Hi @ry4n8r
It looks to me that the "cable" is bending due to the rotation of the arm. My guess is that you did not model a cable which would be pinned at each end and only transmit an axial load. You modeled a solid rod that is rigidly welded to the arm (and rigidly welded to the base, too) which can transmit moments and axial loads.
The limited element types in Fusion cannot model a cable element as would be done in other software (by adding a cable element). To have your "cable" transmit axial loads but no moments, you need to add a clevis to each end, then model the pin that goes through the clevis and arm, then use separation contact between the pin and holes. It is an "expensive" way to do it because of the number of elements and time required to calculate all the contact. If Fusion is your only option, then the cost does not matter. If you have Inventor Nastran, you should do the analysis and use a rod element (can transmit tension and compression) or a cable element (can only transmit tension).
@wmhazzard answer is also correct. The arm is moving downward, so the "cable" and vertical column are both in compression. Since the "cable" is a solid rod, it can resist compression and tension. The results are correct for what you modeled.
John
John Holtz, P.E. Global Product Support
Autodesk, Inc. If not provided, indicate the version of Inventor Nastran you are using.If the issue is related to a model, attach the model! See What files to provide when the model is needed.