Micro-Raman Investigations of Elastic and Plastic Strain Relief in Si1-xGex-Heterostructures

1993 ◽  
Vol 32-33 ◽  
pp. 577-582 ◽  
Author(s):  
B. Dietrich ◽  
E. Bugiel ◽  
H.J. Osten ◽  
P. Zaumseil
Keyword(s):  
Plastic Strain ◽  
Strain Relief

Plastic Deformation in Microtomed Sections

1971 ◽  
Vol 29 ◽  
pp. 458-459
Author(s):  
J. Temple Black
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Applied Stress ◽  
Elastic Strain ◽  
High Strain ◽  
Tool Material ◽  
Cutting Edge ◽  
Material Structure ◽  
Geometrical Constraints

The output of the ultramicrotomy process with its high strain levels is dependent upon the input, ie., the nature of the material being machined. Apart from the geometrical constraints offered by the rake and clearance faces of the tool, each material is free to deform in whatever manner necessary to satisfy its material structure and interatomic constraints. Noncrystalline materials appear to survive the process undamaged when observed in the TEM. As has been demonstrated however microtomed plastics do in fact suffer damage to the top and bottom surfaces of the section regardless of the sharpness of the cutting edge or the tool material. The energy required to seperate the section from the block is not easily propogated through the section because the material is amorphous in nature and has no preferred crystalline planes upon which defects can move large distances to relieve the applied stress. Thus, the cutting stresses are supported elastically in the internal or bulk and plastically in the surfaces. The elastic strain can be recovered while the plastic strain is not reversible and will remain in the section after cutting is complete.

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.

Lamellar grains distribution and plastic strain heterogeneities in TiAI cast samples. Experiments and modelling

2004 ◽  
Vol 92 (1-2) ◽  
pp. 69-76 ◽  
Author(s):  
L. Gélébart ◽  
M. Bornert ◽  
T. Bretheau ◽  
D. Caldemaison ◽  
J. Crépin ◽  
...  
Keyword(s):  
Plastic Strain

CHARACTERIZATION OF AL-6%MG MODIFIED WITH 0.15% OF ZR ALLOY AND SUBMITTED STRAIN RELIEF THE 400°C/1H

2019 ◽  
Author(s):  
Brenda Daniel ◽  
BEATRIZ SEABRA MELO ◽  
Marcus Vinícius Wanderley ◽  
Ricardo França ◽  
Natália Luiza Abucater Brum ◽  
...  
Keyword(s):  
Strain Relief ◽  
Zr Alloy

Results of Applying the Method of Visual Fatigue Prevention Using Low-Intensity Laser Radiation

2020 ◽  
pp. 56-59
Author(s):  
NYu Mal’kova ◽  
MD Petrova
Keyword(s):  
Laser Radiation ◽  
Work Experience ◽  
Study Groups ◽  
Light Sensitivity ◽  
Control Group ◽  
Sensitivity Threshold ◽  
Visual Fatigue ◽  
Strain Relief ◽  
Visual Stress ◽  
Stress At Work

Summary. Introduction: Visual fatigue is caused by changes in the muscular apparatus and retina of the eye and is characterized by deterioration in their functional activity. Along with an increase in work experience and age, workplace visual stress promotes the loss of performance. Known methods of visual fatigue prevention and eye strain relief are ineffective. In this regard, a technique of relieving visual fatigue using scattered low-level red laser radiation was developed and patented. The purpose of our study was a retrospective evaluation of effectiveness of the visual fatigue reduction technique. Materials and methods: We examined two groups of women (PC operators and jewellers) aged 43–57 years experiencing visual stress at work and practicing the method under study over the previous 20 years. The state of daylight vision was assessed by adaptation time. Results: A five-day testing of the method of visual fatigue relief showed stabilization of the light sensitivity threshold throughout the work shift. Over the 20-year period, the female workers had had no complaints of eye strain, burning or lacrimation. Objective studies of the functional state of the organ of sight showed that the light sensitivity threshold during the working day in two study groups was significantly lower than that in the control group with no preventive measures taken. Conclusions: We established that using the technique of eye strain relief based on a two-minute binocular exposure to red laser radiation with the power density of 2×10–7 W/cm2, a 5-day course every six months over the period of 20 years, helped retain retinal activity in terms of light sensitivity, thus preventing visual fatigue.

A Scale Effect Accompanying Autowave Plastic Strain

2020 ◽  
Vol 46 (9) ◽  
pp. 851-853
Author(s):  
L. B. Zuev ◽  
V. I. Danilov ◽  
M. V. Nadezhkin
Keyword(s):  
Plastic Strain ◽  
Scale Effect

scholarly journals On the Plastic Strain Accumulation in Notched Bars During High-Temperature Creep Dwell

2020 ◽  
Vol 36 (2) ◽  
pp. 167-176 ◽  
Author(s):  
Daniele Barbera ◽  
Haofeng Chen
Keyword(s):  
High Temperature ◽  
Cyclic Loading ◽  
Plastic Strain ◽  
Kinematic Hardening ◽  
High Temperature Creep ◽  
Strain Accumulation ◽  
Material Models ◽  
Cyclic Loading Condition ◽  
Hardening Material ◽  
Temperature Creep

ABSTRACTStructural integrity plays an important role in any industrial activity, due to its capability of assessing complex systems against sudden and unpredicted failures. The work here presented investigates an unexpected new mechanism occurring in structures subjected to monotonic and cyclic loading at high temperature creep condition. An unexpected accumulation of plastic strain is observed to occur, within the high-temperature creep dwell. This phenomenon has been observed during several full inelastic finite element analyses. In order to understand which parameters make possible such behaviour, an extensive numerical study has been undertaken on two different notched bars. The notched bar has been selected due to its capability of representing a multiaxial stress state, which is a practical situation in real components. Two numerical examples consisting of an axisymmetric v-notch bar and a semi-circular notched bar are considered, in order to investigate different notches severity. Two material models have been considered for the plastic response, which is modelled by both Elastic-Perfectly Plastic and Armstrong-Frederick kinematic hardening material models. The high-temperature creep behaviour is introduced using the time hardening law. To study the problem several results are presented, as the effect of the material model on the plastic strain accumulation, the effect of the notch severity and the mesh element type and sensitivity. All the findings further confirm that the phenomenon observed is not an artefact but a real mechanism, which needs to be considered when assessing off-design condition. Moreover, it might be extremely dangerous if the cyclic loading condition occurs at such a high loading level.

Ductile Crack Extension Analysis for X80 Bending Deformation Using Damage-Based Model

2014 ◽  
Author(s):  
Satoshi Igi ◽  
Mitsuru Ohata ◽  
Takahiro Sakimoto ◽  
Kenji Oi ◽  
Joe Kondo
Keyword(s):  
Plastic Strain ◽  
Simulation Model ◽  
Crack Growth ◽  
Crack Extension ◽  
Damage Model ◽  
Stress Triaxiality ◽  
Crack Growth Behavior ◽  
Ductile Crack ◽  
Ductile Crack Growth ◽  
Notch Tip

This paper presents experimental and analytical results focusing on the strain limit of X80 linepipe. Ductile crack growth behavior from a girth weld notch is simulated by FE analysis based on a proposed damage model and is compared with the experimental results. The simulation model for ductile crack growth accompanied by penetration through the wall thickness consists of two criteria. One is a criterion for ductile crack initiation from the notch-tip, which is described by the plastic strain at the notch tip, because the onset of ductile cracking can be expressed by constant plastic strain independent of the shape and size of the components and the loading mode. The other is a damage-based criterion for simulating ductile crack extension associated with damage evolution influenced by plastic strain in accordance with the stress triaxiality ahead of the extending crack tip. The proposed simulation model is applicable to prediction of ductile crack growth behaviors from a circumferentially-notched girth welded pipe with high internal pressure, which is subjected to tensile loading or bending (post-buckling) deformation.

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