Papers by Author: Dan Jin

Abstract: A series of tests for low cycle fatigue were conducted on the tubular specimens for 304 stainless steel under variable amplitude and irregular axial-torsional loading. Rainflow cycle counting and linear damage rule are used to calculate fatigue damage and four approaches, e.g. SWT(Smith-Watson-Topper), KBM(Kandil-Brown-Miller), FS(Fatemi-Socie), and LKN(Lee-Kim-Nam) approach are employed to predict the fatigue life. The maximum shear strain plane, the maximum normal strain plane, and the maximum damage plane are considered as the critical plane, respectively. The effects of the choice of the critical plane on previous approaches are discussed. It is shown that comparing with the maximum shear/normal strain approach, the predictions are improved by using the maximum damage plane approach, part nonproportional paths for SWT, AV and part nonproportional paths for KBM, TV paths for FS. But for LKN, the prediction results are nonconservative for some paths than that of the maximum shear/normal strain approach.

Abstract: The residence time distribution in Kenics static mixer is investigated using experimental approaches. Experimentally, RTD measure in SK with pulse tracer technology was used to characterize flow and mixing quality. The effect of velocity on the RTD was investigated for all sections. The results show that the flow in SK mixer tends to the plug flow along the axial direction when the velocity increases. The quantization analysis, the effect of factors on the mean residence time, is done by using the power function considering the numbers of mixer element, diameter, element aspect radio, and velocity. The validity of this function is testified by other experiments.

Abstract: 65Mn spring steel is mainly used for rotary blade which is a vulnerable part of farming machinery. The experiment of the wear-resistance property for 65Mn spring steel under different heat treatments is conducted. The results are discussed based on the regression orthogonal design. The wear-resistance property of 65Mn steel has been discussed by applying diverse heat treatment technology and the optimum parameters of heat treatment for the best anti-wear property are obtained through experiments. The influence of the parameters on anti-wear property is studied by applying the regression orthogonal design. The relation between the wear mass loss and diverse heat treatment parameters has been given by using planar and contour figure. The optimum heat treatment parameter for maximum anti-wear ability is obtained as following: 852.64 for quenching temperature, 18.36min for quenching time, and 145.44 for tempering temperature, respectively.

Abstract: The Fatemi–Socie criterion is evaluated using the combined axial torsion fatigue testing results obtained from extensive experiments on thin-walled tubular specimens made from 304 stainless steel. The Fatemi–Socie criterion combines the maximum shear strain amplitude with a consideration of the normal stress on the critical plane. Rainflow cycle counting and Morrow’s plastic work interaction rule are used to calculate fatigue damage. The fatigue life prediction is conducted by using the maximum shear strain plane as the critical plane by considering the weight function and the maximum damage plane as the critical plane. It is concluded that the results gained by two approaches are both acceptable for the case examined.

Abstract: A series of low-cycle fatigue experiments of axial-torsional loading of variable amplitudes were performed on the tubular specimens of 304 stainless steel. Two models of multiaxial low-cycle fatigue life, KBM and FS method, are evaluated based on the fatigue life data of 304 stainless steel. Rainflow cycle counting and the Liner Damage Rule are used to calculate fatigue damage. It was shown that the part prediction results are nonconservative for the two models. The life prediction is done again based on the weight function critical plane method for the two models. The prediction results are better by using the weight function critical plane method than the previous results for KBM model. But the prediction results are improved little for FS model in spite of the weight function critical plane method being used.

Abstract: Fatigue tests are conducted on 304 stainless steel and 45C steel under fully reversed strain control conditions with two different loading modes. 45C steel exhibits cyclic softening under each phase loading. While for 304 stainless steel, much additional hardening is observed in out-of-phase loading. The damage values for failure of 45C steel is similar to the previous research, however, 304 stainless steel is not. Fatigue life is predicted based on the linear damage rule, the double linear damage rule, and the plastic work model of Morrow. The damage value is different in the same loading mode for the two materials according to linear damage rule.