Applied Mechanics and Materials Vols. 155-156

Abstract: Residual stress distribution plays a very important role in welded structures, the aim of present work is to find out the effect of different welding methods on the residual stress distribution by means of neutron diffraction measurements and FE models simulation. 4 mm thick DH-36 steel plates were butt welded by MIG welding process and 5 mm thick AA 2024 aluminium alloy plates were butt welded by friction stir welding process. Results show that residual stresses of MIG welding process are higher than those of friction stir welding process. The peak residual stress of MIG weld is close to the room temperature uniaxial yield strength of DH-36 while the peak residual stress of friction stir weld is just about 50% of the room temperature uniaxial yield strength of AA2024. The size effect of MIG welded and effect of welding speeds of friction stir welded on the residual stress distribution have also been studied in the paper.

Abstract: Considering the pitch channel simplified model of supersonic missile system, a integral type of sliding surface is constructed with the error of overload and the integration of error and the angle speed signal. Base on the linear sliding mode, a simple PS adaptive integral sliding mode controller is designed In order to improve the performance of the proposed method, two improvements also proposed. Finally, a hybrid PISS adaptive control is formed which contains proportion control, integration control, the sign function and soft function.

Abstract: Dynamic vibration and static deformation are two main factors that affect the machining quality in a long slender shaft turning operation. By simplifying the turning system of a slender shaft into a one-section beam with a clamped-pinned constraint condition, the direct receptance at any arbitrary cutting point is derived. On the basis, the regenerative stability lobes diagram (SLD) for a long slender shaft turing operation is achieved. With the proposed modeling methodology and simulation algorithm, the effect of cutting position on the direct frequency response function (FRF) and the predicated SLD, as well as the effect of the cutting conditions on the predicated SLD are investigated. The predicated direct FRF at the cutting point is validated by hammer tests.

Abstract: Because the characteristics of the liquid level control conditioner are nonlinear, strong inertia, time-variant and pure delay, the conventional PID control is often ineffective. A fuzzy immune PID controller was designed based on the immune feedback mechanism and the fuzzy control theory, used the genetic algorithm to optimize the immune PID parameters, established a the liquid level control of water tank control system model, and applied fuzzy immune PID control technology to simulate the liquid level control through Matlab emulation., simulation results show that the control system has the characteristic of rapid adjustment, high regulation enec, therefore it has the feasibility and the promotion of a certain value.

Abstract: The experimental teaching is the indispensable organic part of the public management teaching system. It plays an irreplaceable role in training students’ innovative spirit, practice ability and comprehensive ability. This article does research and exploration of the experimental teaching system for specialties of public management, puts forward a multi-layered modular experimental teaching system which focuses on the cultivation of applied and innovative abilities and the connection between experimental and theoretical teaching. At the same time the specific implementation countermeasure is discussed in this article.