Abstract: Free vibration of thermal post-buckled functionally graded material (FGM) beams in a uniform electric field subjected to both temperature rise and voltage is studied. Voltage has a great influence on the deformation of the beam, and Thermo-electric post-buckling equilibrium paths and characteristic curves of the first three natural frequencies versus the temperature, the electricity and the material gradient parameters are plotted. It is found that the three lowest frequencies of the pre-buckled beam decrease with an increase in the temperature, but those of a buckled beam increase monotonically with the temperature rise. The results also show that the tensional force produced in the piezoelectric layers by the voltage can efficiently increase the critical buckling temperature and the natural frequency.
Abstract: Aim at the problem of near surface blind area in ultrasonic TOFD technique, a new testing mode combined to ultrasound time of flight diffraction-reflection(TOFDR) and the three-fold reflected(TOFDW) based on secondary longitudinal waves was put forward. Through analysis the transmission characteristics of TOFDR and TOFDW, the two modes of the detection principle were illustrated, and discussed the ability in near surface detection of the two methods. Finally through the detecting artificial defects detection, the signal and image characteristics and detection sensitivity under the modified detection mode were studied. The artificial defect with buried depth of 1mm can be effectively detected from the D-scan image by the combined TOFDR and TOFDW methods.
Abstract: A real-time WPNN-based model was present for the simultaneous recognition of both mean and variance CCPs. In the modeling of structure for patterns recognition, the combined wavelet transform with probabilistic neural network (WPNN) was proposed. Input data was decomposed by wavelet transform into several detail coefficients and approximations. The approximation obtained and energy of every lever detail coefficients was for the input of PNN. The simulation results shows that it can recognize each pattern of the mean and variance CCPs accurately, which can be used in simultaneous process mean and variance monitoring.
Abstract: The centrifugal acceleration generated by centrifuge is used to simulate the linear acceleration in multi-parameter combined environmental test. To resolve the problems of current centrifuges, such as difficulty to maintain the balance of their arm and difficulty to install many devices on their arm, as their arm was cantilevered, a disc centrifuge which had large capacity of its arm was developed in this paper. The structure of the centrifuge was described in detail. To perform as a platform for other environmental test devices, power and compressed air for the devices on the centrifuge arm were supplied by slip ring and swivel joint respectively. Finite element analysis on the key parts of the centrifuge was performed to ensure their stiffness to meet the requirements. The control system and the precision of the centrifuge were also analyzed. Experimental results show that the centrifuge is slow to start and stop, and works smoothly, and that the acceleration generated by the centrifuge is stable, and that there is little influence on the power network when the centrifuge starts. The linear acceleration is simulated by the centrifuge quite well.
Abstract: The developing and application of activating flux which can dramatically increase the depth of weld bead penetration and improve the properties of weld bead using fusion welding process was summarized. The mechanisms of the activating flux increasing the depth of weld bead penetration especially the theories of arc constriction and the change of temperature gradient of surface tension were analyzed. The research work indicates that the activating flux will be used in more welding process to obtain deep weld penetration, high productivity, low deformation and excellent joint mechanical properties.
Abstract: This paper based on a settled type of structure concerning hydraulic excavator rotary platform as the research object, use the method of finite element analysis to build the finite element model in the conditions of three typicals of representative working condition about this rotary platform. By the analysis concerning the strength and stiffness of this platform structure based on the builded model, the weak link about this structure can be find out by us. Finally , according to the optimization structure design about this device, the maximum combined stress related to the easy fatigue failure area in all working condition could be significantly reduced from 162.93MPa to 115.05MPa, decrease by 29.4 percent. Thus, the structure performance could be greatly improved on the premise of guarantee the weight of construction.
Abstract: Magnetorheological materials belong to a kind of new intelligent materials and their application prospect is very optimistic, however electromagnetic relations are very complex, and with the outside world and boundary conditions have close relations, so each model and theory has its pertinence and limitations, hard to get the universal unified the constitutive relations, so this paper based on energy, gets a set of magnetorheological materials about the theory.
Abstract: The characteristics and mechanism of parallel polygonal line groove multilayer winding drum were investigated by an experimental approach. Strain-electricity method was used to test the stress of the cylinder body and the end plates of the drum. Experimental results show that the distribution of the axial bending stress on cylinder body is symmetric in the radial symmetry section. The largest axial bending stress appears in the symmetry plane; however the minimum stress is in the sections close to the end plates on both sides. The axial bending stress of the cylinder body is found to grow with the number of layers wrapped around the drum increasing, while the increment of the stress decreases. When the layer number of the wire rope increases from 4 to 5, the increment of the stress is less than 3 [MPa].
Abstract: Virtual prototype technology as a new design means, is applied in engineering design and mechanical system performance more and more. In this paper, the change rule of the speed of cloth rolling machine was inferred according to the work principle of the machine. And then the model of the cloth rolling machine was designed, and imported it into the ADAMS software. At last, have a simulation analysis of the cloth rolling machine with the ADAMS software. From the simulation analysis can know that the characteristic of motion of the cloth rolling machine is reasonable.