АNALYSIS OF THE STRESS STATE OF CYLINDRICAL ARTICLES DURING THE CRIMPING ELEMENT OF A PIPE BLANK WITH WALL THINNING

2021 ◽  
Author(s):  
S. N. Larin ◽  
◽  
M. V. Larina ◽  
G. A. Nuzhdin ◽  
◽  
...  
Keyword(s):  
Stress State ◽  
Pipe Blank ◽  
Wall Thinning

Обжим пустотелых цилиндрических заготовок позволяет получать изделия с различными сечениями в ортогональном направлении по высоте. Данная операция является весьма производительной и позволяет получать различного рода соединительные элементы. В статье рассмотрена операция обжима и одновременного утонения стенки изделия на выходе из очага деформации. В процессе обжима происходит набор толщины заготовки в деформируемой части. Ввиду этого в очаге деформации возможно возникновение значительных сжимающих и растягивающих напряжений. Возникают значительные неравномерности напряжений в детали, что плохо сказывается на их качестве. Поэтому актуален вопрос подбора параметров процесса, обеспечивающих наилучшее напряжённое состояние изделий. В статье выполнено исследование напряженного состояния в изделиях при совмещенном процессе обжима с утонением стенки. Установлены зоны с максимальными по значениям сжимающими и растягивающими напряжениями в детали. Установлено влияние коэффициента утонения стенки изделия, коэффициента обжима, контактного трения и угла конусности матрицы на сжимающие и растягивающие напряжения. Получены регрессионные зависимости для определения растягивающих и сжимающих напряжений. Это позволит установить приблизительные значения напряжений при разных ключевых технологических параметрах процесса.

Low Cycle Fatigue Evaluation of Pipe Bends With Local Wall Thinning Considering Multi-Axial Stress State

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Yoshio Urabe ◽  
Koji Takahashi ◽  
Hisanori Abe
Keyword(s):  
Fatigue Strength ◽  
Stress State ◽  
Low Cycle Fatigue ◽  
Axial Stress ◽  
Fatigue Tests ◽  
Cycle Fatigue ◽  
Pipe Bend ◽  
Wall Thinning ◽  
Damage Rule ◽  
Local Wall Thinning

Low cycle fatigue tests and finite element (FEM) analysis were conducted using 100A pipe bend specimens made of STPT410 carbon steel with and without local wall thinning local wall thinning was machined on the inside of the elbow and was prepared at extrados, crown, and intrados. The parameters of the wall thinning were same (the wall thinning ratio = 0.5, the wall thinning angle = 180 deg, and the wall thinning length = 100 mm) in the all test cases. The pipe bend specimens were subjected to the prescribed cyclic in-plane bending displacement with constant internal pressure of 0–12 MPa. Also, low cycle fatigue tests using sound pipe bend specimens were carried out for comparison. According to the test results, low cycle fatigue strength of wall thinned pipe bend specimens was not so different, regardless of location of wall thinning. Low cycle fatigue strength of the pipe bend specimens was beneath the best fit fatigue curve and its reason can be explained quantitatively by a proposed cumulated damage rule introducing ductility exhaustion considering multi-axial stress state. The validity of the new proposed cumulative damage rule was also confirmed by the another sample analysis using other reference data obtained by pre-overloaded in-plane cyclic bending tests.

scholarly journals Stress Evaluation in the Blank Critical Region During Extrusion of the Pipe Blank into the Hole

2021 ◽  
Vol 2096 (1) ◽  
pp. 012207
Author(s):  
S B Maryin ◽  
I K Andrianov ◽  
V V Chernomas
Keyword(s):  
Stress State ◽  
Critical Region ◽  
Research Problem ◽  
Pipe Blank ◽  
Element Formulation ◽  
Surface Loading ◽  
Stress Evaluation ◽  
Loading Mode ◽  
Power Loading ◽  
Analysis Application

Abstract The study assessed the stress state of the pipe blank in the process of extrusion into the hole. A finite element formulation of the research problem with the setting of boundary conditions in displacements and surface loading conditions is presented. The calculation of the workpiece was carried out in an elastic formulation using the Nastran engineering analysis application. The assessment of the stress state in the critical region is presented in two approximations with a thickening of the grid in the stress focus area. Based on the results of the distribution of equivalent stresses, an assessment of the unevenness of the stressed state of the workpiece was carried out. The presented study is important because it allows us to predict the appearance of defects in the process of forming a pipe billet during extrusion into a hole, to evaluate the power loading mode.

Short Stress State Questionnaire

2015 ◽  
Vol 31 (1) ◽  
pp. 20-30 ◽  
Author(s):  
William S. Helton ◽  
Katharina Näswall
Keyword(s):  
Stress State ◽  
Factor Structure ◽  
Human Performance ◽  
Self Report ◽  
Confirmatory Factor ◽  
Stress States ◽  
Related Stress ◽  
Using Data ◽  
Task Conditions ◽  
Multiple Samples

Conscious appraisals of stress, or stress states, are an important aspect of human performance. This article presents evidence supporting the validity and measurement characteristics of a short multidimensional self-report measure of stress state, the Short Stress State Questionnaire (SSSQ; Helton, 2004 ). The SSSQ measures task engagement, distress, and worry. A confirmatory factor analysis of the SSSQ using data pooled from multiple samples suggests the SSSQ does have a three factor structure and post-task changes are not due to changes in factor structure, but to mean level changes (state changes). In addition, the SSSQ demonstrates sensitivity to task stressors in line with hypotheses. Different task conditions elicited unique patterns of stress state on the three factors of the SSSQ in line with prior predictions. The 24-item SSSQ is a valid measure of stress state which may be useful to researchers interested in conscious appraisals of task-related stress.

Simulation of vibration piercing of pipe blank at press

2020 ◽  
Vol 76 (11) ◽  
pp. 1128-1138
Author(s):  
S. R. Rakhmanov
Keyword(s):  
High Frequency ◽  
Deformation Zone ◽  
Pipe Blank ◽  
Equipment Operation ◽  
Metal Deformation ◽  
Technological Tool ◽  
High Frequency Vibrations ◽  
Pipe Blanks ◽  
Wave Phenomena

In some cases, the processes of piercing or expanding pipe blanks involve the use of high-frequency active vibrations. However, due to insufficient knowledge, these processes are not widely used in the practice of seamless pipes production. In particular, the problems of increasing the efficiency of the processes of piercing or expanding a pipe blank at a piercing press using high-frequency vibrations are being solved without proper research and, as a rule, by experiments. The elaboration of modern technological processes for the production of seamless pipes using high-frequency vibrations is directly related to the choice of rational modes of metal deformation and the prediction resistance indicators of technological tools and the reliability of equipment operation. The creation of a mathematical model of the process of vibrating piercing (expansion) of an axisymmetric pipe blank at a piercing press of a pipe press facility is an actual task. A calculation scheme for the process of piercing a pipe plank has been elaborated. A dependence was obtained characterizing the speed of front of plastic deformation propagation on the speed of penetration of a vibrated axisymmetric mandrel into the pipe workpiece being pierced. The dynamic characteristics of the occurrence of wave phenomena in the metal being pierced under the influence of a vibrated tool have been determined, which significantly complements the previously known ideas about the stress-strain state of the metal in the deformation zone. The deformation fields in the zones of the disturbed region of the deformation zone were established, taking into account the high-frequency vibrations of the technological tool. It has been established that the choice of rational parameters (amplitude-frequency characteristics) of the vibration piercing process of a pipe blank results in significant increase in the efficiency of the process, the durability of the technological tool and the quality of the pierced blanks.

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