*UNIT SYSTEM

Define a unit system for an Abaqus model.

This option is used to define mechanical units used in the model for the purpose of translating to other formats. For example, to create a Simpack Flexible Body Interface (FBI) file, which is always in SI units, Abaqus needs to know the units used for the analysis.

This information has no effect on the Abaqus simulation; you must ensure that a consistent set of units is used.

The units of a mechanical system can be defined by specifying one of the basic triples: length-mass-time or length-force-time. These two methods are mutually exclusive. If you specify length-mass-time, the force unit is defined implicitly. If you specify length-force-time, the mass unit is defined implicitly.

This page discusses:

See Also
In Other Guides
Defining a Unit System for an Abaqus/Standard Substructure for a Simpack Flexible Body

ProductsAbaqus/Standard

TypeModel data

LevelModel

There are no parameters associated with this option.

 

Optional data lines to define units for the physical dimensions

First line

  1. Physical dimension name LENGTH, MASS, TIME, or FORCE.

  2. Unit symbol. The unit symbol defines the primary conversion factor, which is the number that Abaqus multiplies by the SI unit to obtain the model unit. If this field is left blank, the following SI units are assumed: length (m), mass (kg), time (s), and force (N).

    The following unit symbols are available: length (m, cm, mm, km, in, ft, yd, and mi); mass (kg, g, t, lb, klb, oz, slug, slinch, and uton); time (s, ms, h, min, and d); and force (N, lbf, kgf, ozf, dyne, kN, klbf, tf, and pdl).

    For a description of unit names, unit symbols, and the associated primary conversion factor, see Defining a Unit System for an Abaqus/Standard Substructure for a Simpack Flexible Body.

  3. Secondary conversion factor. The secondary conversion factor is another multiplier for the conversion from the Abaqus model units to the SI system for units not in the list of unit symbols. If this field is left blank, a secondary conversion factor of 1.0 is used.

Repeat this data line as often as necessary to define units for the physical dimensions.

If the data line for a physical dimension is omitted, the default SI unit is assumed. Data lines for the mass and force physical dimensions are mutually exclusive. If neither mass nor force is specified, the SI unit of mass is assumed, and the force unit is derived.