On the Plastic Constraint Factor of Polymers

2017 ◽  
Vol 373 (1) ◽  
pp. 1600117
Author(s):  
Ralf Lach ◽  
Patricia M. Frontini ◽  
Wolfgang Grellmann
Keyword(s):  
Constraint Factor ◽  
Plastic Constraint

Validation on the Relationship Between J Integral and CTOD for Offshore Structural Steel Weldments by Experimental and Numerical Analyses

2014 ◽  
Author(s):  
Dong Hyun Moon ◽  
Jeong Soo Lee ◽  
Jae Myung Lee ◽  
Myung Hyun Kim
Keyword(s):  
Plastic Deformation ◽  
Crack Tip ◽  
J Integral ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Constraint Factor ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Plastic Constraint ◽  
The Relationship

Elastic plastic fracture mechanics (EPFM) is the domain of fracture analysis which considers extensive plastic deformation at crack tip prior to fracture. J integral and crack tip opening displacement (CTOD) have been commonly used as parameters for EPFM analysis. The relationship between these parameters has been extensively studied by industry and academia. The plastic constraint factor can serve as a parameter to characterize constraint effects in fracture involving plastic deformation. Therefore, the characteristics of plastic constraint factor are important in EPFM analysis. In this study, the relationship between J Integral and CTOD was investigated by conducting fracture toughness tests using single edge notched bend (SENB) specimens. Also, plastic constraint factor was investigated by using finite element analysis. Numerical analysis was carried out using ABAQUS elastic-plastic analysis mode.

Notch Effects on Impact Tensile Properties in A6061-T6 Aluminum Alloy

2004 ◽  
Vol 449-452 ◽  
pp. 137-140
Author(s):  
Tomokazu Masuda ◽  
Hiroyuki Toda ◽  
Toshiro Kobayashi
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
High Strain ◽  
Rate Sensitivity ◽  
Triaxial Stress ◽  
Constraint Factor ◽  
Notched Specimens ◽  
Plastic Constraint ◽  
Reduction Of Area ◽  
Stress And Strain Rate

The strain rate sensitivity of a A6061-T6 aluminum is examined as a function of triaxial stress. The triaxial stress state is changed by changing the notch acuity of notched specimens. Under the high strain rate conditions, increasing triaxiality increases flow stress. Plastic constraint factor decreases in notched specimens under high strain rate conditions. Reduction-of-area in notched specimen increases with increasing strain rate. The relaxation of plastic constraint takes place under high strain rate in the notched specimens. The effects of triaxial stress and strain rate on the fracture surfaces are discussed.

Estimation of Constraint Factor on the Relationship Between J Integral and CTOD for Offshore Structural Steel Weldments

2013 ◽  
Author(s):  
Dong Hyun Moon ◽  
Jeong Soo Lee ◽  
Jae Myung Lee ◽  
Myung Hyun Kim
Keyword(s):  
Heat Input ◽  
Arc Welding ◽  
Crack Tip ◽  
Offshore Structures ◽  
J Integral ◽  
Crack Tip Opening Displacement ◽  
Constraint Factor ◽  
Plastic Constraint ◽  
Flux Cored Arc Welding ◽  
The Relationship

As ships and offshore structures become larger than before the usage of high strength steel and ultra thick plate has been increased. However, the thick plates have disadvantages with respect to brittle fracture and fatigue strength. Elastic plastic fracture mechanics (EPFM) is the domain of fracture analysis which considers extensive plastic deformation at crack tip prior to fracture. The J integral and crack tip opening displacement (CTOD) have been commonly used as parameters for EPFM analysis. The relationship between these parameters has been studied by industry and academia. The plastic constraint factor can serve as a parameter to characterize constraint effects in fracture. Therefore, the characteristics of plastic constraint factor are important in EPFM analysis. In this study, the relationship between J Integral and CTOD was investigated by conducting 3-point bending tests using single edge notched bend (SENB) specimens. Two types of specimens were fabricated. One is API 2W Gr.50 welded by means of flux cored arc welding (FCAW) with heat input 15kJ/cm, and the other is API 2W Gr.50 welded by means of submerged arc welding (SAW) with heat input 45kJ/cm. The plastic constraint factor was estimated considering heat input, temperatures at weldment and heat affected zone (HAZ).

Multiaxial deformation characteristic of a Zr-based bulk metallic glass: Variations of the plastic constraint factor underneath a spherical indenter

2007 ◽  
Vol 22 (10) ◽  
pp. 2895-2901 ◽  
Author(s):  
Yun-Hee Lee ◽  
Ju-Young Kim ◽  
Un-Bong Baek ◽  
Seung-Hoon Nahm
Keyword(s):  
Metallic Glass ◽  
Deformation Characteristic ◽  
Steel Sample ◽  
Assessment Method ◽  
Spherical Indenter ◽  
Plastic Behavior ◽  
Flow Properties ◽  
Rigid Plastic ◽  
Constraint Factor ◽  
Plastic Constraint

Multiaxial deformation of Zr55Al10Ni5Cu30 metallic glass was investigated by instrumented indentation tests with a spherical indenter. Contrary to the elastic–rigid-plastic behavior of bulk metallic glasses (BMGs), indentation pressure showed a significant increase with increasing indentation strain, and it was ascribed to a rapid transition of the plastic constraint factor (PCF). However, it was impossible to measure the PCF values from the indentation pressures in the Zr-based BMG because information on uniaxial flow stress was insufficient due to the limited flow strain of 2.2%. Here we developed a PCF assessment method using a relative residual depth hf/hmax, which was experimentally confirmed by adopting it to spherical indentations of a steel sample having well-known flow properties. Flow properties of the BMG were calculated using the new PCF assessment method, and the effects of the materials pileup and low strain indentations on PCF and flow properties were discussed.

Estimation of Evapotranspiration and Its Components across China Based on a Modified Priestley–Taylor Algorithm Using Monthly Multi-Layer Soil Moisture Data

2021 ◽  
Vol 13 (16) ◽  
pp. 3118
Author(s):  
Wanqiu Xing ◽  
Weiguang Wang ◽  
Quanxi Shao ◽  
Linye Song ◽  
Mingzhu Cao
Keyword(s):  
Soil Moisture ◽  
Arid Region ◽  
Water Movement ◽  
Large Fraction ◽  
Temporal Distribution ◽  
Constraint Factor ◽  
Jet Propulsion ◽  
Original Algorithm ◽  
Important Constraint ◽  
Different Depths

Although soil moisture (SM) is an important constraint factor of evapotranspiration (ET), the majority of the satellite-driven ET models do not include SM observations, especially the SM at different depths, since its spatial and temporal distribution is difficult to obtain. Based on monthly three-layer SM data at a 0.25° spatial resolution determined from multi-sources, we updated the original Priestley Taylor–Jet Propulsion Laboratory (PT-JPL) algorithm to the Priestley Taylor–Soil Moisture Evapotranspiration (PT-SM ET) algorithm by incorporating SM control into soil evaporation (Es) and canopy transpiration (T). Both algorithms were evaluated using 17 eddy covariance towers across different biomes of China. The PT-SM ET model shows increased R2, NSE and reduced RMSE, Bias, with more improvements occurring in water-limited regions. SM incorporation into T enhanced ET estimates by increasing R2 and NSE by 4% and 18%, respectively, and RMSE and Bias were respectively reduced by 34% and 7 mm. Moreover, we applied the two ET algorithms to the whole of China and found larger increases in T and Es in the central, northeastern, and southern regions of China when using the PT-SM algorithm compared with the original algorithm. Additionally, the estimated mean annual ET increased from the northwest to the southeast. The SM constraint resulted in higher transpiration estimate and lower evaporation estimate. Es was greatest in the northwest arid region, interception was a large fraction in some rainforests, and T was dominant in most other regions. Further improvements in the estimation of ET components at high spatial and temporal resolution are likely to lead to a better understanding of the water movement through the soil–plant–atmosphere continuum.

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