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.

scholarly journals Design and analysis of concrete-filled tubular flange girders under combined loading

2021 ◽  
pp. 136943322110015
Author(s):  
Rana Al-Dujele ◽  
Katherine Ann Cashell
Keyword(s):  
Finite Element ◽  
Axial Force ◽  
Failure Modes ◽  
Numerical Study ◽  
Combined Loading ◽  
Torsional Stiffness ◽  
Fe Model ◽  
Combined Effects ◽  
Element Analysis ◽  
Hollow Section

This paper is concerned with the behaviour of concrete-filled tubular flange girders (CFTFGs) under the combination of bending and tensile axial force. CFTFG is a relatively new structural solution comprising a steel beam in which the compression flange plate is replaced with a concrete-filled hollow section to create an efficient and effective load-carrying solution. These members have very high torsional stiffness and lateral torsional buckling strength in comparison with conventional steel I-girders of similar depth, width and steel weight and are there-fore capable of carrying very heavy loads over long spans. Current design codes do not explicitly include guidance for the design of these members, which are asymmetric in nature under the combined effects of tension and bending. The current paper presents a numerical study into the behaviour of CFTFGs under the combined effects of positive bending and axial tension. The study includes different loading combinations and the associated failure modes are identified and discussed. To facilitate this study, a finite element (FE) model is developed using the ABAQUS software which is capable of capturing both the geometric and material nonlinearities of the behaviour. Based on the results of finite element analysis, the moment–axial force interaction relationship is presented and a simplified equation is proposed for the design of CFTFGs under combined bending and tensile axial force.

Investigation of Burst Pressure in T-Joints With Wall-Thinning by Using FEA

2017 ◽  
Author(s):  
Atsushi Yamaguchi
Keyword(s):  
Carrying Capacity ◽  
Safety Margin ◽  
Pressure Vessels ◽  
Burst Pressure ◽  
Load Carrying Capacity ◽  
Working Pressure ◽  
Element Analysis ◽  
T Joints ◽  
Wall Thinning ◽  
Load Carrying

Boilers and pressure vessels are heavily used in numerous industrial plants, and damaged equipment in the plants is often detected by visual inspection or non-destructive inspection techniques. The most common type of damage is wall thinning due to corrosion under insulation (CUI) or flow-accelerated corrosion (FAC), or both. Any damaged equipment must be repaired or replaced as necessary as soon as possible after damage has been detected. Moreover, optimization of the time required to replace damaged equipment by evaluating the load carrying capacity of boilers and pressure vessels with wall thinning is expected by engineers in the chemical industrial field. In the present study, finite element analysis (FEA) is used to evaluate the load carrying capacity in T-joints with wall thinning. Burst pressure is a measure of the load carrying capacity in T-joints with wall thinning. The T-joints subjected to burst testing are carbon steel tubes for pressure service STPG370 (JIS G3454). The burst pressure is investigated by comparing the results of burst testing with the results of FEA. Moreover, the maximum allowable working pressure (MAWP) of T-joints with wall thinning is calculated, and the safety margin for the burst pressure is investigated. The burst pressure in T-joints with wall thinning can be estimated the safety side using FEA regardless of whether the model is a shell model or a solid model. The MAWP is 2.6 MPa and has a safety margin 7.5 for burst pressure. Moreover, the MAWP is assessed the as a safety side, although the evaluation is too conservative for the burst pressure.

Study on the Influence of Deformation of the Slipper of Axial Piston Pump under High Pressure on Oil Film Structure

2014 ◽  
Vol 900 ◽  
pp. 734-737 ◽  
Author(s):  
Huai Chao Wu ◽  
Yun Liu Yu
Keyword(s):  
High Pressure ◽  
Film Structure ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Working Pressure ◽  
Element Analysis ◽  
Oil Film ◽  
The Finite Element Analysis ◽  
Order Of Magnitude ◽  
Axial Piston

The stress and strain of the slipper of 35 MPa high pressure axial piston pump are analyzed by the finite element analysis method, and the following facts are revealed: in spite of the fact that the slipper can satisfy the use requirement in the aspect of stress, whereas, in the aspect of strain, the deformation of the bottom of the slipper increases with the pressure increase, and the deformation of the slipper has reached the order of magnitude of the oil film thickness under 35 MPa working pressure. Therefore, when the slipper pair of 35 MPa high pressure axial piston pump is designed and its oil film performances are studied, the influence of deformation of the slipper on the oil film structure must be considered comprehensively. The results of this study can provide some guides for developing 35 MPa high pressure axial piston pump.

scholarly journals Free oscillations of thin-walled bimetallic pipelines of large diameter on an elastic foundation

2018 ◽  
Vol 193 ◽  
pp. 02027
Author(s):  
Vladimir Sokolov ◽  
Igor Razov ◽  
Evgeniy Koynov
Keyword(s):  
Elastic Foundation ◽  
Nuclear Power ◽  
Large Diameter ◽  
Compressive Force ◽  
Free Oscillations ◽  
Working Pressure ◽  
Momentum Theory ◽  
Internal Working ◽  
Nonlinear Version ◽  
Thin Walled

In the article, solutions are obtained for a thin-walled bimetallic pipeline. Solutions are obtained, and the frequencies of free oscillations are investigated taking into account the internal working pressure, the longitudinal compressive force, and the elastic foundation. The solutions were obtained on the basis of a geometrically nonlinear version of the semi-momentum theory of cylindrical shells of the middle bend. The proposed calculations can find application in the nuclear power industry, aviation, and the petrochemical industry.

Steam Turbine Casing Analyses to Determine Pressure and Temperature Limits

2021 ◽  
Author(s):  
Paul T. Smith ◽  
Daniel J. Griffin
Keyword(s):  
Finite Element ◽  
Steam Turbine ◽  
Elevated Temperatures ◽  
Temperature Limit ◽  
Normal Operation ◽  
Working Pressure ◽  
Element Analysis ◽  
Minimum Width ◽  
Joint Contact ◽  
Joint Contact Pressure

Abstract To ensure safe and reliable operation, steam turbine casings must have acceptable stresses and maintain sealing when subjected to internal pressures and temperatures. To show turbine casings acceptable, analysts conduct structural evaluations using finite element analysis (FEA) techniques. This paper outlines the analytical methods used to perform these types of analyses, provides analysis examples, and summarizes the process to create pressure and temperature limit maps. Finite element models of the main casing and steam chest are used to determine stresses and sealing of the casing horizontal split line and steam chest cover during normal operation. The sealing evaluations consider the sealing capabilities of the bolted joints when the casing is subjected to internal steam pressure and consider the effects of bolt stress relaxation at elevated temperatures, joint contact surface separation, and penetration of the internal pressure into the sealing surface. The acceptance criteria for the bolted joint sealing is based on the minimum width of the contacting surface and the minimum joint contact pressure. A series of analyses were conducted on the various models to create pressure and temperature limit maps, so that the design can be applied for the appropriate conditions. These maps plot maximum allowable working pressure (MAWP) versus maximum allowable working temperature (MAWT), and allow an application engineer to easily determine the acceptability of the casing for a particular application. An explanation of the process used to create the limit maps is presented.

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.

HPHT Subsea Connector Verification and Validation Using an API 17TR8 Methodology

2021 ◽  
Author(s):  
Barry Stewart ◽  
Sam Kwok Lun Lee
Keyword(s):  
Failure Modes ◽  
Production Systems ◽  
Three Dimensional ◽  
Full Scale ◽  
Verification And Validation ◽  
Combined Loading ◽  
Load Path ◽  
Capacity Curves ◽  
Industry Standards ◽  
Full Scale Tests

Abstract Wellhead connectors form a critical part of subsea tree production systems. Their location in the riser load path means that they are subjected to high levels of bending and tension loading in addition to internal pressure and cyclic loading. As more fields continue to be discovered and developed that are defined as High Pressure and/or High Temperature (HPHT) these loading conditions become even more arduous. In order to ensure the integrity of HPHT components, industry requirements for components are setout in API 17TR8. This technical report provides a design verification methodology for HPHT products and some requirements for validation testing. The methodology provides detail on the assessment of static structural and cyclic capacities but less detail on how to assess the functional and serviceability criteria for wellhead connectors. Similarly, API 17TR8 does not include prescriptive validation requirements for wellhead connectors and refers back to historical methods. This paper describes a practical application of the API 17TR8 methodology to the development of a 20k HPHT connector and how it was implemented to verify and validate the connector design through full scale tests to failure. A methodology was developed to meet the requirements of the relevant industry standards and applied to the connector to develop capacity charts for static combined loading. Verification was carried out on three dimensional 180° FEA models to ensure all non axi-symmetric loading is accurately captured. Connector capacities are defined based on API 17TR8 criteria with elastic plastic analysis (i.e. collapse load, local failure and ratcheting), functionality/serviceability criteria defined through a FMECA review and also including API STD 17G criteria including failure modes such as lock/unlock functionality, fracture based failure, mechanical disengagement, leakage and preload exceedance. These capacities are validated through full scale testing based on the requirements of API 17TR7 and API STD 17G with combined loading applied to the Normal, Extreme and Survival capacity curves (as defined by "as-built" FEA using actual material properties). Various test parameters such as strain gauge data, hub separation data, displacements, etc. were recorded and correlated to FEA prediction to prove the validity of the methodology. Further validation was carried out by applying a combined load up to the FEA predicted failure to confirm the design margins of the connector. Post-test review was carried out to review the suitability of the requirements set out in API 17TR8 and API STD 17G for the verification and validation of subsea connectors. The results build on previous test results to validate the effectiveness of the API 17TR8 code for verification and validation of connectors. The results show that real margins between failure of the connector and rated loads are higher than those defined in API 17TR8 and show that the methodology can be conservative.

scholarly journals Towards a Planar Cruciform Specimen for Biaxial Characterisation of Polymer Matrix Composites

2010 ◽  
Vol 24-25 ◽  
pp. 115-120 ◽  
Author(s):  
Michael R.L. Gower ◽  
Richard M. Shaw
Keyword(s):  
Strain Distribution ◽  
Stress Raiser ◽  
Test Method ◽  
Image Correlation ◽  
Strain Gauges ◽  
Test Machine ◽  
Element Analysis ◽  
Full Field ◽  
Cruciform Specimen ◽  
Gauge Section

This paper details work undertaken towards the development of a standard test method for the biaxial response of planar cruciform specimens manufactured from carbon fibre-reinforced plastic (CFRP) laminates and subject to tension-tension loading. Achieving true biaxial failure in a cruciform specimen without the need for the inclusion of a stress raiser, such as a hole, in the gauge-section, is a subject attracting much research globally and is by no means a trivial exercise. Coupon designs were modelled using finite element analysis (FEA) in order to predict the stress and strain distributions in the central region of the specimen. An Instron biaxial strong-floor test machine was used to test the specimens. Strain gauges were used to measure the strain in the specimen arms and to assess the degree of bending. Digital image correlation (DIC) was used to measure the full-field strain distribution in the central gauge-section of the specimen and this was compared to values measured using strain gauges. The strain readings obtained from strain gauges, DIC and FEA predictions were in good agreement and showed that the strain distribution was uniform in the central gauge-section, but that strain concentrations existed around the tapered thickness zone. These regions of strain concentration resulted in interlaminar failure and delamination of the laminate propagating into the specimen arms.

Optimum Design of Ribbon and Wire Wound Cylinders for Metal Forming Dies

1977 ◽  
Vol 99 (3) ◽  
pp. 733-737 ◽  
Author(s):  
J. Gro̸nbaek ◽  
T. Wanheim
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Tensile Stress ◽  
Optimum Design ◽  
Metal Forming ◽  
Working Pressure ◽  
Internal Working ◽  
Shrink Fit

The ribbon winding process enables the manufacture of metal forming dies with higher allowable internal working pressure than is possible by conventional shrink-fit constructions. Varying the tensile stress in the ribbon in the winding process, the stress distribution in the die can be given a predetermined shape. Based on the assumption that all ribbon layers carry the same shear stress when the internal working pressure is acting, a new winding theory is derived. This method permits the internal working pressure to be increased about 30 percent compared to that of the previously known winding theories and about 60 percent compared to that of shrink-fit constructions.

Finite Element Modeling of Effect of Adhesive Layer and Carrier Thickness Used for Strain Gauge Mounting

2015 ◽  
Vol 1119 ◽  
pp. 828-832
Author(s):  
K. Vadivuchezhian ◽  
K. Subrahmanya ◽  
N. Chockappan
Keyword(s):  
Finite Element ◽  
Strain Gauge ◽  
Adhesive Layer ◽  
Element Model ◽  
Strain Gauges ◽  
Single Element ◽  
Metal Foil ◽  
Engineering Structures ◽  
Element Analysis ◽  
Typical Strain

Metal foil strain gauges are most widely used for the stress analysis in engineering structures. Typical strain gauge system includes strain sensitive grid, carrier material, and adhesive layer. Strain measurement from the strain gauge is partially affected by carrier and adhesive materials and their thickness. In the present work, a Finite Element Model is developed in order to study the effect of both adhesive layer and carrier thickness on strain measurements while using strain gauges. To understand the behavior of the adhesive material, mechanical characterization is done on bulk adhesive specimen. Finite Element Analysis (FEA) is carried out with different materials namely epoxy and polyurethane. Initially a single element foil loop is considered for the analysis and further this is extended to metal foil strain gauge with nine end-loops. Finally, the strain variation through thickness of adhesive layer, carrier and strain sensitive grid is obtained from FEA. The results thus obtained are compared with analytical results from Basic Strength of Materials approach.

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