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Abstract When plates with edge cracks in the rolling process is straightened by cyclic tensile and compressive stress, the tip of edge crack always accompanied by stress concentration, which leads to crack propagation. In this paper, damage parameters are imported into the plate straightening model based on determining the GTN damage parameters of magnesium alloy materials by inverse finite element calibration method, the influence of different straightening process schemes and prefabricated V-shaped crack geometry on crack growth is analyzed through the way of the combination of simulation and straightening experiment. The results show that the peak values of equivalent stress and equivalent strain under each straightening roll appear at the crack tip. The value of longitudinal stress and equivalent stain decrease with the distance to crack tip becomes larger. The peak value of longitudinal stress appears when the crack circumferential angle is about 100°, and the crack tip is easy to form crack propagation; when the plate passes roll 2 and roll 4, the equivalent stress and strain concentration at the crack tip are most obvious; when the reduction reaches a certain degree, the void volume fraction (VVF) reaches the VVF of the material breaking; with the increase of the entrance reduction, the number of VVF at the crack tip which reaches the material fracture increases, and the length of crack propagation increases; the stress concentration at the tip of V-shaped crack with large length–width ratio is obvious, and the VVF is more likely to reach the VVF at the time of material fracture, crack initiates and propagates easily.

Temperature-pressure-adsorption equation （TPAE） parameters were calculated based on a series of isothermal adsorption experimental data from medium rank normal coal and deformed coal in Pingdingshan No.5 mine. The results of TPAE show that the adsorption is a spontaneous exothermic reaction, and the desorption is not a spontaneous endothermic reaction. The thermodynamic calculation proves that when the adsorption amount increases, its unit isosteric enthalpy of desorption decreases according to the power function relationship. The unit isosteric enthalpy of desorption of normal coal is 2.2 times that of deformed coal. Coal absorbs environmental energy to desorb gas, reduce temperature, and increase pressure; rising pressure and lowing temperature are promoting the adsorption of coal, which results in a new gas liquid equilibrium. The direct consequence of the continuous increase of coal adsorption is the continuous decline of its unit isosteric enthalpy of desorption. The ambient energy input and the gas internal energy accumulation and transfer show mutual inducement and mutual reinforcement, until the new wave of environmental energy input, induce gas desorption to reach a high pressure gradient sufficiently to cause gas protrusion. The preparation, initiation, development, and termination of gas outburst are sequential processes. The segment node for separating outburst preparation and initiation is whether there is human engineering activity. The segment node for separating initiation and development is whether the wall of the system is broken. The segment node for separating development and termination is whether the adsorption amount of the deformed coal is close to zero.

An SIRS epidemic model with two time delays in healing period and immune expiration period is researched. The threshold conditions which determines the epidemic termination were found out, the free-equilibrium and endemic equilibrium were calculated, and the global stability of free-equilibrium was proved. Using the method of rebuttal evidence and the comparison principle of differential equations, the uniform persistence of disease is proved. Immune expiration period and the recover period for the influence of epidemic model by numerical simulation were analyzed at last. [ABSTRACT FROM AUTHOR]