Critical condition of brittle-ductile transition of optical glasses in ultraprecision grinding

2000 ◽  
Author(s):  
Mingjun Chen ◽  
Feihu Zhang ◽  
Shen Dong
Keyword(s):  
Critical Condition ◽  
Optical Glasses ◽  
Brittle Ductile Transition

Research on Influence of Crystal KDP Anisotropy on Critical Condition of Brittle-Ductile Transition in Ultra-Precision Cutting

2006 ◽  
Vol 315-316 ◽  
pp. 725-730 ◽  
Author(s):  
Ming Jun Chen ◽  
Ying Chun Liang ◽  
Jing He Wang ◽  
Shen Dong
Keyword(s):  
Surface Quality ◽  
Critical Condition ◽  
Influence Factors ◽  
Potassium Dihydrogen Phosphate ◽  
Experimental Results ◽  
Depth Of Cut ◽  
Dihydrogen Phosphate ◽  
Brittle Ductile Transition ◽  
Ultra Precision

In order to machine high accuracy Potassium Dihydrogen Phosphate (KDP) crystal part, the indentation experiments are carried out with various loads and various orientation angles. The experimental results show that the critical condition of brittle-ductile transition of KDP has strong anisotropy. Therefore, the influence factors on the surface quality of crystal KDP was discussed, it is shown that influences of the tool's geometry parameter, feed rate and Nominal depth of cut etc on the surface quality of KDP are main. Afterwards the cutting experimental study on crystal KDP material is carried out. The experimental results show that the super-smooth surface quality only can be obtained while KDP is ultra-precision machined in ductile mode.

Features of the hormonal status at newborns in critical condition. Article

2019 ◽  
pp. 106-112 ◽  
Author(s):  
Yu. S. Aleksandrovich ◽  
◽  
S.A. Fomin ◽  
K.V. Pshenisnov ◽  
◽  
...  
Keyword(s):  
Critical Condition ◽  
Hormonal Status

Strategies for Condition Assessment of Sewer Systems

2007 ◽  
Vol 2 (2) ◽  
Author(s):  
K. Müller
Keyword(s):  
Water Pollution ◽  
Numerical Model ◽  
Critical Condition ◽  
Ground Water Pollution ◽  
Pollution Regulation ◽  
Sewer Systems ◽  
Single Strategy ◽  
Surface Covering ◽  
Critical Class ◽  
Representative Samples

The inspection of sewers can take place whether by means of fixed-intervals in a conventional surface-covering inspection, or by means of need-oriented strategies. Those need-oriented strategies can be differed between a selective inspection, an evaluation of the present sewer condition based on a representative samples and a failure-oriented forecasting strategy. By setting up and implementing a numerical model it is now possible to carry out a comparison between strategies. Herewith, the potential of success from every single strategy concerning different boundary conditions has been evaluated. For larger Sewer Systems a failure-oriented forecasting strategy presents a more reasonable alternative than the conventional surface-covering one. The reason is because the holding time from every sewer in a critical condition can be reduced considerably within this kind of oriented-need inspections compared to the conventional ones. Similarly, this method meets the ability to estimate the whole condition of a sewer for a given term in the minimum time, which usually could not be achieved by a conventional inspection. Oriented-need inspection strategies offer even superior advantages when the crop and the ground water pollution regulation controls have been followed from the beginning, in order to reduce holding times within sewers in a critical class-condition.

scholarly journals Fault reactivation and strain partitioning across the brittle-ductile transition

Geology ◽  
2019 ◽  
Vol 47 (12) ◽  
pp. 1127-1130 ◽  
Author(s):  
Gabriel G. Meyer ◽  
Nicolas Brantut ◽  
Thomas M. Mitchell ◽  
Philip G. Meredith
Keyword(s):  
Fault Slip ◽  
Fault Reactivation ◽  
Ductile Deformation ◽  
Tectonic Deformation ◽  
Gradual Change ◽  
Bulk Rock ◽  
Total Deformation ◽  
Bulk Strain ◽  
Brittle Ductile Transition ◽  
Ductile Flow

Abstract The so-called “brittle-ductile transition” is thought to be the strongest part of the lithosphere, and defines the lower limit of the seismogenic zone. It is characterized not only by a transition from localized to distributed (ductile) deformation, but also by a gradual change in microscale deformation mechanism, from microcracking to crystal plasticity. These two transitions can occur separately under different conditions. The threshold conditions bounding the transitions are expected to control how deformation is partitioned between localized fault slip and bulk ductile deformation. Here, we report results from triaxial deformation experiments on pre-faulted cores of Carrara marble over a range of confining pressures, and determine the relative partitioning of the total deformation between bulk strain and on-fault slip. We find that the transition initiates when fault strength (σf) exceeds the yield stress (σy) of the bulk rock, and terminates when it exceeds its ductile flow stress (σflow). In this domain, yield in the bulk rock occurs first, and fault slip is reactivated as a result of bulk strain hardening. The contribution of fault slip to the total deformation is proportional to the ratio (σf − σy)/(σflow − σy). We propose an updated crustal strength profile extending the localized-ductile transition toward shallower regions where the strength of the crust would be limited by fault friction, but significant proportions of tectonic deformation could be accommodated simultaneously by distributed ductile flow.

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