scholarly journals A combined loading transducer for calculating the bending moment and torque in a slender circular beam using the minimum numbers of strain gauges, strain grids, and measurement channels

2020 ◽  
Vol 16 (6) ◽  
pp. 155014772092177
Author(s):  
Bernard J Socha ◽  
Edward T Bednarz ◽  
Wei-Dong Zhu
Keyword(s):  
Bending Moment ◽  
Longitudinal Axis ◽  
Combined Loading ◽  
Strain Gauges ◽  
Independent Measurement ◽  
Experimental Configuration ◽  
Circular Beam ◽  
Independent Variable ◽  
Measurement Channels ◽  
Minimum Numbers

The purpose of this work is to develop a new methodology that uses the minimum numbers of strain gauges, strain grids, and measurement channels to calculate the bending moment and torque in a slender circular beam under combined loading from measured strains in it. In general, each independent variable requires a minimum of one independent measurement. Two grids of a single-rosette strain gauge located at 45° and −45° from the longitudinal axis of the beam are used in conjunction with two measurement channels to gather all measurements and form a combined loading transducer. A theoretical set of equations of the new methodology is developed to minimize numbers of strain grids and measurement channels, and an experimental configuration was tested in a variety of scenarios. Calibration factors were independently developed for the bending moment and torque of the beam by separately loading it in their respective directions. These calibration factors were applied to different combined loading scenarios, where errors were found to be on average 1.6% for moment comparison and 6.7% for torque comparison.

The Influence of Loads Superposition, Deterioration Due to Cracks and Residual Stresses on the Strength of Tubular Junction

2017 ◽  
Vol 68 (6) ◽  
pp. 1267-1273
Author(s):  
Valeriu V. Jinescu ◽  
Angela Chelu ◽  
Gheorghe Zecheru ◽  
Alexandru Pupazescu ◽  
Teodor Sima ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Residual Stresses ◽  
Bending Moment ◽  
Combined Loading ◽  
Torsional Moment ◽  
Calculation Methods ◽  
State Of Stress ◽  
Cracked Structures ◽  
Total Participation ◽  
Theoretical Results

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.

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

2012 ◽  
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.

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

2010 ◽  
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.

Elastic-plastic bending of the pipeline under combined loading

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.

A Validated Methodology to Establish Structural Capacities for Subsea Connector Families

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.

Validation for External Tieback Connector Bending Capacity by Strain Measurement

2019 ◽  
Author(s):  
Adam Christopherson ◽  
Young-Hoon Han
Keyword(s):  
Axial Strain ◽  
Combined Loading ◽  
Strain Gauges ◽  
Working Pressure ◽  
Element Analysis ◽  
Linear Pattern ◽  
Internal Working ◽  
Industry Standards ◽  
Bending Capacity ◽  
Crucial Information

Abstract Strain gauges provide a convenient and affordable method to accurately measure the strain field for complex systems. Not only do they provide crucial information for predicting the fatigue life of components, but they can also determine the principle stresses which can be used to compare design factors with accepted industry standards. The use of electrical resistance strain gauges for load verification has become an ever-increasing practice in the design of subsea connectors as evidenced by the recent application in the industry guidance API 17TR7 [1]. The design is aided by the development of a Finite Element Analysis (FEA) which is used to predict the load capacities for normal, extreme, and survival conditions. The present work describes the experimental validation of a 18-3/4in 10,000 psi subsea collet connector model by applying linear pattern CEA-06-062UW-350 strain gauges at discrete points along the circumferentially spaced collet segments. The collet segments are the selected components for strain gauge placement because not only are they the primary connecting element between the subsea wellhead and the connector body, but they also only support axial loads. The axial strain of the collet segments in tension were compared at two combined loading cases: maximum bending capacity with and without internal working pressure and found to be in good correlation with the elastic-plastic FEA. The experimentally validated FEA is a crucial tool in determining the connector’s application to project or customer specific load and fatigue requirements and eliminates the need for unnecessary experimentation.

Probabilistic Integrity Assessment of Corroded Gas Pipelines

2006 ◽  
Vol 128 (4) ◽  
pp. 547-555 ◽  
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.

Resistance strain gauges for the measurement of steady strains at temperatures above 650°C

1965 ◽  
Vol 1 (1) ◽  
pp. 11-19 ◽  
Author(s):  
R Bertodo
Keyword(s):  
Longitudinal Axis ◽  
Temperature Gradients ◽  
Moderate Temperature ◽  
Resistance Strain ◽  
Tungsten Alloy ◽  
Strain Gauges ◽  
Strain Sensitivity ◽  
Long Term Stability ◽  
High Electrical Resistivity ◽  
Improved Performance

The paper considers the problem of obtaining steady strain data using electrical resistance strain gauges at temperatures above 650°C, in the presence of moderate temperature gradients, from turbojet components operating in oxidizing environments. The characteristics of forty-six metal and alloy systems are briefly outlined and the properties of platinum, and alloys of face centred cubic platinum metals and metals in the VIa group of the periodic table of elements are discussed in detail. The behaviour of colloidal sols, acid and alkali bonded ceramic cements and flame-sprayed oxides at high temperatures is considered and their effect on the short and long term stability and strain sensitivity of strain gauges presented. Only a limited number of pure oxides possessed an adequately high electrical resistivity at the higher temperatures for use as strain gauge bonding media. Such oxides, when flame-sprayed on to suitably prepared surfaces, developed a bond of sufficient shear strength to transfer the applied strain in a consistent and repeatable manner to the gauge filament. The porosity was low enough to offer some degree of oxidation protection to the strain sensitive grid. The temperature coefficient of resistance, drift rate and strain sensitivity of flat grid, dual-element gauges bonded in this manner to Nimonic specimens are shown and it is concluded that grids of this type, wound from platinum and a commercially available platinum-tungsten alloy, would permit the detection of steady strains within an accuracy of about ±0.5 ton/in2 over the temperature range 600—850°C and within ±1.0 ton/in2 over the approximate range 600—950°C from Nimonic specimens, provided the mean gauge temperature could be determined. Methods of determining this temperature in the presence of moderate temperature gradients along the longitudinal axis of the gauge are discussed and some field data are presented. Drift rates equivalent to less than 0.1 ton/in2/h were noted. It is thought that a coil wound gauge would offer improved performance over a flat grid gauge for temperature gradients across the element, but the problem of providing a suitable former has not been resolved satisfactorily.

scholarly journals Calculation features of compressed-bent build-up timber columns with nonlinear-deformable shear bracings

2022 ◽  
Vol 1211 (1) ◽  
pp. 012007
Author(s):  
E V Popov ◽  
A V Karelsky ◽  
V V Sopilov ◽  
B V Labudin ◽  
V V Cherednichenko
Keyword(s):  
Problem Solving ◽  
Numerical Method ◽  
Compressive Force ◽  
Bending Moment ◽  
Longitudinal Axis ◽  
Nonlinear Dependence ◽  
System Of Equations ◽  
Loading Process ◽  
Is Development

Abstract Object of research is build-up compressed–bent and eccentrically compressed columns on yielding nonlinear – deformable shear bracings. Purpose of the research is development of a numerical method for calculation of columns, allowing to take in account the influence of deflection of elastic axis of bar on the increment of the bending moment from the action of longitudinal compressive force and the nonlinear dependence between the forces and deformations in the shear bracings. Problem-solving method consists in dividing the column into separate sections, a system of equations is compiled from the condition of equality of the increment of concentrated shears. The loading process is divided into a set number of stages, at each forces in the shear bracings, the stresses in the branches, and the buckling function of the elastic axis of the element are determined. The obtained values of forces in the shear bracings and buckling are used to specify stiffness of the bracings and component of the bending moment arising due to eccentric application of the longitudinal compressive force when longitudinal axis of the element is deflecting. To obtain the resulting values, the obtained forces, deflections and stresses in the branches at each calculation stage are summed up.

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

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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