scholarly journals The Prospects for Mechanical Ratcheting of Bulk Metallic Glasses

2003 ◽  
Vol 806 ◽  
Author(s):  
Wendelin J. Wright ◽  
R. H. Dauskardt ◽  
W. D. Nix
Keyword(s):  
Plastic Strain ◽  
Metallic Glasses ◽  
Room Temperature ◽  
Tensile Axis ◽  
Uniaxial Stress ◽  
Temperature Deformation ◽  
Steel Alloys ◽  
Cyclic Torsion ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

ABSTRACTThe major mechanical shortcoming of metallic glasses is their limited ductility at room temperature. Monolithic metallic glasses sustain only a few percent plastic strain when subjected to uniaxial compression and essentially no plastic strain under tension. Here we describe a room temperature deformation process that may have the potential to overcome the limited ductility of monolithic metallic glasses and achieve large plastic strains. By subjecting a metallic glass sample to cyclic torsion, the glass is brought to the yield surface; the superposition of a small uniaxial stress (much smaller than the yield stress) should then produce increments in plastic strain along the tensile axis. This accumulation of strain during cyclic loading, commonly known as ratcheting, has been extensively investigated in stainless and carbon steel alloys, but has not been previously studied in metallic glasses. We have successfully demonstrated the application of this ratcheting technique of cyclic torsion with superimposed tension for polycrystalline Ti–6Al–4V. Our stability analyses indicate that the plastic deformation of materials exhibiting elastic–perfectly plastic constitutive behavior such as metallic glasses should be stable under cyclic torsion, however, results obtained thus far are inconclusive.

Plastic Deformation of Bulk Amorphous Alloys

2000 ◽  
Vol 644 ◽  
Author(s):  
L.Q. Xing ◽  
T.C. Hufnagel ◽  
K.T. Ramesh
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Metallic Glasses ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Serrated Flow ◽  
Perfectly Plastic ◽  
Elastic Loading ◽  
The Difference ◽  
Elastic Perfectly Plastic

AbstractWe have studied plastic deformation, including “serrated flow,” of bulk metallic glasses under quasi-static uniaxial compression. The deformation response is essentially elastic-perfectly plastic, but the “plastic” deformation actually consists of sections of elastic loading separated by abrupt load drops. The load drops are due to the formation of shear bands, which represent the primary mechanism of plastic deformationIn Zr-Ti-Cu-Ni-Al bulk metallic glasses, fracture occurs after about 1-2% plastic strain, but in Zr-Ta-Cu-Ni-Al metallic glass the plastic strain to failure can be as large as 6-7%. The difference appears to be due a strong tendency for the shear bands in this alloy to branch. The branching presumably reduces the stress concentration on the shear bands, retarding the onset of fracture. No evidence is seen for the formation of crystalline phases in this alloy.

Plastic Strain Concentrations in Ligaments

1977 ◽  
Vol 99 (2) ◽  
pp. 328-336 ◽  
Author(s):  
J. S. Porowski ◽  
W. J. O’Donnell
Keyword(s):  
Plastic Strain ◽  
Numerical Solutions ◽  
Pure Shear ◽  
Solid Material ◽  
Shear Loading ◽  
Plastic Strains ◽  
Perfectly Plastic ◽  
Circular Holes ◽  
Elastic Perfectly Plastic ◽  
Conservative Values

The sheet perforated with a uniform array of circular holes arranged in a square pattern is investigated. The plastic strains are derived for progressive in-plane loading which eventually results in gross yielding. The finite element method is used to obtain numerical solutions. Plane stress conditions and elastic perfectly plastic solid material properties are assumed. Thus the results provide conservative values of plastic strain concentrations for a considerable range of perforated materials. The plastic strain multipliers for equibiaxial and pure shear loading are given for three ligament efficiencies of the penetration pattern. The tendency of forming highly localized plastic strains with progressive yielding is observed, and the implications of the results in plastic design are discussed.

Deformation of Bi-PST Crystals of TiAl Produced by Diffusion Bonding

1998 ◽  
Vol 552 ◽  
Author(s):  
D. Imamura ◽  
H. Hoshikawa ◽  
K. Kishida ◽  
H. Inui ◽  
M. Yamaguchi
Keyword(s):  
Plastic Strain ◽  
Yield Stress ◽  
Diffusion Bonding ◽  
Deformation Behavior ◽  
Room Temperature ◽  
Strong Influence ◽  
Tensile Axis ◽  
Lamellar Microstructure ◽  
Deformation Modes

ABSTRACTDiffusion bonded bi-PST crystals of three different series were prepared and they were deformed in tension at room temperature. Yield stress and elongation exhibited by bi-PST crystals consisting of component crystals with the lamellar microstructure aligned along the tensile axis do not significantly differ from those of component crystals. Plastic strain incompatibility at the interface exerts a strong influence on the deformation behavior of bi-PST crystals when the incompatibility activates additional deformation modes which are much harder than deformation modes operative in each component crystal.

Room-Temperature Deformation Behavior in the Localized Regions W-80vol%Cu Composite

2006 ◽  
Vol 15-17 ◽  
pp. 255-260
Author(s):  
H. Hanado ◽  
Yutaka Hiraoka
Keyword(s):  
Plastic Strain ◽  
Deformation Behavior ◽  
Room Temperature ◽  
Testing Machine ◽  
Temperature Deformation ◽  
High Magnification ◽  
Bend Testing ◽  
Before And After ◽  
Point Bend ◽  
Heterogeneous Deformation

Room-temperature deformation behavior in the localized regions of W-80vol%Cu composite was investigated in this study. Plastic strain of about 10 % was added to the specimen at room temperature using a three-point bend testing machine. Then deformation behavior in a localized region was investigated using a high-magnification SEM photograph before and after deformation. Results are summarized as follow. (1) In a localized region near a large pore, heterogeneous deformation had occurred as expected. (2) In a region apart from a pore, mostly homogeneous deformation occurred but occasionally heterogeneous deformation occurred.

scholarly journals Effect of Deformation Conditions on Mechanical Properties of Zr-based Metallic Glasses

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Zhenxiang ZHAO ◽  
Chunyan LI ◽  
Fuping ZHU ◽  
Xinling LI ◽  
Shengzhong KOU
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Aspect Ratio ◽  
Plastic Strain ◽  
Strain Rate ◽  
Fracture Strength ◽  
Metallic Glasses ◽  
Room Temperature

In this paper, the effects of different strain rate(1×10-5 s-1, 5×10-5 s-1, 1×10-4 s-1, 5×10-4 s-1, 1×10-3 s-1) and aspect ratio(1:1, 1.5:1, 2:1, 2.5:1, 3:1) on mechanical properties of Zr-based metallic glasses at room temperature were investigated. The results indicate that as the strain rate increases, the plastic strain and compressive strength of the specimens gradually decrease. The specimen with the strain rate of 1×10-5 s-1 exhibits the higher plastic strain of 10.25 %, compressive strength of 2002 MPa and fracture strength of 1999 MPa. In addition, accompanied with the increase in aspect ratio, the plastic strain of the specimens declines from 25.42 % to 1.97 %, meanwhile, the compressive strength and fracture strength of the specimens also present declining trend.

Ti-Based Bulk Metallic Glass with High Cold Workability at Room Temperature

2005 ◽  
Vol 475-479 ◽  
pp. 3431-3434 ◽  
Author(s):  
J.M. Park ◽  
J.S. Park ◽  
J.H. Kim ◽  
Myung Hyun Lee ◽  
Won Tae Kim ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Metallic Glass ◽  
Cold Rolling ◽  
Metallic Glasses ◽  
Room Temperature ◽  
Shear Bands ◽  
Reduction Ratio ◽  
Large Plastic Strain ◽  
Cold Rolled ◽  
Cold Workability

The cold workability of Ti-based bulk metallic glasses (BMGs) have been investigated. Ti45Zr16Be20Cu10Ni9 BMG with a large compressive plastic strain of 4.7 % shows a high cold workability, i.e. total reduction ratio of 50 % by cold rolling at room temperature. The multiple shear bands formed during rolling are effective in enhancing the plasticity. The cold rolled Ti45Zr16Be20Cu10Ni9 BMG (reduction ratio: 30 %) exhibits a large plastic strain of ~14 %.

Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

1981 ◽  
Vol 39 ◽  
pp. 52-53
Author(s):  
D. L. Rohr ◽  
S. S. Hecker
Keyword(s):  
Plastic Strain ◽  
Cell Walls ◽  
Room Temperature ◽  
Mechanical Response ◽  
Biaxial Tension ◽  
Initial Deformation ◽  
Uniaxial Deformation ◽  
Biaxial Deformation ◽  
Stress States ◽  
Comprehensive Study

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.

scholarly journals Room-temperature deformation of single crystals of ZrB2 and TiB2 with the hexagonal AlB2 structure investigated by micropillar compression

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhenghao Chen ◽  
Bhaskar Paul ◽  
Sanjib Majumdar ◽  
Norihiko L. Okamoto ◽  
Kyosuke Kishida ◽  
...  
Keyword(s):  
Single Crystals ◽  
Plastic Flow ◽  
Room Temperature ◽  
Resolve Shear Stress ◽  
Temperature Deformation ◽  
Slip Systems ◽  
Compression Tests ◽  
Plastic Deformation Behavior ◽  
Bulk Single Crystals ◽  
Micropillar Compression

AbstractThe plastic deformation behavior of single crystals of two transition-metal diborides, ZrB2 and TiB2 with the AlB2 structure has been investigated at room temperature as a function of crystal orientation and specimen size by micropillar compression tests. Although plastic flow is not observed at all for their bulk single crystals at room temperature, plastic flow is successfully observed at room temperature by the operation of slip on {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 3> in ZrB2 and by the operation of slip on {1$${\bar{1}}$$ 1 ¯ 00}<0001> and {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 0> in TiB2. Critical resolve shear stress values at room temperature are very high, exceeding 1 GPa for all observed slip systems; 3.01 GPa for {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 3> slip in ZrB2 and 1.72 GPa and 5.17 GPa, respectively for {1$${\bar{1}}$$ 1 ¯ 00}<0001> and {1$${\bar{1}}$$ 1 ¯ 00}<11$${\bar{2}}$$ 2 ¯ 0> slip in TiB2. The identified operative slip systems and their CRSS values are discussed in comparison with those identified in the corresponding bulk single crystals at high temperatures and those inferred from micro-hardness anisotropy in the early studies.

scholarly journals A FEM analysis of the settlement of a tall building situated on loess subsoil

2020 ◽  
Vol 10 (1) ◽  
pp. 519-526
Author(s):  
Krzysztof Nepelski
Keyword(s):  
Fem Analysis ◽  
Actual Process ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Modified Cam Clay ◽  
Linear Behaviour ◽  
Subsequent Calculation ◽  
Elastic Perfectly Plastic ◽  
Subsoil Model ◽  
Storey Building

AbstractIn order to correctly model the behaviour of a building under load, it is necessary to take into account the displacement of the subsoil under the foundations. The subsoil is a material with typically non-linear behaviour. This paper presents an example of the modelling of a tall, 14-storey, building located in Lublin. The building was constructed on loess subsoil, with the use of a base slab. The subsoil lying directly beneath the foundations was described using the Modified Cam-Clay model, while the linear elastic perfectly plastic model with the Coulomb-Mohr failure criterion was used for the deeper subsoil. The parameters of the subsoil model were derived on the basis of the results of CPT soundings and laboratory oedometer tests. In numerical FEM analyses, the floors of the building were added in subsequent calculation steps, simulating the actual process of building construction. The results of the calculations involved the displacements taken in the subsequent calculation steps, which were compared with the displacements of 14 geodetic benchmarks placed in the slab.

scholarly journals S235JRC+C Steel Response Analysis Subjected to Uniaxial Stress Tests in the Area of High Temperatures and Material Fatigue

2021 ◽  
Vol 13 (10) ◽  
pp. 5675
Author(s):  
Josip Brnic ◽  
Marino Brcic ◽  
Sebastian Balos ◽  
Goran Vukelic ◽  
Sanjin Krscanski ◽  
...  
Keyword(s):  
High Temperatures ◽  
Room Temperature ◽  
Uniaxial Stress ◽  
Fatigue Tests ◽  
Experimental Investigations ◽  
Response Analysis ◽  
Stress Tests ◽  
Staircase Method ◽  
Mechanical Fatigue ◽  
Proper Material

Knowledge of the properties and behavior of materials under certain working conditions is the basis for the selection of the proper material for the design of a new structure. This paper deals with experimental investigations of the mechanical properties of unalloyed high quality steel S235JRC + C (1.0122) and its behavior under conditions of high temperatures, creep and mechanical fatigue. The response of the material at high temperatures (20–700 °C) is shown in the form of engineering stress-strain diagrams while that at creep behavior (400–600 °C) is shown in the form of creep curves. Furthermore, based on uniaxial fully reversed mechanical fatigue tests (R=−1), a stress-life (S-N) fatigue diagram has been constructed and the fatigue (endurance) limit of the material is calculated The experimentally determined value of tensile strength at room temperature is 534 MPa. The calculated value of the fatigue limit, also at room temperature, using the modified staircase method and based on the mechanical fatigue tests data, is 202 MPa. With regard to creep resistance, steel 1.0122 can be considered creep-resistant only at a temperature of 400 °C and at an applied stress not exceeding 50% of the yield strength corresponding to this temperature.

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