Opting for Optimizing, Part 2

By Pamela J. Waterman

In part 1 of this article, we discussed how optimization helps engineers take their designs to the next level by systematically finding design alternatives. We looked at optimization tools from VR&D, SIMULIA, Red Cedar Technology, and Collier Research. This month, we continue the discussion by examining solutions from Altair, Sigma Technology, ESTECO, Phoenix Integration, Optimal Solutions Software and Openeering.

From Weight Reduction to High-Level Optimization

Altair Engineering’s Hyperworks division has been developing optimization tools since 1994, to such an extent that it now has one of the world’s largest organizations addressing various aspects of the subject. The company offers two software choices that help make optimization tasks an integral part of a complete design process  —  Altair OptiStruct and Altair HyperStudy  —  as well as several engineering services.

Altair OptiStruct is a finite-element-based package with an internal solver that uses a gradient-based topology approach to developing lightweight, structurally efficient designs. Given input for size requirements, targeted design parameters and manufacturing process parameters, OptiStruct helps users generate feasible, manufacturable products. Advanced capabilities include optimizing laminate composite ply-up sequences, incorporating multi-disciplinary responses (e.g., buckling or heat transfer), and dealing with multi-body dynamic systems. The latter task is handled via the company’s own Equivalent Static Load Method (ESLM).

Altair HyperStudy applies the concepts of design optimization to a range of tasks  —  from product weight reduction and design of experiments to multidisciplinary studies and stochastic investigations of reliability/robustness factors. HyperStudy is a solver-neutral optimization package with direct interfaces to dozens of popular solvers such as Abaqus, ANSYS, Fluent, LS-DYNA, MARC, Matlab/Simulink, NASTRAN and StarCD. Users can tap an API tool to bring in external related algorithms, while post-processing and data-mining tools help users sort and analyze results.

Another Altair division, the global ProductDesign group, is dedicated to offering client and online resources that include “useful, informative and inspirational content concerned with minimizing the weight of products across industry.” As part of highlighting advances in lightweight design techniques, materials technology and manufacturing processes, the group offers the latest in relevant news at its Enlighten Knowledge Center blog.

Optimization Options Worldwide

Optimization, as with all aspects of engineering design, is clearly a global subject. Two other significant contributors to this field are Sigma Technology of Moscow and ESTECO of Trieste, Italy. Both have US distributors and years of US applications; they share dozens of case-study experiences on their websites.

With Isight optimization software, users can employ graphic “sliders” to see, in real time, the combined effects of changing up to eight individual design variables at once. Here the (Factor of Safety > 2) constraint is overlaid (shaded area) on the predicted value of maximum von Mises stress. Image courtesy of SIMULIA.

For more than 25 years, Sigma Technology has worked to integrate mathematical models, engineering prototypes and exploration methods inside an environment of unified optimization. The result has been an innovative new generation of multidimensional, nonlinear optimization technology termed “indirect optimization based on self-organization (IOSO).” This statistical approach solves practical engineering tasks with non-convex, non-differentiable and stochastic objective functions.

The critical aspect to this approach is the search of optimums in each iteration as two steps:

1. constructing the functions that approximate the objective functions in some region; and then

2. searching for extremum of these functions.

Key to IOSO’s success is its ability to handle tasks involving 100 independent design variables and up to 100 constraints. Its multidisciplinary, multi-objective approach can determine the optimal practical solution that could be implemented with high probability for the given production technology level. The software achieves major processing speed-ups through the use of parallel optimization algorithms, and offers direct integration to FLOW-3D, ANSYS Workbench, FlowVision, Concepts NREC, SolidWorks and Excel.

ESTECO is the developer of modeFRONTIER optimization software. The package offers multi-objective optimization techniques that overcome traditional simplification problems by keeping objectives separate during the optimization process. The company points out that in cases with opposing objectives (minimize a beam’s weight and its deformation under load, for example), frequently there will be no single optimum because any solution will be a compromise. The role of the optimization algorithm, then, is to identify the solutions that lie on the trade-off curve known as the Pareto Frontier, named after the Italian-French economist Vilfredo Pareto.

Through its multi-objective robust design optimization (MORDO) module, modeFRONTIER also helps users perform a design analysis to check on a system’s sensitivity to manufacturing tolerances or small changes in operating conditions. ESTECO has a number of strategic business partnerships with such companies as CD-Adapco, ANSYS, Siemens and SolidWorks.

Take the Next Step Toward Improvement

Once you’ve investigated the general benefits of optimization software, you’ll find even more software options to consider. Check out PHXModelCenter MDO software from Phoenix Integration; Optimizer and Sculptor Core from Optimal Solutions Software; and the open-source SciLab, used by Openeering to create a multi-objective optimizer. Different approaches, application focal areas and price points across the marketplace mean that there’s bound to be a solution that works for your needs.

Structural (FEA) optimization is a mature, robust technology, useful with many applications. Multidisciplinary optimization has shown itself to be a powerful tool for saving time and money. As an example of time saved with Red Cedar Technology software, Ryan notes that previously one customer spent 12 man-weeks manually investigating a military product design using DOEs and response surfaces, but could not find even one feasible solution. The customer then requested 250 evaluations using HEEDS MDO software; after just three days and 200 simulations, HEEDS already had found 63 possible designs that met all design requirements—and identified one with a very high performance/cost ratio.

Today’s computing power and memory capabilities are making this progress possible, so that highly detailed designs don’t have to be simplified to be evaluated. As Collier says, “This is the decade of optimization.”

Contributing Editor Pamela Waterman, DE’s simulation expert, is an electrical engineer and freelance technical writer based in Arizona. You can send her e-mail to [email protected].

MORE INFO

Altair
Autodesk
Collier Research
MSC.Software
ESTECO
NISA Software
Openeering
Optimal Solutions
Phoenix Integration
Red Cedar Technology
Sigma Technology
SIMULIA
Vanderplaats Research & Development