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Research Papers

FEAsy: A Sketch-Based Tool for Finite Element Analysis

[+] Author and Article Information
Sundar Murugappan

C-Design Lab,
School of Mechanical Engineering,
Purdue University,
West Lafayette, IN 47907
e-mail: sundar.murugappan@gmail.com

Cecil Piya

C-Design Lab,
School of Mechanical Engineering,
Purdue University,
West Lafayette, IN 47907
e-mail: cpiya@purdue.edu

Maria C. Yang

Associate Professor
Department of Mechanical Engineering;
Engineering Systems Division,
Massachusetts Institute of Technology,
Cambridge, MA 02139
e-mail: mcyang@mit.edu

Karthik Ramani

Donald W. Feddersen Professor
School of Mechanical Engineering;
School of Electrical Engineering (by courtesy),
Purdue University,
West Lafayette, IN 47907
e-mail: ramani@purdue.edu

Contributed by the Design Engineering Division of ASME for publication in the JOURNAL OF COMPUTING AND INFORMATION SCIENCE IN ENGINEERING. Manuscript received July 18, 2016; final manuscript received July 31, 2016; published online February 16, 2017. Editor: Bahram Ravani.

J. Comput. Inf. Sci. Eng 17(3), 031009 (Feb 16, 2017) (11 pages) Paper No: JCISE-16-2015; doi: 10.1115/1.4034387 History: Received July 18, 2016; Revised July 31, 2016

Freehand sketching is an integral part of early design process. Recent years have seen an increased interest in supporting sketching in computer-based design systems. In this paper, we present finite element analysis made easy (FEAsy), a naturalistic environment for static finite element analysis. This tool allows users to transform, simulate, and analyze their finite element models quickly and easily through freehand sketching. A major challenge here is to beautify freehand sketches, and to this extent, we present a domain-independent, multistroke, multiprimitive method which automatically detects and uses the spatial relationships implied in the sketches for beautification. Further, we have also developed a domain-specific rules-based algorithm for recognizing commonly used symbols in finite element analysis (FEA) and a method for identifying different contexts in finite element modeling through combined interpretation of text and geometry. The results of the user study suggest that our proposed algorithms are efficient and robust. Pilot users found the interface to be effective and easy to use.

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Figures

Grahic Jump Location
Fig. 1

The FEAsy interface showing (a) a hand-drawn sketch of an example 2D bracket and (b) the deformation results in ansys

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Fig. 2

The system pipeline with two modes of input—geometry and symbol

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Fig. 3

Step-by-step process of analyzing a bracket: (a) user drawn freehand stroke in geometry mode, (b) beautified output, (c) a freehand stroke representing a circle is added to the sketch, (d) result after beautification, (e) symbols input in symbol mode, (f) final sketch after sketch interpretation, (g) finite element integration dialog, (h) generated ansys specific commands, and (i) deformation results in ansys

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Fig. 4

Beautification of a freehand stroke: (a) freehand stroke, (b) raw points, (c) resampled points, (d) critical points, (e) primitives, (f) primitives, and (g) beautified sketch

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Fig. 5

Chord angle computation. The circles represent the resampled points. θ represents the chord angle computed for the resampled point using a window size of 3.

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Fig. 6

Recognition: (a) shows the freehand stroke with critical points. (b) Shows the results of least-squares fitting. There are discontinuities between adjacent segments. (c) Shows the results of our algorithm.

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Fig. 7

Least-squares arc fitting

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Fig. 8

Implicit geometric constraints inferred in our system for beautification

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Fig. 9

The list of finite element symbols recognized in our system

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Fig. 10

Symbol recognition and sketch interpretation. (a) A beautified sketch at the end of geometry mode. (b) Newly added strokes represent the dimensions, loading, and boundary conditions drawn in symbol mode. (c) Clustering of strokes into stroke groups represented by dashed bounding boxes. (d) Classification of stroke groups into text and symbols. (e) Final sketch after sketch interpretation.

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Fig. 11

Problems used in user study

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Fig. 12

Sample sketches from participants for the four problems. From left to right, each sub image inset in (a)–(d) shows the freehand sketch drawn in geometry mode, the beautified sketch, sketch with input symbols and text drawn in symbol mode, sketch after text and symbol recognition, and context interpretation, in that order.

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Fig. 13

Results of user study—beautification

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Fig. 14

Results of user study—symbol and text recognition. (Legend: CR—total number of correctly recognized symbols and T—total number of symbols.)

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Fig. 15

Results of user study—context interpretation. (Legend: CI—total number of correctly interpreted contexts and T—total number of contexts.)

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