximately 6 hours. At times greater than 200 hours post mortem, the tissue properties were found to be very similar to the properties of fresh tissue. These findings suggest that properties of fresh tissue might be estimated using more easily obtained post-rigor tissue.

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