1. Adams/CHASSIS FILE STRUCTURE
SECTION 3
Adams/CHASSIS FILE STRUCTURE

3. Adams/CHASSIS FILE STRUCTURE
What does this section contain?
Databases
Systems
Subsystems
Property Files
XML Data Format
Adams/Chassis File Flow
Bushings

4. DATABASES Vehicle Database (.vdb)
Each model's data is stored in a Vehicle Database (.vdb). A database is a file folder or directory with the extension .vdb. The database contains sub directories, also called tables (.tbl), for different file types.
Databases can be organized to represent:
One vehicle
One vehicle program (with variants)
Common components shared by multiple programs (department-wide library)
Corporate libraries (tires, shocks, bushings, and so on.)

5. DATABASES (CONT.)
There are three major classes of files in the database:
System (stored in system.tbl)
Subsystem (stored in subsystems.tbl)
Property (several tables are possible)
The diagram below shows the file relationship

6. SYSTEMS
System files are also known as Vehicle Configuration Files. They are stored in <model>.vdb/ systems.tbl. System files are the first step in visual data editing. There are three types of systems in Adams/Chassis: front, rear, and full.
System files contain:
Subsystem References - Found in the Subsystem Definition tab in the system editor. Subsystem references include:
References required and any optional subsystems
Optional geometry offset to shift entire subsystem in space
System Parameters - Aspects that affect the model but are not related to a particular subsystem. These are found in the Properties tab in the system editor. System parameters include:
Integrator parameters
Ground height, gravity
Optional requests

7. SYSTEMS (CONT.)
Subsystem References
System Parameters

8. SUBSYSTEMS Subsystem files
Subsystem files are stored in <model>.vdb/subsystems.tbl. They are analogous to the old Adams/Pre data files (.fst, .sst, .rst, and so on).
The primary contents of subsystem files include:
Hardpoints
Parts
Connectors (bushings)
Property file references
Construction options
Subsystem parameters (if applicable)

9. SUBSYSTEMS (CONT.) Below are optional items: Subsystem types: Body
Front suspension
Front wheel and tires
Steering gear
Steering column
Rear suspension
Rear wheel and tires
Below are optional items:
Loading
Instrumentation
Powertrain
Brakes
Controls
Additional rear suspensions (trailers)

10. PROPERTY FILES
Property files represent data for a particular component. Property files contain:
Object attributes
Spline data
Parts
Connectors
Property files can also reference other property files (for example, stabilizer bar property file references a bushing property file for the mounts).
After Adams2007r1, the property files has been merged into subsystem file. Here is the knowledge base article,
ACH-001: Using Property Files Merged into Subsystems

11. PROPERTY FILES (CONT.) Property file types
Following is a list of property file types and their locations in the database:
Aerodynamic forces - aero_forces.tbl
Bumpstops - bumpstops.tbl
Bushings - bushings.tbl
Dampers - dampers.tbl
Drivetrain differentials - differentials.tbl
Powertrain data - powertrains.tbl
Rebound stops - reboundstops.tbl
Springs - springs.tbl
Stabilizer bars - stabilizer_bars.tbl
Steering assistants - steering_assists.tbl
Tire models - tires.tbl

12. XML DATA FORMAT
Three file classes (system, subsystems, and property files) are stored using the XML (Extensible Markup Language) data format. Therefore, all of the files have an .xml extension.
XML Advantage
The XML files are text based, but they have tags that are used to define context of data. These tags are similar to tags used to define context of text in HTML. The files can be viewed in any text editor or Web browser. The advantages of using XML include:
Operating system independence
Self-documenting
You can use third-party tools for viewing and editing. Adams/Chassis can be considered an XML editor.

13. Adams/CHASSIS FILE FLOW
Adams/Chassis Pre-Processing file flow:
Review of basic MSC.Adams terminology
Adams/Solver - The solution engine.
Adams/Solver deck (*.adm file) - The actual ASCII file submitted to Adams/ Solver.
Adams/Solver command (*.acf file) - An ASCII file that contains commands to control how Adams/Solver runs the model.

14. Adams/CHASSIS FILE FLOW (CONT.)
Review of basic MSC.Adams terminolgy (Cont.)
Adams/Solver output files
Graphics (*.gra file) – Contains information on how graphics work.
Request (*.req file) – Contains output for a user-defined set of results.
Results (*.res file) – Contains state results for every entity.
Message (*.msg file) – Contains information about the solver/simulation/ problems.
Output (*.out file) – Contains initial conditions and request; content can depend on output specifications.

15. Adams/CHASSIS FILE FLOW (CONT.)
Because simulations run in Adams/Solver, the chart below shows the Adams/Chassis simulation file flow.

16. BUSHINGS
A bushing is a specialized type of connector in Adams/Chassis. A connector describes the interface between two parts in the model. Bushings represent a compliance between two parts with stiffness and damping parameters specified in up to three translational and three rotational directions. Besides bushings, connectors can be:
Constraints
Fixed
Revolute
Hooke
Spherical
Free (no connection)

17. BUSHINGS (CONT.) Types of Bushings
There are five types of bushings classified based on the method of the force-displacement definition. They are:
Linear
Piecewise nonlinear
Spline nonlinear
Spline nonlinear with hysteresis
The linear type bushing uses the Adams/Solver FIELD statement, but it is analogous to using a BUSHING statement. You can combine linear components with each of the three nonlinear bushing types.
BUSH/ ,I= ,J=
, K =5256.0,5256.0,5256.0
, C = 50.00, ,
, KT = e+000, e+000, e+000
, CT = e+000, e+000, e+000

18. BUSHINGS (CONT.) Piecewise nonlinear
The Piecewise nonlinear bushing uses a FIELD statement with an ARRAY defining the force-displacement profile using slopes and breakpoints.

19. BUSHINGS (CONT.) Spline nonlinear
The spline nonlinear bushing uses a GFORCE statement with a SPLINE defining the force-displacement data points with an AKISPL function interpolation.

20. BUSHINGS (CONT.) Spline nonlinear with hysteresis
The spline nonlinear with hysteresis bushing uses a custom FIELD statement with two different spline nonlinear curves. One curve represents the force-displacement profile with movement in a positive direction while another curve represents the force- displacement profile in the negative direction.
For each of the four types of bushings described above, the damping relationship in any or all six directions may be defined as a linear damping coefficient or a spline force-velocity profile.

21. BUSHINGS (CONT.) Bushing orientation
Each bushing in your system has a default orientation, defined by the subsystem template. You can override this orientation and provide your own by selecting Specify Orientation in the Orientation property dialog box. You then have the choice of specifying euler angle or ZP- XP type orientation.
NOTE: The ZP and XP orientation points are specified relative to the location of the bushing, in the global reference frame. This is different than the MARKER statement where ZP and XP were relative to the part coordinate system.

22. BUSHINGS (CONT.) Bushing subsystem/property file distinction
Parameters related to bushings, or any other components in Adams/Chassis, are often stored in the subsystem and property files. Information intrinsic to the component is stored in the property file. Information related to how the component is used is stored in the subsystem file. The best way to be sure which one you are editing is by looking at the Current Active File text box in the property editor. This shows you exactly which file you are editing.

23. BUSHINGS (CONT.) Property file Subsystem File
Stiffness characteristics
Damping characteristics
Graphics - height, radius
Subsystem File
Scale factors
Orientation