Brett W. Clark

Conformal Assembly Meshing with Tolerant Imprinting.

Solid assembly meshing has all of the same “dirty geometry” induced issues as single part meshing but also has the difficulty associated with generating a conformal mesh between solids where solid-solid interfaces are not obvious. Mesh generators usually don’t have CAD assembly constraint information to identify interfacing solids and must therefore rely on geometric proximity to deduce these interactions. “Slop” in the positioning and alignment of parts in the assembly makes automatically discovering the interfaces and generating a conformal mesh at the interfaces very difficult. Most of the efforts in this area resort to some sort of discrete representation to deal with these issues losing the capability to do further solid modeling engine operations often necessary for all-hexahedral meshing. This paper presents a method for defining the non-manifold interfaces between volumes in an assembly required for generating a conformal mesh while maintaining the original solid modeling engine format.

An Immersive Topology Environment for Meshing.

The Immersive Topology Environment for Meshing (ITEM) is a wizard-like environment, built on top of the CUBIT Geometry and Meshing Toolkit. ITEM is focused on three main objectives: 1) guiding the user through the simulation model preparation workflow; 2) providing the user with intelligent options based upon the current state of the model; and 3) where appropriate, automating as much of the process as possible. To accomplish this, a diagnostic-solution approach is taken. Based upon diagnostics of the current state of the model, specific solutions for a variety of common tasks are provided to the user. Some of these tasks include geometry simplification, small feature suppression, resolution of misaligned assembly parts, decomposition for hex meshing, and source and target selection for sweeping. The user may scroll through a list of intelligent solutions for a specific diagnostic and entity, view a graphical preview of each solution and quickly perform the solution to resolve the problem. In many cases, automatic solutions for these tasks can be generated and executed if the user chooses. This paper will discuss the various diagnostics and geometric reasoning algorithms and approaches taken by ITEM to determine solutions for preparing an analysis model.

Removing Small Features with Real CAD Operations

Preparing Computer Aided Design models for successful mesh generation continues to be a crucial part of the design to analysis process. A common problem in CAD models is features that are very small compared to the desired mesh size. Small features exist for a variety of reasons and can require an excessive amount of elements or inhibit mesh generation all together. Many of the tools for removing small features modify only the topology of the model (often in a secondary topological representation of the model) leaving the underlying geometry as is. The availability of tools that actually modify the topology and underlying geometry in the boundary representation (B-rep) model is much more limited regardless of the inherent advantages of this approach. This paper presents a process for removing small featrues from a B-rep model using almost solely functionality provided by the underlying solid modeling kernel. The process cuts out the old topology and reconstructs new topology and geometry to close the volume. The process is quite general and can be applied to complex configurations of unwanted topology.