The Modeling of Combined Stress State of the Drilling Bit Body during the Selective Press Fitting of Picks in it

2019 ◽  
Vol 973 ◽  
pp. 61-64
Author(s):  
Nikolay V. Polezhaev ◽  
Maksim D. Khoroshevskiy ◽  
Mark G. Kristal ◽  
Vladimir V. Preis
Keyword(s):  
Mathematical Model ◽  
Stress State ◽  
Combined Stress ◽  
Number Of Teeth ◽  
Press Fitting ◽  
Deformed State ◽  
Combined Stress State ◽  
The Difference ◽  
Definition Of ◽  
Drilling Bit

A new mathematical model is proposed where breaking down of exploited drilling bits is considered to be a consequence of an unbalanced spreading of charges in drilling bit body, which is caused by the difference in interference values of obstruction in each pair “body-pick”. Fulfilled modeling allow to make a definition of complicated stress-deformed state of the drilling collet’ body with different number of teeth and different combinations of hole sizes and sizes of teeth using different materials for further production.

scholarly journals A model for predicting changes in the electrical conductivity, practical salinity, and absolute salinity of seawater due to variations in relative chemical composition

Ocean Science ◽  
2010 ◽  
Vol 6 (1) ◽  
pp. 361-378 ◽  
Author(s):  
R. Pawlowicz
Keyword(s):  
Mathematical Model ◽  
Electrical Conductivity ◽  
Temporal Variations ◽  
Total Alkalinity ◽  
Biogeochemical Processes ◽  
Model Calculations ◽  
The North ◽  
Historical Continuity ◽  
The Difference ◽  
Definition Of

Abstract. Salinity determination in seawater has been carried out for almost 30 years using the Practical Salinity Scale 1978. However, the numerical value of so-called practical salinity, computed from electrical conductivity, differs slightly from the true or absolute salinity, defined as the mass of dissolved solids per unit mass of seawater. The difference arises because more recent knowledge about the composition of seawater is not reflected in the definition of practical salinity, which was chosen to maintain historical continuity with previous measures, and because of spatial and temporal variations in the relative composition of seawater. Accounting for these spatial variations in density calculations requires the calculation of a correction factor δSA, which is known to range from 0 to 0.03 g kg−1 in the world oceans. Here a mathematical model relating compositional perturbations to δSA is developed, by combining a chemical model for the composition of seawater with a mathematical model for predicting the conductivity of multi-component aqueous solutions. Model calculations for this estimate of δSA, denoted δSRsoln, generally agree with estimates of δSA based on fits to direct density measurements, denoted δSRdens, and show that biogeochemical perturbations affect conductivity only weakly. However, small systematic differences between model and density-based estimates remain. These may arise for several reasons, including uncertainty about the biogeochemical processes involved in the increase in Total Alkalinity in the North Pacific, uncertainty in the carbon content of IAPSO standard seawater, and uncertainty about the haline contraction coefficient for the constituents involved in biogeochemical processes. This model may then be important in constraining these processes, as well as in future efforts to improve parameterizations for δSA.

Sign in / Sign up

Export Citation Format

Share Document