Journal articles: 'Materials – Creep – Testing'

1

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.

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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.

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2

Wolfenden, A., LC McDonald, and KT Hartwig. "Cryogenic Creep Testing." Journal of Testing and Evaluation 19, no. 2 (1991): 107. http://dx.doi.org/10.1520/jte12542j.

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Král, Petr, Jiří Dvořák, Marie Kvapilová, Jaroslav Lukeš, and Vaclav Sklenička. "Constant Load Testing of Materials Using Nanoindentation Technique." Key Engineering Materials 606 (March 2014): 69–72. http://dx.doi.org/10.4028/www.scientific.net/kem.606.69.

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Experiments were conducted to evaluate creep behavior of conventional and ultrafine-grained metallic materials using nanoindentation technique. The polished surface of samples was loaded up to 5 mN. The load was held constant to examine the creep behavior. Nanoindentation tests were performed at room temperature. Strain rate was evaluated from load and displacement data. The stress exponents of strain rates n were determined from loading stress dependences of creep rate. The values of stress exponents of the indentation strain rate indicate that creep behavior of investigated materials is influenced in particular by slip of intragranular dislocations. By contrast, deformation mechanisms like grain boundary sliding and diffusion processes seem to be improbable.

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4

Kuwano, Reiko, and Richard J. Jardine. "On measuring creep behaviour in granular materials through triaxial testing." Canadian Geotechnical Journal 39, no. 5 (October 1, 2002): 1061–74. http://dx.doi.org/10.1139/t02-059.

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The first part of the paper describes the precision and long-term stability that are required in triaxial stress-strain measurements and in stress-path control systems to obtain reliable information on creep in granular media. It is shown that membrane penetration and sample end compliance must be accounted for and that lubricated ends and local strain measurements are essential. The temperature sensitivity of each transducer also needs to be assessed, even when working in a temperature-controlled laboratory. The second part of the paper presents illustrative data that were obtained in tests on sand and Ballotini® glass beads. Considerable creep deformations were observed under both isotropic and anisotropic effective stress conditions, even at relatively low pressures where particle breakage was unlikely to be significant. The experiments show how creep depends on the stress conditions imposed, how the strain increment directions change during creep, and how the creep rates stabilize with time.Key words: sand, creep, triaxial test, yielding, membrane penetration.

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5

Duan, Xiaochang, Hongwei Yuan, Wei Tang, Jingjing He, and Xuefei Guan. "A Phenomenological Primary–Secondary–Tertiary Creep Model for Polymer-Bonded Composite Materials." Polymers 13, no. 14 (July 18, 2021): 2353. http://dx.doi.org/10.3390/polym13142353.

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This study develops a unified phenomenological creep model for polymer-bonded composite materials, allowing for predicting the creep behavior in the three creep stages, namely the primary, the secondary, and the tertiary stages under sustained compressive stresses. Creep testing is performed using material specimens under several conditions with a temperature range of 20 °C–50 °C and a compressive stress range of 15 MPa–25 MPa. The testing data reveal that the strain rate–time response exhibits the transient, steady, and unstable stages under each of the testing conditions. A rational function-based creep rate equation is proposed to describe the full creep behavior under each of the testing conditions. By further correlating the resulting model parameters with temperature and stress and developing a Larson–Miller parameter-based rupture time prediction model, a unified phenomenological model is established. An independent validation dataset and third-party testing data are used to verify the effectiveness and accuracy of the proposed model. The performance of the proposed model is compared with that of an existing reference model. The verification and comparison results show that the model can describe all the three stages of the creep process, and the proposed model outperforms the reference model by yielding 28.5% smaller root mean squared errors on average.

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Sklenička, Vàclav, Květa Kuchařová, Marie Kvapilová, Luboš Kloc, Jiří Dvořák, and Petr Král. "High-Temperature Creep Tests of Two Creep-Resistant Materials at Constant Stress and Constant Load." Key Engineering Materials 827 (December 2019): 246–51. http://dx.doi.org/10.4028/www.scientific.net/kem.827.246.

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Creep is defined as a time dependent component of plastic deformation. Creep tests can be performed either at constant load or at constant applied stress. Engineering creep tests carried out at constant load are aimed at determination of the creep strength or creep fracture strength, i.e. the data needed for design. The constant stress tests are important as a data source for fundamental investigations of creep deformation and fracture mechanisms and for finite element modelling of more complex stress situations. For some materials, the difference between the two type of testing can be very small, while for other materials is large, depending on the creep plasticity of the material under testing. The paper aims to compare the creep results of two different creep-resistant materials: the advanced 9%Cr martensitic steel (ASME Grade P91) and a Zr1%Nb alloy obtained by both testing methods and to clarify the decisive factors causing observed differences in their creep behaviour.

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Maxwell, A. S., M. A. Monclus, N. M. Jennett, and G. Dean. "Accelerated testing of creep in polymeric materials using nanoindentation." Polymer Testing 30, no. 4 (June 2011): 366–71. http://dx.doi.org/10.1016/j.polymertesting.2011.02.002.

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8

Dobeš, F., and K. Milička. "Application of creep small punch testing in assessment of creep lifetime." Materials Science and Engineering: A 510-511 (June 2009): 440–43. http://dx.doi.org/10.1016/j.msea.2008.04.087.

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9

Ballokova,, Beata, Pavol Hvizdos,, Michal Besterci,, Marcus Zumdick,, and Alexander Bohm,. "Creep Testing of MoSi2 - Bases Composites." High Temperature Materials and Processes 25, no. 3 (June 2006): 139–42. http://dx.doi.org/10.1515/htmp.2006.25.3.139.

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10

Ganesh Kumar, J., K. Laha, and M. D. Mathew. "Small Punch Creep Testing Technique for Remnant Life Assessment." Applied Mechanics and Materials 592-594 (July 2014): 739–43. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.739.

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Small punch creep (SPC) testing technique is a material non-intensive testing technique for evaluating creep behavior of materials using miniature specimens. It can be used for remnant life assessment (RLA) studies on components in service, by scooping out limited material for testing without impairing the strength of component. In order to ensure the reliability of use of SPC technique for RLA, it is necessary to establish sound database on SPC properties of the material before putting into service. In this investigation, SPC technique was used to evaluate creep properties of 316LN stainless steel using specimens of size 10 x 10 x 0.5 mm. SPC tests were conducted in load controlled mode at 923 K and at various loads. SPC curves clearly exhibited primary, secondary and tertiary creep stages. The minimum deflection rate increased and rupture life decreased with an increase in applied load. Like in conventional creep test results, the minimum deflection rate obeyed Norton’s power law and Monkman-Grant relationship. SPC test was correlated with corresponding conventional creep test. Good correlation was established between creep rupture life values evaluated from SPC tests and conventional creep tests.

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11

Yang, Z., and T. B. Gibbons. "The use of reference materials to validate creep testing procedures." Materials at High Temperatures 15, no. 1 (January 1998): 23–28. http://dx.doi.org/10.1080/09603409.1998.11689573.

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12

Whittenberger, J. Daniel, and Michael J. Luton. "Elevated temperature creep properties of NiAl eryomilled with and without Y2O3." Journal of Materials Research 10, no. 5 (May 1995): 1171–86. http://dx.doi.org/10.1557/jmr.1995.1171.

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The creep properties of lots of NiAl eryomilled with and without Y2O3 have been determined in compression and tension. Although identical cryomilling procedures were used, differences in composition were found between the lot ground with 0.5 vol % yttria and the lot ground without Y2O3. Compression testing between 1000 and 1300 K yielded similar crecp strengths for both materials, while tensile creep rupture testing indicated that the yttria-containing alloy was slightly stronger than the Y2O3-free version. Both compression and tensile testing showed two deformation regimes; whereas the stress state did not affect the high stress exponent (n ≍ 10) mechanism, the low stress exponent regime n was ∼6 in tension and ∼2 in compression. The strengths in tension were somewhat less than those measured in compression, but the estimated activation energies (Q) of ∼600 kJ/mol for tensile testing were closer to the previously measured values (∼700 kJ/mol) for NiAl-AlN and very different from the Q's of 400 and 200 kJ/mol for compression tests in the high and low stress exponent regimes, respectively. A Larson-Miller comparison indicated that cyromilling can produce an alloy with long-term, high-temperature strength at least equal to conventional superalloys.

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13

Liu, Qing Sheng, Hai Feng Tang, and Hui Fang. "Creep Testing and Visco-Elastic Behaviour Reseach on Carbon Cathodes during Aluminum Electrolysis." Advanced Materials Research 314-316 (August 2011): 1430–34. http://dx.doi.org/10.4028/www.scientific.net/amr.314-316.1430.

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An apparatus to measure compressive creep in carbon cathode materials has been developed. Short-time creep were measured at 30°C，965°C and during aluminum electrolysis at 965°C. The creep strain increases with stress, indicating that the creep behavior is of the stress dependency. The ranking from low to high creep was at 30°C<965°C<during aluminum electrolysis at 965°C. The integral creep conctitutive mdoel were estalished based on the relevant rheological mdoel. The results indicate the proposed rheological model can discribe the creep rate at the first stage and the stady-state stage on the creep strain curves. Simultaneously, the viscous coefficents denoting the viscous behavior in visco-elastic constitutive model were determined by taking use of the creep testing data.

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14

Ali, Balhassn S. M., Tom H. Hyde, and Wei Sun. "Small Two-Bar Specimen Creep Testing of Grade P91 Steel at 650°C." High Temperature Materials and Processes 35, no. 3 (March 1, 2016): 243–52. http://dx.doi.org/10.1515/htmp-2014-0188.

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AbstractCommonly used small creep specimen types, such as ring and impression creep specimens, are capable of providing minimum creep strain rate data from small volumes of material. However, these test types are unable to provide the creep rupture data. In this paper the recently developed two-bar specimen type, which can be used to obtain minimum creep strain rate and creep rupture creep data from small volumes of material, is described. Conversion relationships are used to convert (i) the applied load to the equivalent uniaxial stress, and (ii) the load line deformation rate to the equivalent uniaxial creep strain rate. The effects of the specimen dimension ratios on the conversion factors are also discussed in this paper. This paper also shows comparisons between two-bar specimen creep test data and the corresponding uniaxial creep test data, for grade P91 steel at 650°C.

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15

TAKADA, Akio, Hiroshi DANJO, Masao SAKANE, Yutaka TSUKADA, and Hideo NISHIMURA. "Development of Miniature Creep Testing for Solders." Transactions of the Japan Society of Mechanical Engineers Series A 69, no. 683 (2003): 1082–87. http://dx.doi.org/10.1299/kikaia.69.1082.

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16

Petersen, DR, RE Link, R. Völkl, D. Freund, and B. Fischer. "Economical Creep Testing of Ultrahigh-temperature Alloys." Journal of Testing and Evaluation 31, no. 1 (2003): 10820. http://dx.doi.org/10.1520/jte12351j.

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17

Hiyoshi, Noritake, Takamoto Itoh, Masao Sakane, Takafumi Tsurui, and Masaaki Tsurui. "Development of Multiaxial Creep Testing Machine for Miniature Specimen." MATEC Web of Conferences 300 (2019): 14001. http://dx.doi.org/10.1051/matecconf/201930014001.

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High temperature components such as boiler tube and jet engine turbine blade undergo multiaxial creep damage. Although multiaxial creep testing investigation is required for safety high temperature components designing, there are few commercial testing machines which can conduct multiaxial loading at high temperature. A new miniature cruciform specimen, which has a 5 mm square size plane stress gauge part, was designed by using FE analysis. A biaxial tensile loading creep testing machine was also designed to conduct multiaxial creep testing. The testing machine has 2 kN loading capacity and 1 kW furnace. We had also developed a non-contact displacement measuring method for the miniature specimen. This method uses conventional optical camera to get the surface observation photograph. Chasing the trace of the target mark painted at surface of the specimen, we can get the displacement of the specimen. The calculated strain value obtained from the non-contact displacement measuring method corresponds with the strain gauge value at room temperature. By using the multiaxial creep testing machine and the non-contact observation system, we can investigate not only deformation of the testing specimen but also surface conditions of materials during the creep testing.

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18

Preciado, Mónica, Pedro Bravo, José Calaf, and Daniel Ballorca. "Strain Rate during Creep in High-Pressure Die-Cast AZ91 Magnesium Alloys at Intermediate Temperatures." Materials 12, no. 6 (March 15, 2019): 872. http://dx.doi.org/10.3390/ma12060872.

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During creep, magnesium alloys undergo microstructural changes due to temperature and stress. These alterations are associated with the evolution of the present phases at a microstructural level, creating different strain rates during primary and tertiary creep, and with the stability of the inter-metallic phase Mg17Al12 formed at these temperatures. In this paper, the results of creep testing of high-pressure die-cast AZ91 magnesium alloys are reported. During creep, continuous and discontinuous precipitates grow, which influences creep resistance. The creep mechanism that acts at these intermediate temperatures up to 150 °C is termed dislocation climbing. Finally, the influence of the type of precipitates on the creep behavior of alloys is determined by promoting the formation of continuous precipitates by a short heat treatment prior to creep testing.

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19

Palotás, Béla. "A Simplified Determination of Creep Properties of Steels by Measuring their Crack Opening Displacements (COD) at Elevated Temperatures." Materials Science Forum 729 (November 2012): 114–19. http://dx.doi.org/10.4028/www.scientific.net/msf.729.114.

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The testing of creep resistance (for example σ1%/100000 h) of metals has been required for a long time (about 10 years) and some methods have been worked out to decrease testing time. The application of these methods has some difficulties. Now we have worked out a new empirical method to reduce testing time, namely COD measuring at an elevated temperature. The paper presents this method, which makes it possible to determine creep properties by measuring the materials COD at an elevated temperature. To determine COD we use notched samples with different radii and we tear them at an elevated temperature. The determination of COD is based on the Czoboly Radon method. By opening three different radii notches we approximate to zero radius which gives the COD. Master Curves of COD and creep resistance connections were drawn at 500 °C, which is not dependent on materials and they can be used for determining Creep Properties from COD measured at 500 °C. This method can be used for the comparison of the creep resistance of materials and for that of the creep properties of different zones of welded joints. The method is found useful in technical practice.

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20

Ye, Yong, and Yi Zhou Cai. "The Nonlinear Viscoelastic Behavior for Asphalt Mixture Materials." Advanced Materials Research 255-260 (May 2011): 3268–71. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.3268.

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Compressive behavior of asphalt mixture is studied in creep and strain recovery tests observing large nonlinear viscoelastic strains. The nonlinear viscoelastic material model for asphalt mixture is presented, based on a modified version of Schapery’s constitutive relationship. For the description of the nonlinear viscoelastic response of the material, simple creep and recovery tests for different stress levels were executed. An analytical method and a nonlinear fitting procedure by the least square method are developed to determine nonlinear viscoelastic stress dependent parameters. Constant stress creep testing were also performed to validate the developed material model. The model successfully describes the main features for asphalt mixture and shows good agreement with test data within the considered stress range.

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21

Saucedo-Muñoz, Maribel L., Shin-Ichi Komazaki, Toru Takahashi, Toshiyuki Hashida, and Tetsuo Shoji. "Creep property measurement of service-exposed SUS 316 austenitic stainless steel by the small-punch creep-testing technique." Journal of Materials Research 17, no. 8 (August 2002): 1945–53. http://dx.doi.org/10.1557/jmr.2002.0288.

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The creep properties for SUS 316 HTB austenitic stainless steel were evaluated by using the small-punch creep test at 650 °C for loads of 234, 286, 338, 408, and 478 N and at 700 °C for loads of 199 and 234 N. The creep curves, determined by means of the small-punch creep test, were similar to those obtained from a conventional uniaxial creep test. That is, they exhibited clearly the three creep stages. The width of secondary creep stage and rupture time tr decreased with the increase in testing load level. The creep rupture strength for the service-exposed material was lower than that of the as-received material at high testing loads. However, the creep resistance behavior was opposite at relatively low load levels. This difference in creep resistance was explained on the basis of the difference in the creep deformation and microstructural evolution during tests. It was also found that the ratio between the load of small-punch creep test and the stress of uniaxial creep test was about 1 for having the same value of creep rupture life.

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22

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.

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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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23

Carroll, Daniel F., Sheldon M. Wiederhorn, and D. E. Roberts. "Technique for Tensile Creep Testing of Ceramics +." Journal of the American Ceramic Society 72, no. 9 (September 1989): 1610–14. http://dx.doi.org/10.1111/j.1151-2916.1989.tb06291.x.

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24

Hvizdos,, P., M. Besterci,, M. Šlesár,, and Ch Edtmaier,. "Compressive Creep Testing of Pt-Y2O3 Composites." High Temperature Materials and Processes 24, no. 3 (June 2005): 189–92. http://dx.doi.org/10.1515/htmp.2005.24.3.189.

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25

Roshanianfard, Ali, and Gholamhossein Shahgholi. "Performance Characterization of Automatic Creep Testing Device for Agricultural Product." Applied Engineering in Agriculture 33, no. 3 (2017): 433–40. http://dx.doi.org/10.13031/aea.12122.

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Abstract. The creep test is an important mechanical test used to measure the mechanical properties of materials, especially agricultural viscoelastic products. Unsuitable creep testing methodology and subsequent inaccurate outputs can have severe negative consequences on the agricultural product preservation. The aim of this study was to develop a novel improved creep testing device for viscoelastic materials at room temperature, especially agricultural crops. The performance of methodology against four alternative loading methods (Cycloidal, Cubic, Cosine, and Quintic) was compared. The results showed no significant differences between the generated data and alternative approaches. Some experiments were accomplished to performance evaluation, on Agria potato using stress of 110 kgf at 20°C with five replications and also to compare test results with past developed devices by the stress of 24.4 and 58.8 kgf at 22°C with three replications. The results showed no significant differences between the developed device (ACTeD- 1) data and the standard devices. Loading with Cosine-Cubic method was more applicable because it could control the impulse effects at the first moments of loading and reached the performed force with minimum damage in the material structure. Keywords: Agria, Automatic, Creep, Design, Potato, Viscoelastic.?

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26

Ivanov, E. Yu, and V. A. Kirpichev. "Determining the rheological properties of viscoelastic materials by the values of creep strain." VESTNIK of Samara University. Aerospace and Mechanical Engineering 18, no. 3 (October 31, 2019): 166–72. http://dx.doi.org/10.18287/2541-7533-2019-18-3-166-172.

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Determination of creep strain arising due to stresses acting up to the moment of time t is considered. The phenomenon of constant-stress creep is described. A method is proposed to determine the parameters of the Arutyunyan creep kernel selected to describe the behavior of a material using two creep curves of a material with viscoelastic properties and nonlinear dependence of creep strain on the stress. In addition, the constant in the expression describing nonlinear dependence of creep strain on the stress is defined. The AMg6M alloy, widely used in the design of aerospace products, was chosen as the material to be analyzed. The tests were carried out on samples 3 mm thick at strains of 65 MPa and 156.9 MPa. According to the results of testing samples of materials on the test bench of Samara University creep curves were obtained. By determining the parameters of the approximation of the Arutyunyan kernel and the parameter included in the expression of nonlinear dependence of creep strain on the stress, it is possible to determine the value of the creep strain of the material for arbitrary values of stress and time. Comparison of the experimental and calculated creep curves for the AMg6M alloy confirms the validity of determination of the rheological characteristics of the tested material.

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Petersen, DR, RE Link, J. Lindblom, F. Seitisleam, and PJ Henderson. "Creep Testing of Steels at Very High Temperatures." Journal of Testing and Evaluation 24, no. 5 (1996): 329. http://dx.doi.org/10.1520/jte11312j.

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28

Webster, G. A. "Editorial High temperature multiaxial creep testing and analysis." Fatigue Fracture of Engineering Materials and Structures 27, no. 4 (April 2004): 265. http://dx.doi.org/10.1111/j.1460-2695.2004.00766.x.

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29

Zhang, Qing, Robert Le Roy, Matthieu Vandamme, and Bruno Zuber. "Long-term creep properties of cementitious materials: Comparing microindentation testing with macroscopic uniaxial compressive testing." Cement and Concrete Research 58 (April 2014): 89–98. http://dx.doi.org/10.1016/j.cemconres.2014.01.004.

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Hyde, Thomas H., and W. Sun. "High Temperature Behaviour of Materials and Components under Creep Conditions." Applied Mechanics and Materials 1-2 (September 2004): 25–36. http://dx.doi.org/10.4028/www.scientific.net/amm.1-2.25.

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This paper describes some recent work on the stress analyses and failure prediction of some typical pressurised high temperature components under creep conditions, including plain pipes, pipe bends, branch connections and welds etc, in the main steam pipework of power plant. The materials used are typically low alloy ferritic CrMoV steels. Experimental creep testing methods, and the procedures used for generating the material properties in creep and damage constitutive equations, are briefly described. Some typical numerical results are presented to illustrate the main characteristics of the behaviour of these components and to demonstrate the effects of geometry, material properties and loading modes on stress distributions and failure life predictions. The emphasis of the paper is on welded components.

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Zhan, Z., and J. Tong. "Determination of creep curves from multiple hardening-relaxation testing." Journal of Strain Analysis for Engineering Design 38, no. 3 (April 1, 2003): 277–80. http://dx.doi.org/10.1243/030932403765310608.

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Multiple hardening and relaxation tests have been carried out on a nickel-based superalloy at 650°C. The stress relaxation curves were obtained at selected strain levels, from which the plastic strain rates spanning three decades were obtained. Creep curves were simulated from the relaxation test results and compared reasonably well with those obtained from the creep tests. This method may be useful in the assessment of creep resistance, particularly during the material development stage.

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32

van Rooyen, Melody, Thorsten Hermann Becker, Johan Ewald Westraadt, and Genevéve Marx. "Measurement of creep deformation of ex-service 12% Cr steel using digital image correlation." Journal of Strain Analysis for Engineering Design 55, no. 3-4 (March 10, 2020): 71–85. http://dx.doi.org/10.1177/0309324720904517.

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The effective operation of ageing coal-fired power plants requires routine damage assessment of critical component materials throughout their service history. Traditional post-exposure mechanical testing typically requires large amounts of material for each testing condition. This study introduces an accelerated (high stress and temperature) creep testing technique that employs digital image correlation for strain measurement over a non-uniform temperature field generated by a thermomechanical tester. When applied to different ex-service (exposed to service conditions within a power plant) 12% Cr piping steels, multiple accelerated creep curves at temperatures ranging from 550°C to 600°C are measured from a single specimen for each material condition. Higher creep damage in the steel due to longer service exposure and higher void densities is revealed by shorter rupture times, faster creep rates and tertiary-dominated creep curves when compared to the lower creep damage state. Microstructural study via quantitative electron microscopy confirms the dislocation creep-driven growth of subgrains in the specimen gauge regions relative to the grips. Larger subgrains and a weakening of precipitate distributions for the high damage material were also noted. Digital image correlation–measured strains are in good agreement with traditional techniques of creep testing with standard extensometry. On a comparative basis, the technique is shown to be a plausible form of damage assessment of 12% Cr piping steels with varying levels of service exposure and serve as a suitable mechanical complement to the traditional void replica methodology.

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Mohammad, Khairul Azhar, Edi Syam Zainudin, S. M. Sapuan, Nur Ismarrubie Zahari, and Ali Aidy. "Creep Test of Type Austenitic 316LStainless Steel at High Temperature." Applied Mechanics and Materials 368-370 (August 2013): 708–11. http://dx.doi.org/10.4028/www.scientific.net/amm.368-370.708.

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The aim of this study is to investigate the creep test on static loading of stainless steel materials. Theestablished creep analytical modeling was used to predict the creep life of stainless steel at high temperature. In order to conduct creep testing, the materials were subjected to constant load and high temperature at 565°Cin comparisons with different stresses at the similar temperatures.Time dependent deformation of 316L stainless steel at high temperature at different loading was investigated in this study.The variationof creep strain rates is clearly shown that the secondary creep obeyed and well agreement with a power law relationship as the constant increase creep rate till the tertiary stages of specimen test.

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34

Huang, Yaoying, Lei Xiao, Jun Gao, and Yu Liu. "Tensile Creep and Unloading Creep Recovery Testing of Dam Concrete with Fly Ash." Journal of Materials in Civil Engineering 31, no. 5 (May 2019): 05019001. http://dx.doi.org/10.1061/(asce)mt.1943-5533.0002682.

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35

Ali, Balhassn S. M. "The Pin-Loaded Small One-Bar Specimen in Use to Determine Uniaxial and Multiaxial Creep Data." High Temperature Materials and Processes 35, no. 8 (September 1, 2016): 833–41. http://dx.doi.org/10.1515/htmp-2015-0029.

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AbstractTwo novel small specimen creep testing techniques are presented in this paper. The pin-loaded small one-bar specimen (OBS) and the small notched specimen with four loading pins (SNS4) are designed to determine the remaining lifetime for the high-temperature components. The small OBS is suitable for use in obtaining both uniaxial creep strain and creep rupture life data and the SNS4 is designed to obtain the multiaxial behaviour using small material samples. The specimens can be made from small material samples removed from the component surface or from the heat-affected zone. The specimens can be loaded through pin connections for testing. A conversion relationship and conversion factor have been obtained and used to convert the OBS creep data to the corresponding uniaxial data. For validation two materials have been used, P92 and P91 steels at 650°C. The advantages of these testing techniques are highlighted; the recommendations for future research are also given.

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36

Giese, Sven, Steffen Neumeier, Doris Amberger-Matschkal, Jan Bergholz, Robert Vaßen, and Mathias Göken. "Microtensile creep testing of freestanding MCrAlY bond coats." Journal of Materials Research 34, no. 15 (May 23, 2019): 2643–52. http://dx.doi.org/10.1557/jmr.2019.169.

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Reznicek, Martin, David Manas, Michal Stanek, Martin Ovsik, Vojtech Senkerik, Adam Skrobak, and Petr Kratky. "Creep Test Evalutation." Advanced Materials Research 1025-1026 (September 2014): 270–73. http://dx.doi.org/10.4028/www.scientific.net/amr.1025-1026.270.

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Many methods of result interpretation were developed while testing materials. We can often see evaluation using graphs, tables, numerical expression with effort to present the results of research as clearly as possible to the reader. One of the factors that can negatively affect this interpretation is the number of tested samples. With sufficient number of samples, ordinary arithmetic average is used and standard deviation is used to express uncertainty of measurement. But what to do when we only have small number of measurements? Can big deviation affect the results of the experiment? This article will try to answer this question.

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Guo, Jin Quan, Long Tian, Hui Chao Shi, and Wu Zhou Meng. "Using Stress Relaxation Data to Predict Creep Behavior." Advanced Materials Research 842 (November 2013): 382–85. http://dx.doi.org/10.4028/www.scientific.net/amr.842.382.

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An estimation method to predict creep performances of high temperature structural materials has been proposed. A Stress relaxation equation is obtained by fitting stress relaxation testing curves and modifying Tanaka-Ohba reloading stress relaxation constitutive equation. Based on the relationship between stress relaxation and creep, a unified prediction equation of creep is deduced. The method is to use the unified equation to derive creep strain rates or creep strain vs. time curves from stress relaxation measurements through some specified time increments. In order to validate the approach, the predicted results are compared to the experimental results of uni-axial isothermal creep tests conducted on 1Cr10NiMoW2VNbN steel. Good agreement between results of creep tests and the predicted results indicates that the developed method can be recommended in the creep behavior evaluation of high temperature materials.

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Brito Janeira, Manuel, Carlos M. da Silva, António Mendes Lopes, and Lucas F. M. da Silva. "Thermal Chamber for Adhesives Creep Multi-Station Testing Machine." U.Porto Journal of Engineering 6, no. 2 (November 27, 2020): 1–10. http://dx.doi.org/10.24840/2183-6493_006.002_0001.

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Adhesives have been used in a wide range of industries, due to their good proprieties when compared with traditional joining methods. Therefore, manufacturers and researchers have been making an effort to study these materials and their characteristics.The main goal of the Advance Joining Processes Unit (AJPU) of FEUP/INEGI is to study and evaluate different types of adhesives under different conditions. One equipment available at the AJPU is a creep testing machine with three independent working stations. As the creep tests must be performed under controlled temperature, the implementation of a thermal chamber was required.This paper describes the design of a thermal chamber for the existing creep testing machine. The chamber needs to be capable of operating between -100 and 200 ºC and have a low temperature gradient. The first step was to design a heat insulator for each upper rod of the creep testing machine, in order to limit the temperature at the load cells to service values.Subsequently, the concept of the chamber was developed. The design decisions with influence on the thermal efficiency of the chamber were supported analytically. The structure, insulation, control and automation projects of the chamber are presented in detail.

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Ohji, Tatsuki, and Yukihiko Yamauchi. "Long-Term Tensile Creep Testing for Advanced Ceramics." Journal of the American Ceramic Society 75, no. 8 (August 1992): 2304–7. http://dx.doi.org/10.1111/j.1151-2916.1992.tb04503.x.

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Doan, Hai Giang Minh, and Pierre Mertiny. "Creep Testing of Thermoplastic Fiber-Reinforced Polymer Composite Tubular Coupons." Materials 13, no. 20 (October 17, 2020): 4637. http://dx.doi.org/10.3390/ma13204637.

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Thermoplastic fiber-reinforced polymer composites (TP-FRPC) are gaining popularity in industry owing to characteristics such as fast part fabrication, ductile material properties and high resistance to environmental degradation. However, TP-FRPC are prone to time-dependent deformation effects like creep under sustained loading, which can lead to significant dimensional changes and affect the safe operation of structures. Previous research in this context has focused, mainly, on testing of flat coupons. In this study, a creep testing method for TP-FRPC tubular coupons was developed. Specimens were fabricated using tape winding and subjected to well-defined loading conditions, i.e., pure hoop tensile and pure axial compressive stress. Strain gauges and digital image correlation were both employed for strain measurements and were found to be in good agreement. The evolution of strain rate, Poisson’s ratio and creep compliance were investigated. The prediction of experimental data by the Burgers model and the Findley’s power law model were explored. The research findings suggest that the developed experimental and analysis approach provides valuable information for the design of material systems and structures.

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Pezzotti, Giuseppe, Hans-Joachim Kleebe, Ken'ichi Ota, and Toshihiko Nishida. "Internal friction and torsional creep behavior of chemically vapor deposited boron nitride." Journal of Materials Research 13, no. 12 (December 1998): 3453–57. http://dx.doi.org/10.1557/jmr.1998.0470.

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Dense hexagonal BN processed via chemical vapor deposition (CVD) was tested with respect to damping, shear modulus, and torsional creep rate up to temperatures as high as ≈2300 °C. The microstructural characteristics of the material both before and after creep testing were studied by high-resolution electron microscopy (HREM). The CVD process yields a homogeneous nanosized microstructure with no other secondary phase detectable. Damping experiments revealed no plastic relaxation during testing up to ≈2000 °C, which is consistent with the fact that also no creep deformation could be detected below such a high temperature. Small porosity and an increased amorphization process were noted by HREM inspection after stress exposure at ≈2300 °C. These phenomena may be responsible for both the enhanced damping capacity and the creep rate of the material which, in the range of the present testing conditions, seems to follow the simple viscoelastic behavior of a Maxwell solid.

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Zhao, Bing, Jianhui Hu, Wujun Chen, Jianwen Chen, and Zhongliang Jing. "Simultaneous uniaxial creep testing of time-dependent membrane materials with optical devices." Materials Today Communications 21 (December 2019): 100655. http://dx.doi.org/10.1016/j.mtcomm.2019.100655.

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Ponraj, R., and S. Ramakrishna Iyer. "A simple four-point bend creep testing apparatus for brittle ceramic materials." Journal of Materials Science Letters 11, no. 14 (1992): 1000–1003. http://dx.doi.org/10.1007/bf00729906.

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Cepeda-Rizo, J., and Hsien-Yang Yeh. "Creep Prediction of a Printed Wiring Board For Separable Land Grid Array Connector." Journal of Electronic Packaging 127, no. 2 (October 1, 2004): 185–88. http://dx.doi.org/10.1115/1.1899164.

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The paper presents a study of creep behavior of a printed wiring board caused by the mechanical fastening of separable connector, known as a land grid array. Time-temperature superposition method was employed to predict the lifetime creep behavior. A low-cost testing method based on the ASTM D790 three-point bending procedure was developed to predict and characterize creep of polymeric materials under low temperature, low stress, and large elapsed times.

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Mitchell, M. R., R. E. Link, Robert Leichti, Milo Clauson, and Daniel Cheney. "Flexural Creep Apparatus and Testing for Structural Composite Lumber." Journal of Testing and Evaluation 35, no. 5 (2007): 14102. http://dx.doi.org/10.1520/jte14102.

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Huneault, P. A. "Strain-Hardening Creep Relaxation." Journal of Applied Mechanics 59, no. 1 (March 1, 1992): 217–19. http://dx.doi.org/10.1115/1.2899435.

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Relaxation testing is an important alternative for investigating the creep properties of a material. A solution for the strain-hardening form of the power law is derived and compared to its time-hardening counterpart.

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Peng, Xiang Hua, Ying She Luo, Jing Ye Zhou, Min Yu, and Tao Luo. "Research on Creep Constitutive Model of TC11 Titanium Alloy Based on RBFNN." Materials Science Forum 575-578 (April 2008): 1050–55. http://dx.doi.org/10.4028/www.scientific.net/msf.575-578.1050.

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The paper is aimed to exploit a creep constitutive mode of TC11 titanium alloy based on RBF neural network. Creep testing data of TC11 titanium alloy obtained under the same temperature and different stress are considered as knowledge base and the characteristics of rheological forming of materials and radial basis function neural network (RBFNN) are also combined when exploiting the model. A part of data extracted from knowledge base is divided into two groups: one is learning sample and the other testing sample, which are being performed training, learning and simulating. Then predicting value is compared with the creep testing value and the theoretical value deduced by primary model, which validates that the RBFNN model has higher precision and generalizing ability.

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Oyen, Michelle L. "Spherical Indentation Creep Following Ramp Loading." Journal of Materials Research 20, no. 8 (August 1, 2005): 2094–100. http://dx.doi.org/10.1557/jmr.2005.0259.

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Elastic-viscoelastic correspondence, utilizing Boltzmann integral operators, was used to generate displacement–time solutions for spherical indentation testing of viscoelastic materials. Solutions were found for creep following loading at a constant loading rate and compared with step-loading solutions. Experimental creep tests were performed with different loading rate–peak load level combinations on glassy and rubbery polymeric materials. The experimental data were fit to the spherical indentation ramp–creep solutions to obtain values of shear modulus and time-constants; good agreement was found between the experimental results and known modulus values. A multiple ramp-and-hold protocol was examined for the measurement of creep responses at several loads (and depths) within the same test. Emphasis is given to the use of multiple experiments (or multiple levels within a single experiment) to test a priori assumptions made in the correspondence solutions regarding linear viscoelastic material behavior and the creep function.

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Loveday, Malcolm S. "Creep testing standards and the influence of bending." Materials at High Temperatures 25, no. 4 (December 2008): 277–86. http://dx.doi.org/10.3184/096034008x390611.

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Journal articles on the topic 'Materials – Creep – Testing'

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