Artykuły w czasopismach: „Tensile creep behavior”

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Xu, Zhen, Chuan Guo, Zhen Rong Yu, Xin Li, Xiao Gang Hu i Qiang Zhu. "Tensile and Compressive Creep Behavior of IN718 Alloy Manufactured by Selective Laser Melting". Materials Science Forum 986 (kwiecień 2020): 102–8. http://dx.doi.org/10.4028/www.scientific.net/msf.986.102.

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Tensile and compressive creep behavior of SLMed IN718 alloy under 973K (700°C) were investigated. Crept samples were analyzed by SEM and TEM to expose evolution of microstructure, precipitates and dislocation structure during the creep process. Results show that initial creep rate under compression is higher than under tension for the same creep conditions. Minimum creep rates are approximately the same both in tensile and compressive creep tests. The different creep behaviors may be related to the fact that tension stress promotes precipitations of fine needle-like γ′′ phases, while compression stress promotes precipitations of large size δ phases. The tension-compression asymmetry owns to the increment of chemical potential varying with the stress orientation.

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Sujatanond, Supamard, Yoshiharu Mutoh, Yukio Miyashita i Yuichi Otsuka. "Tensile and Compressive Creep Behavior of Magnesium Alloy AZ91D". Applied Mechanics and Materials 313-314 (marzec 2013): 98–102. http://dx.doi.org/10.4028/www.scientific.net/amm.313-314.98.

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Tensile and compressive creep tests of the extruded magnesium alloy AZ91D were carried out in vacuum at 150°C under constant engineering stresses ranged from 60 to 150 MPa. From the test results, the secondary creep rate in tension was found to be significantly higher than that in compression. Moreover, the estimation method of creep curve under a constant true stress was proposed by considering the reduction of cross sectional area during tensile loading where the specimen cross-sectional area and length were measured periodically until the end of creep test. The creep curve under a constant true stress obtained in the present study was still different between tensile and compressive loadings. Therefore, it should be noted that the different creep curves and creep exponents should be used in the creep deformation analysis of structures.

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Xu, Zhao Yang. "Modeling and Prediction of Creep Behavior of Polypropylene Packaging Belt". Applied Mechanics and Materials 117-119 (październik 2011): 1168–71. http://dx.doi.org/10.4028/www.scientific.net/amm.117-119.1168.

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The short term tensile creep behaviors of polypropylene (PP) packaging belt under different stresses levels were studied through tensile creep test. The four-element model was applied to simulate the creep behaviors of the PP packaging belt. The results show that four-element model can be used to simulate the short time creep of PP packaging belt. The tensile creep behaviors of PP packaging belt have obviously correlation to the stress levels. The instantaneous elastic coefficient, delayed elastic coefficient and glutinous coefficient in Maxell model show a decreasing tendency with the increase of stress level. Based on the time-temperature-stress equivalence principle and take 15% stress level as a reference, the creep compliance master curve of 15% stress level was constructed by horizontal shift of the creep compliance curve of other stress levels, which can predict the creep behavior of PP packaging belt at the 15% stress level.

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Qi, Yi Hui, i Jian Ting Guo. "Tensile Creep Behavior of Two NiAl-Based Alloys". Applied Mechanics and Materials 217-219 (listopad 2012): 334–37. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.334.

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The tensile creep behaviors of two NiAl-based alloys (HIPed NiAl-33.5Cr-0.5Zr and DS NiAl-28Cr-5.8Mo-0.2Hf) have been investigated. The creep results indicated that the creep curves of both alloys have similar shapes, which are composed of primary creep stage, steady-state creep stage, longer accelerated creep stage, and about 25-45% creep strain. The apparent stress exponents are in the range of 4.8-7.5 and the apparent activation energies of 520-584 kJ/mol were also analyzed. The creep deformations were controlled by the sub-grain boundary formation for the HIPed NiAl-Cr(Zr) and dislocation climb for the DS NiAl-Cr(Mo,Hf). The creep rupture data of both alloys obey the Monkman-Grant relationship.

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Zhao, Peng, Qu Dong Wang, Chun Quan Zhai i Wen Jiang Ding. "Tensile and Compressive Creep Behavior of Coarse-Grained Mg-Al-Sr Castings". Materials Science Forum 546-549 (maj 2007): 171–74. http://dx.doi.org/10.4028/www.scientific.net/msf.546-549.171.

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Tensile and compressive creep properties of Mg-5wt.%Al-1wt.%Sr alloy produced by gravity casting were investigated in this paper. Creep tests were carried out in the temperature range from 125 °C to 200 °C and stress range from 35 to 85MPa. The second creep rate in tension is significant different from that in compression, indicating that coarse-grained Mg-Al-Sr alloy exhibits tension/compression asymmetric behavior. Moreover, the activation energies and stress exponent in tension and compression are not the same, which suggest that creep mechanisms in tension and compression are different.

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Ren, Wei Li, Jian Ting Guo, Gu Song Li i Jian Sheng Wu. "Tensile Creep Behavior of NiAl-9Mo Eutectic Alloy". Materials Science Forum 475-479 (styczeń 2005): 763–66. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.763.

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The tensile creep behavior of NiAl-9Mo eutectic alloy has been investigated over a stress range of 50 to 100MPa at the temperatures ranging from 850 to 950°C. All of the creep curves exhibit the very long steady-state stage. The creep parameters and TEM observations indicates the kinetics of the steady-state creep deformation is governed by dislocation climb in the NiAl matrix phase. The crack origination and development at the colony boundary results in the onset of tertiary creep stage and final fracture of the alloy.

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Yang, Yang, Peng Li i Yan Ping Wu. "Tensile Creep Behavior of HPC at Early Ages under Different Curing Temperatures". Advanced Materials Research 250-253 (maj 2011): 434–39. http://dx.doi.org/10.4028/www.scientific.net/amr.250-253.434.

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This paper presents an experimental investigation on tensile basic creep behavior of HPC at early ages by using a uniaxial tensile creep testing apparatus. Concrete specimens of 100×100×400mm with compressive strength class 60MPa was used, sealed and loaded at different curing temperature. The effects of the curing temperature and the age at loading on creep behavior are discussed. The results show that tensile specific creep and creep rate of HPC at early ages were governed by the age at loading. The specific creep, creep coefficient and creep rate were larger at earlier loading ages, and decreased exponentially with age at loading. The tensile specific creep decreased with curing temperature, but the difference in creep due to different curing temperatures decreased with the age at loading, and could be ignored while concrete specimen being loaded after the age of 7 days.

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WU, WEI, i XIAOPING GAO. "Research on mechanical behavior of needle-punched nonwoven fabric". Industria Textila 69, nr 03 (1.07.2018): 230–34. http://dx.doi.org/10.35530/it.069.03.1410.

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The anisotropic properties in tensile and creep behavior of needle-punched nonwoven fabric are studied in this paper. The influences of specimen width and direction of fiber distribution on the tensile behavior of needle-punched nonwoven fabric are experimental analyzed. The result shows that the specimen width has important influence on tensile behavior. The anisotropic creep behavior of needle-punched fabric i.e., the influences of stress and the angle with the machine direction (MD) on creep is investigated. The relationship between creep elongation and time at different stress and different angle with the machine direction (MD) of needle-punched fabric are obtained by applying linear fitting and the empirical model for calculating creep elongation are deduced. The result has an important meaning for predicting the mechanical behavior, such as tensile, creep and relaxation behavior of needle-punched nonwoven fabric and reducing experimental expense and difficulty.

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Chan, K. S., N. S. Brodsky, A. F. Fossum, D. E. Munson i S. R. Bodner. "Creep-Induced Cleavage Fracture in WIPP Salt Under Indirect Tension". Journal of Engineering Materials and Technology 119, nr 4 (1.10.1997): 393–400. http://dx.doi.org/10.1115/1.2812275.

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The phenomenon of cleavage fracture initiation in rock salt undergoing concurrent creep was studied experimentally using the Brazilian indirect tension test technique. The tensile creep and cleavage fracture behaviors were characterized for rock salt from the Waste Isolation Pilot Plant (WIPP) site. The Brazilian test consists of a compressive line load applied diametrically on a disk specimen to produce a region of tensile stress in the center of the disk. The damage processes were documented using video photography. The experimental results were analyzed in terms of a wing-crack fracture model and an independently developed, coupled time-dependent, mechanism-based constitutive model whose parameters were obtained from triaxial compression creep tests. Analytical results indicate that coupling between creep and cleavage fracture in WIPP salt results in a fracture behavior that exhibits time-dependent characteristics and obeys a failure criterion involving a combination of stress difference and tensile stress. Implications of creep-induced cleavage fracture to the integrity of WIPP structures are discussed.

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Ding, J. L., i W. N. Findley. "Simultaneous and Mixed Stress Relaxation in Tension and Creep in Torsion of 2618 Aluminum". Journal of Applied Mechanics 53, nr 3 (1.09.1986): 529–35. http://dx.doi.org/10.1115/1.3171806.

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The time dependent behavior of 2618-T61 aluminum under mixed loads and constraints (tension relaxation and torsion creep) is investigated. Experiments include tensile relaxation; simultaneous tension relaxation with step changes in torsion creep and reversed torsion; and alternate creep and relaxation. Results were compared with theoretical models developed previously using as input creep and creep recovery data under constant stress states only. Experimental observations were generally well described by strain hardening flow rules. Some failures in describing the material behavior by the state variable approaches (kinematic hardening) are also discussed.

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Ohji, Tatsuki, Y. Yamauchi i Shuzo Kanzaki. "Tensile Creep and Creep Rupture Behavior of HIPED Silicon Nitride". Key Engineering Materials 89-91 (sierpień 1993): 569–74. http://dx.doi.org/10.4028/www.scientific.net/kem.89-91.569.

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Bakonyi, Péter, i László Mihály Vas. "Analysis of the Creep Behavior of Polypropylene and Glass Fiber Reinforced Polypropylene Composites". Materials Science Forum 729 (listopad 2012): 302–7. http://dx.doi.org/10.4028/www.scientific.net/msf.729.302.

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In this paper tensile and creep tests were performed on polypropylene (PP) and its glass fiber reinforced composites. The tensile tests were carried out on 6 different glass fiber content reinforced PP composites (0, 5, 10, 20, 30 and 40%) while the creep tests were performed on the unreinforced and 30% and 40% fiber reinforced ones of industrial importance. 50 N/s constant force rate was used until the specimen failed (tensile test) or the preset load level was reached (creep test). The applied load levels for the creep experiments were determined as given ratios of the average breaking force. The tensile breaking strain and tensile strength versus fiber content relationship were analyzed and described by empirical formulas based on the correction and averaging procedure developed.

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Naumann, Tobias, i Markus Stommel. "Influence of hydrostatic pressure and volumetric strain on the mechanical long term behavior of polymers". Journal of Polymer Engineering 32, nr 6-7 (1.10.2012): 327–33. http://dx.doi.org/10.1515/polyeng-2012-0033.

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Abstract One of the most crucial issues in developing a material model to describe the long term behaviour of polymers is to represent adequately the load dependency of the considered material. In many publications, it is shown that the free volume affects the mechanical behavior of polymers. For a further investigation of the dependency of the creep behavior on free volume, different experiments are presented in this paper. In one experiment, the creep behavior under tension and shear are compared, to see how the different hydrostatic pressures in these tests influence mechanical behavior. Furthermore, tensile creep tests under different hydrostatic pressures are conducted experimentally. The experiments are conducted on a polycarbonate, a polypropylene and a polymethyl methacrylate. It is shown that the hydrostatic pressure has a significant influence on the creep behavior of all three materials. This effect is related to the change of free volume.

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Salehi, Hamid Reza, i Manouchehr Salehi. "Effect of TiO2 nanoparticles on the viscoelastic and time-dependent behaviors of TiO2/epoxy particulate nanocomposite". Journal of Polymer Engineering 37, nr 2 (1.02.2017): 185–96. http://dx.doi.org/10.1515/polyeng-2015-0183.

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Abstract In this work, the effects of nano titania are investigated on mechanical, creep, and viscoelastic behaviors of epoxy resin. For this purpose, 0.25, 0.5, and 1 vol.% of TiO2 nanoparticles were mixed with thermoset epoxy resin by mechanical and ultrasonic homogenizers and then the tensile, creep, and DMTA test samples were fabricated. The results of tensile tests show that the addition of TiO2 nanopowder slightly increased the strength and Young’s modulus of epoxy resin. However, the ultimate tensile strain or the rupture strain of nanocomposites is decreased. In addition, to understand the viscoelastic behavior of nanocomposites, the DMTA and tensile creep tests have been done. Tensile creep test has been done by DMTA and universal test machine. Both results confirmed that the creep resistance of nanocomposites has extensively improved by adding the titania nanoparticles. Variations of storage modulus, loss modulus, and tan (δ) by adding TiO2 nanopowder were examined in two modes of bending and tension. Storage and loss moduli of nanocomposite are considerably increased in all the states, but the storage modulus was more sensitive to TiO2 loading intensity. Thus, test results showed that introduction of TiO2 in the epoxy resin leads to the improvement of mechanical, creep resistance, and viscoelastic properties of nanocomposites. Due to the wide applications of epoxy resins in engineering devices, this method of reinforcement can be practical and useful to overcome some limitations of epoxy resins.

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Hamed Mosavian, M. T., A. Bakhtiari i S. Sahebian. "Tensile Creep Behavior of Medium-Density Polyethylene". Journal of Thermoplastic Composite Materials 24, nr 4 (31.12.2010): 555–66. http://dx.doi.org/10.1177/0892705710393125.

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Ivanova, T., J. Zicans, M. Kalnins, R. Maksimov i Ž. Roja. "Thermoplastic multiphase composites: Tensile and creep behavior". Materials Science 42, nr 6 (listopad 2006): 771–77. http://dx.doi.org/10.1007/s11003-006-0144-z.

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Xinjie, Wang, Zhu Pinghua i Xia Qun. "Experimental Research on The Effect of Silica Fume on Tensile Basic Creep of Early-age Concrete". Open Civil Engineering Journal 9, nr 1 (29.10.2015): 997–1001. http://dx.doi.org/10.2174/1874149501509010997.

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The tensile creep behavior is extremely important in crack prediction and stress analysis of concrete. The main objective is investigating the effects of the silica fume on the tensile basic creep of early-aged concrete. The effect of silica fume on tensile creep was studied using lever-type tensile creep tester. Silica fume amount by weight of total cementing material was 0%, 5%, 10% and 15%. Results show that concrete exhibits larger tensile basic creep strain if loaded at early age. The development characteristic of tensile basic creep of concrete with different silica fume content is that development rate is relatively fast after loading 12h, and slowes down gradually after loading 12h. The early age tensile basic creep of concrete increases with the increasing of the content of silica fume.

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Li, Xueliang, Xiaoyu Zhang, Jianzhong Chen, Li Huang i Yong Lv. "Uniaxial Tensile Creep Behavior of Epoxy-Based Polymer Using Molecular Simulation". Polymers 13, nr 2 (14.01.2021): 261. http://dx.doi.org/10.3390/polym13020261.

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Based on the all-atomic molecular dynamics simulation method, the tensile creep behavior of epoxy-based polymer was discussed. The physical and mechanical properties of the model were characterized, such as glass transition temperature and yield strength. The simulation results are very close to the previous simulation and experimental results, and the correctness of the model is verified. On this basis, the tensile creep behavior and free volume evolution of polymer epoxy resin at different temperatures and stress levels were studied. The model fully predicted the three classical stages of epoxy resin creep (the primary, secondary and tertiary) and the dependent behavior of epoxy resin creep on temperature and stress level at the molecular level, and the creep rate increases with the increase of temperature and stress level. It was found that with the progress of the creep process, the proportion of free volume increases gradually under high stress levels, indicating that the effect of creep behavior on the structure of epoxy resin is that the interaction between atoms becomes weaker and weaker by increasing the distance between atoms, which finally induces creep failure in the material.

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Sato, Eiichi, Yuto Komiyama i Yoshimitsu Sato. "Grain-Size Dependency of Low-Temperature Creep in Ultrafine-Grained Aluminum". Materials Science Forum 794-796 (czerwiec 2014): 302–6. http://dx.doi.org/10.4028/www.scientific.net/msf.794-796.302.

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The grain size dependence of creep behavior from coarse grain to ultrafine grain regions was examined using fully-annealed specimens fabricated from a single process route. For coarse-grained sample, in tensile deformation, stress-strain curves show slow work hardening, and the proof stress shows typical Hall-Petch behavior. On the other hand, creep behavior is observed under the stress above the proof stress, and the creep rate has no grain size dependence. For ultrafine-grained sample, in the tensile deformation, stress-strain curves show yielding behavior, and the yield stress shows Hall-Petch behavior also. On the other hand, creep behavior was observed below the proof stress, but the creep rate decreases with a decrease in grain size.

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Dib, Elias, Jean François Caron, Wassim Raphael, Ioannis Stefanou i Fouad Kaddah. "Numerical analysis and investigation of short- and long-term behavior of unidirectional composites". Journal of Composite Materials 52, nr 5 (6.06.2017): 659–78. http://dx.doi.org/10.1177/0021998317713355.

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This study gives a detailed analysis on estimating the ultimate tensile strength of unidirectional fiber reinforced composites and its creep behavior under sustained tension load. We develop two different micromechanical models that allow us to estimate the longitudinal tensile strength and the evolution with time of fiber and matrix stresses around arbitrary array of fiber breaks. The first model is based on the shear-lag theory while the second one is developed using the software Abaqus. The comparison of the above models allowed to validate the fundamental assumptions of the shear-lag theory (first model) as well as several numerical issues related to time integration and spatial discretization. The Monte–Carlo method was used in order to account for the stochastic fiber strength and its impact on the ultimate tensile strength (short-term) and creep (long-term behavior) of unidirectional composites. Finally, a parametric investigation on the fiber type and the load level on the long-term behavior of unidirectional composites was performed showing an accelerating creep effect for fibers of inferior quality such as glass fibers compared to carbon fibers.

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Boumerzoug, Zakaria, Zakaria Boumerzoug i Vincent Ji. "Heat Treatments Effect on the Mechanical Properties of Industrial Drawn Copper Wires". Advanced Materials Research 811 (wrzesień 2013): 9–13. http://dx.doi.org/10.4028/www.scientific.net/amr.811.9.

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In this present investigation, the mechanical properties of industrial drawn copper wires have been studied by creep tests, tensile tests and hardness Vickers. The effect of prior heat treatments at 500°C for different time on the drawn wires behavior was the main goal of this investigation. We have found that these heat treatments influenced the creep behavior of drawn wires and recorded shape curves. The creep tests were applied under ambient atmosphere at 240 °C. The creep duration before rupture decreased with the prior heat treatment time. The creep tests results were confirmed by tensile tests. A relationship between the hardness and the ultimate tensile strength of this industrial material has been established. Optical and scanning electron microscopy observations have been also used. Cross section observations of the wire after tensile or creep-rupture tests have shown that the mechanism of rupture was mainly controlled by the void formation.

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Zhao, Baoyun, Dongyan Liu, Tianzhu Huang, Wei Huang i Wei Liu. "Mechanical Behavior of Red Sandstone under Incremental Uniaxial Cyclical Compressive and Tensile Loading". Shock and Vibration 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/4350437.

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Uniaxial experiments were carried out on red sandstone specimens to investigate their short-term and creep mechanical behavior under incremental cyclic compressive and tensile loading. First, based on the results of short-term uniaxial incremental cyclic compressive and tensile loading experiments, deformation characteristics and energy dissipation were analyzed. The results show that the stress-strain curve of red sandstone has an obvious memory effect in the compressive and tensile loading stages. The strains at peak stresses and residual strains increase with the cycle number. Energy dissipation, defined as the area of the hysteresis loop in the stress-strain curves, increases nearly in a power function with the cycle number. Creep test of the red sandstone was also conducted. Results show that the creep curve under each compressive or tensile stress level can be divided into decay and steady stages, which cannot be described by the conventional Burgers model. Therefore, an improved Burgers creep model of rock material is constructed through viscoplastic mechanics, which agrees very well with the experimental results and can describe the creep behavior of red sandstone better than the Burgers creep model.

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Zhang, Jian Qiang, Yan Jun Zheng, Li Wang, Shao Wei Li, Jing Xu i Yi Cao. "The Effect of Precipitated Phases on Creep Behavior". Applied Mechanics and Materials 703 (grudzień 2014): 363–69. http://dx.doi.org/10.4028/www.scientific.net/amm.703.363.

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The effect of precipitated phases on the creep in 300s type austenitic stainless steel used in auto-tailpipe was studied. Flat tensile samples with marker scratches on the surface were strained at slow rate at 400°C. It show that the sensitized material decreased creep rate and needed more stress to generate deformation of grain boundary, suggesting Cr carbides decreased the grain boundary sliding. Thus, the resistance to SCC crack propagation could be improved. Characterizations of the tensile samples were carried out using a SEM in order to understand whether second phases can affect the creep behavior and grain boundary moving.

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Song, Yan, Mengyu Chai, Zelin Han i Pan Liu. "High-Temperature Tensile and Creep Behavior in a CrMoV Steel and Weld Metal". Materials 15, nr 1 (24.12.2021): 109. http://dx.doi.org/10.3390/ma15010109.

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The 2.25Cr1Mo0.25V steel is a vanadium-modified 2.25Cr1Mo steel and is being widely used in the manufacture of heavy-wall hydrogenation reactors in petrochemical plants. However, the harsh service environment requires a thorough understanding of high-temperature tensile and creep behaviors of 2.25Cr1Mo0.25V steel and its weld for ensuring the safety and reliability of hydrogenation reactors. In this work, the high-temperature tensile and creep behaviors of base metal (BM) and weld metal (WM) in a 2.25Cr1Mo0.25V steel weldment used for a hydrogenation reactor were studied experimentally, paying special attention to its service temperature range of 350–500 °C. The uniaxial tensile tests under different temperatures show that the WM has higher strength and lower ductility than those of BM, due to the finer grain size in the WM. At the same time, the short-term creep tests at 550 °C reveal that the WM has a higher creep resistance than that of BM. Moreover, the creep damage mechanisms were clarified by observing the fracture surface and microstructures of crept specimens with the aid of scanning electron microscopy (SEM). The results showed that the creep damage mechanisms of both BM and WM are the initiation and growth of creep cavities at the second phase particles. Results from this work indicate that the mismatch in the high-temperature tensile strength, ductility, and creep deformation rate in 2.25Cr1Mo0.25V steel weldment needs to be considered for the design and integrity assessment of hydrogenation reactors.

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Li, Si Chen, Ting Yao, Yu Jiang Wang, Hua Li, Jun Cheng, Lei Li i Qian Tian. "Determination of Tensile Creep and Stress Relaxation of Concrete by Ring Test". Applied Mechanics and Materials 584-586 (lipiec 2014): 1172–75. http://dx.doi.org/10.4028/www.scientific.net/amm.584-586.1172.

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The understanding of stress relaxation and tensile creep behavior is extremely important in accurate stress analysis and crack prediction of early-age concrete. The free shrinkage deformations of concrete with different strength grade were examined. The early-age tensile elastic modulus of concrete was investigated through temperature-stress testing machine. The tensile creep and shrinkage stress were obtained through the modified restrained ring test. The results indicate that the development of free shrinkage coordinates well with the inner strain of steel ring. Tensile creep decreases as water-binder ratio increases. Creep counteracts tensile stress of concrete by 28%~40% , decreases the possibility of cracking of concrete at early ages.

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Wiederhorn, Sheldon M., Ralph F. Krause, František Lofaj i U. Täffner. "Creep Behavior of Improved High Temperature Silicon Nitride". Key Engineering Materials 287 (czerwiec 2005): 381–92. http://dx.doi.org/10.4028/www.scientific.net/kem.287.381.

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New data are presented on the tensile creep behavior of silicon nitride sintered with Lu2O3. The data are compared with two earlier sets of data collected on the same material. The older sets gave results that are difficult to explain theoretically: a high value for the stress exponent, n=5.33, and no cavitation. The new set of data also gave no cavitation, but gave a stress exponent, n=1.81, that can be rationalized theoretically in terms of solution-precipitation creep of the silicon nitride grains. An analysis of variance showed that one of the earlier sets of data was statistically consistent with the newer set, whereas the other set of data was not. Combining the two sets of data that agreed statistically yields a consistent picture of creep with a low value of the stress exponent and no cavitation. The stress exponent for the combined set of data is n=1.87±0.48 (95 % confidence limits). The tensile creep mechanism of the silicon nitride containing Lu2O3, solution-precipitation, differs from those of other silicon nitrides, for which tensile creep has been attributed to cavitation. Enhancement of the creep resistance of the silicon nitride sintered with Lu2O3 may be a consequence of the fact that Lu2O3 produces a more deformation resistant amorphous phase at the two grain junctions, than do Y2O3 or Yb2O3. In parallel, reducing the amount of secondary phase below a critical limit, or increasing the viscosity of the two grain boundaries relative to three-grain junctions reduces the ability of the material to cavitate during creep, and forces the creep mechanism to change from cavitation to solution-precipitation.

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Nishimura, Toshiyuki, Naoto Hirosaki, Yoshinobu Yamamoto, Yorinobu Takigawa i Jian-Wu Cao. "Tensile Creep Behavior in Lutetia-doped Silicon Nitride Ceramics". Journal of Materials Research 20, nr 8 (1.08.2005): 2213–17. http://dx.doi.org/10.1557/jmr.2005.0278.

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We studied tensile creep behavior in two silicon nitride ceramics, i.e., 4.8 mol% Lu2O3 (SN48) and 1.2 mol% Lu2O3 (SN12), at 1400–1500 °C under applied stress of 137–300 MPa. Time to failure of SN48 increased with decreasing applied stress and minimum strain rate. The stress–rupture parameter was 10.7 at 1400 °C and 11.4 at 1500 °C. Pore formation was confirmed in a creep-tested specimen of SN48 by transmission electron microscopy. These results suggest that SN48 was fractured by creep rupture. The minimum strain rate of SN12 was almost below the measurement system limitation at temperatures below 1500 °C. Time to failure tended to increase with decreasing applied stress. The stress–rupture parameter was 41 at 1400 °C and 73 at 1500 °C. These results suggest that SN12 was fractured by subcritical crack growth.

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Slouf, Miroslav, Milos Steinhart, Pavel Nemecek, Veronika Gajdosova i Jiri Hodan. "Correlations between Microscale Indentation Creep and Macroscale Tensile Creep of Polymers". Materials 16, nr 2 (15.01.2023): 834. http://dx.doi.org/10.3390/ma16020834.

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We compared the results of various microscale indentation creep (microcreep) measurements with macroscale tensile creep (macrocreep) measurements of three common polymers: high-density polyethylene (PE), polypropylene (PP), and polystyrene (PS). The main objective was to verify if the short-term microcreep experiments could predict long-term macrocreep behavior of the selected polymers, whose properties ranged from very soft and ductile (PE) to very hard and brittle (PS). The second objective was to compare several creep predictive schemes: the empirical power law model (PL) and several types of phenomenological elasto-visco-plastic models (EVP). In order to facilitate this task, we developed a universal program package named MCREEP, which fits PL and EVP models to both tensile and indentation creep data. All experimental results and theoretical predictions documented that: (i) regardless of the creep experiment type, both micro- and macrocreep resistance increased in the following order: PE < PP < PS, (ii) the short-term microcreep experiments could be used to predict qualitatively the long-term macrocreep behavior, and (iii) the simple empirical power law model yielded better predictions of long-term creep behavior than the more sophisticated elasto-visco-plastic models.

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Kim, Woo-Jin, Oscar A. Ruano, Jeffrey Wolfenstine, Georg Frommeyer i Oleg D. Sherby. "Superplastic behavior of a kappa carbide material (Fe3AlCx)". Journal of Materials Research 12, nr 9 (wrzesień 1997): 2317–24. http://dx.doi.org/10.1557/jmr.1997.0307.

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Fine-grained kappa carbide (Fe3AlCx) materials, containing 12.5 and 14% Al, and 3.5% C, were prepared by powder processing and hipping procedures. The creep behavior of the kappa materials was shown to be identical to that observed in superplastic iron carbide, and was shown to follow a grain boundary–diffusioncontrolled grain boundary sliding relation. The tensile fracture strains in kappa, however, were shown to be considerably less than in iron carbide with a maximum elongation of 92% noted. This difference is attributed to either a low stress intensity factor or to contamination of the powder surface in the kappa material. The compression creep strength, at a given strain rate, was shown to be about two times higher than the tension creep strength.

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Ji, Yameng, Yanpeng Yuan, Weizheng Zhang, Yunqing Xu i Yuwei Liu. "Elevated Temperature Tensile Creep Behavior of Aluminum Borate Whisker-Reinforced Aluminum Alloy Composites (ABOw/Al–12Si)". Materials 14, nr 5 (4.03.2021): 1217. http://dx.doi.org/10.3390/ma14051217.

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In order to evaluate the elevated temperature creep performance of the ABOw/Al–12Si composite as a prospective piston crown material, the tensile creep behaviors and creep fracture mechanisms have been investigated in the temperatures range from 250 to 400 °C and the stress range from 50 to 230 MPa using a uniaxial tensile creep test. The creep experimental data can be explained by the creep constitutive equation with stress exponents of 4.03–6.02 and an apparent activation energy of 148.75 kJ/mol. The creep resistance of the ABOw/Al–12Si composite is immensely improved by three orders of magnitude, compared with the unreinforced alloy. The analysis of the ABOw/Al–12Si composite creep data revealed that dislocation climb is the main creep deformation mechanism. The values of the threshold stresses are 37.41, 25.85, and 17.36 at elevated temperatures of 300, 350 and 400 °C, respectively. A load transfer model was introduced to interpret the effect of whiskers on the creep rate of this composite. The creep test data are very close to the predicted values of the model. Finally, the fractographs of the specimens were analyzed by Scanning Electron Microscope (SEM), the fracture mechanisms of the composites at different temperatures were investigated. The results showed that the fracture characteristic of the ABOw/Al–12Si composite exhibited a macroscale brittle feature range from 300 to 400 °C, but a microscopically ductile fracture was observed at 400 °C. Additionally, at a low tensile creep temperature (300 °C), the plastic flow capacity of the matrix was poor, and the whisker was easy to crack and fracture. However, during tensile creep at a higher temperature (400 °C), the matrix was so softened that the whiskers were easily pulled out and interfacial debonding appeared.

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Shekarian, Reyhaneh, Sayyed Mahdi Hejazi i Mohammad Sheikhzadeh. "A model on the viscoelastic behavior of sewn knitted fabrics". International Journal of Clothing Science and Technology 31, nr 3 (3.06.2019): 362–75. http://dx.doi.org/10.1108/ijcst-12-2016-0135.

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Purpose Knitted fabrics have been widely used in a wide range of applications such as apparel industry. Since these fabrics are continuously subjected to the long-term tensile stresses or tensile creep in real conditions, investigation of viscoelastic behavior of sewn knitted fabrics would be important especially at the seamed area. The paper aims to discuss this issue. Design/methodology/approach A lockstitch machine was used to produce sewn samples by knitted fabric. Factors such as stitch per inch (SPI), thread tension and thread type were variables of the model. Tensile creep tests under constant load of 200 N were conducted, and creep compliance parameter D(t) of samples was obtained as a response variable. A successive residual method (SRM) was also used to characterize viscoelastic properties of sewn-seamed fabrics. Findings The instantaneous elastic responses of the seamed samples were less than those of the neat fabric (fabric with no seam). An increase in sewing thread strength increases the instantaneous elastic response of the sample. SPI and thread tension have an optimum value to increase E0. High tenacity polyester thread, due to its higher elastic modulus, caused a larger E0 than polyester/cotton thread in sewn knitted fabric. Characteristics of seam including sewing thread type, SPI and sewing tension have significant influence on T0. Sewn-seamed fabric by high modulus thread shows less viscous strain T0 than the neat fabric (fabric with no seam). Viscous strain T0 decreases as SPI changes from 8 to 4 and/or 12. SPI and thread tension have an optimum value to increase the viscous strain T0. E1 is the same for optimum seamed fabric and fabric sample but T1 is about two times greater for seamed fabric. Retarded time for creep recovery increases by sewing process but characteristics of seam have significant influence on E1 and T1. All sewn knitted fabric samples used in this study could be described by Burger’s model, which is a Maxwell model paralleled with a Kelvin one. Originality/value This paper is going to use a different method named successive residuals to model the creep behavior of seamed knitted fabric. On the whole, this paper paved a way to obtain viscoelastic constants of sewn-seamed knitted fabrics based on different sewing parameters such as the modulus of elasticity of the sewing thread, SPI and sewing thread tension.

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Rodriguez, R., R. W. Hayes, P. B. Berbon i E. J. Lavernia. "Tensile and creep behavior of cryomilled Inco 625". Acta Materialia 51, nr 4 (luty 2003): 911–29. http://dx.doi.org/10.1016/s1359-6454(02)00494-9.

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Lofaj, František. "Tensile creep behavior in an advanced silicon nitride". Materials Science and Engineering: A 279, nr 1-2 (luty 2000): 61–72. http://dx.doi.org/10.1016/s0921-5093(99)00645-0.

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Ohji, Tatsuki, Atsushi Nakahira, Takeshi Hirano i Koichi Niihara. "Tensile Creep Behavior of Alumina/Silicon Carbide Nanocomposite". Journal of the American Ceramic Society 77, nr 12 (grudzień 1994): 3259–62. http://dx.doi.org/10.1111/j.1151-2916.1994.tb04580.x.

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Saito, Takuma, Akira Ishida, Michinari Yuyama, Yuji Takata, Kyoko Kawagishi, An-Chou Yeh i Hideyuki Murakami. "Tensile Creep Behavior of Single-Crystal High-Entropy Superalloy at Intermediate Temperature". Crystals 11, nr 1 (30.12.2020): 28. http://dx.doi.org/10.3390/cryst11010028.

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In this study, we investigated the creep deformation mechanism of a single-crystal high-entropy superalloy (HESA) with the spherical γ′ precipitates at 760 °C. Before the creep tests, long-term aging tests at 760 °C without load were conducted, which showed Ostwald ripening of the secondary γ′ precipitates up to 50 h. The creep tests revealed that in the range of 500 and 600 MPa at 760 °C, the creep deformation mechanism of HESA was independent of applied stress in both the primary and secondary creep regions. The deformation mechanism of HESA was further investigated under the condition of 760 °C and 520 MPa by performing creep interrupted tests and microstructural analysis. Scanning electron microscope observation showed elongated γ′ precipitates along the applied stress axis near the ruptured surface. This could have been caused by the multi-slip around <100> preceded by the lattice rotation into <100> along the tensile axis, which was confirmed by the electron backscatter diffraction analysis. Transmission electron microscope observation of the creep interrupted and ruptured specimens showed bypass and climb motion of dislocations in the 2-h interrupted, shearing of the γ′ precipitates by the paired straight dislocations in the 50-h interrupted, and shearing of the γ′ precipitates by both the straight and the curved paired dislocations in the ruptured specimens, respectively. The secondary γ′ precipitates do not affect creep behavior as long as the deformation mechanism is a bypass and climb motion of dislocations.

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36

Mao, Qiang, Buyun Su, Ruiqiang Ma i Zhiqiang Li. "Investigation of Tensile Creep Behavior for High-Density Polyethylene (HDPE) via Experiments and Mathematical Model". Materials 14, nr 20 (18.10.2021): 6188. http://dx.doi.org/10.3390/ma14206188.

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Temperatures of −25 °C, +5 °C, and +35 °C were selected to study the creep behavior of high-density polyethylene (HDPE). The ultimate tensile strength of HDPE materials was obtained through uniaxial tensile experiments and the time–strain curves were obtained through creep experiments. When the loaded stress levels were lower than 60% of the ultimate strength, the specimens could maintain a longer time in the stable creep stage and were not prone to necking. In contrast, the specimens necked in a short time. Then, the time hardening form model was applied to simulate the time–strain curve and the parameter values were solved. The parameter values changed exponentially with the stresses, thereby expanding and transforming the time hardening model. The expanded model can easily and accurately predict creep behaviors of the initial and stable creep stages as well as the long-term deformations of HDPE materials. This study would provide a theoretical basis and reference value for engineering applications of HDPE.

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Li, Dao-Hang, i De-Guang Shang. "Thermo-mechanical fatigue damage behavior for Ni-based superalloy under multiaxial loading". MATEC Web of Conferences 165 (2018): 19002. http://dx.doi.org/10.1051/matecconf/201816519002.

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The fatigue damage behavior was experimentally investigated in different axial-torsional thermo-mechanical loading conditions for Ni-based superalloy GH4169. The strain controlled tests were carried out with the same von Mises equivalent mechanical strain amplitude of 0.8% in the temperature range from 360°C to 650°C. The results show that the fatigue life is drastically reduced when the axial mechanical strain and the temperature are in-phase, which can be due to that the creep damage is induced by the tensile stress at high temperature. Moreover, the fatigue life is further decreased when the axial mechanical strain and the shear strain are out-of-phase, which can be attributed to that the non-proportional hardening can increase the creep and the oxidation damages. Furthermore, the tensile stress is crucial to the nucleation of creep cavities at high temperature compared with the shear stress. The tensile and shear stresses all can increase the creep damage under fatigue loading at high temperature. In addition, the oxidation damage can be induced during cyclic loading at high temperature, and it can be increased by the tensile mean stress caused in non-isothermal loading.

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38

Holmes, John W., Yong H. Park i J. Wayne Jones. "Tensile Creep and Creep-Recovery Behavior of a SiC-FiberSi3N4-Matrix Composite". Journal of the American Ceramic Society 76, nr 5 (maj 1993): 1281–93. http://dx.doi.org/10.1111/j.1151-2916.1993.tb03753.x.

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Hu, Xuteng, Shuying Zhuang, Haodong Zheng, Zuopeng Zhao i Xu Jia. "Non-Unified Constitutive Models for the Simulation of the Asymmetrical Cyclic Behavior of GH4169 at Elevated Temperatures". Metals 12, nr 11 (2.11.2022): 1868. http://dx.doi.org/10.3390/met12111868.

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The tensile, creep, fatigue and creep-fatigue tests of the nickel-based superalloy GH4169 were carried out. According to the deformation characteristics of GH4169 alloy, the Ohno-Karim kinematic model (O-K model) can be used to describe the tensile behavior. The creep constitutive model presented in this paper can be used to predict the three-stage creep characteristics of the GH4169 alloy. The modified Ohno-Karim kinematic hardening model, combined with an isotropic hardening model, can well predict the cyclic softening behavior of the material under symmetric loads and the mean stress relaxation behavior under asymmetric loads. Based on the modified Ohno-Karim kinematic hardening model, isotropic hardening model and creep constitutive model, a non-unified constitutive model was established. The creep-fatigue behavior of the GH4169 alloy under symmetric and asymmetric loads is simulated by using the non-unified constitutive model. The simulation results are very close to the experimental results; however, the prediction results of the time-dependent relaxation load are relatively small.

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Metin, F., i M. Cengil. "Short-term creep and recovery behavior of medical grade ultra-high molecular weight polyethylene (UHMWPE)". Journal of Achievements in Materials and Manufacturing Engineering 78, nr 2 (3.10.2016): 65–70. http://dx.doi.org/10.5604/01.3001.0010.1496.

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Purpose: In this study, short-term tensile creep and recovery behaviors of medical gradeultra-high molecular weight polyethylene (UHMWPE) were investigated to contributedeformation behaviour of UHMWPE components in knee and hip prosthesis during daily lifeactivities of patients.Design/methodology/approach: Tensile test specimens were machined fromcompression molded UHMWPE sheets having commercial brand name: Chirulen 1020 andthey were prepared according to ASTM 527-2. The tensile creep tests were performed atconstant stress levels of 5, 9, 13, 18 and 21 MPa as long as 1 hour for each test. Then, thespecimens were allowed to recover unloaded for 1 hour. Automatic extensometer was usedto measure the deformations precisely for each test.Findings: Results show that creep rate linearly increased with increasing the stress levels.Permanent deformations were observed after recovery. Recovery of the material becamedifficult with increasing the applied load at intended time interval.Research limitations/implications: UHMWPE components used in prosthesis havebeen subjected to complex loading conditions during service life. Polymeric materials showthe viscoelastic material properties like strain rate sensitivity, relaxation, creep and recoveryat room temperature. Because of the viscoelastic material properties of the UHMWPE,it makes difficult to predict the failure of the UHMWPE components in hip and knee prosthesis.Therefore, deformation behavior of medical grade UHMWPE should be investigated in manydifferent loading conditions.Practical implications: Medical grade ultra-high molecular weight polyethylene(UHMWPE) have been used commonly in total hip replacements as acetabular cup and intotal knee replacements as tibial insert since early 1960s.

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Declet-Vega, Amarilis, Nelson Sepúlveda-Ramos, Sandra Crespo-Montoya i Oscar Marcelo Suárez. "Bio-Composites Reinforced with Strontium Titanate Nanoparticles: Mechanical Behavior and Degradability". Journal of Composites Science 3, nr 1 (9.01.2019): 7. http://dx.doi.org/10.3390/jcs3010007.

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Bio-polymer-based composites are appealing cost-effective and environmentally friendly materials for electronic applications. This project relates to bio-composites made of chitosan and cellulose and reinforced with strontium titanate nanoparticles. Upon their fabrication, relevant parameters studied were the acetic acid concentration, the cellulose content, and the amount of strontium titanate nanoparticles. The specimens were characterized using thermogravimetric and degradation analyses, as well as via creep and tensile tests. The results revealed how higher cellulose levels lowered the ultimate tensile strength and the degradation temperature of the bio-composites. Moreover, when nanoparticles are present, higher cellulose levels contributed to their tensile strength. Additionally, more acidic solutions became detrimental to the mechanical properties and the thermal degradation temperature of the composites. Furthermore, the creep studies allowed determining elastic coefficients and viscous coefficients using the Burgers’ model. Those creep results suggest that higher amounts of SrTiO3 (STO) nanoparticles raised the composites creep strain rate. As a whole, the study provides a baseline characterization of these novel bio-composites when subject to aggressive environments.

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Gariboldi, Elisabetta, Chiara Confalonieri i Marco Colombo. "High Temperature Behavior of Al-7Si-0.4Mg Alloy with Er and Zr Additions". Metals 11, nr 6 (28.05.2021): 879. http://dx.doi.org/10.3390/met11060879.

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In recent years, many efforts have been devoted to the development of innovative Al-based casting alloys with improved high temperature strength. Research is often oriented to the investigation of the effects of minor element additions to widely diffused casting alloys. The present study focuses on Al-7Si-0.4Mg (A356) alloy with small additions of Er and Zr. Following previous scientific works on the optimization of heat treatment and on tensile strength, creep tests were carried out at 300 °C under applied stress of 30 MPa, a reference condition for creep characterization of innovative high-temperature Al alloys. The alloys containing both Er and Zr displayed a lower minimum creep strain rate and a longer time to rupture. Fractographic and microstructural analyses on crept and aged specimens were performed to understand the role played by eutectic silicon, by the coarse intermetallics and by α-Al matrix ductility. The creep behavior in tension of the three alloys has been discussed by comparing them to tension and compression creep curves available in the literature for Al-7Si-0.4Mg improved by minor elemental additions.

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Jun, Joong Hwan, Bong Koo Park, Jeong Min Kim, Ki Tae Kim i Woon Jae Jung. "Microstructure and Tensile Creep Behavior of Mg-Nd-RE-Ca Casting Alloys". Key Engineering Materials 345-346 (sierpień 2007): 557–60. http://dx.doi.org/10.4028/www.scientific.net/kem.345-346.557.

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Influences of Ca addition on microstructures and mechanical properties at room and elevated temperatures have been investigated for Mg-1.5%Nd-1.0%RE-0.5%Zn-(0~1.0)%Ca casting alloys, on basis of experimental results from X-ray diffractometry (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), tensile and creep tests. Microstructures of the alloys are characterized by dendritic α-(Mg) grains surrounded by Mg12Nd-Zn-(Ca) eutectic network phase. The average size of α grains decreases gradually with an increase in Ca content. At room temperature, yield strength (YS) is enhanced with increasing Ca content with a decrease in ultimate tensile strength (UTS) and elongation to fracture, whereas the Ca addition leads to greater YS and UTS at 175oC. The tensile creep strain and secondary creep rate, measured at 150 and 200oC under 100MPa for 100hrs, become lower with the increase in Ca content. The obtained tensile properties at elevated temperature demonstrate that the addition of Ca plays a role in improving high temperature mechanical properties including creep resistance for the Mg-Nd-RE-Zn-(Ca) alloys. In view of microstructural evolution, this would be attributed to the refined primary α grains and higher thermal stability of the Mg12Nd-Zn-Ca eutectic strengthening phase.

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44

Abdullah, Orhan Sabah, Shaker S. Hassan i Ahmed N. Al-Khazraji. "Evaluating and Modeling of Tensile Creep Rupture Behavior for Neat and Reinforced Polyamide 6.6". Materials Science Forum 1002 (lipiec 2020): 95–103. http://dx.doi.org/10.4028/www.scientific.net/msf.1002.95.

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Generally, thermoplastic polymers due to their viscoelastic behavior tend to appear creep deformation at low temperature compared to metals; this continuous creep deformation caused irregular shapes with time and resultant unstable dimensional parts. Therefore, the investigation of creep behavior in thermoplastic polymers must be considered as an essential requirement in the design process. This work exanimated the creep rupture behavior for Polyamide 6.6 and their composites which content of 1%MWCNTS or 30 short carbon fibers under variant applied stresses and temperatures, as well as, to create analytical model to the obtained results Findley power law model was employed for this purpose with a comprehensive verification to their compatibility to the experimental results. The results appeared that the addition of reinforced materials and decreasing applied stresses and temperatures will cause an enhancement in creep resistance by increasing rupture time and decreasing the minimum creep rate values. On the other hand, using of Findley power law model gives a good agreement to the obtained experimental results.

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45

Little, R. E., W. J. Mitchell i P. K. Mallick. "Tensile Creep and Creep Rupture of Continuous Strand Mat Polypropylene Composites". Journal of Composite Materials 29, nr 16 (listopad 1995): 2215–27. http://dx.doi.org/10.1177/002199839502901607.

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This paper describes an experimental study on the tensile creep behavior of a random continuous fiber mat reinforced polypropylene composite, commercially known as Azdel. A special experimental setup was designed and used to conduct these creep tests at 75 and 100°C with stress levels ranging from 30 to 60 percent of the tensile strength of Azdel. The test duration was 3,000 hours or the time to creep rupture response, whichever occurred first. A straight line on a semi-log plot adequately described the relationship between the imposed stress and the creep rupture response time for the range of stress levels studied. Moreover, the estimated secondary creep rate was inversely related to the observed creep rupture response time.

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Ferron, G., H. Karmaoui Idrissi i A. Zeghloul. "A State Variable Modeling of Plasticity and Necking Under Uniaxial Tension". Journal of Engineering Materials and Technology 114, nr 4 (1.10.1992): 378–83. http://dx.doi.org/10.1115/1.2904188.

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Constitutive equations based on a state variable modeling of the thermo-viscoplastic behavior of metals are discussed, and incorporated in an exact, long-wavelength analysis of the neck-growth process in uniaxial tension. The general formalism is specialized to the case of f.c.c. metals in the range of intragranular, diffusion controlled plastic flow. The model is shown to provide a consistent account of aluminum behavior both under constant strain-rate and creep. Calculated uniaxial tensile ductilities and rupture lives in creep are also compared with experiments.

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Mao, Yong, i Masuo Hagiwara. "Tensile Properties and Creep Behavior of Compositional Modified Orthorhombic Ti₂AlNb Alloys". Materials Science Forum 539-543 (marzec 2007): 1549–52. http://dx.doi.org/10.4028/www.scientific.net/msf.539-543.1549.

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Several beta stabilizing elements such as Mo, Cr, W, V and Fe have been added to Ti- 22Al-27Nb alloy for substituting a portion of Nb in order to further improve the tensile properties and creep resistances of orthorhombic Ti2AlNb-based alloys. Six compositional modified alloys Ti- 22Al-19.2Nb-2Cr, Ti-22Al-12.5Nb-2W-2Cr, Ti-22Al-10.8Nb-2Mo-2Cr, Ti-22Al-16Nb-2Cr-2V, Ti-22Al-11Nb-2Mo-1Fe, Ti-22Al-16.3Nb-2V-1Fe were prepared by plasma arc melting. The phase constitutions of these alloys were found to be B2+O or B2+O+α2 phases. The tensile properties were investigated at room temperature, and the creep behaviors were investigated under 650oC/310MPa and 650 to 750oC/200MPa. The results showed that Mo+Fe and W+Cr addition improved effectively the 0.2% yield strength and creep resistance. Ti-22Al-11Nb-2Mo-1Fe alloy exhibited the lower transient creep strain and steady-state creep rate, and longer 1% creep-strain lifetime than Ti-22Al-27Nb alloy at 650 to 700oC creep. The dislocation-controlled creep deformation mechanism was suggested to the creep behaviors of the Mo+Fe-modified alloy.

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48

Totey, Arvind, Hardik Ramani, Yogesh Joshi, Shubham Padhal i Harish Bhatkulkar. "Experimental Investigation of Creep Behavior of Polypropylene (PP) Material". SAMRIDDHI : A Journal of Physical Sciences, Engineering and Technology 14, nr 01 SPL (30.06.2022): 129–32. http://dx.doi.org/10.18090/samriddhi.v14spli01.23.

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This paper covers the experimental investigation on creep for polypropylene material with constant and varying load conditions. In first condition with the help of load hanger a constant load was applied till the specimen breaks and in second condition using tensile helical spring and turnbuckle arrangement, a constant reducing load with respect to time was applied till the specimen breaks. The specimen was subjected to a load of 30 Kg at 700c and 50Kg at 750c. The result shows that the creep behavior is significantly a time dependent phenomenon. The result also shows that using tension helical spring and turnbuckle arrangement the specimen deflection itself reduces the applied load with respect to time.

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Hockey, B. J., i S. M. Wiederhorn. "Tensile creep of Y-Si3N4: I. Microstructure". Proceedings, annual meeting, Electron Microscopy Society of America 49 (sierpień 1991): 932–33. http://dx.doi.org/10.1017/s042482010008897x.

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The tensile creep behavior of three different silicon nitrides has been investigated. Two of these materials were hot-pressed with yttria (6w/o) and alumina (1.5 w/o) as sintering aids; one, W/YAS, was reinforced with SiC whiskers (30 v/o) while the other, YAS, was not. The third material, (YS), was HIP ed with yttria (4.0 w/o) as the sole sintering aid. In this paper (Part I), microstructural analysis by ATEM is used to describe and discuss the effect of microstructure on the creep of these materials. Particular emphasis is placed on describing the time dependent changes that occur within the intergranular phase, since these changes alter the interfacial properties that effectively govern creep deformation and rupture. A companion paper, Part II, describes the cavitation processes, which are ultimately responsible for creep rupture.

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Gao, Yan, Qu Dong Wang, Jin Hai Gu, Yang Zhao i Yan Tong. "Mechanical Properties and Creep Behavior of Mg-Gd-Y-Zr Alloys". Materials Science Forum 546-549 (maj 2007): 163–66. http://dx.doi.org/10.4028/www.scientific.net/msf.546-549.163.

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The microstructure, mechanical properties and creep behavior of Mg-Gd-Y-Zr alloys at different temperatures and stresses have been investigated. Results show that the tensile properties and creep resistance at T6 condition is much higher than that at as-cast condition. The creep resistance of Mg-Gd-Y-Zr alloy at 250°C/80MPa is markedly better than that at 300°C/50MPa, indicating that temperature makes more effects on the creep resistance than the stress.

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