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High temperature multiaxial low cycle fatigue of cruciform specimen
74
Fatigue Abstracts
could successfully predict the initial and saturated TMF response, and block isothermal response of Rene 80 from several tests between 649 and 1093°C. Graphs, 19 ref. New method of crankshaft design for high speed diesel engines, lto, M.,
Method of resonant testing of fatigue at pure bend. Bondarenko, Industrial Laboratory (Russia) (Sept. 1993) 59 (4), 426-429
Yu.D.
Methods of resonant testing of fatigue at pure bend as well as testing installation were developed. Kinematics and dynamics of testing were described on an example of metallic constructions.
Himokouchi, H., Arakawa, H., Numata, A. and Kajimoto, K. Mitsubishi Juko Giho (1993) 30 (6), 531-534 (in Japanese) High-speed diesel engines are increasingly required to output more power, to be lighter in weight, and smaller in size, maintaining high reliability, and higher in fuel economy and lower in emission. This trend requires the crankshaft, the most important component of the engine, to be smaller and lighter, and to withstand a higher combustion force. A sophisticated approach to optimum crankshaft design, which consists of stress analysis and fatigue strength evaluation, is described. Bending and torsional stresses are calculated by the latest high-accuracy three-dimensional finite element method, which is backed up by real crankshaft measurements. In terms of material, the effects of non-metallic inclusions on the fatigue strength of high-strength alloy steel (SCM440) are studied and a search for surface treatments to increase the fatigue strength is made. Fatigue testing of real crankshafts is performed to confirm the fatigue strength. Graphs. 5 ref. Effect of a change in interfaciai geometry on the fatigue strength of porouscoated Ti-6AI-4V. Wolfarth, D. and Ducheyne, P. J. Biomed. Mater. Res. (Apr. 1994) 28 (4), 417-425 Porous-coated Ti-6AI-4V has a fatigue strength approximately one-third that of the uncoated alloy. The interracial geometry between the porous coating and the implant substrate is notch-like, leading to stress concentrations that have been shown to be the main cause for the reduction in fatigue strength. The effect of interfacial geometry on fatigue strength of porous-coated Ti-6AI-4V is quantified. The interface between porous coating and implant is modelled using linear elastic, plane strain finite element analysis. Integrated with the numerical analysis is an experimental verification of enhanced fatigue behaviour. Changes in interfacial geometry are conceived, and their effectiveness in reducing stress concentrations is determined. A doubling of fatigue strength can be achieved for newly conceived geometries over conventional porous coating geometries. Graphs, photomicrographs, 17 ref. Fatigue behavior of a 22Cr-20Ni-18Co-Fe alloy at elevated temperatures.
Krukemyer, T.H., Fatemi, A. and Swindeman, R.W. J. Eng. Mater. Technol. (Trans, ASME) (Jan. 1994) 116 (1), 54-61 An experimental investigation was conducted on Haynes Alloy 556 to study the fatigue behaviour of the material at elevated temperatures. Fatigue tests were run at constant temperatures ranging from room temperature to 871°C with strain ranges from 0.265 to 1.5%, resulting in lives between 102 and 10 6 cycles. Cyclic deformation properties were evaluated based on the fatigue data. Three fatigue life models were evaluated for their ability to predict the isothermal fatigue lives of the material. These included the Ostergren, frequency separation and stress-strain-time models. Strengths and weaknesses of each model are discussed based on experimental results. Graphs, photomicrographs, 19 ref. High temperature multiaxiai low cycle fatigue of cruciform specimen. Itoh,
T., Sakan, M. and Ohnami, M. J. Eng. Mater. Technol. (Trans. ASME) (Jan. 1994) 116 (1), 90-98
Installation for fatigue testing during cyclic pure bending. Dolgushev, A.A.,
Kurteev, V.F. Dubrov, V.N. and Vasilevich, D.I. Industrial Laboratory (Russia) (Sept. 1993) 59 (3), 320-322
An installation for determination of strength characteristics of structurally heterogeneous materials, for example welded joints, was developed. Cyclic pure bending was chosen as loading method. Samples of zirconium base alloy with welded joints were investigated. Installation allowed to detect small invisible cracks and to measure fatigue strength index. Influence of ratio of biharmonic vibration load amplitudes to parameters of fatigue curve. Surin, V.M. and Mikhalev, B.S. Industrial Laboratory (Russia) (Sept. 1993) 59 (3), 304-306 Problems of reduction of biharmonic process of vibration load to sinusoidal process as well as influence of amplitude ratio on gradient of fatigue curve and value of fatigue limit were investigated. An installation consisting of a vibration electrodynamic UVE-5-1000-1 apparatus and controlling system was developed. Copper flat samples were tested and it was shown that fatigue limit was not dependent on amplitude ratio at constant frequency ratio.
Analysis of the growth of short fatigue cracks in a steel rod at degree Rankine, Reaumur = - 1 . McEvily, A.-J. and Jang, Z. Materials Science (Russia) (Nov. 1993) 13 (3), 308-312 A modified linear elastic fracture mechanics approach to the analysis of the growth of short cracks has been presented. Good agreement is found between predicted and experimental crack growth rates at the shortest crack lengths for 1045 carbon steel. It is shown that the agreement is not as good for the longer crack lengths. The rate of growth of short semicircular cracks as a function of crack length at degree Rankine, Reaumur = - 1 (degree Rankine, Reaumur is the ratio of the minimum to the maximum stress in a cycle) is presented. Graphs.
Shear fatigue crack growth and its analysis. Liu, H.-W., Chen, Qi, and Lai, D. Materials Science (Russia) (Nov. 1993) 13 (3), 300-307 It is shown that the fatigue cracks of aluminium alloy 7029 and steels HY130 and HY-100 generally prefer tensile growth. For a shea- crack in a crystal in small-scale yielding, degree of Kelvin RSS intensity coefficient is capable of characterizing the resolved shear stress field on the active slip system at a crack tip. In single crystals and large grains, TOPKRSS can be used as the primary correlation parameter for shear fatigue crack growth. Photomicrographs, Graphs.
Development of the microstructure based stochastic life prediction models.
Przystupa, M.A. and Vasudevan, A.K. Report AD-A270 453/4/XAB (1993) 4 pp
This paper describes high-temperature multiaxial low-cycle fatigue lives of type SUS 304 stainless steel and 1Cr-IMo-1/4V steel cruciform specimens at 923 and 823K in air. Strain-controlled multiaxial low-cycle fatigue tests were carried out using cruciform specimens at the principal strain ratios between - 1 and 1. The principal strain ratio had a significant effect on lowcycle fatigue lives. Fatigue lives drastically decreased as the principal strain ratio increased. Multiaxial low-cycle fatigue strain parameters were applied to the experimental data and the applicability of the parameters was discussed. The equivalent strain based on crack opening displacement (COD strain) developed in the paper and F'-plane parameter successfully predicted multiaxial low-cycle fatigue lives. The crack morphology was also extensively discussed from not only the surface crack direction but also the crack inclination into the specimen. Graphs, photomicrographs, 17 ref.
This study explores the methods of incorporating material microstructural characteristics into the fatigue life prediction models based on the results of the microstructural characterizations and fatigue testing of aluminum 7050T7451 plate alloys. The emphases in the microstructural characterization part of the programme are on the identification of the fatigue-relevant microstructural features and on the characterizations of the microstructural gradients. The characterizations are carried out using both the standard and novel techniques such as tessellation, fractai and modified linear intercept methods. The key measurement is determination of the size distributions of the fatigue crack initiating flaws; they are assumed equal to the extreme value distributions of the micropore and/or constituent particle size distributions measured on the metallographic sections.
Estimation of influence of medium stresses on fatigue resistance using scale effect. Domozhirov, L.I. Industrial Laboratory (Russia) (Dec. 1993) 53 (6), 613-619
Main factors affecting blade failure of marine propeller. I. Effects of material defects and hydrodynamic fluctuating stress of blades. Kawazoe, T., Matsuo,
Analysis of influence of medium stresses on fatigue strength for estimation of scale effect under asymmetrical cyclic loads and tensile stresses was made. Mechanical properties of 06Khl2N3D duplex stainless steel were studied. It was shown that increase of sample size led to gain of medium stresses influence on fatigue strength and to increase of scale effect. Graphs. Automatized complex for fatigue life testing. Neimark, A.S., Ryzhev, E.E.
and Gorelov, V.N. Industrial Laboratory (Russia) (Nov. 1993) 59 (5), 509-511 A set of minature machines for the production of standard, quick and program testing was developed. The complex allows one to perform fatigue tests under pure and cross bending, repeat tension tests and cycle torsion tests. It can be used for investigation of mechanical properties of steels, alloys and nonferrous metals.
S. and Nishikido, S. Nagasaki Daigaku Kogakubu Kenkyu Hokoku (Reports of the Faculty of Engineering Nagasaki University) (Jan, 1994) 24 (42), 7-12 (in Japanese)
In recent years, many failures in marine propeller blades of Ni-AI bronze (AIBC3) for motor car carriers have occurred. The high fluctuating stress on these blades induced by hydrodynamic force has been reported as the main cause of the trouble under severe operating conditions, including high ship speed. The systematic investigations of the main factors affecting a blade failure of propeller for a chemical tanker, which seldom occurred in the past, are presented. A few factors were extracted from many causes based on the examinations of the conditions of the blade failure and the hull. The early blade failure (within one year) was discussed in view of the estimations of the material defects by SEM and the fatigue life by fracture mechanics. It is shown that there are a few possibilities for the early failure judging from the small initial defects and the ordinary hydrodynamic force. Graphs. photomicrographs, 10 ref.
Fatigue Abstracts
could successfully predict the initial and saturated TMF response, and block isothermal response of Rene 80 from several tests between 649 and 1093°C. Graphs, 19 ref. New method of crankshaft design for high speed diesel engines, lto, M.,
Method of resonant testing of fatigue at pure bend. Bondarenko, Industrial Laboratory (Russia) (Sept. 1993) 59 (4), 426-429
Yu.D.
Methods of resonant testing of fatigue at pure bend as well as testing installation were developed. Kinematics and dynamics of testing were described on an example of metallic constructions.
Himokouchi, H., Arakawa, H., Numata, A. and Kajimoto, K. Mitsubishi Juko Giho (1993) 30 (6), 531-534 (in Japanese) High-speed diesel engines are increasingly required to output more power, to be lighter in weight, and smaller in size, maintaining high reliability, and higher in fuel economy and lower in emission. This trend requires the crankshaft, the most important component of the engine, to be smaller and lighter, and to withstand a higher combustion force. A sophisticated approach to optimum crankshaft design, which consists of stress analysis and fatigue strength evaluation, is described. Bending and torsional stresses are calculated by the latest high-accuracy three-dimensional finite element method, which is backed up by real crankshaft measurements. In terms of material, the effects of non-metallic inclusions on the fatigue strength of high-strength alloy steel (SCM440) are studied and a search for surface treatments to increase the fatigue strength is made. Fatigue testing of real crankshafts is performed to confirm the fatigue strength. Graphs. 5 ref. Effect of a change in interfaciai geometry on the fatigue strength of porouscoated Ti-6AI-4V. Wolfarth, D. and Ducheyne, P. J. Biomed. Mater. Res. (Apr. 1994) 28 (4), 417-425 Porous-coated Ti-6AI-4V has a fatigue strength approximately one-third that of the uncoated alloy. The interracial geometry between the porous coating and the implant substrate is notch-like, leading to stress concentrations that have been shown to be the main cause for the reduction in fatigue strength. The effect of interfacial geometry on fatigue strength of porous-coated Ti-6AI-4V is quantified. The interface between porous coating and implant is modelled using linear elastic, plane strain finite element analysis. Integrated with the numerical analysis is an experimental verification of enhanced fatigue behaviour. Changes in interfacial geometry are conceived, and their effectiveness in reducing stress concentrations is determined. A doubling of fatigue strength can be achieved for newly conceived geometries over conventional porous coating geometries. Graphs, photomicrographs, 17 ref. Fatigue behavior of a 22Cr-20Ni-18Co-Fe alloy at elevated temperatures.
Krukemyer, T.H., Fatemi, A. and Swindeman, R.W. J. Eng. Mater. Technol. (Trans, ASME) (Jan. 1994) 116 (1), 54-61 An experimental investigation was conducted on Haynes Alloy 556 to study the fatigue behaviour of the material at elevated temperatures. Fatigue tests were run at constant temperatures ranging from room temperature to 871°C with strain ranges from 0.265 to 1.5%, resulting in lives between 102 and 10 6 cycles. Cyclic deformation properties were evaluated based on the fatigue data. Three fatigue life models were evaluated for their ability to predict the isothermal fatigue lives of the material. These included the Ostergren, frequency separation and stress-strain-time models. Strengths and weaknesses of each model are discussed based on experimental results. Graphs, photomicrographs, 19 ref. High temperature multiaxiai low cycle fatigue of cruciform specimen. Itoh,
T., Sakan, M. and Ohnami, M. J. Eng. Mater. Technol. (Trans. ASME) (Jan. 1994) 116 (1), 90-98
Installation for fatigue testing during cyclic pure bending. Dolgushev, A.A.,
Kurteev, V.F. Dubrov, V.N. and Vasilevich, D.I. Industrial Laboratory (Russia) (Sept. 1993) 59 (3), 320-322
An installation for determination of strength characteristics of structurally heterogeneous materials, for example welded joints, was developed. Cyclic pure bending was chosen as loading method. Samples of zirconium base alloy with welded joints were investigated. Installation allowed to detect small invisible cracks and to measure fatigue strength index. Influence of ratio of biharmonic vibration load amplitudes to parameters of fatigue curve. Surin, V.M. and Mikhalev, B.S. Industrial Laboratory (Russia) (Sept. 1993) 59 (3), 304-306 Problems of reduction of biharmonic process of vibration load to sinusoidal process as well as influence of amplitude ratio on gradient of fatigue curve and value of fatigue limit were investigated. An installation consisting of a vibration electrodynamic UVE-5-1000-1 apparatus and controlling system was developed. Copper flat samples were tested and it was shown that fatigue limit was not dependent on amplitude ratio at constant frequency ratio.
Analysis of the growth of short fatigue cracks in a steel rod at degree Rankine, Reaumur = - 1 . McEvily, A.-J. and Jang, Z. Materials Science (Russia) (Nov. 1993) 13 (3), 308-312 A modified linear elastic fracture mechanics approach to the analysis of the growth of short cracks has been presented. Good agreement is found between predicted and experimental crack growth rates at the shortest crack lengths for 1045 carbon steel. It is shown that the agreement is not as good for the longer crack lengths. The rate of growth of short semicircular cracks as a function of crack length at degree Rankine, Reaumur = - 1 (degree Rankine, Reaumur is the ratio of the minimum to the maximum stress in a cycle) is presented. Graphs.
Shear fatigue crack growth and its analysis. Liu, H.-W., Chen, Qi, and Lai, D. Materials Science (Russia) (Nov. 1993) 13 (3), 300-307 It is shown that the fatigue cracks of aluminium alloy 7029 and steels HY130 and HY-100 generally prefer tensile growth. For a shea- crack in a crystal in small-scale yielding, degree of Kelvin RSS intensity coefficient is capable of characterizing the resolved shear stress field on the active slip system at a crack tip. In single crystals and large grains, TOPKRSS can be used as the primary correlation parameter for shear fatigue crack growth. Photomicrographs, Graphs.
Development of the microstructure based stochastic life prediction models.
Przystupa, M.A. and Vasudevan, A.K. Report AD-A270 453/4/XAB (1993) 4 pp
This paper describes high-temperature multiaxial low-cycle fatigue lives of type SUS 304 stainless steel and 1Cr-IMo-1/4V steel cruciform specimens at 923 and 823K in air. Strain-controlled multiaxial low-cycle fatigue tests were carried out using cruciform specimens at the principal strain ratios between - 1 and 1. The principal strain ratio had a significant effect on lowcycle fatigue lives. Fatigue lives drastically decreased as the principal strain ratio increased. Multiaxial low-cycle fatigue strain parameters were applied to the experimental data and the applicability of the parameters was discussed. The equivalent strain based on crack opening displacement (COD strain) developed in the paper and F'-plane parameter successfully predicted multiaxial low-cycle fatigue lives. The crack morphology was also extensively discussed from not only the surface crack direction but also the crack inclination into the specimen. Graphs, photomicrographs, 17 ref.
This study explores the methods of incorporating material microstructural characteristics into the fatigue life prediction models based on the results of the microstructural characterizations and fatigue testing of aluminum 7050T7451 plate alloys. The emphases in the microstructural characterization part of the programme are on the identification of the fatigue-relevant microstructural features and on the characterizations of the microstructural gradients. The characterizations are carried out using both the standard and novel techniques such as tessellation, fractai and modified linear intercept methods. The key measurement is determination of the size distributions of the fatigue crack initiating flaws; they are assumed equal to the extreme value distributions of the micropore and/or constituent particle size distributions measured on the metallographic sections.
Estimation of influence of medium stresses on fatigue resistance using scale effect. Domozhirov, L.I. Industrial Laboratory (Russia) (Dec. 1993) 53 (6), 613-619
Main factors affecting blade failure of marine propeller. I. Effects of material defects and hydrodynamic fluctuating stress of blades. Kawazoe, T., Matsuo,
Analysis of influence of medium stresses on fatigue strength for estimation of scale effect under asymmetrical cyclic loads and tensile stresses was made. Mechanical properties of 06Khl2N3D duplex stainless steel were studied. It was shown that increase of sample size led to gain of medium stresses influence on fatigue strength and to increase of scale effect. Graphs. Automatized complex for fatigue life testing. Neimark, A.S., Ryzhev, E.E.
and Gorelov, V.N. Industrial Laboratory (Russia) (Nov. 1993) 59 (5), 509-511 A set of minature machines for the production of standard, quick and program testing was developed. The complex allows one to perform fatigue tests under pure and cross bending, repeat tension tests and cycle torsion tests. It can be used for investigation of mechanical properties of steels, alloys and nonferrous metals.
S. and Nishikido, S. Nagasaki Daigaku Kogakubu Kenkyu Hokoku (Reports of the Faculty of Engineering Nagasaki University) (Jan, 1994) 24 (42), 7-12 (in Japanese)
In recent years, many failures in marine propeller blades of Ni-AI bronze (AIBC3) for motor car carriers have occurred. The high fluctuating stress on these blades induced by hydrodynamic force has been reported as the main cause of the trouble under severe operating conditions, including high ship speed. The systematic investigations of the main factors affecting a blade failure of propeller for a chemical tanker, which seldom occurred in the past, are presented. A few factors were extracted from many causes based on the examinations of the conditions of the blade failure and the hull. The early blade failure (within one year) was discussed in view of the estimations of the material defects by SEM and the fatigue life by fracture mechanics. It is shown that there are a few possibilities for the early failure judging from the small initial defects and the ordinary hydrodynamic force. Graphs. photomicrographs, 10 ref.