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Non-uniform deformation in the thickness of tubular spun parts is a common problem in the flow forming process and has a significant impact on the performance of spun parts. In this paper, the plastic strain distribution in the wall thickness of tubular spun parts made of Haynes230 superalloy was obtained by the finite element method and microindentation hardness measurements. Moreover, the causes of the non-uniformity in plastic strain distribution were analysed, particularly the effect of main processing factors such as thickness reduction, feed rate and forming passes on plastic strain distribution in the thickness direction. The results indicate that the factors that have significant impacts on uniformity of deformation are thickness reduction and forming passes; deformation in the material is mainly concentrated in the outer layer of the spun part and less so in the inner layer. Furthermore, the plastic strain increases with an increase in thickness reduction, and the number of forming passes with the former process more favourably increasing the plastic strain in the inner layer than the latter. Therefore, in order to improve deformation uniformity in the spun parts, thickness reduction should be increased and the number of forming passes should be decreased when determining the total thickness reduction. This study is equally applicable to other materials.

Flow forming manufacturing technique has a unique advantage in producing thin-walled cylindrical parts, witnessing a growing demand in defense, aerospace and other fields. However, some of mechanisms of flow forming have not been deeply understood yet. Aiming at easily appearing problems of the crack and expanding, a finite element model with implicit code has been developed to simulate backward flow forming process for production of thin-walled superalloy tubular parts. The material displacement and stressstrain field distribution were obtained, impact of material displacement to dimensional accuracy and residual stress of spun part was analyzed; distribution of strain vector along thickness of spun part and its influence on the occurrence of fracture was analyzed. The results indicate that inhomogeneous distribution of material displacement in thickness brings about residual tensile stress in outer layer and residual compressive stress in inner layer of spun part; plastic deformation occurs mainly in the outer layer; shear plastic strain on the outer surface is much larger than the inner, which may lead to fracture on the outer surface. Above research can play an active role in understanding the mechanism of backward flow forming and deepening the understanding of fracture and the optimization of the process parameters.

Turntable is the main bearing component of truck crane, its structural-load-carrying capacity influences the operational capability directly. This paper adopts the HyperWorks software to make topology optimization for the turntable structure of QY70G truck crane, and carry out the finite element analysis and comparison for the models before and after optimization, which provides an effective method to improve the turntable structure of truck crane. Turntable is one of the important components of truck crane，it bears hoist boom、lifting、luffing mechanism and bob-weight and so on, it is the transfer center of truck crane when it works, the structure will directly affect the lifting performance of the machine. But, the rotary table structure design is affected by the vehicle shape size and installation and space layout. The traditional design method is based the experience of analogy to check by finite element software, it is difficult to get the design scheme which meets the requirements given above and own better strength and stiffness, it also have the disadvantages of long design cycle and large workload. This article is based on the finite element method and structural topology optimal idea, by means of HyperWorks-OptiStruct, makes finite element analysis for the turntable structure of certain QY70G truck crane, and carries on the structural topology in the condition of setted installation location and space, in order to obtain the ideal design plan.

This paper fusions advantages of the grey forecast, fuzzy control and the traditional PID control, puts forward the grey prediction fuzzy PID control method. This method is based on PID Controlling Regulation determine interrelated parameters with the fuzzy reasoning, use online grey prediction theory forecast the system outputs which instead of the controlled object measurement value to exert feedback control for the system. The simulation results show that this control ways have more excellent control quality than traditional PID and Fuzzy PID.