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A New Additive Manufacturing (AM) File Format Using Bezier Patches

Allavarapu, Santosh

Abstract Details

2013, MS, University of Cincinnati, Engineering and Applied Science: Mechanical Engineering.
Additive Manufacturing (AM) process is used to fabricate parts with complex geometries in a layer by layer approach. Current AM machines use Stereolithography (STL) file format to manufacture parts. An STL file format is a discrete representation of a CAD model which uses planar triangular facets to approximate the surface of part. Due to this planar approximation, the STL format does not retain the complete geometric information of a CAD model which leads to approximation errors in the STL files. The higher the curvature of a design surface, the larger is the approximation error of the STL file. Currently, translation errors are minimized by using finer tessellations with smaller triangular facets which increases the size and memory of the STL file. Moreover, even with finer tessellations, it is not possible to exactly represent a CAD part with curved surfaces. This thesis presents a methodology for developing a new file format using curved bi-quadratic Bezier patches which can better approximate a CAD model compared to the STL file. Two new Bezier based formats are presented in this research: the first format uses curved Bezier patches with linear edges and the second format uses curved Bezier patches with curved edges. In the first format named as the linear edge format, the patches are modeled such that the edges remain coincident with those of the original STL facets. In the second format called the curved edge format, the Bezier patch edges are modeled as quadratic Bezier curves. The new file formats have been developed for a test surface as well as several solid parts including cylinders and spheres. The accuracies of the new formats have been compared to those of the existing STL format for these test parts. Further validation of the file formats has been performed by comparing the profile errors, volumetric errors, cylindricity and sphericity errors for the chosen examples by virtually simulating the manufactured parts using the new Bezier formats and the STL format.
Sundararaman Anand, Ph.D. (Committee Chair)
Sundaram Murali Meenakshi, Ph.D. (Committee Member)
David Thompson, Ph.D. (Committee Member)
98 p.

Recommended Citations

Citations

  • Allavarapu, S. (2013). A New Additive Manufacturing (AM) File Format Using Bezier Patches [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1385114646

    APA Style (7th edition)

  • Allavarapu, Santosh. A New Additive Manufacturing (AM) File Format Using Bezier Patches. 2013. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1385114646.

    MLA Style (8th edition)

  • Allavarapu, Santosh. "A New Additive Manufacturing (AM) File Format Using Bezier Patches." Master's thesis, University of Cincinnati, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1385114646

    Chicago Manual of Style (17th edition)