What are the units used in the ABAQUS model?
¡¡ This answer is just a summary of the article Units in Abaqus. If you need more information and deeper insight, I suggest to read that article after visiting this page. ¡¡
You specify the units in Abaqus, and this is a nice approach allowing a lot of flexibility. Abaqus assumes you use consistent units. It does not matter which units you use, as they match with each other.
See the table below as a reference to select consistent units for your problem:
| Quantity | SI units | ||||||||||
| Mass | kg | ton | kg | kg | kg | kg | g | g | g | g | |
| Length | m | mm | cm | cm | cm | mm | cm | cm | mm | mm | |
| Time | s | s | s | ms | µs | ms | s | µs | s | ms | |
| Force | N | N | 1e-2N | 1e+4N | 1e+10N | kN | dyne | 1e7N | 1e-6N | N | |
| Stress | Pa | MPa | Pa | Pa | Pa | GPa | Dy/cm2 | Mbar | Pa | MPa | |
| Energy | J | N-mm | J | J | J | KN-mm | erg | 1e7N-cm | J | N-mm | |
| Gravity | 9.81 | 9.81e+3 | 9.81e2 | 9.81e-4 | 9.81e-10 | 9.81e-3 | 9.81e+2 | 9.81e-10 | 9.81e+3 | 9.81e-3 | |
| Steel | Density | 7.83e-9 | 7.83e-9 | 7.83e+3 | 7.83e+3 | 7.83e+3 | 7.83e-6 | 7.83 | 7.83 | 7.83e-3 | 7.83e-3 |
| Young Modulus | 2.07e+5 | 2.07e+5 | 2.07e+9 | 2.07e+3 | 2.07e+3 | 2.07e+2 | 2.07e+12 | 2.07 | 2.07e+11 | 2.07e+5 | |
* µs= micro second=10-6 s, ms= millisecond= 10-3 s
And this (for comparing SI and Imperial units):
Notes:
- Abaqus uses radians for rotational DOF. All other angles (prescribed in defining geometry, material properties, etc.) are expressed in degrees.
- The absolute zero temperature and the Stefan-Boltzmann constant must be given (consistent with other units in the model) in heat transfer analyses when surface emissivity and radiation are present. It is true also for the universal gas constant. They can be specified as:
[In any Module] Menu Bar > Model > Edit attributes
I strongly recommend you to visit the article Units in Abaqus too. In this article, you about Abaqus consistent units and how to choose a suitable one. Also, if you need a practical example to learn about this issue or to see a compression between Abaqus results and theoretical results, the cantilever beam example in the “Cantilever beam analysis” section in the Abaqus course could be a great deal.
