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Статті в журналах з теми "Full notch creep testing":
1
Jaske, Carl E., and R. Viswanathan. "Use of Miniature Specimens for Creep-Crack-Growth Testing." Journal of Engineering Materials and Technology 122, no. 3 (March 16, 2000): 327–32. http://dx.doi.org/10.1115/1.482814.
Анотація:
Measuring the condition of high-temperature components after many years of service is an important part of remaining life assessment. Tests of miniature specimens have been utilized for this purpose because they require that only small samples be removed from the components, which minimizes or eliminates the need for costly repairs. Miniature-specimen techniques have been developed and validated for creep-rupture testing but not for creep-crack-growth testing. The objective of this research was to develop and validate a procedure for measuring creep-crack-growth behavior using miniature specimens. Based on a past study of Type 316 stainless steel, the single-edge-notch-tension (SENT) specimen configuration was chosen for the current work. SENT specimens were designed and prepared from both base metal and weldments of 2-1/4Cr-1Mo and 1-1/4Cr-1/2Mo steels. The base metal was ASME SA 387, Grade P22 and Grade P11 plate, respectively. The 2-1/4Cr-1Mo steel weldment was a seam-weld hot reheat steam pipe that had been in service for 106,000 hours, while the 1-1/4Cr-1/2Mo steel weldment was from a pipe that had been weld repaired after 244,200 hours of service. SENT specimens with test sections of 10×5×1.5 mm, 15×7.5×1.5 mm, and 20×10×1.5 mm were evaluated. Tests were conducted under constant weight loading or constant load-line displacement loading. Specimens were heated to 538°C using a standard laboratory furnace. Crack length was measured using the DC electric potential drop method. The test results were analyzed to produce creep-crack-growth rate da/dt as a function of the C* integral and compared with data from tests of half-size (1/2T-CT) and standard full-size (1T-CT) compact-tension specimens. For both base metals, the 1/2T-CT and three sizes of SENT specimens gave results that agreed well with those of 1T-CT specimens. For the 2-1/4Cr-1Mo steel weldments, SENT specimens produced good results. However, SENT specimens of the 1-1/4Cr-1/2Mo steel weldments exhibited cracking blunting and no creep crack growth. The reasons for the differences in behavior are discussed and guidance for application of miniature specimens to creep-crack-growth testing is presented. [S0094-4289(00)01403-1]
2
Swaminathan, V. P., N. S. Cheruvu, and A. Saxena. "Life Assessment of an HP-IP Rotor Under Creep Service Conditions." Journal of Engineering for Gas Turbines and Power 112, no. 2 (April 1, 1990): 237–42. http://dx.doi.org/10.1115/1.2906169.
Анотація:
A CrMoV high and intermediate-pressure (HP-IP) rotor exhibited in-service cracking in the blade groove walls. Cracks initiated from a notch and propagated under creep conditions to a depth of 0.255 in. (6.5 mm). Since the unit was base loaded, the contribution of cyclic loading (startups and shutdowns) was not significant. The total life of the groove walls is predicted by applying a life prediction approach that accounts for both crack initiation and propagation. Crack initiation life is based on short-term creep tests extrapolated to long times using a time-temperature parameter. Crack propagation time is estimated using a newly developed time-dependent fracture mechanics concept. A parameter Ct is used to express the crack growth rate under creep loading conditions. Pertinent material properties such as creep deformation and creep crack growth rate were obtained by testing the material from the subject rotor. The results obtained by this analysis show that about 50 percent of the estimated life was spent in crack propagation. Predicted service life time compares very favorably with the actual operating life of the rotor.
3
Merah, N. "Notch-Strengthening Phenomenon Under Creep-Fatigue Loading Conditions." Journal of Pressure Vessel Technology 122, no. 1 (October 11, 1999): 15–21. http://dx.doi.org/10.1115/1.556140.
Анотація:
A study of the notch and frequency effects on fatigue life at high temperature is carried out using notched and unnotched plate specimens of SS 304 under stress-controlled testing conditions. Analysis of the σ-Nf results obtained at 600°C under fatigue and creep-fatigue conditions allowed the generalization of the σ-Nf-Kt relation proposed in an earlier study. Examinations of the experimental data with hold-time testing suggested that in these conditions, the frequency effect should be incorporated in the relationship. Results obtained from the modified relation are in agreement with the experimental data, within a factor of two. Finite element analysis was carried out to determine the state of stresses and strains at the notch root by simulating four creep-fatigue cycles. The computed results indicated that, under zero-to-tension cyclic loading with controlled nominal stress, the maximum local stress at the notch root relaxes; this results in a minimum local stress in compression, and as a consequence, the mean local stress is significantly reduced. The stress relaxation as well as the creep strain accumulation were found to occur only in the vicinity of the notch (within 0.75 mm). The numerical results concerning the local stress relaxation and the time-dependent strain accumulation are used to explain the notch-strengthening effect on life observed in the present study. [S0094-9930(00)00401-7]
4
Griffin, D. S., A. K. Dhalla, and W. S. Woodward. "Validation of Inelastic Analysis by Full-Scale Component Testing." Journal of Pressure Vessel Technology 109, no. 1 (February 1, 1987): 42–49. http://dx.doi.org/10.1115/1.3264854.
Анотація:
This paper compares theoretical and experimental results for full-scale, prototypical components tested at elevated-temperatures to provide validation for inelastic analysis methods, material models, and design limits. Results are discussed for piping elbow plastic and creep buckling, creep ratcheting, and creep relaxation; nozzle creep ratcheting and weld cracking; and thermal striping fatigue. Comparisons between theory and test confirm the adequacy of components to meet design requirements, but identify specific areas where life prediction methods could be made more precise.
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FERDOUS, IMAM UL, NASRUL AZUAN ALANG, Juliawati Alias, and Suraya Mohd Nadzir. "Numerical Prediction of Creep Rupture Life of Ex-Service and As-Received Grade 91 Steel at 873 K." International Journal of Automotive and Mechanical Engineering 18, no. 3 (September 19, 2021): 8845–58. http://dx.doi.org/10.15282/ijame.18.3.2021.01.0678.
Анотація:
Infallible creep rupture life prediction of high temperature steel needs long hours of robust testing over a domain of stress and temperature. A substantial amount of effort has been made to develop alternative methods to reduce the time and cost of testing. This study presents a finite element analysis coupled with a ductility based damage model to predict creep rupture time under the influence of multiaxial stress state of ex-service and as-received Grade 91 steel at 873 K. Three notched bar samples with different acuity ratios of 2.28, 3.0 and 4.56 are modelled in commercial Finite Element (FE) software, ABAQUS v6.14 in order to induce different stress state levels at notch throat area and investigate its effect on rupture time. The strain-based ductility exhaustion damage approach is employed to quantify the damage state. The multiaxial ductility of the material that is required to determine the damage state is estimated using triaxiality-ductility Cock and Ashby relation. Further reduction of the ductility due to the different creep mechanisms over a short and long time is also accounted for in the prediction. To simulate the different material conditions: ex-service and as-received material, different creep coefficients (A) have been assigned in the numerical modelling. In the case of ex-service material, using mean best fit data of minimum creep strain rate gives a good life prediction, while for new material, the lower bound creep coefficient should be employed to yield a comparable result with experimental data. It is also notable that ex-service material deforms faster than as-received material at the same stress level. Moreover, higher acuity provokes damage to concentrate on the small area around the notch, which initiates higher rupture life expectancy. It also found out that, the stress triaxiality and the equivalent creep strain influence the location of damage initiation around the notch area.
6
Beech, S. H., and E. Q. Clutton. "Interpretation of results of full notch creep test and comparison with notched pipe test." Plastics, Rubber and Composites 34, no. 7 (September 2005): 294–300. http://dx.doi.org/10.1179/174328905x59791.
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Dennies, Daniel P., and Robert Kupkovits. "Room-Temperature Creep Testing of Grade 2 CP Titanium Plate Using Notch Tensile Samples." Journal of Failure Analysis and Prevention 14, no. 4 (May 24, 2014): 437–42. http://dx.doi.org/10.1007/s11668-014-9831-5.
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Pinter, Gerald, Markus Haager, and Reinhold W. Lang. "Influence of nonylphenol–polyglycol–ether environments on the results of the full notch creep test." Polymer Testing 26, no. 6 (September 2007): 700–710. http://dx.doi.org/10.1016/j.polymertesting.2007.01.010.
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Fleissner, M. "Experience with a full notch creep test in determining the stress crack performance of polyethylenes." Polymer Engineering & Science 38, no. 2 (February 1998): 330–40. http://dx.doi.org/10.1002/pen.10194.
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Hyde, C. J., Thomas H. Hyde, and Wei Sun. "Small Ring Testing of High Temperature Materials." Key Engineering Materials 734 (April 2017): 168–75. http://dx.doi.org/10.4028/www.scientific.net/kem.734.168.
Анотація:
In service components such as steam pipes, pipe branches, gas and steam turbine blades, etc. which operate in engineering applications such as power plant, aero-engines, chemical plant etc., can operate at temperatures which are high enough for creep to occur. Often, only nominal operating conditions (i.e. pressure, temperatures, system load, etc.) are known and hence precise life predictions for these components, which may be complex in terms of geometry or weld characteristics, are not possible. Within complex components it can also be the case that the proportion of the material creep life consumed may vary from position to position within the component. It is therefore important that non-destructive techniques are available for assisting in the making of decisions on whether to repair, continue operating or replace certain components. Small specimen creep testing is a technique which can allow such analyses to be performed. Small samples of material are removed from the component to make small creep test specimens. These specimens can then be tested to give information on the remaining creep life of the component. This paper presents the results of small ring specimens tested under creep conditions and shows the comparison to standard (full size) creep testing for materials used under high temperature in industry.
Дисертації з теми "Full notch creep testing":
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Křivánková, Eliška. "Klíčové vlastnosti vybraných tenzidů pro test odolnosti vysokohustotního polyetylénu metodou napěťového krípu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-449709.
Анотація:
The thesis deals with the study of surface-active properties, zeta potential, particle size and adhesion of surfactants (Arkopal N110, Igepal CO-520, Igepal CO-890, Dehyton PL, sodium dodecyl sulfate and dodecyltrimethylammonium bromide) selected for full notch creep test method. To determine the surface phenomena occuring in a solution due to their presence at 25, 50 and 80 °C, the Du Noüy ring method of surface tension measurement was used. The importance of factors such as concentration, ionic character and the molecular structure of the surfactants, temperature and dispersion media (pH, purity) were analysed. Dynamic light scattering measurements were performed in order to evaluate the particle size and the electrophoresis method was used to determine the zeta potential. The results were compared to the contact angle measurements, i. e. adhesion tendency between surfactant solutions and the surface of selected types of high density polyethylene. The optical analysis was used to evaluate the contact angle. The negative impact of water purity was negated. The temperature dependecy was specific for each of the examined surfactant species, however the relationship between temperature and the length of hydrophilic chain was discovered. Alkaline pH was less convenient for amphoteric surfactant than acid or neutral environment, but this might have been caused by components contained in the buffer. The character of surfactant solutions was mostly monodisperse. The only exceptions were 1mM Igepal CO-520 and 3mM Dehyton PL. Further investigation led to conclusion that the molecules tend to form agglomerates. Adhesion was in accordance with surfactant effectiveness of surface reduction and adsorption. However, this theory did not match the data obtained from testing acid and neutral Dehyton PL solutions' adhering to polyethylene species containing carbon black.
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Porubský, Tomáš. "Studium vztahu mezi podmínkami testu FNCT (Full Notched Creep) a rychlostí šíření trhliny SCG (Slow Crack Growth) pro hodnocení odolnosti HDPE vůči růstu trhlin." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2015. http://www.nusl.cz/ntk/nusl-217107.
Анотація:
Theoretical part of this thesis presents summary of material and testing parameters which influence SCG and consequently the duration of the FNCT test. The experimental part focuses on modification of testing conditions of FNCT test in order to minimize the test time. FNCT tests were performed for four types of surfactants: Arkopal N110, Sodium dodecylbenzensulfonate (NaDBS), Disponil LDBS55 and Simulsol SL8. The most pronounced accelerating effect was observed for NaDBS surfactant, which in comparsion with commonly used Arkopal N110 doubled the test speed at the same concentration (11 %) and other test conditions. The accelerating effect of NaDBS was also observed for two different PE grades: Liten VB85 and VL 20N. Under the test conditions 80 °C and 4 MPa, 5% NaDBS water solution caused for VL 20N almost 12,5-fold acceleration compared to conventional 2% Arkopal N110 and almost 8,5-fold acceleration for VB 85. The correlation between wettability of surfactant solution and FNCT time to fracture was found.
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Kotoučková, Simona. "Vliv vybraných povrchově aktivních látek na čas do porušení vysokohustotního polyetylénu metodou napěťového krípu v korozivním prostředí." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2021. http://www.nusl.cz/ntk/nusl-444215.
Анотація:
The thesis deals with the study of the influence of concentration and different types of surfactants (Igepal CO-520, Arkopal N110, Igepal CO-890, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, dodecyltrimethylammonium bromide and Dehyton PL) on the environmental stress cracking resistance of high-density polyethylene by means of Full Notch Creep Test. Furthermore, the influence of ligamental stress (3,5; 4,0 a 4,5 MPa), pH of the prepared active environment and type of the water used as a solvent for the surfactants on the time to failure was monitored. An accelerating effect was observed at increased concentration, stress and molecular weight. Faster failure was achieved after exposure to ionic types compared to nonionic. The rate of the notch opening was determined. The brittle and ductile behavior during the process of failure was evaluated by microscopic analysis of the morphology of the fracture surfaces. Based on the pH change after the test, the stability of the active environment was evaluated. Deteriorating quality of surfactant solutions was observed. Raman spectroscopy and Fourier transform infrared spectroscopy were used to detect the surfactant on the surface of the test specimen after the test.
Частини книг з теми "Full notch creep testing":
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Loveday, Malcolm S. "Practical Aspects of Testing Circumferential Notch Specimens at High Temperature." In Techniques for Multiaxial Creep Testing, 177–97. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-3415-3_10.
2
Coleman, M. C., R. Fidler, and J. A. Williams. "Full Size Component Testing under Creep Conditions." In Techniques for Multiaxial Creep Testing, 333–56. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-3415-3_20.
Тези доповідей конференцій з теми "Full notch creep testing":
1
Cosham, Andrew, Brian N. Leis, Mures Zarèa, Fabian Orth, and Valerie Linton. "Full-Scale Step-Load-Hold Tests on X65 and X70 Line Pipe Steels." In 2020 13th International Pipeline Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/ipc2020-9438.
Анотація:
Abstract A time-delayed failure due to stress-activated creep (cold-creep) will occur if the applied load is held constant at a level above the threshold. The results of small and full-scale tests on line pipe steels conducted by the Battelle Memorial Institute and the British Gas Corporation in the 1960s and 70s indicated that the (empirical) threshold for a time-delayed failure was approximately 85–95% SAPF (straight-away-pressure-to-failure). The line pipe steels were Grades X52 or X60, and the full-size equivalent Charpy V-notch impact energy (where reported) did not exceed 35 J. The strength and toughness of line pipe steels has significantly increased over the decades due to developments in steel-making and processing. The question then is whether an empirical threshold based on tests on lower strength and lower toughness steels is applicable to higher strength and higher toughness steels. A Tripartite Project was established to answer this question. The Australian Pipelines and Gas Association (APGA), the European Pipeline Research Group (EPRG) and the Pipeline Research Council International (PRCI) collaborated in conducting six full-scale step-load-hold tests on higher strength and higher toughness steels. Companion papers present the other aspects of this multi-year project. The line pipe supplied for testing is summarised below. • Identifier — Dimensions and Grade — f.s.e. Charpy V-notch impact energy at 0 C • APGA [A] — 457.0 × 9.1 mm, Grade X70M, ERW — 263 J • EPRG [E] — 1016.0 × 13.6 mm, Grade X70M, SAWL — 165 J • PRCI [P] — 609.6 × 6.4 mm, Grade X65, SAWL — 160 J Six step-load-hold tests, each with four part-through-wall defects, were conducted. Test Nos. APGA 1 and 2, and Nos. EPRG 1 and 2 were conducted at Engie, France. Test Nos. PRCI 1 and 2 were conducted at EWI, USA. The full-scale tests, and associated small-scale testing, are described and discussed. A time-delayed failure due to stress-activated creep occurred in each of the step-load-hold tests. The failures occurred during a hold-period at 93.7–104.4% SAPF, after a hold of approximately 1.0–13.9 hours. The results of the six step-load-hold tests are consistent with a threshold for a time-delayed failure of approximately 90% SAPF.
2
Kobayashi, Daisuke, Tsutomu Takeuchi, and Katsushi Nakabeppu. "Creep Damage Assessment of Notched Material Made of a Solidification Control Ni-Base Superalloy Using the EBSD Method." In ASME 2017 Power Conference Joint With ICOPE-17 collocated with the ASME 2017 11th International Conference on Energy Sustainability, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/power-icope2017-3229.
Анотація:
Changes in misorientation with deformation were measured by various misorientation analysis methods using the electron backscattered diffraction (EBSD) method, and quantitative assessments were attempted to estimate the amount of strain or damage. Misorientations were correlated with macroscopic plastic or creep strains for comparative well-strained materials such as austenitic stainless steels. Ni-base superalloys used for components requiring high temperature strength such as gas turbine blades, have low ductility with precipitation of the γ’ phase in grains, therefore the change of crystal orientation was considered to be extremely suppressed in comparison with austenitic stainless steels. In addition, it was anticipated that the extremely large grains of Ni-base superalloys made it difficult to properly assess the damage as misorientation. However, with the current advances in the EBSD acquisition systems in conjunction with scanning electron microscopy, it has become possible to make unprecedented resolved measurements of the local crystal structure distribution at a millimeter scale. In particular, in order to assess the damage of gas turbine blades, the complex blade inner cooling system complicates the distribution of temperatures and stresses in the blades, which implies that it is required to assess the influence of geometry at stress concentrated regions in addition to the condition of temperatures, stresses and creep fatigue wave forms. To date, in the case of the conventional casting material or the same geometry notched specimen of the directionally solidified (DS) superalloy, the average misorientation which means the grain reference orientation deviation (GROD) within grains in a certain predetermined evaluation area including the notch increases linearly up to the initiation of creep cracks regardless of the testing temperatures, strain rates and the effect of fatigue under the creep dominant condition. However, the different notch geometry of the DS superalloy shows the different characteristics of the misorientation development. This paper focuses on a misorientation parameter which can assess the creep crack initiation life independent of the geometry at stress concentrated regions. In order to assess the creep crack initiation life at various stress concentrated areas of the DS superalloy, the development of a unified life assessment method independent of the individual notch geometries was discussed. As a result of this study, a parameter dividing the GROD by the initial notch opening value, φ0, was proposed and it was confirmed that the proposed parameter, GROD/φ0 shows similar characteristics with the relative notch opening displacement (RNOD) curves which correspond to the local strain energy and the initiation of creep crack at the notch tip independent of the geometry at a stress concentrated region.
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Džugan, Jan, Pavel Konopik, Martin Rund, and Radek Prochazka. "Determination of Local Tensile and Fatigue Properties With the Use of Sub-Sized Specimens." In ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45958.
Анотація:
Determination of mechanical properties with the use of sub-sized specimens is very important topic nowadays. The use of sub-sized samples can be quite wide in all cases when limited amount of the experimental material is available such as evaluation of residual life of in-service components, properties determination of developed nano-structured materials, assessment of dilatometric samples used for thermal and thermo-mechanical treatment development, local properties of weld joints and so on. Concerning this large application field it would be very useful to prepare standard for small size samples especially for most demanded material properties: tensile properties, notch impact transition temperature, fatigue properties, fracture toughness and creep. One of the widely used methods of miniature sample testing is Small Punch Test (SPT) that is used for determination of all above mentioned properties. However the main drawback of this method is need of known correlation relation between considered property and SPT for the material of interest. The correlation is needed due to different loading mode in comparison between SPT and standard test methods. Unfortunately, transferability of these correlation parameters between labs is very limited and thus each lab has to determine its own that limits the use of this method. More interest is recently paid to development of small size samples procedures using miniaturized standardized samples maintaining big advantage — the same loading mode between small sized and full sized samples. The same loading mode significantly reduces or completely removes complexity of the results transfer from small to standard size samples. The current paper is dealing with overview of various applications of small sized tensile tests and fatigue tests. Concerning tensile tests quasi static tensile test at room temperature as well as at elevated temperature are show together with results of dynamic tests and special tests of metastable supercooled austenite. The developed procedures performance is demonstrated by comparison of standard size and sub-size specimens results comparison for all tests, except supercooled austenite tests, where no standard size specimen exists.
4
Tanner, David W. J., Wei Sun, and Thomas H. Hyde. "Cross-Weld Creep Comparison of Power Plant Steels CrMoV, P91 and P92." In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78577.
Анотація:
Results obtained from high temperature creep tests of ferritic steel CrMoV, P91 and P92 cross-weld specimens are compared. Data is presented normalized with the results of the corresponding parent metals in order to compare the materials tested at different temperatures and stresses, and to identify characteristic cross-weld material trends. All cross-weld failures occurred in the heat-affected zone (HAZ) adjacent to the parent metal, known as type IV, at earlier test durations than for the parent material specimens. The relative performance of the cross-welds was found to decrease with decreasing stress. The CrMoV cross-weld specimens showed by far the lowest weld strength reduction factors and greatest notch strengthening, determined by testing uniaxially loaded bars with semi-circular circumferential notches located in the heat-affected zone. The P91 and P92 cross-weld specimens were found to have similar (high) weld strength reduction factors and showed little or no notch strengthening. It was observed that the failure time of a P92 cross-weld specimen relative to the P92 parent material could be estimated using data from P91 cross-weld and relative parent material tests.
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Mourad, A.-H. I., J. Altarawneh, A. El Domiaty, and Y. J. Chao. "Fracture Toughness Determined From Full-Scale Pipe." In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78783.
Анотація:
Fracture toughness for full scale steel pipe of API 5L grade X65 PSL1 (ASTM A694F65) medium strength grade pipeline steel has been measured by a new test specimen utilizing the same procedure of the standard test methods ASTM E 399-90 and E 1820-01. Full scale pipe with circumferentially machined notch is pulled axially by tensile load up to fracture. An external circumferential sharp notch has been machined in the wall of the pipe to simulate the crack. To insure a plane strain condition around the crack a well lubricated and axially free loaded plug has been mounted, symmetrically around the circumferential notch, inside the pipe. Evidences of cleavage fracture have been observed on the fracture surface. The measured value of the fracture toughness has been found to be very close to the values measured according to the standard test for steel plates of similar grade. The new proposed testing method for full scale pipe can be used regardless its dimensions since it appears to provide plane strain condition around the crack.
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Tarnowski, K. M., C. M. Davies, K. M. Nikbin, and D. W. Dean. "Experimental Determination of Elastic and Plastic LLD Rates During Creep Crack Growth Testing." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65685.
Анотація:
Elastic and plastic load line displacement (LLD) rates are often ignored when analyzing Creep Crack Growth (CCG) tests due to difficulties in accurately determining their value for complex crack morphologies typical of creep. Instead, the total LLD rate is assumed to be entirely due to creep. This simplistic approach overestimates the crack tip characterizing parameter C* which is non-conservative. This paper presents a review of the current method of interpreting CCG test data in ASTM E1457 and proposes an improved approach which accounts for the elastic and plastic LLD rates. Estimations of the elastic and plastic LLD rate are obtained from a partial unload immediately after load-up and a full unload, at the end of the test, prior to final failure. Some finite element validation of this method is presented. Implementing this approach will facilitate more realistic CCG laws.
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Djomseu, Patricia, Max A. Sardou, and Thomas R. Berg. "Composite Coil Spring Development and Testing." In IEEE/ASME/ASCE 2008 Joint Rail Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/jrc2008-63019.
Анотація:
This paper will present the development of composite coil springs made from glass-fiber-epoxy materials. It will also review the results from prototype springs that have been manufactured and tested. Sardou S.A. has been developing and manufacturing composite structures and components of various designs for over 27 years. This experience, especially with composite torsion springs, has led to development, prototype production, and testing of several designs of composite coil springs. The design takes advantage of commercially available glass fiber and epoxy materials. The development process led to proprietary design methods and computer models to simulate unique configurations and material characteristics. The development process also allows design of composite springs for the same or smaller design volume as steel coil springs with comparable spring characteristics. The manufacturing methods that are used apply existing lost mold and winding processes in unique ways to produce prototype composite coils springs. These methods were also developed considering scaling-up and automation for volume production. Several generations of prototype composite coil springs have been produced and tested. Each generation has advanced the design and manufacturing methods. Several features of composite coil springs including light weight, dynamic response, flexibility of design, and fatigue resistance have been demonstrated through testing. Depending the steel counterpart considered, composite coils springs offer weight saving of about 75%, fatigue life improvement, no rust, no creep, and no notch sensitivity at a cost close to that of a steel spring.
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Guerrero, Hector N., Christine A. Langton, and Michael L. Restivo. "Testing and Analysis of Early Age Stress-Strain Development of Concrete Overlay for Reactor In-Situ Decommissioning." In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57902.
Анотація:
Non-uniform moisture distribution during early age drying and curing of protective concrete overlays for Savannah River Site reactors decommissioned in-situ were expected to result in differential shrinkage that lead to tensile stresses and possible cracking. The goal was to not exceed the concrete tensile strength of 2.8 MPa or compressive strength of 23.8 MPa. An experimental study was performed on the development of shrinkage and creep strains in concrete slab specimens embedded with strain gages and relative humidity sensors at controlled ambient temperature and relative humidity conditions. The experimental data was used to verify the validity of available physics-based methods and code calculations to predict early age shrinkage and creep strains, respectively. Data on the expansive effect of a shrinkage compensating admixture based on CaO was also obtained. Prediction of the surface stress in the test specimen suggests that without the shrinkage compensating admixture, the tensile strength would be slightly exceeded. However with the admixture, the combined effects of shrinkage, creep and expansion due to the admixture is predicted to result in all compressive stresses within the full scale slab, eliminating the possibility of cracking.
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Park, Dong-Yeob, Hisakazu Tajika, Takahiro Sakimoto, Satoshi Igi, James A. Gianetto, Jie Liang, Jean-Philippe Gravel, and Joe Kondo. "Relationship of Fracture Behaviours Between Full-Scale Pipe Bending and Small-Scale Toughness Tests." In ASME 2018 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/pvp2018-84138.
Анотація:
A comparison of the fracture behaviours for a full-scale (FS) pipe bending test and small-scale fracture toughness tests was carried out in this investigation. For the FS pipe test, two 4-meter long large diameter (914 mm) X70 pipes were girth-welded together to facilitate bend testing with an internal pressure of 72% of specified miniminm yield strength (SMYS). The test assembly also contained a semi-ellipical notch that was prepared by means of electrical discharge machining (EDM) from the outside surface in the heat-affected zone. Single-edge notched bend (SE(B) or SENB) and single-edge notched tension (SE(T) or SENT) test specimens were prepared from a duplicate girth weld produced with the same pipe and weld procedure with equivalent notch depths. The FS pipe test showed deformation along the pipe axis asymmetric to the girth weld centre. The comparison of fracture behaviours between small-scale and FS tests suggests that toughness measurements (crack-tip opening displacement or J-integral) at maximum load might be useful as a reference for strain-based design although further work is needed.
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May, Gerry. "The Need for In-Situ Pipe Support Testing." In ASME 2004 Power Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/power2004-52031.
Анотація:
Pipe support functionality is critical to the long term life of piping system. Spring supports degrade with time due to flexing in the spring and wear in constant support bearings. It is not unusual to measure constant support hangers with resistance 25% to 50% different than the design load. This leads to excessive sustained pipe stress, pipe sag (or uplift), and in high temperature systems, accelerated creep damage. Supports may also not move properly from shut down to full operation, which can create excessive fatigue stress, failed hanger components, and other piping system damage. In-situ hanger testing has been found to be a reliable and cost effective method to determine the functionality of pipe supports. Results are used as input to set revised recommended loads, and to determine if any hangers need to be replaced. This paper provides examples of the types of problems that are often found in the field, the method to test, and typical resolutions to maximize the pipe life and minimize the risk of failure.