Study of nonlinear deformation and stability of reinforced shells under combined loading by a bending moment and a transverse boundary force

In the paper the interaction of several loads like pressure, axial force, bending moment and torsional moment are analyzed, taking into account the deterioration due to cracks and the influence of residual stresses. A nonlinear, power law, of structure material is considered. General relationships for total participation of specific energies introduced in the structure by the loads, as well as for the critical participation have been proposed. On these bases: - a new strength calculation methods was developed; � strength of tubular cracked structures and of cracked tubular junction subjected to combined loading and strength were analyzed. Relationships for critical state have been proposed, based on dimensionless variables. These theoretical results fit with experimental date reported in literature. On the other side stress concentration coefficients were defined. Our one experiments onto a model of a pipe with two opposite nozzles have been achieved. Near one of the nozzles is a crack on the run pipe. Trough the experiments the state of stress have been obtained near the tubular junction, near the tip of the crack and far from the stress concentration points. On this basis the stress concentration coefficients were calculated.

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Effect of Torsion on Collapse Bending Moment for 24-Inch Diameter Schedule 80 Pipes With Wall Thinning

Volume 1: Codes and Standards ◽

10.1115/pvp2012-78736 ◽

2012 ◽

Cited By ~ 2

Author(s):

Kunio Hasegawa ◽

Yinsheng Li ◽

Bostjan Bezensek ◽

Phuong Hoang

Keyword(s):

Power Plants ◽

Bending Moment ◽

Combined Loading ◽

Bending Moments ◽

Compressive Stresses ◽

Wall Thinning ◽

Nominal Thickness ◽

Calculation Results ◽

Loading Modes ◽

Local Wall Thinning

Piping items in power plants may experience combined bending and torsion moments during operation. Currently, there is a lack of guidance in the ASME B&PV Code Section XI for combined loading modes including pressure, torsion and bending. Finite element analyses were conducted for 24-inch diameter Schedule 80 pipes with local wall thinning subjected to tensile and compressive stresses. Plastic collapse bending moments were calculated under constant torsion moments. From the calculation results, it can be seen that collapse bending moment for pipes with local thinning subjected to tensile stress is smaller than that subjected to compressive stress. In addition, equivalent moment is defined as the root the sum of the squares of the torsion and bending moments. It is found that the equivalent moments can be approximated with the pure bending moments, when the wall thinning length is equal or less than 7.73R·t for the wall thinning depth of 75% of the nominal thickness, where R is the mean radius and t is the wall thickness of the pipe.

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Prediction Method for Plastic Collapse of Pipes Subjected to Combined Bending and Torsion Moments

ASME 2010 Pressure Vessels and Piping Conference: Volume 1 ◽

10.1115/pvp2010-25101 ◽

2010 ◽

Cited By ~ 4

Author(s):

Yinsheng Li ◽

Kunio Hasegawa ◽

Phuong H. Hoang ◽

Bostjan Bezensek

Keyword(s):

Entire Range ◽

Estimation Method ◽

Prediction Method ◽

Bending Moment ◽

Combined Loading ◽

Plastic Collapse ◽

Finite Element Analyses ◽

Pure Torsion ◽

Stainless Steel Pipe ◽

Service Inspection

When a crack is detected in a pipe during in-service inspection, the failure estimation method given in the codes such as ASME Boiler and Pressure Vessel Code Section XI non-mandatory Appendix C or JSME S NA-1-2008 Appendix E-8 can be applied to assess the integrity of the pipe. In the current editions of these codes, the failure estimation method is provided for bending moment and pressure. Torsion load is assumed to be relatively small and is not considered in the method. In this paper, finite element analyses are conducted for 24-inch stainless steel pipe with a circumferential surface crack subjected to the combined bending and torsion moments, focusing on large and pure torsion moments. Based on the analysis results, a prediction method for plastic collapse under the combined loading conditions of bending and torsion is proposed for the entire range of torsion moments.

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Elastic-plastic bending of the pipeline under combined loading

SCIENCE & TECHNOLOGIES OIL AND OIL PRODUCTS PIPELINE TRANSPORTATION ◽

10.28999/2541-9595-2021-11-4-372-377 ◽

2021 ◽

pp. 372-377

Author(s):

Виктор Миронович Варшицкий ◽

Евгений Павлович Студёнов ◽

Олег Александрович Козырев ◽

Эльдар Намикович Фигаров

Keyword(s):

Internal Pressure ◽

Limit State ◽

Bending Moment ◽

Axial Direction ◽

Longitudinal Force ◽

Combined Loading ◽

Dimensional Problem ◽

Elastic Plastic ◽

Pipeline Section ◽

Thin Walled Pipe

Рассмотрена задача упругопластического деформирования тонкостенной трубы при комбинированном нагружении изгибающим моментом, осевой силой и внутренним давлением. Решение задачи осуществлено по разработанной методике с помощью математического пакета Matcad численным методом, основанным на деформационной теории пластичности и безмоментной теории оболочек. Для упрощения решения предложено сведение двумерной задачи к одномерной задаче о деформировании балки, материал которой имеет различные диаграммы деформирования при сжатии и растяжении в осевом направлении. Проведено сравнение с результатами численного решения двумерной задачи методом конечных элементов в упругопластической постановке. Результаты расчета по инженерной методике совпадают с точным решением с точностью, необходимой для практического применения. Полученные результаты упругопластического решения для изгибающего момента в сечении трубопровода при комбинированном нагружении позволяют уточнить известное критериальное соотношение прочности сечения трубопровода с кольцевым дефектом в сторону снижения перебраковки. Применение разработанной методики позволяет ранжировать участки трубопровода с непроектным изгибом по степени близости к предельному состоянию при комбинированном нагружении изгибающим моментом, продольным усилием и внутренним давлением. The problem of elastic plastic deformation of a thin-walled pipe under co-binned loading by bending moment, axial force and internal pressure is considered. The problem is solved by the developed method using the Matcad mathematical package by a numerical method based on the deformation theory of plasticity and the momentless theory of shells. To simplify the solution of the problem, it is proposed to reduce a twodimensional problem to a one-dimensional problem about beam deformation, the material of which has different deformation diagrams under compression and tension in the axial direction. Comparison with the results of numerical solution of the two-dimensional problem with the finite element method in the elastic plastic formulation is carried out. The obtained results of the elastic-plastic solution for the bending moment in the pipeline section under combined loading make it possible to clarify criterion ratio of the strength of the pipeline section with an annular defect in the direction of reducing the rejection. Application of the developed approach allows to rank pipeline sections with non-design bending in the steppe close to the limit state under combined loading of the pipeline with bending moment, longitudinal force and internal pressure.

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A Validated Methodology to Establish Structural Capacities for Subsea Connector Families

10.2118/205412-ms ◽

2021 ◽

Author(s):

Michael John Stephens ◽

Simon John Roberts ◽

Derek James Bennet

Keyword(s):

Failure Modes ◽

Bending Moment ◽

Full Scale ◽

Structural Testing ◽

Combined Loading ◽

Test Sequence ◽

Fea Model ◽

Analysis Methodology ◽

Industry Standards ◽

Physical Testing

Abstract Understanding the structural limits of subsea connectors used in offshore environments is critical to ensure safe operations. The latest industry standards establish the requirement for physical testing to validate analysis methodologies for connector designs. In this paper, an analysis methodology, compliant with the latest API 17G standard, is presented for calculating structural capacities of non-preloaded connectors. The methodology has been developed for complex combined loading scenarios and validated using full-scale physical testing for different connector families. Detailed 3-D, non-linear, finite element models were developed for three different non-preloaded connections, which consisted of threaded and load shoulder connectors. A comprehensive set of combined tension and bending moment structural capacities at normal, extreme and survival conditions were calculated for each connection. The calculated capacities were validated for each connection by performing a test sequence using full-scale structural testing. A final tension or bending to failure test was also completed for each test connection to validate the physical failure mode, exceeding the latest API 17G requirements. For all connections tested, capacities calculated using the methodology were validated from the successful completion of the test sequences. The physical failure modes of the test connections also matched the predicted failure modes from the FEA, and the tensile or bending moment loading at physical collapse exceeded that predicted by the global collapse of the FEA model. Using the validated approach described in this paper significantly reduces the requirement of physical testing for connector families, establishing confidence in the structural limits that are critical for safe operations.

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Probabilistic Integrity Assessment of Corroded Gas Pipelines

Journal of Pressure Vessel Technology ◽

10.1115/1.2349566 ◽

2006 ◽

Vol 128 (4) ◽

pp. 547-555 ◽

Cited By ~ 6

Author(s):

Sang-Min Lee ◽

Yoon-Suk Chang ◽

Jae-Boong Choi ◽

Young-Jin Kim

Keyword(s):

Probabilistic Approach ◽

Bending Moment ◽

Combined Loading ◽

Gas Pipelines ◽

Index Method ◽

Integrity Assessment ◽

Assessment Program ◽

Simulation Techniques ◽

Reliable Assessment ◽

Assessment Procedures

Pressurized gas pipelines are subject to harmful effects from both the surrounding environments and the materials passing through them. Reliable assessment procedures, including fracture mechanics analyses, are required to maintain their integrity. Currently, integrity assessments are performed using conventional deterministic approaches, even though there are many uncertainties to hinder rational evaluations. Therefore, in this study, a probabilistic approach was considered for gas pipeline evaluations. The objectives are to estimate the failure probability of corroded pipelines in the gas and oil industries and to propose operating limit conditions for different types of loadings. To achieve these objectives, a probabilistic assessment program was developed using reliability index method and simulation techniques, and applied to estimate the failure probabilities of corroded API-5L-X52/X60 gas pipelines subjected to internal pressure, bending moment, and combined loading. The operating limit conditions as well as prototypal evaluation and sensitivity analysis results showed a promising applicability of the probabilistic integrity assessment program.

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Failure Envelopes of Composite Bucket Foundation for Offshore Wind Turbines under Combined Loading with considering Different Scour Depths

Shock and Vibration ◽

10.1155/2021/7922572 ◽

2021 ◽

Vol 2021 ◽

pp. 1-15

Author(s):

Yuanxu Jing ◽

Yuan Wang ◽

Jingqi Huang ◽

Wei Wang ◽

Lunbo Luo

Keyword(s):

Wind Turbines ◽

Bending Moment ◽

Offshore Wind ◽

Combined Loading ◽

Failure Envelope ◽

Bucket Foundation ◽

Offshore Wind Turbines ◽

Failure Envelopes ◽

The Stability ◽

The Right

The composite bucket foundation of offshore wind turbines is subjected to a variety of loads in the marine environment, such as horizontal load H, vertical load V , bending moment M, and torque T. In addition, due to the characteristics of its connection section, the water flow around the foundation will produce scour pits of various degrees, reducing the depth of the bucket foundation, which has a nonnegligible impact on the overall stability of the bucket foundation. In this paper, the failure envelope characteristics of different combinations of loads on bucket foundations, including V -H-T, V -M-T, conventional V -H-M, and noncoplanar V -H-M, are numerically investigated with considering different scour depths. The numerical results indicate that the V -H-T, V -M-T, conventional V -H-M, and noncongruent V -H-M failure envelopes gradually shrink inwards with increasing scour depth, and the stability of the composite bucket foundation decreases; the conventional V -H-M failure envelope shows an asymmetry of convexity to the right, and the noncongruent V -H-M failure envelope shows an asymmetry of outward convexity to the left and right. The corresponding mathematical expressions for the failure envelope are obtained through the normalized fitting process, which can be used to evaluate the stability of the bucket foundation based on the relative relationship between the failure envelope and the actual load conditions, which can provide practical guidance for engineering design.

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Upheaval Buckling of Small Diameter Pipelines Induced by Strong Ground Shaking

Volume 4: Pipelining in Northern and Offshore Environments; Strain-Based Design; Risk and Reliability; Standards and Regulations ◽

10.1115/ipc2012-90281 ◽

2012 ◽

Author(s):

Hiroyuki Horikawa ◽

Yoji Tsunasawa ◽

Hajime Shinkai ◽

Nobuhisa Suzuki

Keyword(s):

Local Buckling ◽

Small Diameter ◽

Field Tests ◽

Bending Moment ◽

Design Guidelines ◽

Combined Loading ◽

Pipe Material ◽

Effective Parameters ◽

Ground Shaking ◽

Upheaval Buckling

Upheaval buckling of small diameter gas pipeline occurred due to strong seismic excitation during the 2007 Niigata-ken Chuetsu-Oki earthquake whose diameters were 4″ and smaller. This paper deals with investigation of the upheaval buckling of gas pipes conducted by Ministry of Economy, Trade and Industry of Japan to establish seismic design guidelines to mitigate upheaval buckling. Sand box and field tests were conducted using small diameter pipes to simulate the upheaval buckling behaviors and construct a simple finite element model. The results clarified that the tensile properties of pipe material and pipe-soil interaction were the most effective parameters to explain the buckling behaviors. Interaction curve of pipes can be found in the relationship between compression and bending moment in the combined loading tests. The deformation behaviors of the buried pipe tests followed the interaction curve and local buckling of buried pipes occurred in lower bending moment than that of pipes not buried.

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Probabilistic Fracture Mechanics Assessment of Wall-Thinned Nuclear Piping System

Volume 5: High Pressure Technology, Nondestructive Evaluation, Pipeline Systems, Student Paper Competition ◽

10.1115/pvp2005-71284 ◽

2005 ◽

Author(s):

Sang-Min Lee ◽

Yoon-Suk Chang ◽

Young-Jin Kim

Keyword(s):

Fracture Mechanics ◽

Probabilistic Approach ◽

Bending Moment ◽

Simulation Method ◽

Combined Loading ◽

Probabilistic Assessment ◽

Piping System ◽

Integrity Assessment ◽

Assessment Program ◽

Reliability Method

The integrity of nuclear piping systems must be maintained during operation. In order to maintain the integrity, reliable assessment procedures including fracture mechanics analysis, etc, are required. Up to now, the integrity assessment has been performed using conventional deterministic approaches even though there are many uncertainties to hinder a rational evaluation. In this respect, probabilistic approach is considered as an appropriate method for piping system evaluation. The objectives of this paper are to develop a probabilistic assessment program using reliability index and simulation technique and to estimate the failure probability of wall-thinned pipes in secondary systems. The probabilistic assessment program consists of three evaluation modules that are: first order reliability method, second order reliability method and crude Monte Carlo simulation method. The developed program has been applied to evaluate failure probabilities of wall-thinned piping system subjected to internal pressure, global bending moment and combined loading. The evaluation results showed a promising applicability of the probabilistic integrity assessment program.

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