Function and Methods

SISAME-3D performs three-dimensional lumped-parameter Structural Impact Simulation And Model Extraction for vehicle impact events. Static and dynamic load-path parameters and Mass weights can be extracted for given motion and/or load data with a user-supplied model configuration. Fully defined models can be used to simulate a range of events.

SISAME-3D uses a global approach to find the optimal model parameters. Simulation is performed with standard integration techniques.

Features and Options

SISAME-3D provides a number of static and dynamic types. Masses can be simulated or have motions specified by instrument data. Fixed Mass elements can also be specified to represent barriers, poles, and the ground surface. Models can have more extracted load-paths than targeted motions. Defined and extracted load-paths can be combined in the same SISAME-3D run, as can instrumented and simulated Masses. Load-paths can have any subset of axial, torsion, bending, and rotation characteristics. Instrumented Mass motions are filtered to a user-specified cutoff frequency with a special simultaneous motion filter (based on the SimFil program). Extraction iterations are performed when model features preventing a one-pass solution are present.

Multiple-event runs allow extraction of a models that best match a set of events of different speeds or impact modes.

SISAME-3D is driven by self-documenting ASCII input files that specifies the run, model, and output information. Extensive defaulting and input checking are performed. A variety of outputs is available in ASCII or UDS file format, and POV-Ray frame images can be generated for processing into animations. SISAME-3D can produce a simulation-ready extracted model file.

Setup and Run Instructions

The command line syntax is: SISAME3D [input_file]

SISAME-3D will prompt for an input file if none is specified on the command line. Either an Event file for a single-event run or a Master file for a multiple-event run can be specified. A log file containing summary information is created with a .log extension.

Known Problems and Constraints

SISAME-3D modeling is inherently sensitive to motion data errors, particularly when accelerations are provided and small-deflection load-paths are being extracted. Although it is currently a uniaxial tool, the VeCor program can be useful in assessing and correcting motion and loading data prior to its use with SISAME-3D.

SISAME-3D is under ongoing development and additional capabilities will be rolled out in upcoming releases. Limitations of this release include:

• Shape-based contacts are not yet implemented: Links can provide point-to-point contact loads
• No joint, slider, etc. connections: Stiff, heavily damped Links can constrain motions
• Mass instruments and output signals are at Mass CGs for now and in inertial frame only
• The Mass Inertia tensor is not yet extractable

Additional Documentation

See The SISAME-3D Program: Structural Crash Model Extraction and Simulation for complete SISAME-3D documentation.

A template for the Event file can be found in the SISAME-3D Event Template.

A template for the Master file can be found in the SISAME-3D Master Template.

A history of program changes can be found in the SISAME-3D Change Log.