Computation of Midsurface by Feature-Based Simplification–Abstraction–Decomposition

2016 ◽  
Vol 17 (1) ◽  
Author(s):  
Yogesh H. Kulkarni ◽  
Anil Sahasrabudhe ◽  
Mukund Kale
Keyword(s):  
Computer Aided Design ◽  
Real Life ◽  
Boundary Representation ◽  
Manual Task ◽  
Computer Aided ◽  
Cad Models ◽  
Feature Based ◽  
Feature Information ◽  
Plastic Parts ◽  
Aided Design

Computer-aided design (CAD) models of thin-walled solids such as sheet metal or plastic parts are often reduced dimensionally to their corresponding midsurfaces for quicker and fairly accurate results of computer-aided engineering (CAE) analysis. Computation of the midsurface is still a time-consuming and mostly, a manual task due to lack of robust and automated techniques. Most of the existing techniques work on the final shape (typically in the form of boundary representation, B-rep). Complex B-reps make it hard to detect subshapes for which the midsurface patches are computed and joined, forcing usage of hard-coded heuristic rules, developed on a case-by-case basis. Midsurface failures manifest in the form of gaps, overlaps, nonmimicking input model, etc., which can take hours or even days to correct. The research presented here proposes to address these problems by leveraging feature-information available in the modern CAD models, and by effectively using techniques like simplification, abstraction, and decomposition. In the proposed approach, first, the irrelevant features are identified and removed from the input FbCAD model to compute its simplified gross shape. Remaining features then undergo abstraction to transform into their corresponding generic Loft-equivalents, each having a profile and a guide curve. The model is then decomposed into cellular bodies and a graph is populated, with cellular bodies at the nodes and fully overlapping-surface-interfaces at the edges. The nodes are classified into midsurface-patch generating nodes (called “solid cells” or sCells) and interaction-resolving nodes (“interface cells” or iCells). In a sCell, a midsurface patch is generated either by offset or by sweeping the midcurve of the owner-Loft-feature's profile along with its guide curve. Midsurface patches are then connected in the iCells in a generic manner, thus resulting in a well-connected midsurface with minimum failures. Output midsurface is then validated topologically for correctness. At the end of this paper, real-life parts are used to demonstrate the efficacy of the proposed approach.

Orthogonal Distance Fields Representation for Machine-Learning Based Manufacturability Analysis

2020 ◽  
Author(s):  
Aditya Balu ◽  
Sambit Ghadai ◽  
Soumik Sarkar ◽  
Adarsh Krishnamurthy
Keyword(s):  
Machine Learning ◽  
Computer Aided Design ◽  
Boundary Representation ◽  
Engineering Product ◽  
Distance Fields ◽  
Computer Aided ◽  
Cad Models ◽  
Product Design Process ◽  
3D Cnn ◽  
Aided Design

Abstract Computer-aided Design for Manufacturing (DFM) systems play an essential role in reducing the time taken for product development by providing manufacturability feedback to the designer before the manufacturing phase. Traditionally, DFM rules are hand-crafted and used to accelerate the engineering product design process by integrating manufacturability analysis during design. Recently, the feasibility of using a machine learning-based DFM tool in intelligently applying the DFM rules have been studied. These tools use a voxelized representation of the design and then use a 3D-Convolutional Neural Network (3D-CNN), to provide manufacturability feedback. Although these frameworks work effectively, there are some limitations to the voxelized representation of the design. In this paper, we introduce a new representation of the computer-aided design (CAD) model using orthogonal distance fields (ODF). We provide a GPU-accelerated algorithm to convert standard boundary representation (B-rep) CAD models into ODF representation. Using the ODF representation, we build a machine learning framework, similar to earlier approaches, to create a machine learning-based DFM system to provide manufacturability feedback. As proof of concept, we apply this framework to assess the manufacturability of drilled holes. The framework has an accuracy of more than 84% correctly classifying the manufacturable and non-manufacturable models using the new representation.

Graph-Based Simplification of Feature-Based Three-Dimensional Computer-Aided Design Models for Preserving Connectivity

2015 ◽  
Vol 15 (3) ◽  
Author(s):  
Soonjo Kwon ◽  
Byung Chul Kim ◽  
Duhwan Mun ◽  
Soonhung Han
Keyword(s):  
Computer Aided Design ◽  
Three Dimensional ◽  
Evaluation Metrics ◽  
Prototype System ◽  
Cad Model ◽  
3D Cad ◽  
Computer Aided ◽  
Cad Models ◽  
Feature Based ◽  
Aided Design

The required level of detail (LOD) of a three-dimensional computer-aided design (3D CAD) model differs according to its purpose. It is therefore important that users are able to simplify a highly complex 3D CAD model and create a low-complexity one. The simplification of a 3D CAD model requires the application of a simplification operation and evaluation metrics for the geometric elements of the 3D CAD model. The evaluation metrics are used to select those elements that should be removed. The simplification operation removes selected elements in order to simplify the 3D CAD model. In this paper, we propose the graph-based simplification of feature-based 3D CAD models using a method that preserves connectivity. First, new evaluation metrics that consider the discrimination priority among several simplification criteria are proposed. Second, a graph-based refined simplification operation that prevents the separation of a feature-based 3D CAD model into multiple volumes is proposed. Finally, we verify the proposed method by implementing a prototype system and performing simplification experiments using feature-based 3D CAD models.

scholarly journals An isogeometric b-rep mortar-based mapping method for non-matching grids in fluid-structure interaction

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Andreas Apostolatos ◽  
Altuğ Emiroğlu ◽  
Shahrokh Shayegan ◽  
Fabien Péan ◽  
Kai-Uwe Bletzinger ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Fluid Structure Interaction ◽  
Mapping Method ◽  
Boundary Representation ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Discrete Surface ◽  
Cad Models ◽  
Volume Method ◽  
Aided Design

AbstractIn this study the isogeometric B-Rep mortar-based mapping method for geometry models stemming directly from Computer-Aided Design (CAD) is systematically augmented and applied to partitioned Fluid-Structure Interaction (FSI) simulations. Thus, the newly proposed methodology is applied to geometries described by their Boundary Representation (B-Rep) in terms of trimmed multipatch Non-Uniform Rational B-Spline (NURBS) discretizations as standard in modern CAD. The proposed isogeometric B-Rep mortar-based mapping method is herein extended for the transformation of fields between a B-Rep model and a low order discrete surface representation of the geometry which typically results when the Finite Volume Method (FVM) or the Finite Element Method (FEM) are employed. This enables the transformation of such fields as tractions and displacements along the FSI interface when Isogeometric B-Rep Analysis (IBRA) is used for the structural discretization and the FVM is used for the fluid discretization. The latter allows for diverse discretization schemes between the structural and the fluid Boundary Value Problem (BVP), taking into consideration the special properties of each BVP separately while the constraints along the FSI interface are satisfied in an iterative manner within partitioned FSI. The proposed methodology can be exploited in FSI problems with an IBRA structural discretization or to FSI problems with a standard FEM structural discretization in the frame of the Exact Coupling Layer (ECL) where the interface fields are smoothed using the underlying B-Rep parametrization, thus taking advantage of the smoothness that the NURBS basis functions offer. All new developments are systematically investigated and demonstrated by FSI problems with lightweight structures whereby the underlying geometric parametrizations are directly taken from real-world CAD models, thus extending IBRA into coupled problems of the FSI type.

scholarly journals Automatized Evaluation of Students’ CAD Models

2021 ◽  
Vol 11 (4) ◽  
pp. 145
Author(s):  
Nenad Bojcetic ◽  
Filip Valjak ◽  
Dragan Zezelj ◽  
Tomislav Martinec
Keyword(s):  
Computer Aided Design ◽  
Three Dimensional ◽  
Computer Application ◽  
Test Cases ◽  
Cad Model ◽  
Computer Solution ◽  
3D Cad ◽  
Computer Aided ◽  
Cad Models ◽  
Aided Design

The article describes an attempt to address the automatized evaluation of student three-dimensional (3D) computer-aided design (CAD) models. The driving idea was conceptualized under the restraints of the COVID pandemic, driven by the problem of evaluating a large number of student 3D CAD models. The described computer solution can be implemented using any CAD computer application that supports customization. Test cases showed that the proposed solution was valid and could be used to evaluate many students’ 3D CAD models. The computer solution can also be used to help students to better understand how to create a 3D CAD model, thereby complying with the requirements of particular teachers.

A New Family of Bricard-Derived Deployable Mechanisms

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
Hailin Huang ◽  
Bing Li ◽  
Jianyang Zhu ◽  
Xiaozhi Qi
Keyword(s):  
Large Volume ◽  
Computer Aided Design ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
New Family ◽  
Revolute Joints ◽  
Computer Aided ◽  
Cad Models ◽  
Aided Design

This paper proposes a new family of single degree of freedom (DOF) deployable mechanisms derived from the threefold-symmetric deployable Bricard mechanism. The mobility and geometry of original threefold-symmetric deployable Bricard mechanism is first described, from the mobility characterstic of this mechanism, we show that three alternate revolute joints can be replaced by a class of single DOF deployable mechanisms without changing the single mobility characteristic of the resultant mechanisms, therefore leading to a new family of Bricard-derived deployable mechanisms. The computer-aided design (CAD) models are used to demonstrate these derived novel mechanisms. All these mechanisms can be used as the basic modules for constructing large volume deployable mechanisms.

Simultaneous Computer-Aided Design of Rotational Plastic Parts

1993 ◽  
Author(s):  
Colin Chong ◽  
Kiyoshi Sogabe ◽  
Kosuke Ishii
Keyword(s):  
Injection Molding ◽  
Dynamic Characteristics ◽  
Computer Aided Design ◽  
Critical Speed ◽  
Dynamic Balance ◽  
Cad System ◽  
Compatibility Analysis ◽  
Computer Aided ◽  
Plastic Parts ◽  
Aided Design

Abstract This paper addresses the problem of balancing rotational plastic parts during the early stages of design. The study develops an interactive methodology that uses a solid modeling CAD system and considers injection molding concerns simultaneously with static and dynamic balance. The Transfer Matrix Method evaluates the dynamic characteristics by predicting the approximate critical speed of the part. Design Compatibility Analysis (DCA) checks for injection molding guidelines. Using these evaluation modules interactively, designers can develop a functional and manufacturable part quickly.

scholarly journals Feature-based translation of CAD models with macro-parametric approach: issues of feature mapping, persistent naming, and constraint translation

2020 ◽  
Vol 7 (5) ◽  
pp. 603-614 ◽  
Author(s):  
Mutahar Safdar ◽  
Tahir Abbas Jauhar ◽  
Youngki Kim ◽  
Hanra Lee ◽  
Chiho Noh ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Parametric Approach ◽  
Model Data ◽  
Feature Mapping ◽  
Product Model ◽  
Cad Systems ◽  
Cad System ◽  
Cad Models ◽  
Feature Based ◽  
Aided Design

Abstract Feature-based translation of computer-aided design (CAD) models allows designers to preserve the modeling history as a series of modeling operations. Modeling operations or features contain information that is required to modify CAD models to create different variants. Conventional formats, including the standard for the exchange of product model data or the initial graphics exchange specification, cannot preserve design intent and only geometric models can be exchanged. As a result, it is not possible to modify these models after their exchange. Macro-parametric approach (MPA) is a method for exchanging feature-based CAD models among heterogeneous CAD systems. TransCAD, a CAD system for inter-CAD translation, is based on this approach. Translators based on MPA were implemented and tested for exchange between two commercial CAD systems. The issues found during the test rallies are reported and analyzed in this work. MPA can be further extended to remaining features and constraints for exchange between commercial CAD systems.

The CAD/CAM Interface: A 25-Year Retrospective

2005 ◽  
Vol 5 (3) ◽  
pp. 188-197 ◽  
Author(s):  
J. Corney ◽  
C. Hayes ◽  
V. Sundararajan ◽  
P. Wright
Keyword(s):  
Computer Aided Design ◽  
Future Research ◽  
Manufacturing Processes ◽  
Sheet Metal Parts ◽  
Multiaxis Machining ◽  
Computer Aided ◽  
Cad Cam ◽  
Feature Based ◽  
Manufacturing Applications ◽  
Aided Design

The vision of fully automated manufacturing processes was conceived when computers were first used to control industrial equipment. But realizing this goal has not been easy; the difficulties of generating manufacturing information directly from computer aided design (CAD) data continued to challenge researchers for over 25 years. Although the extraction of coordinate geometry has always been straightforward, identifying the semantic structures (i.e., features) needed for reasoning about a component’s function and manufacturability has proved much more difficult. Consequently the programming of computer controlled manufacturing processes such as milling, cutting, turning and even the various lamination systems (e.g., SLA, SLS) has remained largely computer aided rather than entirely automated. This paper summarizes generic difficulties inherent in the development of feature based CAD/CAM (computer aided manufacturing) interfaces and presents two alternative perspectives on developments in manufacturing integration research that have occurred over the last 25 years. The first perspective presents developments in terms of technology drivers including progress in computational algorithms, enhanced design environments and faster computers. The second perspective describes challenges that arise in specific manufacturing applications including multiaxis machining, laminates, and sheet metal parts. The paper concludes by identifying possible directions for future research in this area.

Paired Computer-Aided Design: The Effect of Collaboration Mode on Differences in Model Quality

2020 ◽  
Author(s):  
Hamza Arshad ◽  
Vrushank Phadnis ◽  
Alison Olechowski
Keyword(s):  
Computer Aided Design ◽  
Shared Control ◽  
Control Mode ◽  
Pair Programming ◽  
Design Teams ◽  
Model Quality ◽  
Computer Aided ◽  
Parallel Cad ◽  
Cad Models ◽  
Aided Design

Abstract We present the results of an experiment investigating two different modes of collaboration on a series of computer-aided design (CAD) tasks. Inspired by the pair programming literature, we anticipate that partners working in a fully synchronous collaborative CAD environment will achieve different levels of quality in CAD models depending on their mode of collaboration — one in which the pair is free to work in parallel, and another where the pair must coordinate to share one control. We found that a shared CAD control led to significantly better overall CAD quality than parallel CAD control. In addition, the shared control mode led to more complete and consistent CAD models, as well as the tendency for participants to follow instructions to correctly replicate features for the design task. As is predicted in the literature, a trade-off relationship (albeit weak) between quality and speed via the parallel collaboration was found. In contrast, the shared control mode shows no clear relationship between speed and quality. Collaborative CAD is increasingly seen as an appealing tool for modern product design teams. This study suggests that the benefits of this tool are not solely the effect of the tool itself, but result from the collaboration style of the designers using the tool.

Toward Effective Mechanical Design Reuse: CAD Model Retrieval Based on General and Partial Shapes

2009 ◽  
Vol 131 (12) ◽  
Author(s):  
Min Li ◽  
Y. F. Zhang ◽  
J. Y. H. Fuh ◽  
Z. M. Qiu
Keyword(s):  
Computer Aided Design ◽  
Mechanical Design ◽  
Three Dimensional ◽  
Cad Model ◽  
Model Retrieval ◽  
Cad Models ◽  
Feature Based ◽  
Novel Method ◽  
Aided Design ◽  
Model Similarity

In product design, a large proportion of three-dimensional (3D) computer-aided design (CAD) models can be reused to facilitate future product development due to their similarities in function and shape. This paper presents a novel method that incorporates modeling knowledge into CAD model similarity assessment to improve the effectiveness of reuse-oriented retrieval. First, knowledge extraction is performed on archived feature-based CAD models to construct feature dependency directed acyclic graph (FDAG). Second, based on the FDAG subgraph decomposition, two useful component partitioning approaches are developed to extract simplified essential shapes and meaningful subparts from CAD models. Third, the extracted shapes and their FDAG subgraphs are indexed. Finally, the indexed shapes that are similar to user-sketched queries are retrieved to reuse, and FDAG information of the retrieved shapes is provided as redesign suggestions. Experimental results suggest that the incorporation of modeling knowledge greatly facilitates CAD model retrieval and reuse. Algorithm evaluations also show the presented method outperforms other 3D retrieval methods.

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