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2018-12-16 251 words 2 minutes - views

Before starting to define any model, which system of units to use need to be decided. However, ABAQUS has no built-in system of units. Do not include unit names or labels when entering data in c.

Consistent units

All input data must be specified in consistent units, which means it doesn’t matter which units you use, as long as they match with each other. This approach allows a lot of flexibility, but sometimes leads to unexpected errors, especially when you copy a material from other place.

Some common systems of consistent units are shown in the following table:

Quantity	SI	SI (mm)	US Unit (ft)	US Unit (inch)	(Lxcad)cm
Length	$$\rm m$$	$$\rm mm$$	$$\rm ft$$	$$\rm in$$	$$\rm cm$$
Force	$$\rm N$$	$$\rm N$$	$$\rm lbf$$	$$\rm lbf$$	$$\rm N$$
Mass	$$\rm kg$$	$$\rm tonne (10^3 kg)$$	$$\rm slug$$	$$\rm lbf\ s^2/in$$	$$\rm (10^2 kg)$$
Time	$$\rm s$$	$$\rm s$$	$$\rm s$$	$$\rm s$$	$$\rm s$$
Stress	$$\rm Pa (N/m^2)$$	$$\rm MPa (N/mm^2)$$	$$\rm lbf/ft^2$$	$$\rm psi (lbf/in^2)$$	$$\rm N/cm^2$$
Energy	$$\rm J$$	$$\rm mJ (10^{–3 }J)$$	$$\rm ft\ lbf$$	$$\rm in\ lbf$$
Density	$$\rm kg/m^3$$	$$\rm tonne/mm^3$$	$$\rm slug/ft^3$$	$$\rm lbf\ s^2/in^4$$	$$\rm 10^2 kg/cm^3(10^8)$$
Acceleration	$$\rm m/s^2$$	$$\rm mm/s^2$$			$$\rm cm/s^2$$

The SI system of units is recommended.

Angles and rotations

The only built-in units in ABAQUS are for angles and rotation. ABAQUS uses radians for ratational degrees of freedom, while all other angles measures are expressed in degrees.

Reference

ABAQUS manual
Units in ABAQUS Simuleon FEA Blog