Rong Qiang Liu

A Study on Out-of-Plane Compressive Properties of Metal Honeycombs by Numerical Simulation

To provide theoretical basis for metal honeycombs used as buffering and crashworthy structures, the effect of the cell length and foil thickness on compressive properties of metal honeycombs is investigated by numerical simulation. Numerical results are well consistent with the corresponding experimental results. The numerical results show that metal honeycombs have cyclic buckling when loaded in out-of-plane direction. The thicker the foil is or the shorter the cell length is, the higher the plastic collapse stress is and the plastic collapse stress is much sensitive when cell length is short. The numerical simulation used in this paper can well predict the crush behavior. Single and doubled foil portions of cell walls are also accounted in the FE model. The results demonstrate that the method is effective which can be used in optimization design of buffers.

Dynamics Analysis and Experiments of an Underactuated Cable-Truss Mechanism

While many researchers have investigated the dynamics analysis of underactuated mechanisms in recent years, little work has been published on that with underactuated cable-truss mechanism. Dynamics analysis has important significance in the research of trajectory planning, driven project designing and the optimization design of the mechanisms. The mechanism dynamics equations were established based on Lagrange equation and the dynamics equations corresponding to the capture scheme that has been chosen were separately listed. To prove the correctness of the dynamics analysis, the simulation of the capture scheme was presented. Some capture experiments were done in order to verify the adaptive capture function of the underactuated cable-truss mechanism.

Thermal Tuning of Vibration Band Gaps in Thin Phononic Crystal Plates with Nitinol

Vibration band structures of thin phononic crystal plates (PCPs) with square array and graphite array of nitinol inserts are calculated by the plane wave expansion (PWE) method. The influences of filling fraction are considered when investigating the effects of the varying temperature on the band gaps. Vibration band gaps of these PCPs can be tuned by changing temperature. This study will be useful in designing PCPs with tunable gaps.

Driving Characteristic Analysis of a Planar Deployable Support Truss Structure for Space Antenna

As the development of space structures is increasing fast, analysis on the characteristics of those deployable structures deserve to be paid enough attention to ensure a reliable deployment on orbit. For a deployable truss structure, more than one position can be chosen as the driving positions, especially when the structure has not only 1 degree of freedom (DOF), an available choice of the driving positions shows significant importance on the performance of the space deployable structure. This paper mainly deals with a planar deployable support truss structure for space antenna by means of the closed loop equations and the Kane equation to discuss the deployment characteristics by comparison of the driving torque needed over time. A full comparison of all the possible examples of deployment analysis results under different driving modes is presented. The results show the importance of the choice of driving movements and the design of parameters and also provide a useful reference to other related truss structures.

Design and Optimization of Magnetic Levitation Actuators for Active Vibration Isolation System

Actuator based on Lorentz force exhibits excellent isolating performance with its non-contact characteristic, especially during frequency bandwidth below 5Hz. In this paper, mathematical model of the magnetic levitation actuator is constructed. In order to obtain better performance, parametric design of the structure of magnetic actuator is carried out and a multi-objective optimization method is proposed to maximize Lorentz force and minimize the mass of coil on the basis of genetic algorithm in the optimization process. A designing optimization program is developed, by which optimized parameters of magnetic actuator with maximal actuator force and minimal mass of coil can be identified to conduct experiment on ground. Compared with initial values in an instance, the optimized method is proven to be feasible and has the value of practical application.

Kinematics Modeling and Driving Spring Design of Truss Structure for Deployable Truss Antenna

To design a truss structure of deployable truss antenna with 7 modules and ensure that the truss structure can be deployed successfully in space environment, kinematics equation of single module with homogeneous coordinate transformation method is built based on the structure and deployment principle of truss structure. By using dynamics software ADAMS, simulation analysis on the deployment is carried out and the driving force of single module is obtained in the ground condition. On this basis, driving spring is designed, and all the important design parameters are obtained. The analytical results show that the driving spring can meet the requirement of deployment in the ground condition. So it can be deployed in orbit (0G). This method can be taken as the theoretical basis for the design and deployment experiment of truss structure.

Performance Analysis and Testing of Four-Quadrant Position Sensitive Detector

The working principle of four-quadrant position sensitive detector(4Q-PSD) as a spot center position measurement detector is presented. Influence of the photoelectric non-uniformity of detector and background light on the detector measurement precision is analyzed. The operational circuit to solve the relationship of spot center position in the coordinates of detector and detector output voltage is designed. And the detector performance testing system based on laser alignment measurement is developed. The relationship between the output voltage of detector and the spot center position in the coordinates of detector is tested. The linearity of output voltage and spot center position in the uniaxial direction of the detector within a small range is good. The influence of measurement distance on the accuracy of the detector is tested. Method of 2-D plane calibration of the 4Q-PSD is proposed, and the detector is 2-D plane calibrated using proposed method. Which extended the available working range of the detector, and with higher measurement accuracy.

Mechanics Analysis of Beam-Like Space Deployable Truss Mast

A kind of beam-like space deployable truss mast with square batten frames supported by four longerons and two diagonal cables cross laced per face is described. A simple method for deriving mechanics parameters of the mast is presented. Element loads for mast to maintain self-equilibrating structure are calculated. Symbolic equations for the axial, bending, shear, torsional stiffness and bending strength of the mast are derived based on proposed method. Equations derived by simple method are consistent with expressions for the effective continuum mechanics of beam-like truss derived previously based on equivalent continuum method, these equations are helpful for mast preliminary design and mechanics analysis. Influence of mast structural parameters on mast stiffness and strength is analyzed, mast stiffness and strength can been improved by selecting reasonable structural parameters.

Design Optimization of Opposite Tape-Spring Flexure Hinges

An optimal design method for the qusai-static folding and deployment of opposite tape-spring flexure (OTSF) hinges is presented based on the response surface method. The full factorial method is employed to design of experiments, and the qusai-static folding and deployment nonlinear analysis is obtained by ABAQUS/Explicit slover. The surrogate models of the OTSF flexure hinge are derived by the response surface method. Considering lightweight and high stability, the peak moment of quasi-static folding and deployment, and maximum Mises stress in complete folding configuration as well as mass are set as the objectives to get the optimal performances. The modified NSGA-II is used to seek for an optimal design. The relative errors of the objectives between the optimal design and the FE analysis results are less than 3.5%.

Effects of Material Parameters on Longitudinal Vibration Band Gaps in Thin Phononic Crystal Plates

The improved plane wave expansion method is used to investigate the effects of material parameters on the longitudinal vibration band gaps in thin phononic crystal plates. Both square lattice and graphite lattice are considered. Results show that the parameters playing the essential roles are the mass density ratio and the Young modulus ratio of the scatterers and the host materials.