Applied Mechanics and Materials Vol. 307

Abstract: In this paper, design, simulation and optimization of a novel electrothermally-activated polymeric microactuator capable of generating combination of bidirectional lateral and rotational motions are presented. The composite structure of this actuator is consisted of a symmetric meandered shape silicon skeleton, a SU8 thermal expandable polymer and a thin film chrome layer heater. This actuator is controlled by applying appropriate voltages on its four terminals. With the purpose of dimension optimization, a numerical parametric study is executed. The modeled actuator which is 1560 μm long, 156 μm wide and 30 μm thick, demonstrates a remarkable lateral displacement of 23 μm at power consumption of 38 mW and a considerable rotation of about 7.5° at the same power consumption but with excitation of different terminals.

Abstract: Biped robot with heterogeneous legs (BRHL) can simulate amputees dressed with intelligent above/knee (A/K) prosthesis and can be used to evaluate intelligent prosthesis (IP) performance. First the concept of virtual prototype technology and BRHL is introduced. Then virtual prototypes of BRHL mechanical system, ground environment, perception and control system are established. In the end, the continuously walking simulation of BRHL based on virtual prototype is done. The research indicates that virtual prototype modeling based on Pro/E, ADAMS and MATLAB/Simulink is feasible.

Abstract: A kind of mini underwater robot is introduced in this artical. Aim at the situation of shallow water area(5m~30m)，we analyzed and designed the structure of the whole robot pertinently, and calculated the underwater movement resistance, which thereby could give theoretical support on the choice of thrusters. The robot detects the underwater situation effectively by high definition camera that installed in the front of the robot, and achieves lifting and turning movement though 3 propellers. The manipulator installed in above of the robot could grab underwater objects effectively.

Abstract: This paper presents an experimental investigation for deflection control of two degree of freedom building-like structure system against scaled Northridge Earthquake by using PI (Proportional-Integral) controlled active mass damping. Proposed structure consist of two floors with a cart mounted on the second floor such as active mass damping (AMD) and which is used to suppress horizontal deflections. Moreover a shake table under the structure is used to create the acceleration effect of scaled earthquake. Kp and Ki gain parameters of PI controller is determined by observing passive mode behaviour of the structure against Northridge and it is used to control cart movement according to pre-determined deflection criterias of the floors. Deflection and acceleration results of the floors are obtained separately for passive and active mode responses of the system in the form of graphics.

Abstract: This paper demonstrates the modeling of an Electro-Hydrostatic Actuator prototype. The mathematical derivation of the physical model is reported.Parametric model was obtained through system identification.

Abstract: Based on performance comparison of PDM equidistant and conventional elastomer lining, the impacts on the PDM performance were presented with different equidistant lining thickness. According to the Mooney-Rivlin two-parameter model and the Poisson radio equaling to 0.5, the elastomer is incompressible during the calculation and its relational material parameters such as elastic modulus and shear modulus were determined. The PDM stator and rotor curve equations were established according to hypocycloid theory. The lobe configuration is 3:4, the performance comparisons were investigated including deformation and Mises stress between conventional and equidistant elastomer lining of PDM with contact model. The test data pointed out torque, rotation speed, volumetric and overall efficiency variation results with the motor pressure difference changing from 1.93MPa to 5.90MPa. The presented results could be used for PDM design optimization and performance improvement.

Abstract: Fatigue failure of machine components is caused by cyclic load. Non-destructive observation methods that can be related to stress are necessary to study the fatigue phenomena. In the present work, a three-dimensional scanning Hall probe microscope (SHPM) equipped with GaAs film sensors was used to observe the fundamental features of the magnetic fields in a tool steel specimen (SKS93, JIS B 4404: 2006, equivalent to AISI W4 tool steel) during tensile loading. The nature of the magnetic fields during tensile loadings of 430μstrain and 640μstrain was observed using the SHPM. It was found that the magnetic fields decrease due to the tensile loading.

Abstract: Based on the model, it firstly gets the fluid distribution of noise barrier of high-speed railway, which is under the action of train-induced impulsive wind pressure and natural wind load, then transfers the computed result as exported load to the structural analysis module through the coupling interface, by proceeding the transient dynamic analysis and modal analysis, it finally obtains the equivalent stress, total deformation and modal distribution of noise barrier. The results indicate that, compared with train-induced impulsive wind pressure, the natural wind load has a more obvious effect on the structural performance of noise barrier, and its natural frequency is much less than the external load’s, so there will be no resonate happen in practice.

Abstract: Because of reducing aerodynamic drag, the maglev train could run at a high-speed in the partial vacuum tube. Scientists of some conutries such as U.S., Swiss and China, have started the research work on high-speed tube trains. In this situation, evacuated tube transportation aerodynamics becomes an important theory research aspect, in which the main study content is how to calculate aerodynamic drag. Based on the explicit formula for estimating aerodynamic drag on moving body in an infinite boundary surroundings put up by Isaac Newton, the evacuated tube surroundings is analyzed and the explicit formula with blockage ratio as an independent variable for estimating aerodynamic drag acted on trains running in the evacuated tube which is a finite space is deduced. With the calculation case, compared with the results came out from the explicit formula got in this paper and the results got by Fluent software, it was found that those results are closed. Thus, the explicit formula created in this paper for conveniently estimating aerodynamic drag based on trains running in evacuated tube transportation is credible.

Abstract: A multi-objective genetic algorithm is applied into the layout optimization of tracked self-moving power. The layout optimization mathematical model was set up. Then introduced the basic principles of NSGA-Ⅱ, which is a Pareto multi-objective optimization algorithm. Finally, NSGA-Ⅱwas presented to solve the layout problem. The algorithm was proved to be effective by some practical examples. The results showed that the algorithm can spread toward the whole Pareto front, and provide many reasonable solutions once for all.