Feature-based modeling for mechanical design

doi:10.1016/0097-8493(90)90031-R

Computers & Graphics

Volume 14, Issue 2, 1990, Pages 189-199

https://doi.org/10.1016/0097-8493(90)90031-R Get rights and content

Abstract

It has been recognized that feature-based modeling can provide the needed design information that facilitates bridging the gap between engineering design and manufacturing. Feature-based modeling allows part geometry to be represented by higher-level entities that relate directly to certain design functionalities or manufacturing characteristics. In this paper we discuss two prototype systems which use feature-based modeling. The first system links a solid modeler and an expert system to reason about the gating design for investment casting. The second system uses feature-based modeling to create a sheetmetal product model from which related applications may be automated. Geometry representation based on features allows easy integration with other applications such as analysis, cost estimation, flat pattern layout, and many others. Finally, an overall framework incorporating feature-based modeling, geometric reasoning, and variational geometry is proposed as a future research direction.

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Topology optimization design of stretchable metamaterials with Bézier skeleton explicit density (BSED) representation algorithm
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Citation Excerpt :
For the design generated with BSED method, the designs are described by Bézier curve with certain thickness, the boundary can be smooth enough due to explicit geometric description without any limitation of FEM mesh resolution. The other merit of BSED is that it is easier to generate standard CAD model and edited in general CAD software [73], because the optimal design is described by parametric space, which is ready to directly define geometry in software using feature-based modeling [74], instead of converting the STL (stereolithography) file to ISO standard exchange format (i.e. STEP file [75]). Meanwhile, the number of design variables is reduced significantly compared to standard density-based method.
A new density field representation technique called the Bézier skeleton explicit density (BSED) representation scheme for topology optimization of stretchable metamaterials under finite deformation is proposed for the first time. The proposed approach overcomes a key deficiency in existing density-based optimization methods that typically yield designs that do not have smooth surfaces but have large number of small intricate features, which are difficult to manufacture even by additive manufacturing. In the proposed approach, Bézier curves are utilized to describe the skeleton of the design being optimized where the description of the entire design is realized by assigning thickness along the curves. This geometric representation technique ensures that the optimized design is smooth and concise and can easily be tuned to be manufacturable by additive manufacturing. In the optimization method, the density field is described by the Heaviside function defined on the Bézier curves. Compared to NURBS or B-spline based models, Bézier curves have fewer control parameters and hence are easier to manipulate for sensitivity derivation, especially for distance sensitivities. Due to its powerful curve fitting ability, using Bézier curve to represent density field allows exploring design space effectively and generating concise structures without any intricate small features at the borders. Furthermore, this density representation method is mesh independent and design variables are reduced significantly so that optimization problem can be solved efficiently using small-scale optimization algorithms such as sequential quadratic programming. Numerical optimization results in three typical tests, uniaxial tension, biaxial tension and shear tests are presented by imposing symmetry on a unit cell for lattice structure design. Numerical examples illustrate that the optimized metamaterials have better stretchability and higher stiffness, and hence the proposed method has great potential of impacting the design of future applications that exploit stretchability of structures.
STEP-based product modeling for concurrent stamped part and die development
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Standard for the Exchange of Product Model Data (STEP) is an international standard designed to provide a complete, unambiguous, computer-readable definition of the physical and functional characteristics of a product throughout its life-cycle. In this paper, a STEP-based product modeling system for concurrent stamped part and die development is presented. First, an architecture of this system is established using a three-layer architecture (application, logical and physical layers) recommended by STEP, and a new concept — Die & Product Integrated Information Model (DPIIM) is proposed to fully support the complete product data representation in concurrent stamped part and die design process. Then, six EXPRESS-defined schemas are constructed to represent DPIIM using the Integrated Resources of STEP, which can support the concurrent stamped part and die development with a complete product information representation and a standard data format.
A new feature-based design system with dynamic editing
1997, Computers and Industrial Engineering
This paper proposes a feature-based design system for prismatic parts in which predefined 3D features, instead of low-level 2D lines and points, are used as entities for representation and manipulation. Two special sets of functions, a new construction function and a dynamic editing function, enable designers to freely construct and modify parts. The parts are saved as feature-based files in CSG form, while a B-rep form is also created. The feature-based file allows the proposed 3D part-design system to be easily integrated into CAPP/CAM systems without complex feature-recognition and -extraction processes. Object-oriented concepts are used in implementing the proposed system, and examples are given to show its feasibility and effectiveness.
An intelligent multi-blackboard CAD system
1996, Artificial Intelligence in Engineering
In this paper, automatic modeling techniques in intelligent CAD systems are discussed and a multi-blackboard based modeling method is presented. It supports modeling with multilevel accuracy and can convert abstract symbolbased description of a design object into the desired 3D model. These characteristics meet the modeling requirements for supporting the overall design process and are suitable for intelligent CAD systems. We implement them in an intelligent chair design system, AUTOCHAIR.
Geometric reasoning for manufacturability evaluation - application to powder metallurgy
1996, CAD Computer Aided Design
A new approach to perform geometric reasoning for manufacturability evaluation is developed using three-dimensional objects that are based on a process-dependent geometric model. It is demonstrated that by incorporating the limitations of the process directly in the geometric representation scheme, the task of manufacturability evaluation becomes straightforward and can be performed without either feature extraction or designing with features. The new approach is illustrated for the cold die compaction of powdered metals (PM). The geometric model for PM consists of a set of fundamental three-dimensional manufacturable entities, plates, blind cavities, and through cavities, all of arbitrary shape. The new approach is further enhanced by using a single, compact data structure that captures the shape characteristics to fully define the PM parts, and to support the reasoning required for manufacturability evaluation. Using this approach provides the ability to perform geometric reasoning easily that: (1) determines a part's orientation and tooling; (2) identifies sharp corners, feathered edges, thin walls, grooves, shelves, and notches, and other part attributes that adversely affect die fill, tooling cost and life, part integrity, and density control; and (3) automatically adds fillets, chamfers, edge rounds, tapers, and axial flats, which are common to PM parts. Furthermore, the reasoning is performed using a small set of algorithms to manipulate the appropriate information in the data structure, and is sufficiently robust to account for all practical shapes. The close coupling of the data structure and the algorithms permits the evaluation and modifications to take only a few seconds on a 486-based personal computer, and therefore, are performed in real time as the parts are created.
On editability of feature-based design
1995, Computer-Aided Design
Techniques needed for editing generative designs are presented. When a feature is edited, all features attached later must be re-evaluated to satisfy the required constraints and shape references in the initial design. We describe name matching techniques that support the design reevaluation procedure. The algorithms account for failed or multiple matches. The matching uses a naming schema based on historical, topological, and geometric design information that has been described in a companion paper.

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Features and geometric reasoningFeature-based modeling for mechanical design

Abstract

Computer-Aided Design

Extraction of Feature Information from Three Dimensional CAD Data

Feature extraction by volume decomposition

Designing with features: Design and analysis of extrusions as an example

Designing with features: Casting as an example

Requirements for Support of Form Features in a Solid Modeling System

A Method for Representation and Manipulation of Geometric Features in a Solid Model

Representing dimensions, tolerances, and features in MCAE systems

IEEE Computer Graphics and Applications

Features and geometric reasoning
Feature-based modeling for mechanical design