To evaluate the control performance of the PID controller for the cars, a 3D car dynamic model with 8-DOF which can fully reflect the pitch and roll of the car body is proposed in this study. The PID controller is then researched and applied to control the active suspension system of the cars under the different excitations of the road surface and the various car speeds. The control performance for improving the ride comfort of the driver is evaluated via the root-mean-square (RMS) of acceleration responses of the vertical driver's seat, pitching and rolling car body angles. The research results show that the PID controller for the car suspension system have an obvious impact on reducing the vibration and controlling the car body shaking in comparison with the passive suspension system.

In this paper, discrete wavelet transform (DWT) is used to analyze the acceleration signals near to the loose bolt, in order to study the characteristics of bolted joint condition. Firstly, an experimental system is built based on the NI data acquisition equipment. Secondly, based on qualitative analysis of the loose process of the bolted joints and spectrum analysis of response signals, an appropriate wavelet function is chosen and decomposed levels are determined. Lastly, according to the amplitude of each level, the contour diagrams are drawn and the Root Mean Square (RMS) of detailed coefficients at the sensitive level is calculated. Experimental result shows that both DWT contour diagrams and RMS at sensitive level have significant difference when preload changes.

using polyetherketone(PEK), modified polytetrafluoroethene(PTFE), modified glass fiber, zinc oxide and asbestos fiber as raw material, use self-made portable gasket production device to produce gasket. gasket is installed on the flange that is on specially crafted oil high temperature detecting device pipeline, and use the flue gas monitor device detect sealing. The experimental results show that, When the mass percentage of the material were: ketone28%, modified PTFE 26%, modified glass fiber 7%, zinc oxide 23% and asbestos fiber 6%, conducting oil temperature of 350 °C, the pressure ≤ 0.5MPa, it did not detect the leakage of heat conducting oil .contrasting stainless steel gasket spiral wound gasket, special oil resistant asbestos mat, this composite material is more suitable for special high-temperature heat-conducting oil sealing.

Based on the vibration mechanics theory and system’s state equation, the state-space model of the flange bolted-joints structure is established. According to the dynamic characteristics of bolted connection, the parameters of the state-space model, such as rigidity and damping, can be identified. The accuracy of simulation model is validated, by comparing the simulation analysis results with the vibration test results, and an efficient method of recognition or fault diagnosis of bolted joints in vibratory environment is proposed.