Chun Jie Wang

Robust Topology Optimization of Structures Under Loading Uncertainty

A new efficient and accurate approach to robust structural topology optimization is developed in this work. The objective is to minimize the expected compliance of structures under loading uncertainty. The new approach is akin to a deterministic multiple load case problem where the load cases and weights are derived by numerical methods. Efficient and accurate methods to compute expected compliance and its derivatives are developed for both concentrated and distributed uncertain loads. The Monte Carlo method and matrix decomposition are employed for concentrated loads, and the Karhunen–Loeve expansion and its orthogonal properties of random variables are used for distributed loads. Numerical examples using the modified solid isotropic material with penalization approach are provided to demonstrate the accuracy and efficiency of the proposed approach.

Truss topology optimization under uncertain nodal locations with proportional topology optimization method

ABSTRACT This paper presents an approach to solving truss topology optimization problem with small uncertainty in the locations of the structural nodes. The nodal locations in the truss are assumed to be random, and the probabilistic method is used here to deal with the uncertainty. The objective of the optimization problem is to minimize the mean compliance of the truss structure under nodal location uncertainty. It is a well-acknowledged barrier to compute the inverse of the structural stiffness matrix which involves variations in the optimization problem. In this paper, based on Neumann series expansion, this optimization problem can be recast into a simpler deterministic structural optimization problem. In order to avoid the sensitivity calculations for the objective function, the proportional topology optimization method which shows comparable efficiency and accuracy with gradient-based method is used. The numerical examples demonstrate the effectiveness and high efficiency of the proposed approach, and further illustrate that the optimal truss topology can be dramatically impacted by nodal location uncertainties.

Large SAR Antenna Deployable Structure Design and Optimization

Remote sensing satellites equipped with large synthetic aperture radar (SAR) can image the earth in all weather and lighting conditions. For high packaging efficiency in launch and precise configuration on orbit, deployable mechanisms are designed to deploy the large SAR antenna panels. For the two-panel antenna, a six-bar-linkage deployable driving mechanism is designed. According to the design, a parameterized dynamic model is built in ADAMS software with secondary development technology to obtain its dynamics characteristics through simulation analysis. To improve the dynamic characteristics and the precision of deployment design of experiments and optimizations were carried through in this paper.

Effects of Different Solder Alloys on Reliability of 3D PLUS Solder Joint

Thermal cycling was applied to assess the effect of tin-lead solder 63Sn37Pb and lead-free solder 95.5Sn3.8Ag0.7Cu on the reliability of 3D PLUS solder joints. Nonlinear finite element method and viscoplastic Anand model were used to evaluate the stress and strain distribution and dangerous position of solders under the thermal cycling condition. The law of solder joints stress and plastic strain were finally obtained and showed significant cyclical changes. The stress and strain emerged the trend of accumulated enhancement with the process of time, then ultimately stabilized. Comparing two curves of equivalent stress and plastic strain obtained from lead-free and tin-lead solder, it was found that the reliability of 95.5Sn3.8Ag0.7Cu was better than that of 63Sn37Pb.

Reliability Analysis of Deployment Mechanism of Solar Arrays

This paper contraposed the reliability analysis of deployment mechanism of solar arrays. First, the configuration and function of solar arrays were described briefly. According to the deploying principle of mechanism, the model of the reliability was established in order to make the calculation and analysis of structural reliability. There was some propose to improve the reliability of the system according to the weakness from the analysis. Secondly, from two aspects of static torque margin and torque, the motor function reliability analysis of deployment mechanism of solar arrays was developed

Design and Development on the Processing and Managing System of Spaceflight Products Analysis and Experimental Data

Based on analysis of problems in spaceflight products R&D data process and management, a solution is proposed in this paper. An analysis and experimental data processing and managing system is realized in a WEB environment based on B/S frame. This paper has also introduced the composition and principle of the system.

Dynamic Analysis of Extendible Support Structure Deployment

To study the dynamic behavior of the extendible support structure deployment, a digital simulation using the multibody system dynamics methodology is conducted. Floating frame of reference formulations are used to establish the flexible dynamics model, in which the deformation vector of each flexible part is modeled with the component mode synthesis technique based on the Craig-Bampton method. Modal truncation is implemented through modal participation factors to reduce the computational burden. Angular displacements results of antenna panels as well as those of truss rods are then obtained and show that all parts of the structure have reached accurate positions and keep stable after deployment as expected. Start torque of the driving motor is also acquired and proved acceptable according to the design requirements. Impact forces acting on the hinges at locking moment are finally extracted to evaluate performances of locking processes.

Research on Automatic Design of Extendable TrussBased on CAD Software

This paper provides a method of automatic design for extendable truss based on CAD software. The method mainly consists of parametrical design, automatic assembly, interference checking and extraction of model properties. With Visual C + + as programming language, secondary development was done on automatic assembly and other related modules of CAD software, which can achieve parametrically automatic assembly, interference checking and automatically extracting properties of extendable truss model. Thus, this method can guide the design staff performing program design, improve the correctness and accuracy of design, shorten the design cycle of extendable truss and also has reference value on rapid design and development for other products.

A Citrix XenApp and Web Based System for Product Design and Management

This paper describes a system for product design and management. The system based on Citrix XenApp and Web to take advantage of common CAD softwares own interfaces for product design as well as provide user friendly web interfaces to manage product models. The innovation of this work lies in its concept concerning integrating Citrix XenApp and Web application to produce a highly interactive product design environment while keep those merits of the Web, such as ease of use, collaboration, cross-platform capability, controlled access, etc. In this paper, we first give an overview of the system architecture and then describe the highly-interactive product design environment and product model management interfaces. And at last we talk some issues and approaches used to achieve integration of Citrix XenApp and Web application to realize the efficient design and management system.

The Application of Modal Synthesis Method in the Processing Center Dynamics Analysis

Modal synthesis method is a method which can reduce structural degrees of freedom, it is applicable for analysis and calculations of Machining centers and other large-scale structure. In this paper, the dynamical performance of Five-axis boring and milling processing center was studied with component mode synthesis technology . Compared with full model FEM, component mode synthesis technology could meet the accuracy requirements and have higher computational efficiency. Modal characteristics of processing center in different positions was studied, the result showed that each frequency of processing center in different position was different while the vibration mode remained unchanged.