Unbalance Force for Engine Vibration in SACS


Product(s):SACS
Version(s):All
Area:Dynamic Response

Problem

When I define the unbalance dynamic load in X, Y, & Z Direction at the interface joints with no phase angle being input with non-linear interpolation to be used by SACS, how SACS use the information?

Solution

The UNBAL force response is essentially periodic vibration force which is used to generate a modal response of the structure. The loads will be generated for every speed defined in the USRSP line. If there is no RSPEED and UNBAL line which matches the speed in the USRSP line, SACS will interpolate the forces from the other UNBAL load lines using the non-linear interpolation factor you defined. The modal response will contain multiple responses, not just the closest frequency as the other modes will still contribute to the overall response.