No abstract

There are severe uneven “cat ear” wear contours of work rolls, the key factors to affect high‐quality profile and flatness control of electrical steel strips, in the schedule‐free rolling process with a large number of the same width strip rolling campaigns of hot rolling mills. The work roll wear prediction model, thermal roll contour model, and a 3D finite‐element model of roll stacks and strip are established using MATLAB and ABAQUS software. The effects of the work roll wear contour on the loaded roll gap profile within the entire rolling campaign are analyzed. A variable stroke and step (VSS) shifting strategy is developed based on the exponentially damped sinusoids function, which can get the smooth work roll wear contours. The main parameters including attenuation coefficient of stroke, the coil number and the attenuation coefficient of the first shifting cycle, and the initial phase avoiding repetition of the shifting position, are obtained by genetic optimization. The industrial application of the VSS shifting strategy gives remarkable results. The “cat ear” height value of local work roll wear contours is decreased by 67.3% and the high‐precision rate of crown from 25 to 40 μm of the electrical steel is increased by 22.5%.

The reasons for studying single flexible body dynamics are that on one hand, it is the basis of flexible multi-body dynamics. If the theory of the single flexible body dynamics has been deeply studied, the theory of flexible multi-body dynamics will be researched easily. On the other hand, it has its unique and important applications. Quasi-variational principle of non-conservative single flexible body dynamics is established under the cross-link of particle rigid body mechanics and deformable body mechanics. Taking the interceptor as an example, this paper has explained the physical meaning of the quasi-stationary value condition of the quasi-variational principle in non-conservative single flexible body dynamics. Taking the launch of rocket as an example, it has illustrated the features of "one force for two effects" in a single flexible body dynamics. With an example of the extending flexible beam coupled with the spacecraft attitude, it has shown the transition from the single flexible body dynamics to the flexible multi-body dynamics. Finally, a number of related problems are discussed.variational principle, non-conservative system, aerospace dynamics, flexible multi-body dynamics, single flexible body dynamics

Abstract.Based on the analysis of crankshaft fillet rolling process, used ANSYS finite element analysis software to conduct the elastic-plastic mechanical simulation of crankshaft rolling process, and gained the variation law of the residual stress and plastic deformation in the radial path of the fillet under different rolling laps and rolling pressure. Established the relationship between the rolling pressure and the plastic deformation and residual stress of the fillet, and provided theoretical support for the evaluation and detection of the crankshaft rolling quality.

A model of crankshaft under working condition is established based on LS-DYNA. The stress distributions of crankshaft and its regularities of the stress along surface of crankshaft and layer depth at the fillet are studied. The results show that the obvious stress concentration exist in the upper end of fillet on main journal and the lower end of fillet on rod journal when the piston arrives at top dead center, and the maximum equivalent stress occurs at the fillet on rod journal, so the fracture of crankshaft is most likely to occur in the lower end of fillet on rod journal. With the increase of depth, the stress on the surface of fillet reduces correspondingly, and the equivalent stress begins to stabilize when the depth reaches up to 2.8 mm. The study of maximum working stress provides the theory basis for the selection of residual stress.