Standard Unit Systems |
 
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Standard Unit Systems |
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Units systems are composed of base units, measures which cannot be represented in any other way, and derived units. Derived units can be represented in terms of a combination of base units.
Flexcom requires base units for the dimensions of length, mass, time and temperature. All other units in the program are derived from these four base units. In fact, the use of temperature is so extremely limited that we will confine our discussion to length, mass and time from here on.
There are two base unit systems commonly used in Flexcom. A metric system based on meter-kilogram-second and an imperial system based on foot-slug-second. We will refer to these two systems as Standard Metric and Standard Imperial.
Unit System |
Length [L] |
Mass [M] |
Time [T] |
Standard Metric |
Meter |
Kilogram |
Second |
Standard Imperial |
Foot |
Slug |
Second |
Taking the above systems as examples, we can see how derived units are obtained. Acceleration, for example, is length over time squared. Dimensionally this can be represented as [L][T]-2. In the Standard Metric system this gives acceleration units of m/s2. In Standard Imperial the units of acceleration would be ft/s2. Building on our definition of acceleration, we know that force is mass times acceleration. Dimensionally, we can take our representation for acceleration and add mass, giving [M][L][T]-2. This means that, in the Standard Metric and Standard Imperial systems, force units are kg.m/s2 (i.e. Newtons) and slugs.ft/s2 respectively.
Keyword files which use either the Standard Metric or Standard Imperial unit system have file extensions of .KEYXM (Metric) or .KEYXI (Imperial), respectively. Refer to Files with Explicit Units for further information.
Note also that Flexcom keyword files with the .KEYX extension are said to be using User-Defined Units. These are typically legacy keyword files which were created with an earlier version of the software prior to the release of Flexcom 8.4. Recommended practice is to convert any such files into one of the Standard Unit Systems using the Units Project Importer.
For a full list of the units accepted by Flexcom, in both metric and imperial systems, refer to Units Reference Guide.