Feature-based parametric design automation for complex geometry objects in CAD systems
Creators: Zhou, Tianyu
Publisher: name: University of Alberta Library
Year: 2023

<p>With the rapid development of advanced manufacturing technologies, the fabrication of complex structures with enhanced functional properties has been realized. As a result, a wide exploration of the design space for functional geometric objects has been enabled in research and engineering applications. Due to the iterative construction/optimization process of functional structures, the geometries of these objects are complex. In the actual product development process of complex geometry objects, a parametric CAD model with good compatibility and editability is needed. However, the model construction efficiency for complex geometry objects in contemporary CAD systems is low, and the manual construction processes for complex geometry objects are repetitive, tedious, and time-consuming. Therefore, it is important to construct parametric models automatically for complex geometry objects to improve modeling efficiency in CAD systems, which is the aim of the proposed parametric design automation. <br>
There are still some challenges to realize parametric design automation in CAD systems. For parametric modeling, feature-based method is a powerful approach, where the model is properly defined by several editable parameters so that the constructed CAD models are easy to be modified. A CAD model can be flexibly defined and modified in many different ways. However, the modeling efficiency will be low if all design parameters need to be carefully defined and set values, especially for objects with complex geometry features. For design automation, many approaches have been widely applied in product design and optimization processes, where the models of the product are constructed/updated automatically according to specific rules. For example, generative design is an iterative design process which can automatically update design models algorithmically. However, the models created by design automation approaches might not be parametric CAD models and post-processing operations and compatibility of these models in computer-aided environments are limited. Therefore, it is important to combine the advantages of feature-based parametric modeling and design automation in product development processes.<br>
In this research, feature-based parametric design automation methods in CAD systems were proposed, developed, and applied. In my methods, associative relationships among design parameters are built algorithmically for complex geometry objects so that the designers don’t need to define and assign value for every parameter. The concept of associative features is extended to CAD models which are constructed iteratively or by a loop cycle. The modeling process is automatic, and the constructed models are parametric CAD models. A balance between modeling efficiency and design flexibility is made. The concept of generative design is applied to either create a design or build a CAD model iteratively with intelligent algorithms. In this research, two typical types of complex geometry objects, fractal geometry design and material distribution structures, were studied and their parametric design automation was realized in CAD systems. <br>
In my case study, complex geometry models with a background in design and engineering applications were automatically constructed in a CAD system with editable design parameters. For CAD fractal modeling, a CAD fractal model of Koch Snowflake with variant indentation angles was realized in its parametric design automation. A comparison of modeling efficiency between traditional manual construction method (2880 seconds in average) and my proposed automatic method (6 seconds in average) was made in building a fractal CAD model with 768 edges. For modeling material distribution structures in CAD systems, several CAD models of topology optimized structures were constructed automatically. A complex multi-scale structure with 2800 elements of 5 parameters each was automatically constructed in 45 minutes. In this research, all CAD models built in my proposed methods were feature-based parametric models. My methods were found to be of sufficient efficiency and flexibility for parametric design automation.</p>