Systems Design5 Jan, 2004 By: Adrian Scholes
Almost all 3D design processes involve the creation of virtual assemblies that can reduce the need to produce expensive physical prototypes. For a complete virtual prototyping environment, however, it's not enough to focus only on how parts fit together. You must also emphasize the function of a product and how components interact.
This is where Solid Edge's Systems Design takes over, giving you tools to advance beyond fit to create intelligent, functionally realistic models that emulate real-world situations.
Enabling Solid Edge's unique approach to Systems Design are Systems Libraries, introduced in v14. Systems Libraries let you define and store sets of parts, features, and constraints for reuse as a fully functional system in future projects.
Systems in the library are preloaded with sufficient information to describe how they should relate to other components and how they need to perform to meet known design criteria. Critical relationships are captured and reused, material is automatically added or removed from related components to ensure correct placement, moving parts maintain their predefined paths and loads, and sensors monitor critical distances and other variables that affect the desired performance of the system. In other words, original design intent is captured, stored, and maintained throughout the design process.
Version 15 extends Solid Edge's Systems Design capabilities with:
- Adjustable assemblies that allow placement of the same subassembly to accommodate different positions.
- A new user capability to create and control features at the assembly level and choose how the feature, depending on design intent, will affect corresponding parts. As such, Assembly Features may appear in an assembly, but not necessarily in the individual parts.
- Interactive physical analysis of assembly mechanisms that efficiently validates the motion behavior of assemblies and mechanisms, realistically simulating the interaction between contacting parts as they collide and push each other around.
When working with assemblies, you sometimes need to allow movement within a subassembly while working in a higher-level assembly. For example, if you have two hydraulic cylinders in an assembly, you may need to show the cylinders in two different positions.
There are several approaches to solving this problem. You can create uniquely named subassemblies for each of the hydraulic cylinders so you can assign unique offset values to the affected relationships. This creates extra files and complicates data management.
You can create a single-level assembly with the hydraulic cylinder components placed as discrete parts. This also lets you assign unique offset values to the affected relationships, but makes it more difficult to reuse the hydraulic cylinder components later in another assembly.
Finally, you can use the Adjustable Assembly functionality within Solid Edge V15. As seen in Figure 1, this approach eliminates the need to copy the hydraulic cylinder subassembly data set or to create new single-level assemblies. When you specify that a subassembly is adjustable, you can apply relationships to a part in the subassembly, rather than to the subassembly itself.
Figure 1. The same hydraulic cylinder system was selected from the library and placed in three different locations. Solid Edge eliminates the need to create new assemblies to show the cylinders in various positions. Each system also understands how it should function in the context of the higher-level assembly.
You can specify that a subassembly is flexible in several ways. For example, you can select a subassembly within Assembly PathFinder, and then click the Adjustable Assembly command on the shortcut menu. Only subassemblies that contain parts that are not fully positioned can be marked as adjustable.
Solid Edge V15 introduces two new commands and a few enhancements that you can use to construct material removal features on parts while working in an assembly. You can also specify whether the feature is written to and viewable only from the assembly document (assembly feature) or is written to and viewable from the affected part documents (assembly-driven part feature). This allows you to fully control whether a feature affects only the specific parts it touches or all parts within the same assembly (figure 2).
Figure 2. Assembly features and assembly-driven part features are both created at the assembly level. However, assembly features live in the assembly, not in parts, while assembly-driven part features are pushed into the part level.
These assembly feature commands work like the material removal commands in the Weldment environment in that you can specify which parts are modified. The assembly feature command set consists of:
- A new Hole command for constructing hole features.
- A new Revolved Cutout command for constructing revolved cutout features.
- The enhanced Multi-Part Cutout command is now named the Cutout command to be consistent with other environments.
Solid Edge V15 adds several enhancements to the Move Part command. One key addition is Physical Motion (figure 3). The Physical Motion option added to the ribbon bar detects contacts between unconstrained surfaces and applies temporary constraints between the contacting surfaces.
Figure 3. The D-Cubed AEM Integration provides automatic simulation of mechanisms such as gears, racks, and cams. Once validated, this worm box can be stored in the Solid Edge Systems Library and reused in future assemblies.
With no setup involved, Physical Motion is a great way to detect collisions and observe the realistic effects of contacts and forces that influence a part's movement. As parts collide, they either stop or push each other around, depending on how you defined them in the assembly.
These extended capabilities in Move Part nicely complement Solid Edge's existing Simply Motion environment, which allows designers to run a kinematic analysis that involves multiple parts and forces at once, taking into account timing and other criteria to accurately simulate complex movement.
Beat the system
Close integration of all of these applications helps Solid Edge establish a new benchmark for Systems Design, enabling an understanding of how systems interact with each other when placed into an assembly. Not only can you efficiently simulate and validate the behavior of the assemblies and mechanisms used in your designs, you can also save them as reusable systems that you know will maintain this built-in knowledge and function correctly when applied to future projects. To see a video of Systems Design in action, visit: Solid Edge Online Demos.
See you On the Edge next month.
About the Author: Adrian Scholes
In her easy-to-follow, friendly style, long-time Cadalyst contributing editor Lynn Allen guides you through a new feature or time-saving trick in every episode of her popular AutoCAD Video Tips. Subscribe to the free Cadalyst Video Picks newsletter, and we'll notify you every time a new video tip is published. All exclusively from Cadalyst!