LMS combines real and virtual worlds

LMS International's "hybrid-simulation" approach to virtual prototyping is realized through its Virtual.Lab engineering desktop, which, according to the company, combines the reliability and speed of testing with the rapid prototyping capabilities of virtual models.

To facilitate a shift in the product-development and engineering processes from a "test, analyze, and fix" paradigm toward an industry-ideal "design-right-first-time" model, LMS International—headquartered in Leuven, Belgium—has adopted an approach called "hybrid simulation," which integrates data garnered from physical prototype testing with virtual prototype simulation.

According to Dr. Urbain Vandeurzen, Chairman and CEO of LMS, this hybrid approach can help improve product performance and quality, accelerate the development process—specifically by streamlining relevant data used for modeling and by potentially reducing the number of prototype cycles a component, system, or vehicle must go through—and increase the amount of value-added-engineering time in the process. "Currently, around 80% of CAE time can be 'wasted,'" Vandeurzen said. "The goal is to cut down on trivial items such as information searching, unnecessary data transfers and translations, and duplication of information and testing, and to spend more time on engineering."

Hybrid simulation also calls for shifting the balance of analysis up front, so engineers and technicians can diagnose and refine problems earlier when design flexibility is greater, not after numerous physical prototypes have been built. According to LMS, this is particularly important with "system-level, functional-performance" attributes, such as noise and vibration, ride and handling, and overall comfort, which are subtle details dependent upon the final system and traditionally realized late in the development process. "(The goal is) an engineering process where critical product qualities are designed in, then refined throughout the development process by using up-front analysis at the concept stages, managing refinement and cross-disciplinary product optimization via virtual models, and performing in-depth testing of a reduced number of physical prototypes," said Tom Curry, Executive Vice President and Chief Marketing Officer, LMS.

To help attain these product-development and engineering goals in the automotive industry, LMS will introduce its next-generation product suite, LMS Virtual.Lab, this September. Virtual.Lab is a stand-alone, unified engineering desktop for multidisciplinary virtual prototyping "that allows engineers to freely combine and synthesize system models and load data from test-based, simulation-based, or even empirical sources," said Dr. Jan Leuridan, Executive Vice President and Chief Technical Officer, LMS. "It ties the design, virtual prototyping, and test worlds together."

Virtual.Lab is designed to help engineers solve complex problems at the full-system level by predicting how individual components and subsystems interact as part of a full vehicle.

The technology allows design engineers to combine the "old" with the new. According to LMS, almost 80% of a "new-car" design is actually just a modification of an existing platform. Within Virtual.Lab, test data from existing components and systems can be combined with simulated data of new vehicle features. For example, the effect of adding a new mounting fixture between an existing engine and a choice of alternators from different suppliers can be modeled quickly and accurately, according to the company. It thus can help reduce product-development times while increasing efficiency by reusing models rather than rebuilding them for each application.

Based on the V5 architecture from Dassault Systémes, Virtual.Lab allows full interoperability with CATIA as well as transparent access to other CAD models such as I-DEAS, Unigraphics, and Pro/ENGINEER. It can also import models and analysis results from finite-element (FE) codes, including NASTRAN, ANSYS, and ABAQUS. In addition, the engineering desktop is fully design associative, maintaining the links with the geometry from various CAD systems, and has a unified graphical user interface for all test- and CAE-based analyses, according to Leuridan. "Virtual.Lab is highly graphical and interactive, and combines geometry-related visualizations with the specialized tools developed through 20 years experience in prototype refinement," said Leuridan. "For example, the user can see the predicted sound field of an engine in terms of spectrum traces, waterfalls, FRFs, and color-mapped animated geometries."

As part of the first deliverable set of products, the Virtual.Lab desktop will enable the integration and visualization of data from current LMS CAE products, including CADA-X and Test.Lab (test data), Gateway (test-FE correlation), DADS (multi-body motion), SYSNOISE (acoustic radiation prediction), and FALANCS (fatigue-life prediction) along with other CAE systems, thus providing a common post-processing platform. "Virtual.Lab allows the designer to seamlessly flow from CAD geometry, through automated meshing, to structural analysis and cross-attribute optimization," said Leuridan. "It removes the barriers between CAD and FEA."

This integrated platform can be used to analyze—and optimize—structural, motion, acoustics, NVH, and durability characteristics of a virtual prototype at the full-assembly system level, not just the component level. "Presently, CAE is used mainly for design verification at the component level and almost 'outside-the-process'—not as a proactive design optimization tool," said Leuridan. "While prediction of vibro-acoustic or fatigue-life responses at the component level gives good results, functional-performance attributes such as sound quality or vibration comfort are functions of the individual performance of many components, the myriad of operating loads, and the numerous transfer paths between source and receiver. Virtual.Lab predicts performance at the full-system level, where engineers can reliably assess and refine those functional-performance qualities earlier in the process."

One of the application modules of the desktop is Virtual.Lab System Analysis. It allows the engineer to assemble/substructure components using FRF or modal models developed from either test or FE simulations, to define rigid and/or flexible connectors, to create a full FE synthesis subject to boundary conditions, and to predict the final structural response. All of the visualization tools are built-in for interactive component assembly, transfer path analysis, and result interpretation.

The Virtual.Lab Pre-Acoustics module reduces the complexity of the structural model to reflect only those physical features that will have an effect on the acoustic field; therefore, the acoustic radiation calculation of an engine, for example, becomes significantly faster.

The second module, Virtual.Lab Pre-Acoustics, is an advanced mesher that, according to LMS, addresses a major bottleneck in the current acoustic simulation process: the creation of the acoustic mesh for boundary-element analysis (see AEI, July 2001). This mesh reduces the complexity of the structural FE model, reflecting only those physical features that will have an effect on the acoustic field, and results in a faster acoustic solver run. "This application can reduce pre-acoustic modeling from days to hours," said Leuridan, "and the total acoustic analysis from two to three weeks down to two or three days." He also noted that since a complete acoustic model is created, an analysis of all points is possible as opposed to that of only certain, potentially weak points.

At its launch, the engineering desktop will also include Virtual.Lab Motion and Virtual.Lab Durability modules. With future versions, the desktop's capabilities will be expanded. "Virtual.Lab is going to be open to analysis results for other application codes, and we will actively engage with third parties to develop complementary capabilities for, say, crash and occupant safety, computational fluid dynamics, and any other attributes that our customers need to have," said Curry.

In addition, Leuridan noted that all of Virtual.Lab's modules are intricately linked to one another; they are not completely disconnected applications. "In executing the analyses, full associativity is maintained across the different applications," said Leuridan. "This means that once the virtual loads are applied to calculate the vibration response of the assembly, the structural responses can be used immediately to predict fatigue-life and the sound it would produce. Any subsequent change to the virtual prototype definition can then be propagated in an automated manner through the entire analysis sequence. In this way, alternative design variations can be evaluated and traded-off against each other in a very efficient manner."

"The integrated design, analysis, and testing approach (this product enables) can greatly increase the efficiency of design engineers," said Curry. "They can develop and refine product target specifications at the concept stages using data gathered from the testing of preceding designs and competitive products. They can test, modify, and retest analytical models in simulations that with every run come closer to reality," adding, "Virtual.Lab creates a new type of virtual prototype model that is more representative of the 'real world.'"

- Ryan Gehm