The effect of hot isostatic pressing(HIP)treatment on the fatigue notch sensitivity of Ti-6A1-4V alloy fabricated by electron beam melting(EBM)was investigated.The results indicate that the fatigue notch sensitivity o...The effect of hot isostatic pressing(HIP)treatment on the fatigue notch sensitivity of Ti-6A1-4V alloy fabricated by electron beam melting(EBM)was investigated.The results indicate that the fatigue notch sensitivity of the as-fabricated samples is much lower than that of HIPed samples.The variation of α lamella thickness and the distribution of pore defects have an effect on the fatigue strength in smooth and notched EBM Ti-6A1-4V samples,resulting in the divergence of the as-fabricated and HIPed samples on fatigue notch sensitivity.展开更多
The fatigue notch factors （K<sub>f</sub>） of metallic materials with high and low notch sensitivities, which have been derived in theory, are K<sub>t</sub><sup>1</sup>/（1+n） and...The fatigue notch factors （K<sub>f</sub>） of metallic materials with high and low notch sensitivities, which have been derived in theory, are K<sub>t</sub><sup>1</sup>/（1+n） and K<sub>t</sub><sup>2</sup>/（3+n） respectively. The diagram of K<sub>f</sub> vs. K<sub>t</sub> is obtained by means of comprehensive analysis of alarge number of data, and the applicable range of the above two K<sub>c</sub> relations is given. The calculation results for steel and aluminum alloy agree with the measured values very well.The fatigue limit of smooth specimens are also derived in this paper, i. e. σ<sub>theory</sub>=（K/E<sup>n</sup>）<sup>1</sup>/（1+n）. The calculation results are σ<sub>theory</sub>=σ<sub>cy</sub> （cyclic yield strength）.展开更多
An investigation was carried out to examine the influence of notch sensitivity on fatigue behaviour of austempered ductile iron (ADI). Samples were made of ductile iron with a chemical composition of 3.55% C, 2.18% Si...An investigation was carried out to examine the influence of notch sensitivity on fatigue behaviour of austempered ductile iron (ADI). Samples were made of ductile iron with a chemical composition of 3.55% C, 2.18% Si, 0.35% Mn, 0.022 P, 0.008 S and 0.045% Mg. The samples were heat treated by austenitizing at 900℃?for 1 h and then rapidly quenched into two different salt baths at 350 and 400℃?for 1 h each. This work aims at studying the capability of mechanical stress analysis software (ANSYS 12.0), as a nondestructive tool, to characterize and quantify the fatigue strength of the notched ADI samples with different radii (from 1 to 3 mm). In addition, experimental testing was performed using rotary bending fatigue machine on notched samples with radii of 1, 1.5 and 2-mm to verify the theoretical data obtained by ANSYS-12. The results show that the predicted fatigue strength estimated by ANSYS-12 is very close to the experimental one. Therefore, fatigue performance of the rotating parts made of ADI can be estimated theoreticcally using ANSYS 12.0. The fatigue strength of these parts can also be improved by increasing the formed filled radius due to decreasing the notch sensitivity factor.展开更多
An expression describing the size effect on fatigue strength is presented, which is deduced based on the fatigue design approach of stress field intensity. The fatigue size factors under rotating-bending or reversed t...An expression describing the size effect on fatigue strength is presented, which is deduced based on the fatigue design approach of stress field intensity. The fatigue size factors under rotating-bending or reversed torsion for smooth specimen and under rotating-bending for notched specimen are estimated, and the main effects on the fatigue size factor are discussed. Some experimental data are analysed and it is shown that the description of fatigue size factor developed in this paper is satisfactory.展开更多
In this paper,stress states under corresponding condition of an aero-engine fan blade using finite element stress-strain analysis for three work cycles in the 900 h load spectrum are obtained.Through the nominal stres...In this paper,stress states under corresponding condition of an aero-engine fan blade using finite element stress-strain analysis for three work cycles in the 900 h load spectrum are obtained.Through the nominal stress method,we calculated the fatigue notch factor and combined the material characteristics of TC6 to correct the material curve to the fan blades curve. Finally,the fatigue life of a fan blade was estimated using the linear cumulative damage rule and nonlinear cumulative damage theory.展开更多
基金supported financially by the National Natural Science Foundation of China (No. 51274063)the Fundamental Research Funds for the Central Universities (No. N170704015)
文摘The effect of hot isostatic pressing(HIP)treatment on the fatigue notch sensitivity of Ti-6A1-4V alloy fabricated by electron beam melting(EBM)was investigated.The results indicate that the fatigue notch sensitivity of the as-fabricated samples is much lower than that of HIPed samples.The variation of α lamella thickness and the distribution of pore defects have an effect on the fatigue strength in smooth and notched EBM Ti-6A1-4V samples,resulting in the divergence of the as-fabricated and HIPed samples on fatigue notch sensitivity.
文摘The fatigue notch factors （K<sub>f</sub>） of metallic materials with high and low notch sensitivities, which have been derived in theory, are K<sub>t</sub><sup>1</sup>/（1+n） and K<sub>t</sub><sup>2</sup>/（3+n） respectively. The diagram of K<sub>f</sub> vs. K<sub>t</sub> is obtained by means of comprehensive analysis of alarge number of data, and the applicable range of the above two K<sub>c</sub> relations is given. The calculation results for steel and aluminum alloy agree with the measured values very well.The fatigue limit of smooth specimens are also derived in this paper, i. e. σ<sub>theory</sub>=（K/E<sup>n</sup>）<sup>1</sup>/（1+n）. The calculation results are σ<sub>theory</sub>=σ<sub>cy</sub> （cyclic yield strength）.
文摘An investigation was carried out to examine the influence of notch sensitivity on fatigue behaviour of austempered ductile iron (ADI). Samples were made of ductile iron with a chemical composition of 3.55% C, 2.18% Si, 0.35% Mn, 0.022 P, 0.008 S and 0.045% Mg. The samples were heat treated by austenitizing at 900℃?for 1 h and then rapidly quenched into two different salt baths at 350 and 400℃?for 1 h each. This work aims at studying the capability of mechanical stress analysis software (ANSYS 12.0), as a nondestructive tool, to characterize and quantify the fatigue strength of the notched ADI samples with different radii (from 1 to 3 mm). In addition, experimental testing was performed using rotary bending fatigue machine on notched samples with radii of 1, 1.5 and 2-mm to verify the theoretical data obtained by ANSYS-12. The results show that the predicted fatigue strength estimated by ANSYS-12 is very close to the experimental one. Therefore, fatigue performance of the rotating parts made of ADI can be estimated theoreticcally using ANSYS 12.0. The fatigue strength of these parts can also be improved by increasing the formed filled radius due to decreasing the notch sensitivity factor.
文摘An expression describing the size effect on fatigue strength is presented, which is deduced based on the fatigue design approach of stress field intensity. The fatigue size factors under rotating-bending or reversed torsion for smooth specimen and under rotating-bending for notched specimen are estimated, and the main effects on the fatigue size factor are discussed. Some experimental data are analysed and it is shown that the description of fatigue size factor developed in this paper is satisfactory.
文摘In this paper,stress states under corresponding condition of an aero-engine fan blade using finite element stress-strain analysis for three work cycles in the 900 h load spectrum are obtained.Through the nominal stress method,we calculated the fatigue notch factor and combined the material characteristics of TC6 to correct the material curve to the fan blades curve. Finally,the fatigue life of a fan blade was estimated using the linear cumulative damage rule and nonlinear cumulative damage theory.
