Fatigue Design and Evaluation of Head to Skirt Welded Joint of a Pressure Swing Adsorber Vessel

2011 ◽  
Author(s):  
Mingxin Zhao
Keyword(s):  
Cyclic Loading ◽  
Welded Joints ◽  
Evaluation Method ◽  
Welded Joint ◽  
Evaluation Process ◽  
Pressure Vessels ◽  
Practical Case ◽  
Pressure Swing ◽  
Fatigue Evaluation ◽  
Selection Of

For pressure vessels and other welded structures subjected to cyclic loading conditions, fatigue failure of welded joints has been a major concern in design and operation. ASME Boiler and Pressure Vessel Code Section VIII Division 2 [1] provides different methods for fatigue evaluation on welded joints with various geometries, which facilitates the design and evaluation of welded joints subjected to cyclic loading. The selection of fatigue evaluation method will affect accuracy and outcome. This study attempts to demonstrate the design and evaluation process of a welded joint. Two major different fatigue evaluation methods have been used and results are analyzed and compared against operation data. The intention of this study is simply to present a practical case, through which proper selection of fatigue evaluation method for the specific welded joint could be suggested to achieve a safe, and yet, economical design.

Testing of Welded Joints between Pipes for Pressure Vessels Made of Hot Rolled Fine-Grained Steel P460NL1

2020 ◽  
Vol 1157 ◽  
pp. 15-20
Author(s):  
Miodrag Arsić ◽  
Srđan Bošnjak ◽  
Vencislav Grabulov ◽  
Mladen Mladenović ◽  
Zoran Savić
Keyword(s):  
Tensile Properties ◽  
Welded Joints ◽  
Arc Welding ◽  
Welded Joint ◽  
Welding Process ◽  
Pressure Vessels ◽  
Parent Material ◽  
Fine Grained ◽  
Hot Rolled ◽  
Material Standard

This paper contains results of tests performed in order to determine mechanical properties of steel P460NL1, used as filler material during the execution of welded joints. Arc welding of samples from which the specimens were taken was carried out through the application of welding process 111, because it is one of the processes for the execution of pipelines for pressure equipment. Microspecimens with diameter of Ø1,5 mm were tested in order to determine tensile properties of material taken from the heat-affected zone and weld metal, while specimens with diameter of Ø6 mm were tested in order to determine tensile properties of parent material. Standard Charpy V-notch specimens were used in order to determine impact energy. Results of metallographic tests which refer to the structure of a pipe welded joint are also presented.

scholarly journals Asymptotic response of friction stir welded joint under cyclic loading

2021 ◽  
Vol 15 (58) ◽  
pp. 202-210
Author(s):  
Imane Elmeguenni
Keyword(s):  
Cyclic Loading ◽  
Mechanical Behavior ◽  
Welded Joints ◽  
Welded Joint ◽  
Fatigue Behavior ◽  
Welding Process ◽  
Numerical Work ◽  
Promising Alternative ◽  
Friction Stir ◽  
The Impact

Fatigue takes a place more and more important in the design of structures, it remains a key point in the mechanical dimensioning of structures. The Friction Stir Welding (FSW) process is regarded today as the most promising alternative to traditional joining methods. It ranks among the most recent assembly processes and is considered a new technique for the 21st century. Indeed, if the FSW welding process has several advantages, it introduces very strong microstructure heterogeneities in the welded joints. This leads to heterogeneous mechanical behavior in each of the constituent zones. some important efforts have been deployed in industry as well as in research laboratories to understand the behavior of welded joints by the FSW process. There are many questions about the behavior of these areas. This study led to the characterization and understanding of the fatigue behavior of a 2024T351 structure welded by the FSW process. It presente in a numerical work which aims to help determine the asymptotic response of each zone constituting the 2024T351 joint welded by FSW subjected to a cyclic loading and to fully understand the behavior of these zones. To carry out an analysis and a simulation under cyclic loading, our choice fell on the use of the direct cyclic method. Numerical simulation of crack propagation was performed using the extended finite element method XFEM. This research consists in the implementation of the X-FEM in fatigue in a multiscale model X-FEM / direct cyclic. The numerical results consist in highlighting the heterogeneities in the mechanical behavior of the welded joint and in evaluating the impact of the FSW process on the failure of these FSW zones.

Optimization of Environmental Fatigue Evaluation: Step 2

2009 ◽  
Author(s):  
Yuichirou Nomura ◽  
Kazuya Tsutsumi ◽  
Toshihide Inoue ◽  
Seiji Asada ◽  
Takao Nakamura
Keyword(s):  
Evaluation Method ◽  
Fatigue Curve ◽  
Pressure Vessels ◽  
Austenitic Steels ◽  
Transient Conditions ◽  
Future Studies ◽  
Data Scatter ◽  
Fatigue Evaluation ◽  
Design Factors ◽  
Typical Design

In order to introduce environmental effects into fatigue evaluation of design and construction codes, the environmental fatigue evaluation method should not only be established, but the conservativeness of the codes, design transient conditions and so on should also be reviewed. The former paper [1] presented in 2007 ASME Pressure Vessels and Piping Conference reviewed and discussed design factors of design fatigue curves, design transient conditions, stress analysis techniques and environmental fatigue evaluation methods. In this paper, rationalization of typical design transient conditions is discussed and design factors of a design fatigue curve for austenitic steels are studied. Rationalized numbers and/or conditions are proposed for the typical design transients that are dominant for fatigue evaluation. A mean fatigue curve of austenitic steels is analyzed by using a statistical method with the latest data. The design factors of the fatigue curve of austenitic steels are investigated for parameters decreasing fatigue life such as size effect, surface finish and data scatter and appropriate design factors are proposed. Future studies are discussed.

Evaluation of Fatigue Strength of Similar and Dissimilar Welded Joints of Modified 9Cr–1Mo Steel

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Shigeru Takaya
Keyword(s):  
Experimental Data ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Welded Joints ◽  
Strain Distribution ◽  
Evaluation Method ◽  
Welded Joint ◽  
Element Model ◽  
Fast Breeder Reactor ◽  
Good Agreement

This paper presents an evaluation method for the fatigue strength of similar and dissimilar welded joints of modified 9Cr–1Mo steel, which is a candidate structural material for demonstration of fast-breeder reactor being developed in Japan. The discontinuity of the mechanical properties across a welded joint causes a nonhomogeneous strain distribution, and this effect should be considered in the evaluation of the fatigue strength of welded joints. In this study, a “two-element model,” which comprises base metal and welded metal, was employed. First, the strain ranges of each element are calculated, and second, the fatigue lives of each element are evaluated. Finally, the shorter fatigue life is selected as the fatigue life of the welded joint. The failure position can be also estimated by this model. The evaluation results were compared with experimental data obtained at elevated temperature, and the results were in good agreement.

scholarly journals Evaluation Method of Complex Slope Stability in Construction Industry Based on Correlation Calculation

CONVERTER ◽  
2021 ◽  
pp. 647-657
Author(s):  
Weiwei Zhu
Keyword(s):  
Correlation Function ◽  
Slope Stability ◽  
Construction Industry ◽  
Evaluation Method ◽  
Evaluation Process ◽  
Classical Domain ◽  
Stability Class ◽  
Evaluation Indexes ◽  
Slope Engineering ◽  
Selection Of

Based on the basic-element expression method and correlation function theory in Extenics, combined with the knowledge of slope engineering, a method for evaluating the stability of complex slope is proposed. The evaluation process includes the selection of suitable evaluation indexes of slope stability, identificationof the classification standard for the slope stability, identificationof the weights of evaluation indexes by using the improved analytic hierarchy process,identificationof the classical domain, node domain and matter-element under evaluation,the calculation of the correlation of each stability class for each evaluation index, normalization of correlation,and so on. The selection rule of the slop stability evaluation indexes and selection of correlation function and optimal points are also discussed, which can provide reference for slope engineering designin construction industry.

Fatigue Crack Propagation Properties of Welded Joints at 300°C

2003 ◽  
Vol 125 (2) ◽  
pp. 131-135
Author(s):  
Akihiko Ohta ◽  
Naoyuki Suzuki ◽  
Yoshio Maeda
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Welded Joints ◽  
Room Temperature ◽  
Welded Joint ◽  
Type Specimen ◽  
Pressure Vessels ◽  
Fatigue Threshold ◽  
Propagation Properties

Fatigue crack propagation properties of welded joints were investigated on steel plate for boilers and other pressure vessels. The fatigue crack propagation properties at 300°C became similar to those at room temperature when the thermal stress could be reduced down to −1 MPa by using center cracked type specimen with longitudinal slits and a specially designed furnace. The tensile residual stress was +152 MPa in the as-welded joint, and +12 MPa after PWHT. The fatigue threshold was about 2.7, 5.1 and 7.3 MN/m3/2 for weld metal in the as-welded condition, after PWHT and the base metal, respectively.

scholarly journals A Nondestructive Evaluation Method: Measuring the Fixed Strength of Spot-Welded Joint Points by Surface Electrical Resistivity

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Akira Shimamoto ◽  
Keitaro Yamashita ◽  
Hirofumi Inoue ◽  
Sung-mo Yang ◽  
Masahiro Iwata ◽  
...  
Keyword(s):  
Welded Joints ◽  
Electrical Resistance ◽  
Spot Welding ◽  
Evaluation Method ◽  
Welded Joint ◽  
Nondestructive Method ◽  
Nugget Diameter ◽  
Two Factors ◽  
Surface Electrical Resistance ◽  
Spot Welded

Destructive tests are generally applied to evaluate the fixed strength of spot-welding nuggets of zinc-plated steel (which is a widely used primary structural material for automobiles). These destructive tests, however, are expensive and time-consuming. This paper proposes a nondestructive method for evaluating the fixed strength of the welded joints using surface electrical resistance. A direct current nugget-tester and probes have been developed by the authors for this purpose. The proposed nondestructive method uses the relative decrease in surface electrical resistance, α. The proposed method also considers the effect of the corona bond. The nugget diameter is estimated by two factors: RQuota, which is calculated from variation of resistance, and a constant that represents the area of the corona bond. Since the maximum tensile strength is correlated with the nugget diameter, it can be inferred from the estimated nugget diameter. When appropriate measuring conditions for the surface electrical resistance are chosen, the proposed method can effectively evaluate the fixed strength of the spot-welded joints even if the steel sheet is zinc-plated.

Расчетные методы оценки ударной вязкости сварных элементов с трещинами

2020 ◽  
Vol 44 (3) ◽  
pp. 22-36
Author(s):  
Keyword(s):  
Stress Intensity ◽  
Impact Strength ◽  
Welded Joints ◽  
Development Process ◽  
Welded Joint ◽  
Operating Temperature ◽  
Crack Development ◽  
Heterogeneous Structure ◽  
Critical Crack Length ◽  
The Impact

Практика показывает, что для сварных конструкций, эксплуатируемых в условиях Крайнего Севера необходимо уделять внимание работоспособности сварных соединений при низких температурах. Металл сварных соединений в процессе воздействия обработки изменяет свои свойства, снижается ударная вязкость, образуется гетерогенная структура с большой степенью разнозернистости. Чтобы оценивать и иметь возможность правильно контролировать термическое воздействие и последствия сварочного процесса, требуется решить задачу аналитического определения ударной вязкости для всех зон сварного соединения. В настоящей статье представлен инженерный метод оценки ударной вязкости, применимый для любой зоны сварного соединения, в которой имеется острый или особый концентратор напряжений – трещина. Разработанный аналитический метод расчета ударной вязкости отражает качественную и количественную картину взаимосвязи структурно-механических характеристик и работы развития трещины в диапазоне температур 77…300 К. Предложенная схематизация зависимости критического коэффициента интенсивности напряжений от температуры позволила найти коэффициенты, характеризующие свойства материала, и выполнить расчеты изменения предела текучести и предела прочности от температуры эксплуатации. Построены графики зависимости работы развития трещины от температуры эксплуатации для сталей 15ГС и 17ГС, сравнение которых с экспериментальными данными показывает удовлетворительное согласование. Найдено, что при напряжениях предела выносливости отношение работы развития трещины к критической длине трещины постоянно, не зависит от температуры и для сталей 15ГС и 17ГС равно около 10. Ключевые слова: ударная вязкость, работа разрушения, коэффициент интенсивности напряжений, трещина, феррито-перлитная сталь, зона термического влияния. For welded structures under operation in the Far North, attention must be paid to the performance of welded joints at low temperatures. The properties of metal of welded joints are changed in the process of treatment, its toughness decreases, and a heterogeneous structure with a large range of different grain sizes is formed. In order to evaluate and be able to correctly control the thermal effect and the consequences of the welding process, it is necessary to solve the problem of analytical determination of impact strength for all zones of the welded joint. The paper presents an engineering method for evaluation of the impact strength applicable to any area of the welded joint in which there is a sharp or super sharp stress concentrator – a crack. The developed analytical method for calculating the impact strength reflects a qualitative and quantitative codependency of structural and mechanical characteristics and the process of crack development in the temperature range of 77–300 K. The proposed schematization of dependence of the critical coefficient of stress intensity on the temperature made it possible to find coefficients characterizing the properties of the material and to perform calculations of changes in yield strength and tensile strength on operating temperature. Graphs of the crack development process dependency on the operating temperature for 15ГС and 17ГС steels were constructed, and their comparison with experimental data displays satisfactory agreement. It was found that at endurance limit stresses, the ratio of the crack development process to the critical crack length is constant, non-dependent on temperature, and is equal to 10 for 15ГС and 17ГС steels. Keywords: impact strength, fracture work, stress intensity factor, crack, ferrite-pearlite steel, heat affected zone, steel tempering.

The Challenge of Evaluating Virtual Communities of Practice: A Systematic Mapping Study

10.28945/4505 ◽  
2020 ◽  
Vol 15 ◽  
pp. 039-064
Author(s):  
Rogerio Ferreira da Silva ◽  
Itana Maria de Souza Gimenes ◽  
José Carlos Maldonado
Keyword(s):  
Communities Of Practice ◽  
Virtual Communities ◽  
Evaluation Process ◽  
Evaluation Methods ◽  
Systematic Mapping Study ◽  
Research Gaps ◽  
Systematic Mapping ◽  
Research Questions ◽  
Virtual Communities Of Practice ◽  
Selection Of

Aim/Purpose: This paper presents a study of Virtual Communities of Practice (VCoP) evaluation methods that aims to identify their current status and impact on knowledge sharing. The purposes of the study are as follows: (i) to identify trends and research gaps in VCoP evaluation methods; and, (ii) to assist researchers to position new research activities in this domain. Background: VCoP have become a popular knowledge sharing mechanism for both individuals and organizations. Their evaluation process is complex; however, it is recognized as an essential means to provide evidences of community effectiveness. Moreover, VCoP have introduced additional features to face to face Communities of Practice (CoP) that need to be taken into account in evaluation processes, such as geographical dispersion. The fact that VCoP rely on Information and Communication Technologies (ICT) to execute their practices as well as storing artifacts virtually makes more consistent data analysis possible; thus, the evaluation process can apply automatic data gathering and analysis. Methodology: A systematic mapping study, based on five research questions, was carried out in order to analyze existing studies about VCoP evaluation methods and frameworks. The mapping included searching five research databases resulting in the selection of 1,417 papers over which a formal analysis process was applied. This process led to the preliminary selection of 39 primary studies for complete reading. After reading them, we select 28 relevant primary studies from which data was extracted and synthesized to answer the proposed research questions. Contribution: The authors of the primary studies analyzed along this systematic mapping propose a set of methods and strategies for evaluating VCoP, such as frameworks, processes and maturity models. Our main contribution is the identification of some research gaps present in the body of studies, in order to stimulate projects that can improve VCoP evaluation methods and support its important role in social learning. Findings: The systematic mapping led to the conclusion that most of the approaches for VCoP evaluation do not consider the combination of data structured and unstructured metrics. In addition, there is a lack of guidelines to support community operators’ actions based on evaluation metrics.

Influence of post-welding tempering on mechanical behavior of friction welded joints from medium-carbon steels during tensile test

2020 ◽  
pp. 40-49
Author(s):  
A. S. Atamashkin ◽  
E. Yu. Priymak ◽  
N. V. Firsova
Keyword(s):  
Mechanical Behavior ◽  
Welded Joints ◽  
Welded Joint ◽  
Crack Nucleation ◽  
Carbon Steels ◽  
Uniaxial Tensile ◽  
Medium Carbon ◽  
Uniaxial Tensile Testing ◽  
Rotary Friction Welding ◽  
Medium Carbon Steels

The paper presents an analysis of the mechanical behavior of friction samples of welded joints from steels 30G2 (36 Mn 5) and 40 KhN (40Ni Cr 6), made by rotary friction welding (RFW). The influence of various temperature conditions of postweld tempering on the mechanical properties and deformation behavior during uniaxial tensile testing is analyzed. Vulnerabilities where crack nucleation and propagation occurred in specimens with a welded joint were identified. It was found that with this combination of steels, postweld tempering of the welded joint contributes to a decrease in the integral strength characteristics under conditions of static tension along with a significant decrease in the relative longitudinal deformation of the tested samples.

Sign in / Sign up

Export Citation Format

Share Document