Results for calculation of optimal delta-criteria for deformation zone shape in drawing of round solid profi le

Author(s):  
G.N. Gur'yanov

Formulas for calculating of the optimal delta-criterion are proposed, which, in contrast to the two similar formulas of foreign researchers considered, take into account the back-pull stress and the hardening model. The optimal delta-criterion depends on the deformation parameters and the hardening model. Approximate equalities are proposed that refl ect the relationship between the criteria of the deformation zone and the indicators of the strain state. The values of the criteria for the deformation zone and the strain state for the drawing angles is 4 and 9° and the optimal drawing angle are given. According to two formulas of foreign researchers and the proposed formula, dependencies for the optimal delta-criterion on the drawing and friction coeffi cients are constructed. The criteria values for these formulas do not differ signifi cantly. Taking into account the nature of the relationship for the criteria of the deformation zone shape and the strain state contributes to rational choice of drawing modes.

2020 ◽  
pp. 348-359
Author(s):  
G.N. Gur’yanov

The combined criterion, which includes forming effectiveness indicator and the I.L. Perlin’s safety margin is proposed. Interdependencies for different criteria for the shape of the deformation zone are given. Suggested indicators for assessing of the shape of plastic deformation zone are simpler than delta criterion used in the foreing theory of drawing. For different hardening models, the results for the calculation of the axial stress, the absolute safety margin, the I.L. Perlin’s wire safety margin, V.L. Kolmogorov’s stress state indicator stress state indicator and the proposed criteria for assessing of the forming effectiveness when drawing round solid profile depending on the drawing coefficient, drawing angle and criteria for the shape of the plastic deformation zone. In the plastic deformation zone with equal average yield strength, the equality of the strain indicators of the wire is not ensured if hardening curves of material are different. In particular, when the drawing coefficient ensures equal yield strength for different hardening curves and is equal to the initial yield strength, the drawing stress is more at more convex shape of the hardening curve. At the optimum drawging angle, when the minimum axial stress, the maximum values of the safety margin indicators and the proposed criteria for the forming effectiveness and the minimum stress state indicator are observed. Equal minimum values of the drawing stress when varying the drawing angle, the length of the plastic deformation zone or other criteria. The nature of the relationship between the stress state indicators, the safety margin and the forming effectiveness is shown. With different hardening models of lines for the relationship of the I.L. Perlin’s safety margin and V.L. Kolmogorov’s stress state indicator are located along one curve, as are the lines for the relationship between the dimensionless axial stress and the stress state indicator. With the strain parameters, when the drawing stress under the action of back tension is less than this stress in the absence of back tension, the safety margin and the new combined forming effectiveness indicator are more under the action of back tension. This is possible with intensive hardening of the wire material in the draft of drawing, reduced drawing angles and increased values of drawing and friction coefficients. Different values of strain indicators of steel 12Kh18N10T wire after quenching and annealing are shown.


Author(s):  
G.N. Gur'yanov

The limiting and legitimate values of the drawing coefficient and delta-criterion Δ for the deformation zone shape depending on the friction coefficient for different models of hardening and the values of the drawing angle and the back-pull stress are determined by numerically solving the corresponding equations. The limiting and legitimate values of the drawing coefficient decrease with increase in the friction coefficient, while the analogous values of the criterion increase. Increase in the safety factor causes decrease in the allowable drawing and increase in the delta-criterion. The limiting and legitimate values of the drawing coefficient decrease from the application of back tension in the absence of strain hardening. The nature of the effect of back tension on the limiting and legitimate values of the drawing coefficient and the delta-criterion depends on the deformation parameters with intensive hardening and significant value of the friction coefficient. The possibility of the absence of limiting values of the drawing coefficient and criterion Δ under hypothetical drawing conditions is shown: intensive hardening of the wire material at low friction coefficient and the calculation of the limiting values of these indicators based on the value of the I.L. Perlin safety factor, equal to 1. The estimation of the reliability of the approximate equality is carried out to determine the nature of the relationship between the criterion Δ and the index of the deformed state. It is shown that with small value of the delta-criterion (Δ < 2) wire breakage at the die exit is not guaranteed, since the limiting value of the drawing coefficient is slightly greater than 1. The drawing production technologist needs assessment of the limiting and legitimate values of the drawing coefficient and delta-criterion for predicting of wire (rod) breakage at given deformation parameters.


2015 ◽  
Vol 752-753 ◽  
pp. 268-271 ◽  
Author(s):  
Valery V. Kuzin ◽  
Stanislav Grigoriev ◽  
Marina Volosova ◽  
Mike Fedorov

Composite character of ceramics is a base for creating new generation materials. It is established that the rational choice of the basic structural elements allows to control stress-strain state of the "loaded" ceramics and to slow down process of its degradation. The developed method of designing of details taking into account ceramics degradation at exploitation is described.


2000 ◽  
Vol 45 (1) ◽  
pp. 63-66 ◽  
Author(s):  
Yves Lamontagne ◽  
Richard Boyer ◽  
Céline ILL Hétu ◽  
Céline Lacerte-Lamontagne

Objective: To evaluate the relationship among demographic data, anxiety, significant losses, depression, and irrational beliefs reported by first-offence shoplifters. Method: One hundred and six adult shoplifters who were first-time offenders completed a self-administered questionnaire. Results: Men and women were equally likely to be arrested for this offence. The majority of offenders were poor and unemployed. Depression, but not anxiety, was the most common psychiatric disorder associated with shoplifting. Subjects with depression presented the greatest number of irrational beliefs related to shoplifting. Conclusions: The authors suggest 2 categories of shoplifters: those who shoplift through rational choice; and those for whom shoplifting is a response to depression or leads to the fulfilment of some psychological needs. In conclusion, shoplifting does not have a unitary motive, and the clinical implications are that the affective and cognitive aspects of shoplifters' behaviours must be taken into account.


Author(s):  
S. Shekhar ◽  
S. Abolghasem ◽  
S. Basu ◽  
J. Cai ◽  
M. R. Shankar

Machining induces severe plastic deformation (SPD) in the chip and on the surface to stimulate dramatic microstructural transformations which can often result in a manufactured component with a fine-grained surface. The aim of this paper is to study the one-to-one mappings between the thermomechanics of deformation during chip formation and an array of resulting microstructural characteristics in terms of central deformation parameters–strain, strain-rate, temperature, and the corresponding Zener–Hollomon (ZH) parameter. Here, we propose a generalizable rate-strain-microstructure (RSM) framework for relating the deformation parameters to the resulting deformed grain size and interface characteristics. We utilize Oxley’s model to calculate the strain and strain-rate for a given orthogonal machining condition which was also validated using digital imaging correlation-based deformation field characterization. Complementary infrared thermography in combination with a modified-Oxley’s analysis was utilized to characterize the temperature in the deformation zone where the SPD at high strain-rates is imposed. These characterizations were utilized to delineate a suitable RSM phase-space composed of the strain as one axis and the ZH parameter as the other. Distinctive one-to-one mappings of various microstructures corresponding to an array of grain sizes and grain boundary distributions onto unique subspaces of this RSM space are shown. Building on the realization that the microstructure on machined surfaces is closely related to the chip microstructure derived from the primary deformation zone, this elucidation is expected to offer a reliable approach for controlling surface microstructures from orthogonal machining.


2016 ◽  
Vol 851 ◽  
pp. 728-732
Author(s):  
Liang Liang Xia ◽  
Gui Jie Zhang ◽  
Chun Hong Ma ◽  
Quan Yi Liu ◽  
Kun Kun Li ◽  
...  

With the rapid development of automobile industry, automobile panel material has also gained great attention, the IF steel has got more and more applications in automobile panel production for its excellent deep drawing propertie s, such as, high strain ratio, high extensibility, high yield ratio, etc. In this paper, through the analysis of thermal simulation results and microstructure of IF steel, we studied the influences of microstructure changes on IF steel with different deformation parameters, obtained the influence laws of the deformation parameters on deformation resistanc e of IF steel. So there is a certain directive significance to control the rolling process of IF steel in the actual production of IF steel.


Author(s):  
Suhadi

Tujuan penelitian ini adalah untuk memetakan penelitian sosiologis dan antropologis tentang pernikahan dan perceraian dengan menggunakan perspektif komprehensif. Penelitian yang sudah ada tentang pernikahan dini, perceraian, dan pernikahan ulang dianalisi dan dikelompokkan dalam perpektif fungsional, perspektif konflik, dan perspektif interaksionisme simbolik ini.Penelitian dilakukan terhadap 12 judul penelitian pernikahan dini, 10 judul penelitian perceraian, dan 3 judul penelitian pernikahan ulang. Fenomena pernikahan dini, perceraian dan nikah ulang ternyata memiliki relasi kompleks terhadap kehidupan sosial. Relasi tersebut diantaranya; beragamnya realitas sosial yang melahirkan perceraian, perceraian untuk meraih kekuasaan, terdapat redefinisi bahwa perceraian itu pilihan rasional. Perpektif sosiologi yang sering digunakan dalam penelitian perkawinan dan perceraian adalah perspektif fungsional dan perspektif konflik, diperlukan kajian dengan pendekatan interaksionisme simbolik untuk menghasilkan nuansa baru dalam kajian perkawinan.The objective of this study is to map the existing sociological and anthropological researches about marriage and divorce using a comprehensive perspective. Existing research on early marriage, divorce, and remarriage are analyzed and grouped into functional perspective,  conflict perspective and  symbolic interactionist perspective. Twelve research reports on early marriage, 10 research  titles on divorce and 3  titles on remarriage are analysed. The phenomenon of early marriage, divorce and re-marriage appears to have a complex relationship to social life. The relationship for exampple include the diverse factors that contribute to divorce, the use of divorce to gain power, the redefinition of divorce as rational choice and so on. Sociological perspective often used in the study of marriage and divorce is a functional and conflict perspective. It is necessary to study the symbolic interactionism approach to produce a new nuance in the study of marriage.


Sign in / Sign up

Export Citation Format

Share Document