Modeling and Analysis of Truck Mounted Concrete Pump Boom by Virtual Prototyping

By far there is lack of research on different working conditions between rigid and flexible dynamics of truck mounted concrete pump booms. First a 3D model has been established by using virtual prototyping technology of a 37 m long boom in Pro/Engineering software. Then the rigid body simulation model has been built. Next modal superimposition method is adopted to change the 4 rigid body booms into flexible ones. Kinematics law and dynamic characteristics of 4 common working conditions had been studied then. Next tip displacement and the first boom hydraulic cylinder force of the 4 working conditions between rigid and flexible models have been researched. Furthermore the first natural frequencies of the structure have been calculated. The results show that the frequency of the horizontal condition has the lowest of all and the roof condition has the largest of all. Besides the cylinder forces of the flexible model are larger than the corresponding rigid ones because of the flexible boom vibration. Finally an experiment has been done on a boom test rig which proved that the established simulation model is reasonable and the frequency results are correct. All of these provide design reference to mechanical manipulator as well as reducing product development cost of such mechanism

Epoxy composite with high thermal conductivity by constructing 3D-oriented carbon fiber and BN network structure

As electronic devices tend to be integrated and high-powered, thermal conductivity is regarded as the crucial parameter of electronic components, which has become the main factor that limits the operating speed and service lifetime of electronic devices. However, constructing continuous thermal conductive paths for low content particle fillers and reducing interface thermal resistance between fillers and matrix are still two challenging issues for the preparation of thermally conductive composites. In this study, 3D-oriented carbon fiber (CF) thermal network structures filled with boron nitride flakes (BN) as thermal conductive bridges were successfully constructed. The epoxy composite was fabricated by thermal conductive material with a 3D oriented structure by the vacuum liquid impregnation method. This special 3D-oriented structure modified by BN (BN/CF) could efficiently broaden the heat conduction pathway and connected adjacent fibers, which leads to the reduction of thermal resistance. The thermal conductivity of the boron nitride/carbon fiber/epoxy resin composite (BN/CF/EP) with 5 vol% 10 mm CF and 40 vol% BN reaches up to 3.1 W m(-1) K-1, and its conductivity is only 2.5 x 10(-4) S cm(-1). This facile and high-efficient method could provide some useful advice for the thermal management material in the microelectronic field and aerospace industry

Epoxy Composites with High Thermal Conductivity by Constructing Three-Dimensional Carbon Fiber/Carbon/Nickel Networks Using an Electroplating Method

Heat dissipation problem is the primary factor restricting the service life of an electronic component. The thermal conductivity of materials has become a bottleneck that hinders the development of the electronic information industry (such as light-emitting diodes, SG mobile phones). Therefore, the research on improving the thermal conductivity of materials has a very important theoretical value and a practical application value. Whether the thermally conductive filler in polymer composites can form a highly thermal conductive pathway is a key issue at this stage. The carbon fiber/carbon felt (CF/C felt) prepared in the study has a three-dimensional continuous network structure. The nickel-coated carbon fiber/carbon felt (CF/C/Ni felt) was fabricated by an electroplating deposition method. Three-dimensional CF/C/Ni/epoxy composites were manufactured by vacuum-assisted liquid-phase impregnation. By forming connection points between the adjacent carbon fibers, the thermal conduction path inside the felt can be improved so as to improve the thermal conductivity of the CF/C/Ni/epoxy composite. The thermal conductivity of the CF/ C/Ni/epoxy composite (in-plane KO is up to 2.13 W/(m K) with 14.0 wt % CF/C and 3.70 wt % Ni particles (60 min electroplating deposition). This paper provides a theoretical basis for the development of high thermal conductivity and high-performance composite materials urgently needed in industrial production and high-tech fields