The Analysis and Optimization Design of Thermal-Electrical Coupling System with Consideration of Numerical Noises

The optimization function for designing is usually not smooth or discontinuous due to numerical noises, which makes the multidisciplinary decoupling and optimization design more difficult. An global multidisciplinary optimization approach with consideration of numerical noises is proposed in this paper. First, the decoupling problem is transferred into optimization in line with the idea of Simultaneous Analysis and Design (SAND). Kriging models are introduced as surrogate models in order to filter the numerical noises, then the location of new samples is determined with the method of Maximum Likelihood Estimation (MLE), in order to reduce repetitive times of decoupling analysis. Second, the multidisciplinary optimization model of coupling systems is set up using the penalty function method. Finally, the proposed model and method is verified through a typical thermalelectrical coupling example.

A System for First Order Reliability Estimation of Solder Joints in Area Array Packages

In this paper, a methodology, and a program based on the methodology, are presented, which, using the reliability of solder joints for various values of design/process parameters, can be estimated in seconds on a personal computer. The proposed methodology accurately captures the behavior of a solder joint in an artificial neural network (ANN) model trained to relate design as well as analysis parameters to fatigue life. The proposed methodology is novel since such simultaneous analysis and design (SAND) procedures do not appear to have been employed until now for reliability estimation of solder joints. The use of Moire´ interferometry as an experimental technique to estimate the analysis-related inputs to the neutral network model is also presented in the paper. [S1043-7398(00)01101-4]

A Comparison of Equality Constraint Formulations for Concurrent Design Optimization

This paper investigates a concurrent approach for design optimization. The method of Simultaneous ANalysis and Design (SAND) is tested in application to three Multidisciplinary Design Optimization (MDO) test problems. A Generalized Reduced Gradient (GRG) optimizer and a Sequential Quadratic Programming (SQP) optimizer are compared with respect to their efficacy in handling three different forms of equality constraints referred to as compatibility constraints in the SAND based optimization procedure. Results highlight the need for both strategies in application of SAND based design to different engineering test problems. More importantly significant savings in the number of analyses required for design optimization are observed when using the SAND approach of concurrent design. SAND based design delivers on the promise of concurrent engineering, namely to develop optimal designs, working concurrently, while reducing design cycle time.