Adams/CHASSIS FILE STRUCTURE SECTION 3 Adams/CHASSIS FILE STRUCTURE

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

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.)

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

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

SYSTEMS (CONT.) Subsystem References System Parameters

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)

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)

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 http://support.mscsoftware.com/kb/results_kb.cfm?S_ID=1-43315518

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

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.

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.

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.

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

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)

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/1104112,I=1181112,J=1104112 , K =5256.0,5256.0,5256.0 , C = 50.00, 50.00, 25.00 , KT =0.00000e+000,0.00000e+000,0.00000e+000 , CT =0.00000e+000,0.00000e+000,0.00000e+000

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

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.

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.

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.

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.

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