for me, the slice tool only works reliably when surfaces are derived from 2D profiles. Your curved surface is probably compound.
Notwithstanding that, this is what I did:
1. Turn off the part tree.
2. Explode each object, so they are both ACIS solids.
3. Give some thickness to the curved object, say 0.01 mm, using the shell tool.
4. Boolean subtract the curved object from the beam, remembering to select "Don't remove the subtrahend" if you wish to retain this part.
5. Select the beam and explode once, to create two separate ACIS solids.
« Last Edit: January 14, 2019, 12:44:46 PM by Tim Stewart »
You can design without engineering, but you cannot engineer without design.
Using Win 10 with Designer 2017 and TurboCAD Pro. Plat. 2016/2017/2018 + Lightworks (64-bit versions) + AnimationLab.