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--- wiki:sns:intactgh:consistent_units [2022/08/10 10:24] – michael
+++ wiki:sns:intactgh:consistent_units [2023/06/07 11:03] (current) – paul
@@ Line 2: / Line 2: @@
 {{TOC:wide}}
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-===== Importance of Unit System =====
+====== Unit System ======
-Intact.Simulation computations are fundamentally based on the unit system in use in the Rhino document.  Failure to pay heed to the unit system can lead to unexpected and incorrect results.
+The geometry simulated by Intact.Simulation is based on the unit system used in the Rhino document, which can be set in the Rhino file settings. Other input quantities, such as vector loads or pressure loads are based on the Meter Kilogram Second (MKS) unit system by default. The unit system can be changed by right-clicking a block and selecting a different unit system.
-For example, consider a beam restrained at the left end with a 1000 N load applied to the right end as shown below.  With a simulation set up using millimeter length units in Rhino, the danger level in the beam exceeds 1 almost everywhere and indicates the beam is grossly overloaded.
+<WRAP group>
+<WRAP half column>
+Failure to pay heed to the unit system can lead to unexpected and incorrect results.
-{{ :units_box_mm_results.png?400 }}
+Choose a different unit system by right-clicking on the block and selecting the unit system.
+</WRAP>
+<WRAP half column>
+{{ :wiki:sns:intactgh:units_context_menu.png?400 }}
+</WRAP>
+</WRAP>
-However, if the beam is modeled with units of meters, the result is quite different: the beam will not fail.  Note that in both cases, Rhino shows the dimension of the beam to be 10.00.
+===== Unit Systems in Intact.Simulation =====
+The default unit system is Meter Kilogram Second (MKS). The supported unit systems are described in the following table:
+^ Analysis units   ^ Mass                  ^ Force  ^ Stress               ^ Length ^
+| MKS (m kg s)     | kg                    | N      | Pa                   | m      |
+| CGS (cm g s)     | g                     | dyne   | dyne/cm<sup>2</sup>  | cm     |
+| MMS (mm Mg s)    | Mg                    | N      | MPa                  | mm     |
+| FPS (ft lbf s)   | slug                  | lbf    | lbf/ft<sup>2</sup>   | ft     |
+| IPS (in lbf s)   | lbf s<sup>2</sup>/in  | lbf    | psi                  | in     |
-{{ :units_box_meters_results.png?400 }}
-====== Unit System for Simulation======
-The unit system in a simulation is based on the length units of the current Rhino document and follow the following table:
-{{:wiki:sns:intactgh:pasted:20220809-214029.png}}
 ===== Derived Units =====
 Derived units such as acceleration, torque, and density are consistent within each unit system.
@@ Line 21: / Line 32: @@
   * Density units are mass/length<sup>3</sup>
 ===== Independent Units =====
-Across the several unit systems, the rotational units are the same.  Namely:
+Across the several unit systems, rotational units are the same.  Namely:
   * Rotational velocity units are rad/s
   * Rotational acceleration units are rad/s<sup>2</sup>