Designed for personal computers, 3D video games are powerful tools with respect to graphics rendering, real world physics simulation, human-computer interaction and multi-user communication. Because of these favorable features of 3D games, their adaption for serious applications has been widely researched recently. These applications generally focus on topics such as real world scenario reconstruction, which require no or only minor development efforts on the game engines themselves. Contrary to this, the development of virtual education and training environments requires the integration of complex engineering systems into games, which poses greater challenges and thus causes this topic to be covered less frequently. This article presents a framework for authoring virtual environments (VEs) for mechanical assembly training using a commercially available 3D game engine. The VE presented here allows multiple users to conduct simulations of assembly procedures in a collaborative manner and provides an immersive user experience with user-friendly human-computer interactions. In order to enable diverse types of assemblies, the VE uses feature-based representations of assemblies. CAD concepts such as form features, parts, kinematic joints and sub-assemblies are modified for implementation into the VE. This framework is explained through a sample assembly process of a planet gear train. The results of a study conducted in an undergraduate mechanical engineering laboratory are summarized briefly. From the study results, it can be concluded that this VE has the potential to become a valuable education and training tool for users, helping them to acquire mechanical assembly skills that can be applied to fields such as manufacturing, maintenance and repair.

This paper presents a contribution to the automation and integration of topology optimization methods (TOM) with CAD, in the context of the design of statically loaded mechanical structures and parts. Starting from an initial CAD model with relevant engineering data, the goal is automatically generating an optimized CAD model with respect to engineering objectives and constrains. Though many optimization methods are now available, their complete and efficient integration into the design process faces several problems. After introducing the basic steps involved in the whole process and identifying the challenges inherent to this integration, this paper presents our contribution in addressing these challenges. The paper is focused on the specification of design and non-design sub-domains, on automatic mesh generation problems induced and on the adaptation of TO concepts in the context of 3D unstructured meshes. TO itself is adapted from a SIMP scheme, which is an arbitrary choice as any other optimization method could also have been used. Sets of results are presented to illustrate the potential and difficulties inherent to integrating TOM into the product design process with CAD.