Conversion from U3D to IAM is not supported yet :(

Universal 3D (U3D) is a compressed file format standard for 3D computer graphics data.

The format was defined by a special consortium called 3D Industry Forum that brought together a diverse group of companies and organizations, including Intel, Boeing, HP, Adobe Systems, Bentley Systems, Right Hemisphere and others whose main focus had been the promotional development of 3D graphics for use in various industries, specifically at this time manufacturing as well as construction and industrial plant design. The format was later standardized by Ecma International in August 2005 as ECMA-363.

The goal is a universal standard for three-dimensional data of all kinds, to facilitate data exchange. The consortium promoted also the development of an open source library for facilitating the adoption of the format.

An IAM file is an assembly model created with Inventor CAD and engineering software by Autodesk.

The IAM format comprises parts and subassemblies linked through assembly relationships. A subassembly in an IAM file is a self-contained unit with its collection of parts.

The .iam extension of an Autodesk Inventor Assembly Data File can be viewed using the following software: Autodesk Inventor / Inventor View, and Spaceclaim Engineer software. Autodesk Viewer web application and Fusion 360 integrated CAD / CAM / CAE software environment can import and render an assembly model created with Inventor.