U3D is a mesh based format. The only 2 applications I have that show it as an import option are Adobe Photoshop and Simlab Composer, from there you could save it to an STL or other mesh that SolidWorks can read.
You can't import u3d into SW. You can import it with Bluebeam Revu CAD, Acrobat Pro X+ with Tetra 4D's plugin or older versions Acrobat 7-9 3D/Pro Extended had a built in converter. U3d is a file format used for 3D enabled pdf's. If you want to use SW 3D representation in pdf's then look into the ifc export file format. Bluebeam Revu CAD also supports that.
Elmer & Chris,
.U3D Import Into SW
Thanks for you input. Had no luck with Bluebeam Revu, installed it but had no success with opening .u3d file test. I installed the free Slimlab Composer and the free version does not export .u3d. The $99 version apparently does, trying to avoid a purchase to convert just yet. Okino PolyTrans is probably the best solution but it runs $400 plus with Add-on Packs U3d and many other supported formats.
Giving this his some more thought I remembered that SW Visualize could read several formats. So opening up my 2018 SP1.0 app I created a new file and went to Import. Sure enough Visualize provides a .u3d import options....but guess what it crashes on my test file. Tried a variety of import settings same crash. Also tried the import on my 2017 Visualize same results. My SW VAR was contacted same crash with 2017 Visualize but succcess for their 2018 test. My VAR created a new Case to resolve the issue. Will aim to update post when I have success or new info. FYI Visualize can export to .obj Object formats that can be read back into SW my current objective. The second export option is .fbx but not an import option for SW Pro.
The u3d file format won't import into SW. It does import into Bluebeam. What you get is a 3D Pdf. If you want to export out from SW use IFC instead. It will import ifc into SW as well. SW support for u3d was dropped in 2015.I have Revu 2015 and all you do is drag and drop the u3d file into the empty Bluebeam screen and the rest is waiting.
The publishing file format 3D PDF is not intended for backward conversions and importing to CAD applications. If 3D PDF file contains U3D data (PRC B-rep), in some cases it can be convertible back to a 3D CAD model. For such conversion, you can use Adobe Acrobat/Tetra4d, SimLab etc.
From Bluebeam Revu 2017 Help