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EHL film thickness, additives and gear surface fatigue
608
Fatigue Abstracts
as shown per provided figure. These are compared with diagrams by Haigh, Smith, Ros and Moor-Kommers-Jasper. Nishihara et al. used a tensile compression machine to test carbon steel, and several types of duralmin (equivalent to 2017, 2024 alloys) with N = 107 and 5 x 107 repeated latigue curve. Graphs, 29 ref.
Development of a general multiaxial fatigue criterion for high cycle fatigue behaviour prediction. Lu, J., Flat'enot, J.F., Diboine, A., &tsserre, S., Froustey, C., Bemlebach, M. and Palin-Luc, T. Proc. 4th lnt. Conf on Biaxial/Multia.~ial l'-atigue 11, St, Germain en Laye, France, 31 May-3 June 1994, pp. 399-408 The most frequent and most serious incident likely to occur to a mechanical structure is its failure as a result of fatigue. Although it is now possible to calculate the fatigue strength of a part or structure subjected to uniaxial stresses, a solution has still not been found for the more general case in which the stresses are multiaxial and the part is subjected to complex static stresses resulting from either loading or residual stress produced during manufacture. There is no recognized general calculation method which can be used when the applied cyclic stresses are multiaxial and when a stress gradient is present (due to the loading or due to the geometry of the part). [n reality, stresses are very rarely simple stresses, but rather a combination of normal alternating stresses and shear alternating stresses superimposed on mean stresses. It is practically impossible to test each material under all the possible combinations of altemating stress and static stress; however, it is essential to make an estimation of the fatigue strength of the lifetime of a mechanical part based on the usual laboratory tests. A global approach is proposed for calculating the fatigue strength in the presence of multiaxial stresses, stress field and stress gradient, In order to develop a general criterion, an attempt has been made to take into account the different important effects involved, based on the results obtained for different materials. These include the notch effect and the scale effect (this is to say the gradient effect) in the case of notched parts, the effect of a combined in-phase or out-of-phase stress and the effect of residual stresses. To complete the study and validate the criterion on a material in the presence of all the parameters, tests were carred out on FGS700-2 cast iron, strengthened using roller burnishing. Graphs, 17 ref.
Effect of stress state type on both durability and deformation process of austenitic steel under thermal cycling conditions. Zuchowski, R. Proe. 4th Int. Cot~fi on Biaxial/Multiaxial Fatigue 11, St. Germain en Laye, France, 31 May 3 June 1994, pp. 391-398 The effect of stress state type on the durability of a specimen as well as on the deformation process under thermal cycling conditions was examined. Thinwalled tubular specimens made of austenitic steel were used in the experiments. They were subjected to pure tension and pure torsion as well as to complex loading (tension and torsion). A constant value of stress intensity was obtained in each case. The influence of stress state type on both specimen life and strain rate intensity has been found. It was found that the Monkman-Grant failure criterion and the Norton-Bailey law can be valid under plane stress conditions as long as the contribution f the shear stress component to stress intensity does not prevail. The analysis of the obtained results has also shown that the Huber-Mises criterion can be applied for the highest value of stress intensity while for the lowest one the Tresca-Guest criterion would be more satisfied. Graphs, 5 ref.
The fatigue behaviour of an initial mixed mode fatigue crack from a design viewpoint. Pook, L.P. Prof 4th lnr Conf on Biaxial/Multiaxial Fatigue H, St. Germaiu en Laye, France, 31 May-3 June 1994, pp. 369-378 In any fatigue design situation, including those involving mixed mode loading, difficulties can arise in estimates of fatigue strength. A possible approach is to transform a mixed mode initial crack to an equivalent mode 1 crack so that procedures developed for an initial 1 crack may be used. Fatigue crack growth from an initial mixed mode crack is usually in mode 1, but can be complex, and the associated fracture mechanics is not completely understood. This makes it difficult to extract useful generalizations. Nevertheless, the use of an equivalent initial mode crack is satisfactory provided it has been validated for a particular situation. 25 ref.
Multiaxial fatigue criterion under proportional loading including mean strain effect. Golos, K.M. and Osinski, Z. Proc. 4th Int. Conf. on Biaxial/Multiaxial Fatigue H, St. Germain en Laye, France, 31 May 3 June 1994, pp. 303-315 A mean strain effect on fatigue life under proportional cyclic multiaxial loading is investigated. It is shown that total strain energy density, AW, correlates with both low- and high multiaxial proportional cyclic loading. This damage parameter can also be used in the analysis of multiaxial cyclic loading with mean strain. A brief description of how AW' can be calculated is given. Finally, an extended energy based fatigue damage criterion with mean strain effect is proposed. The predicted results are compared with experimental data for the medium carbon steel St5. The agreement for analysed material and loading condition is found to be good. Graphs, 20 ref.
Multiaxial thermomechanical behaviour of IN738LC. Ziebs, J., Meersmann, J., Kahn, H.-J., Hulsmann, N. and Olschewski, J. Proc. 4th hit. Conf on Biaxial/Multia:dal Fatigue H, St. German cn Laye, France, 31 May-3 June 1994, pp. 247-259 A study has been undmlaken to develop an understanding of the fatigue life of IN738LC under simple and simulated operating thermomechanical cycling (TMF) in air. The experiments were conducted in the temperature ranges 450950, 450 760 and 600-850°C. The results indicate that the lives differ with strain-temperature phasing. Diamond cycles gave the longest lives. Simple nonproportional strain paths with a 90 ° phase angle gave the shortest lives. Lile prediction models can be derived by simple thermomechanical low cycle fatigue tests. Significant parameters governing cycles to failure were found to be the mechanical inelastic strain range, the maximum stress range, the total strain range and the energy criteria A%,~,,. A~...... and A~,,,. A~.,.,. TMF life can be approximated by isothermal life at maximum and minimum temeprature since the saturated response of IN738LC is the same lk~r both test methods However, the TMF response cannot be predicted completely using only iso thermal parameters. The J2 theory can also be used to describe the TMF behaviour at the highest and lowest temperature. Graphs, 9 rcf.
A unified Altenbaeh, Proc. 4th France, 3I
model of low cycle fatigue damage. H. and Zoloehevsky. A. lur Conf on Biaxial/Multiaxial Fatigue II, St. Germain en Laye. May-3 June 1994. pp. 117-128
A generalized fatigue limit criterion under the conditions of muhiaxial stress is predicted. It is shown that the fatigue criteria of Sines and Crossland follow as a particular case from the formulated criterion. The practical recommen dafions for usage of different fatigue limit criteria are established. Theoretica! predictions are compared with experimental data. Finally a continuum damage mechanics model for low cycle fatigue is proposed. This model describes simultaneously the iufluence of the stress amplitude and the mean stress on the damage of materials. Specific damage models with a smaller number of material parameters are obtained. Graphs, 5 ref.
EHL film thickness, additives and gear surface fatigue. Tawnsend. D.7~ and Shimski, J. Gear Teehnol. (1995) 12 (3), 26-31 The effect of seven lubricants (NASA identification A G) with the same base stock, but with different viscosities on the surface fatigue life of AISI 9310 spur gears was investigated in the NASA Lewis Research Center's gear test apparatus. Lubricants with a viscosity providing a specific film thickness greater than I and with an additive package produces surface fatigue lives 4 8.6 times those of lubricants providing thinner films. Gear surface fatigue life is fl~rther increased when the EHL specific fihn thickness is well above I. A low viscosity lubricant with an additive package produced lives equivalent to similar base stock lubricants with 30~7, high viscosity, but without an additive package. Graphs, photomicrographs, 9 ref.
An analysis for the effects of compressive load excursions on fatigue crack growth in metallic materials. Kardomateas, G.A. and Carlson, R,L. J. Appl. Mech. (7)'ans. ASME) (1995) 62 (I). 24(I 243 A mathematical model of fatigue crack growth based on inelastic crushing of asperities under compressive load excursions was developed for metallic raaterials. The effect of asperity loading and unloading during cyclic deformation on asperity load and height were determined. The model was successfully applied to a single-edge-cracked specimen of hot rolled steel, and it was shown that the effective range of the stress intensity factor increased due to compressive excursions crushing the asperities. As a result, subsequent increases in crack growth rate are expected. Graphs, 4 ref.
Creep-fatigue life prediction--a ductility model. Goswami, T. High Temp. Mater. Proees~. (1995) 14 (2), 101 114 Creep-fatigue life prediction methods are briefly reviewed. Pbenomenological methods of life prediction are very popular, since they use several test and metaflographic parameters in model formulation. They also require numerous test parameters determined from specialized tests. Requirements of phenomenological methods have been summarized. Ductility measurement and modeling aspects have been reviewed. A new model has been developed with the assumption that with increasing fatigue cycles the ductility gradually decreases and the specimen fails as a result of exhaustion of ductility. ]'his has been achieved in terms of dynamic viscosity (product of stress and cycle time), equated with material toughness, which is a product of material strength and ductility. There is a limiting value of ductility and yield to tensile strength ratio, where this method applies. Creep-fatigue data on five 'test materials', namely AMZIRC, Ti-6AI-4V, IN 100, Waspaloy and ICr-Mo-V steels, have been assessed with the proposed method. Nearly 70% of the test data points with or without hold times were predicted within a factor of +×2. Graphs, 44 ref.
Applicability of modified Diercks equation with NRIM data. Goswami, T. High Temp. Mater. Proc'ess. (1995) 14 (2), 81 90 The applicability of the modified Diercks equation (MDE) was assessed with elevated temperature low cycle fatigue (ETLCF) data generated by the National Research Institute for Metals (NRIM) for ICr-Mo-V, 1.25Cr-Mo, 2.25Cr-Mo and 9Cr-IMo steels, respectively. The modified Diercks equation was assessed
Fatigue Abstracts
as shown per provided figure. These are compared with diagrams by Haigh, Smith, Ros and Moor-Kommers-Jasper. Nishihara et al. used a tensile compression machine to test carbon steel, and several types of duralmin (equivalent to 2017, 2024 alloys) with N = 107 and 5 x 107 repeated latigue curve. Graphs, 29 ref.
Development of a general multiaxial fatigue criterion for high cycle fatigue behaviour prediction. Lu, J., Flat'enot, J.F., Diboine, A., &tsserre, S., Froustey, C., Bemlebach, M. and Palin-Luc, T. Proc. 4th lnt. Conf on Biaxial/Multia.~ial l'-atigue 11, St, Germain en Laye, France, 31 May-3 June 1994, pp. 399-408 The most frequent and most serious incident likely to occur to a mechanical structure is its failure as a result of fatigue. Although it is now possible to calculate the fatigue strength of a part or structure subjected to uniaxial stresses, a solution has still not been found for the more general case in which the stresses are multiaxial and the part is subjected to complex static stresses resulting from either loading or residual stress produced during manufacture. There is no recognized general calculation method which can be used when the applied cyclic stresses are multiaxial and when a stress gradient is present (due to the loading or due to the geometry of the part). [n reality, stresses are very rarely simple stresses, but rather a combination of normal alternating stresses and shear alternating stresses superimposed on mean stresses. It is practically impossible to test each material under all the possible combinations of altemating stress and static stress; however, it is essential to make an estimation of the fatigue strength of the lifetime of a mechanical part based on the usual laboratory tests. A global approach is proposed for calculating the fatigue strength in the presence of multiaxial stresses, stress field and stress gradient, In order to develop a general criterion, an attempt has been made to take into account the different important effects involved, based on the results obtained for different materials. These include the notch effect and the scale effect (this is to say the gradient effect) in the case of notched parts, the effect of a combined in-phase or out-of-phase stress and the effect of residual stresses. To complete the study and validate the criterion on a material in the presence of all the parameters, tests were carred out on FGS700-2 cast iron, strengthened using roller burnishing. Graphs, 17 ref.
Effect of stress state type on both durability and deformation process of austenitic steel under thermal cycling conditions. Zuchowski, R. Proe. 4th Int. Cot~fi on Biaxial/Multiaxial Fatigue 11, St. Germain en Laye, France, 31 May 3 June 1994, pp. 391-398 The effect of stress state type on the durability of a specimen as well as on the deformation process under thermal cycling conditions was examined. Thinwalled tubular specimens made of austenitic steel were used in the experiments. They were subjected to pure tension and pure torsion as well as to complex loading (tension and torsion). A constant value of stress intensity was obtained in each case. The influence of stress state type on both specimen life and strain rate intensity has been found. It was found that the Monkman-Grant failure criterion and the Norton-Bailey law can be valid under plane stress conditions as long as the contribution f the shear stress component to stress intensity does not prevail. The analysis of the obtained results has also shown that the Huber-Mises criterion can be applied for the highest value of stress intensity while for the lowest one the Tresca-Guest criterion would be more satisfied. Graphs, 5 ref.
The fatigue behaviour of an initial mixed mode fatigue crack from a design viewpoint. Pook, L.P. Prof 4th lnr Conf on Biaxial/Multiaxial Fatigue H, St. Germaiu en Laye, France, 31 May-3 June 1994, pp. 369-378 In any fatigue design situation, including those involving mixed mode loading, difficulties can arise in estimates of fatigue strength. A possible approach is to transform a mixed mode initial crack to an equivalent mode 1 crack so that procedures developed for an initial 1 crack may be used. Fatigue crack growth from an initial mixed mode crack is usually in mode 1, but can be complex, and the associated fracture mechanics is not completely understood. This makes it difficult to extract useful generalizations. Nevertheless, the use of an equivalent initial mode crack is satisfactory provided it has been validated for a particular situation. 25 ref.
Multiaxial fatigue criterion under proportional loading including mean strain effect. Golos, K.M. and Osinski, Z. Proc. 4th Int. Conf. on Biaxial/Multiaxial Fatigue H, St. Germain en Laye, France, 31 May 3 June 1994, pp. 303-315 A mean strain effect on fatigue life under proportional cyclic multiaxial loading is investigated. It is shown that total strain energy density, AW, correlates with both low- and high multiaxial proportional cyclic loading. This damage parameter can also be used in the analysis of multiaxial cyclic loading with mean strain. A brief description of how AW' can be calculated is given. Finally, an extended energy based fatigue damage criterion with mean strain effect is proposed. The predicted results are compared with experimental data for the medium carbon steel St5. The agreement for analysed material and loading condition is found to be good. Graphs, 20 ref.
Multiaxial thermomechanical behaviour of IN738LC. Ziebs, J., Meersmann, J., Kahn, H.-J., Hulsmann, N. and Olschewski, J. Proc. 4th hit. Conf on Biaxial/Multia:dal Fatigue H, St. German cn Laye, France, 31 May-3 June 1994, pp. 247-259 A study has been undmlaken to develop an understanding of the fatigue life of IN738LC under simple and simulated operating thermomechanical cycling (TMF) in air. The experiments were conducted in the temperature ranges 450950, 450 760 and 600-850°C. The results indicate that the lives differ with strain-temperature phasing. Diamond cycles gave the longest lives. Simple nonproportional strain paths with a 90 ° phase angle gave the shortest lives. Lile prediction models can be derived by simple thermomechanical low cycle fatigue tests. Significant parameters governing cycles to failure were found to be the mechanical inelastic strain range, the maximum stress range, the total strain range and the energy criteria A%,~,,. A~...... and A~,,,. A~.,.,. TMF life can be approximated by isothermal life at maximum and minimum temeprature since the saturated response of IN738LC is the same lk~r both test methods However, the TMF response cannot be predicted completely using only iso thermal parameters. The J2 theory can also be used to describe the TMF behaviour at the highest and lowest temperature. Graphs, 9 rcf.
A unified Altenbaeh, Proc. 4th France, 3I
model of low cycle fatigue damage. H. and Zoloehevsky. A. lur Conf on Biaxial/Multiaxial Fatigue II, St. Germain en Laye. May-3 June 1994. pp. 117-128
A generalized fatigue limit criterion under the conditions of muhiaxial stress is predicted. It is shown that the fatigue criteria of Sines and Crossland follow as a particular case from the formulated criterion. The practical recommen dafions for usage of different fatigue limit criteria are established. Theoretica! predictions are compared with experimental data. Finally a continuum damage mechanics model for low cycle fatigue is proposed. This model describes simultaneously the iufluence of the stress amplitude and the mean stress on the damage of materials. Specific damage models with a smaller number of material parameters are obtained. Graphs, 5 ref.
EHL film thickness, additives and gear surface fatigue. Tawnsend. D.7~ and Shimski, J. Gear Teehnol. (1995) 12 (3), 26-31 The effect of seven lubricants (NASA identification A G) with the same base stock, but with different viscosities on the surface fatigue life of AISI 9310 spur gears was investigated in the NASA Lewis Research Center's gear test apparatus. Lubricants with a viscosity providing a specific film thickness greater than I and with an additive package produces surface fatigue lives 4 8.6 times those of lubricants providing thinner films. Gear surface fatigue life is fl~rther increased when the EHL specific fihn thickness is well above I. A low viscosity lubricant with an additive package produced lives equivalent to similar base stock lubricants with 30~7, high viscosity, but without an additive package. Graphs, photomicrographs, 9 ref.
An analysis for the effects of compressive load excursions on fatigue crack growth in metallic materials. Kardomateas, G.A. and Carlson, R,L. J. Appl. Mech. (7)'ans. ASME) (1995) 62 (I). 24(I 243 A mathematical model of fatigue crack growth based on inelastic crushing of asperities under compressive load excursions was developed for metallic raaterials. The effect of asperity loading and unloading during cyclic deformation on asperity load and height were determined. The model was successfully applied to a single-edge-cracked specimen of hot rolled steel, and it was shown that the effective range of the stress intensity factor increased due to compressive excursions crushing the asperities. As a result, subsequent increases in crack growth rate are expected. Graphs, 4 ref.
Creep-fatigue life prediction--a ductility model. Goswami, T. High Temp. Mater. Proees~. (1995) 14 (2), 101 114 Creep-fatigue life prediction methods are briefly reviewed. Pbenomenological methods of life prediction are very popular, since they use several test and metaflographic parameters in model formulation. They also require numerous test parameters determined from specialized tests. Requirements of phenomenological methods have been summarized. Ductility measurement and modeling aspects have been reviewed. A new model has been developed with the assumption that with increasing fatigue cycles the ductility gradually decreases and the specimen fails as a result of exhaustion of ductility. ]'his has been achieved in terms of dynamic viscosity (product of stress and cycle time), equated with material toughness, which is a product of material strength and ductility. There is a limiting value of ductility and yield to tensile strength ratio, where this method applies. Creep-fatigue data on five 'test materials', namely AMZIRC, Ti-6AI-4V, IN 100, Waspaloy and ICr-Mo-V steels, have been assessed with the proposed method. Nearly 70% of the test data points with or without hold times were predicted within a factor of +×2. Graphs, 44 ref.
Applicability of modified Diercks equation with NRIM data. Goswami, T. High Temp. Mater. Proc'ess. (1995) 14 (2), 81 90 The applicability of the modified Diercks equation (MDE) was assessed with elevated temperature low cycle fatigue (ETLCF) data generated by the National Research Institute for Metals (NRIM) for ICr-Mo-V, 1.25Cr-Mo, 2.25Cr-Mo and 9Cr-IMo steels, respectively. The modified Diercks equation was assessed