Manufacturing

First Look: SimDesigner Enterprise--A Specialized Tool Set for Specialized Needs

1 Mar, 2006 By: Jeffrey Rowe

SimDesigner Enterprise from MSC.Software works within CATIA to provide powerful simulation capabilities for automotive suspensions and other assemblies.


I'll Admit UP front that SimDesigner Enterprise is a specialized simulation environment that can be used to model components, assemblies and vehicle suspension systems within CATIA. Suspensions may not be the most attractive part of a vehicle, but these complex subsystems are vital components of any vehicle's safety, handling and overall performance. Like other engineering simulation products, SimDesigner Enterprise lets you create, analyze and review results of virtual prototypes.

 SimDesigner Enterprise
SimDesigner Enterprise

SimDesigner Enterprise embeds other MSC.Software applications—MSC Nastran, Adams and Marc—and runs in conjunction with CATIA. Because I recently reviewed CATIA (Cadalyst, January 2006, http://manufacturing.cadalyst.com/0106catia/), I was familiar with its user interface and behavior, and that helped in getting acquainted with SimDesigner Enterprise.

Beginning users need to get a handle on a couple of aspects of the application:

Like CATIA, SimDesigner Enterprise uses workbenches—different environments with integrated tools for performing specific sets of tasks such as linear, nonlinear, motion, impact and thermal analysis. SimDesigner Enterprise workbenches are used with existing CATIA subsystems to create and analyze assemblies.

Two levels of components make up a SimDesigner Enterprise model hierarchy (stored in CATProducts). When modeling and simulating suspensions, for example, the suspension assemblies are made up of suspension subsystems that are selectively grouped together.

So what exactly can you do with SimDesigner Enterprise? Basically, you create assemblies by defining vehicle subsystems, such as front and rear suspensions and steering mechanisms. To analyze an assembly, a user specifies simulation inputs, and SimDesigner Enterprise applies them. Examples of simulations possible with this program are:

  • 1. Move wheels through bump-rebound travel and measure the effects on several parameters, such as toe, camber and roll rate.
  • 2. Apply lateral load and aligning torque at the tire contact path and measure angle changes and lateral deflection of the wheel.
  • 3. Rotate a steering wheel and evaluate the clearance, clash and collision between the components.
  • 4. Extract loads form the Motion workbench to apply automatically to the Structures workbench. Extracted loads can be used for component or subsystem analysis with the integrated MSC Nasran application.
  • 5. Define modal flexibility to review the full mechanism and suspension system, including flexible components. Stress is computed using a modal stress recovery technique.

When users review analysis results, they can easily modify parameters to optimize a suspension for desired results—for example, change parameters to yield the best handling characteristics for a vehicle.

With CATIA installed (a prerequisite), installing SimDesigner Enterprise is an easy task. It requires CATIA Generative Part Stress for finite-element analysis.

SimDesigner Enterprise from MSC.Software is a capable tool for designing and testing vehicle suspension systems in CATIA.
SimDesigner Enterprise from MSC.Software is a capable tool for designing and testing vehicle suspension systems in CATIA.

Once everything is installed, the steps for creating and analyzing a suspension model are: build a suspension model, test it, review the results and improve the design based on the results. This cycle continues until the suspension design is optimized according to design needs.

Users start by creating the subsystem. Once a subsystem is created, it can be modified by changing its components (the building blocks that define topological systems). After a suspension is defined, it can be analyzed to understand how it controls wheel motions and transmits loads from the wheels to the chassis using the Motion workbench. The Motion workbench facilitates the addition of entities such as springs, bushings and 2D and 3D contacts for more realistic simulation. It provides postprocessing capabilities for forces, velocities, accelerations and contacts.

Next, specify ranges for suspension parameters, such as vertical wheel travel, wheel base change, etc., as well as the number of steps to run for the analysis. Submit the analysis using SimDesigner Enterprise. Components then can be analyzed for stress, deflection or strain with large deformation.

The Flex module enables users to replace one or more rigid bodies with flexible bodies to achieve more realistic results. Flexible bodies can help capture inertial and compliance properties during handling and comfort simulations, study part deflection and predict loads with greater accuracy by allowing a mechanism to account for flexibility.

During the analysis, the system articulates the assembly in the specified number of steps and applies the inputs. At each step, the system calculates characteristics that can be plotted. Viewing analysis results is straightforward, but remember to click the Load button in the analysis dialog box to load results.

Admittedly, SimDesigner Enterprise is a specialized tool, but if suspensions are part of your design world, this tool should serve you quite well.

Jeffrey Rowe is an independent mechanical design and technical communications consultant. With offices in Colorado and Michigan, he can be reached at 719.539.8549 or jrowe@cairowest.com.


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