Key Engineering Materials Vols. 326-328

Abstract: The behavior of a circular piezoelectric actuator for volumetric micropump has been investigated by using theoretical and finite element analyses. A modified theoretical model was developed to predict the behavior of a piezoelectric actuator induced by the applied voltage. The theoretical results for the diaphragm deflection were in good agreement with the results from numerical simulation. Based on the theoretical analysis, the effects of several important parameters on actuation performance have been investigated. These parameters include the dimensions and mechanical properties of the piezoelectric disk, bonding layer and elastic diaphragm materials. Consequently, it is thought that above theoretical model might be employed as a tool for design and optimization of the piezoelectric actuator for micropump application.

Abstract: A novel core-shell material composed of closely packed gold shells on poly (divinylbenzene) (PDVB) cores was fabricated via the reduction of a gold complex. PDVB beads (2-5 +m) were synthesized by precipitation polymerization. The surface of the PDVB beads was modified by three different methods, viz. sulfonation, chloromethylation, and thiolation. The modification of the surface of the PDVB beads was designed to allow the facile attachment of the gold layer onto the PDVB cores. The gold seeding layer was initially formed on the modified PDVB cores by the chemical reduction of a gold-phenanthroline complex. The subsequent growing reactions of NH2OH and HAuCl4 increased the gold coverage to more than 90%. The structure of the PDVB/Au core-shell material was characterized by SEM, XPS, and FT-IR.

Abstract: Flexible and thin conductive films of poly(3,4-ethylenedioxythiophene) (PEDOT) on PET substrate were obtained by an in- situ vapor-phase polymerization (VPP) method using ferric toluene sulfonate as an oxidant. The addition of epoxy acrylate resin used as a binder to provide adhesive strength between PEDOT and PET also afforded the possibility of the surface patterning through UV exposure. The electrical and optical properties of the conductive PEDOT films were characterized by UV-Vis spectroscopy and conductivity measurement. Surface resistance below 150./sq. was achieved for 100 nm thick films with UV-vis-spectrum transparency exceeding 80%. The combination of these properties makes the films highly suitable for numerous device applications.

Abstract:
In order to control the IPMC (Ionic Polymer Metal Composite) actuators, it is necessary to use a vision sensing system and a reduced order model from the vision sensing data. In this study, the MROVS (Modal Reduced Order Vision Sensing) model using the least square method has been developed for implementation of the biomimetic motion generation. The simulated transverse displacement is approximated with a sum of the lower mode shapes of the cantilever beam. The NIPXI 1409 image acquisition board and CCD camera (XC-HR50) are used in the experimental setup. Present results show that the MROVS model can efficiently process the vision sensing of the biomimetic IPMC actuator with cost-effective computational time.

Abstract: The aim of present paper is to experimentally investigate the dynamic strength characteristics of LNG cargo containment system under impact loads. A series of impact tests for full-scale MARK III insulation system is undertaken using a custom-built drop test facility as varying height and weight of the drop object. Based on a series of repeated drop tests, displacement recovery was measured for the assessment of damping characteristic of insulation system. Crack initiation was also measured during the cyclic drop test. The quantitative relationship between impact load and crack initiation as well as the crack propagation with respect to drop number are derived.

Abstract: In this paper, a numerical model to simulate the interaction of pile-soil based on the one-dimension stress wave theory is established, which can provide the propagating process and reflection characteristics of stress wave under impulsed load in concrete piles. The simulation is carried on about the stress wave in integrated pile and defective pile, which provide all kinds of the propagating characteristics. It can enhance the accuracy of dynamic test. The validity of this approach is verified through the comparison of the measured curve and the simulated curve.

Abstract: The amount of the external impulse exerted on the object being sawn has been treated one of important control parameters. At the same time, the internal impulses experienced in the joints should be taken into account to avoid serious damage or injury at the joints of robot. This paper discusses the impulse models in a straight sawing task. And, a motion planning algorithm is proposed, which employs the external and internal impulses as performance indices. For this, the gradient projection method is employed to exploit the kinematic redundancy of the robot structure. Finally, through both simulation and experimentation for the sawing task, the effectiveness of the proposed motion planning algorithm could be verified.

Abstract: The dynamic behaviour of ceramic particle reinforced metal matrix composites (MMCs) is a key to its application. In this paper, the computational micro-mechanics method (CMM) is used to simulate SHPB experiment of MMCs. The numerical SHPB’s specimen of MMCs is firstly generated by CMM. Then, for verifying the correction of numerical experiment, the Al2O3/6061- T6Al composite is used to carry out numerical experiment, and the Johnson-Holmquist (JH-2) damage model is used to describe the ceramic mechanics behaviour, and a comparison between this numerical method and Unit Cell analytical model is carried out. Lastly, the dynamic behaviour of T6061Al/Al2O3 is investigated by this method.

Abstract: Many structures and buildings such as nuclear power station and chemical plant are often subjected to impact and explosive loadings. The understanding of material response to highamplitude, short-duration, impulse loads is very important, dynamic behavior of concrete under high strain rate has been paid much attention to. In the present paper, experimental study on the dynamic tension behavior of concrete is carried out. Based on the former theoretical introduction, dynamic splitting tensile tests at different strain rates are conducted on 74mm diameter concrete specimens in a Split Hopkinson Pressure Bar to study the effect of strain rate on the dynamic tension behavior of concrete. The mechanism and speed of crack propagation of concrete cylinder planar surface in dynamic splitting tensile test are discussed briefly.

Abstract: Stress-strain curves of some kinds of materials at high strain-rate conditions were able to be determined by a drop weight experiment system which has only to measure the force-time relation using a load-cell but not to measure directly the deformation or deformation-rate of specimen. To evaluate the strain-rate or the strain of the specimen it had been necessary to measure the motion, i.e. the velocity or the displacement of tup and anvil so far. In this new method the velocity and the displacement of the tup and the anvil which contacted the both end surfaces of specimen were calculated using a personal computer on the basis of the equations of motion for the tup and the anvil, respectively. The differential equations, in which the measured dynamic-force versus time characteristics were contained, were integrated by Runge-Kutta method using the personal computer. In the differential equation of motion of the anvil, a spring coefficient K for the rubber cushion beneath the anvil is used. For the first approximation of the coefficient K is assumed to be the value determined by the oscillation method of cantilever beam. The spring coefficient K with high accuracy is determined when the computed strain of the specimen on the basis of the method described above is almost equal to the measured strain of it by using a micrometer caliper after the dynamic compression. The coefficient K with the higher accuracy can be obtained the incremental compression experiment using some kinds of hard stop ring in the prescribed height.