Papers by Author: Chang Feng Yan

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Authors: You Tang Li, Zhi Yuan Rui, Chang Feng Yan
Abstract: The stress singularity eigen-equation for V-notch in a bi-material plate is obtained. A new definition of dynamic stress intensity factor of a crack perpendicular to bi-material interface is put forward, and then is extended to any V-notch in bi-material plate. A formula of stress extrapolation method to calculate dynamic stress intensity factors of V-notch in bi-material plate is obtained. As an example, the three points bending sample with two materials is investigated.
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Authors: You Tang Li, Ping Ma, Chang Feng Yan
Abstract: The anti-fatigued design is an important field in product lifecycle management. A uniform criterion of annularly breached spindle was put forward in this paper. The crack, V-notch, U-notch and arc were described as breach uniformly according to the tip radius, depth and field angle of breach in the method. The connection between sharp V-notch and crack, between V-notch and U-notch has been set up. We fuse the fatigue fracture theory and life prediction techniques together on the design technology of lifecycle safety guarantee of mechanical structures. The relationship between life and detectability of the breached spindle system was discussed to provide useful guidance for practical applications. The criterion for the safety design and fracture design both of which on fα was obtained. The criterion of annular breached spindle under torsion was obtained at first and then the effects of bending to lifecycle of spindle were analyzed.
755
Authors: You Tang Li, Chang Feng Yan, Ping Ma
Abstract: Rotating bending and inverse rotating bending are the two different forms of fatigue. The application of regular blanking for brass under extra-low cycle inverse rotating bending fatigue was investigated. The principle of inverse rotating bending fatigue was explained at first. And then the experiment of inverse rotating bending fatigue was made in special equipment designed by the authors. Several problems, i.e. the relations of the quantities such as cycle times of fracture, the strain amplitude near the notch tip and fracture toughness of fatigue to the presetting deflection, the effects of depth and tip radius of notch on the cycle times of fracture, were discussed with the helps of experiment. Finally, The relation of depth of crack propagation to cycle times were discussed also. The suitable parameters of inverse rotating bending fatigue for blanking of brass were obtained.
1077
Authors: You Tang Li, Chang Feng Yan, Rui Cheng Feng
Abstract: The dynamics stress intensity factor of fixed specimen with several notches was analyzed by semi-analytic method. The semi-analytic formula was taken as the interpolation function near notch tip and the degrees of freedom near notch tip were transformed into a small set of generalized coordinates by means of the series expansion formulas of the displacement field. The dynamics stress intensity factor for fixed specimen with two notches or cracks under centralized loading and well-proportioned loading was obtained. The results show that the KI and KII are existed at the same time for fixed specimen with several notches under dynamics loading.
473
Authors: You Tang Li, Ping Ma, Chang Feng Yan
Abstract: A model of notched shaft in which the crack, V-notch, U-notch and arc were described as notch uniformly, was put forward. The stress field near the notch tip of notched shaft was given using quadric coordinate system by selecting an appropriate displacement function at first, and then the stress field in Cartesian co-ordinates system was obtained. The 3-D model was set up and the local stress and strain near the tip of notch was calculated by using finite element software ANSYS, and the effect of notched parameters of shaft on stress was analysed. The results show that there is a small region, in which the effect of the tip radius and depth on the stresses is obviously. The effect of an open angle of notch on stress is very small. The smaller the ratios between the tip radius and depth of notch, the larger the stress concentrations near the tip of notch.
166
Authors: You Tang Li, Bo Chen, Chang Feng Yan
Abstract: For designing the fatigue life of shaft with a circumferential notch exactly, the influencing factors have been analyzed completely. The modified mechanics model to estimate the fatigue life of shaft with a circumferential notch is set up. The assessment method of fatigue life for shaft with a circumferential notch is put forward. The effects of notch on stress concentration factor and fatigue life of shaft with a circumferential notch are discussed and the influencing parameters are obtained. The results show that the tip radius of notch has a great effect on fatigue life of shaft; on the other hand, the open angle of notch has a little effect on it. The results will establish the base of anti-fatigue design of shaft.
3864
Authors: You Tang Li, Zhi Yuan Rui, Chang Feng Yan
Abstract: Anti-fatigue design is a key content in product lifecycle management and there are many factors to affect the fatigue life of parts. For designing the fatigue life of shaft with a circumferential notch exactly, the influencing factors have been analyzed completely. The mechanics model for assessing the fatigue life of shaft is set up. The assessment method of fatigue life for shaft is set up according to the traditional fatigue life estimation. The effect of wearing parameter to fatigue life is analyzed and the results show that the wear is an important factor to affect the fatigue life.
469
Authors: You Tang Li, Chang Feng Yan
Abstract: The fracture designs of metallic matrix crack for bi-materials were studied. The stress field and displacement field of plane matrix crack was setup at first. Then the finite element method is used to analyses the stress singularity of matrix cracks between different materials. The solutions of stress singularity of a cracked bi-materials beam under uniform tension, and the three-point bending of bi-materials specimen were computed. The result lays a theoretic and applied foundation for the practical engineering application of metallic matrix crack for bi-materials.
7
Authors: Guo Tao Zhang, Zhi Yuan Rui, Rui Cheng Feng, Yan Rui Zuo, Chang Feng Yan
Abstract: For the shorting of fracture mechanism from the point of high temperature condition, so a new method of illustration, which is carried out under the condition of high temperature, for fracture mechanism will be adopted in this paper. And a more accuracy and more understandability result can be got by this new method. Besides, the performance of TiAl alloys can be improved by making grains refined to decrease the slip plane spacing, which can be got from the mechanics analysis.
19
Authors: Yan Rui Zuo, Zhi Yuan Rui, Rui Cheng Feng, Chang Feng Yan, Hai Yan Li
Abstract: Study of grain size and lamellar spacing on fatigue crack propagation resistance in TiAl alloy has been done. The effects have been analyzed specifically. Meanwhile, the influence has been verified with some fatigue crack propagation experimental results and Paris formula. The experimental results confirmed that the grain size and lamellar spacing have significant effect on fatigue crack growth resistance. According to the Paris formula, the specific values of the constants in the formula were calculated.
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