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.

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.

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

scholarly journals Free-volume dependent pressure sensitivity of Zr-based bulk metallic glass

2009 ◽  
Vol 24 (8) ◽  
pp. 2697-2704 ◽  
Author(s):  
Alban Dubach ◽  
K. Eswar Prasad ◽  
Rejin Raghavan ◽  
Jorg F. Löffler ◽  
Johann Michler ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Free Volume ◽  
Structural State ◽  
Shear Bands ◽  
Compressive Yield Strength ◽  
Pressure Sensitivity ◽  
Constraint Factor ◽  
Shear Transformation Zones

Instrumented indentation experiments on a Zr-based bulk metallic glass (BMG) in as-cast, shot-peened and structurally relaxed conditions were conducted to examine the dependence of plastic deformation on its structural state. Results show significant differences in hardness, H, with structural relaxation increasing it and shot peening markedly reducing it, and slightly changed morphology of shear bands around the indents. This effect is in contrast to uniaxial compressive yield strength, σy, which remains invariant with the change in the structural state of the alloys investigated. The plastic constraint factor, C = H/σy, of the relaxed BMG increases compared with that of the as-cast glass, indicating enhanced pressure sensitivity upon annealing. In contrast, C of the shot-peened layer was found to be similar to that observed in crystalline metals, indicating that severe plastic deformation could eliminate pressure sensitivity. Microscopic origins for this result, in terms of shear transformation zones and free volume, are discussed.

scholarly journals Design of connections in composite timber-concrete structures

2006 ◽  
Vol 4 (2) ◽  
pp. 127-138
Author(s):  
Dragoslav Stojic ◽  
Radovan Cvetkovic
Keyword(s):  
Composite Structures ◽  
Concrete Structures ◽  
Steel Structure ◽  
Plastic Behavior ◽  
Bending Moments ◽  
Rigid Plastic ◽  
Moment Capacity ◽  
Building Conditions ◽  
New Type

This work deals with composite timber concrete structures. By combining timber and concrete in new type of composite material and using the best properties both materials, the high tensile strength of a timber and the high compressive strength of a concrete, depending of different building conditions we can find a lot o reasons for decision to apply this type of the structure in comparison to concrete or steel structure. Here, design methods and procedures for determination of load bearing capacity bar shaped connectors (fasteners) very often used as element connecting timber and concrete in composite structures will be given. The procedure will be exposed and explained according to the new fashioned methods collected as set of Euro-norms in Eurocode 5. The design equations in Eurocode 5 derived from Johansen's work are based on a rigid plastic behavior of the fastener under bending moments and the timber under embedding stresses and take into account the plastic moment capacity of the fastener.

Recent Studies on the Dynamic Plastic Behavior of Structures

1989 ◽  
Vol 42 (4) ◽  
pp. 95-115 ◽  
Author(s):  
Norman Jones
Keyword(s):  
Brittle Fracture ◽  
Dynamic Loads ◽  
Large Impact ◽  
Plastic Behavior ◽  
Impact Loads ◽  
Plastic Strains ◽  
Review Of The Literature ◽  
Rigid Plastic ◽  
Plastic Buckling ◽  
Fracture Transition

This article contains a review of the literature, which has been published recently, on the dynamic plastic behavior of simple structures. The dynamic loads cause large plastic strains which dominate material elastic effects. Thus, the accuracy of various refinements of simple rigid-plastic methods are discussed, together with the phenomena of pseudoshakedown under repeated loads, dynamic plastic buckling, and dynamic progressive buckling. Recent studies are also reported on similitude under large impact loads, and on the ductile-brittle fracture transition due to the changes in the physical dimensions of a structure.

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