• Title/Summary/Keyword: STL

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The Study on the Reduction of Laser Scanning Path Creation Time during Jewellery Pattern Manufacturing (쥬얼리 패턴제작시 주사경로생성시간 단축에 관한 연구)

  • Kim, T.H.;Kim, S.Y.;Park, J.D.;Kim, M.J.;Jeon, E.C.
    • Korean Journal of Computational Design and Engineering
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    • v.11 no.6
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    • pp.440-446
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    • 2006
  • This study relates to the effect of forming time of injection path on the total process. The whole process can be divided into build process of forming path of injection and after treatment process. The total time required for the whole process could be reduced by reducing the forming time of injection path using SLC file to correct the problems of STL file that is the basic file format for high speed molding devices. First of all, I verify the forming time of injection path according to the conditions of STL file during the formation of injection path. And I verify problems using STL file during formation of injection path. And then I tried to solve problems of STL file by comparing between the formation time of injection path and the existing method using SLC files.

A Study on Feature Division using Sliced Information of STL Format (STL 포맷의 단면정보를 이용한 형상분할에 관한 연구)

  • Ban, Gab-Su
    • Journal of the Korean Society of Industry Convergence
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    • v.5 no.2
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    • pp.141-146
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    • 2002
  • Stereolithography is the best known as rapid prototyping system. It uses the STL format data which is generated from CAD system. In this study, One of the main function of this developed CAM system deals with shape modification which divide a shape into two parts or more. The cross section of a STL part by a z-level is composed with nested or single polygonal closed loop. In order to make RP product, closed loops must fill with triangular facets from SSET and recover sliced triangular facets which is located normal direction to the cross sectional plane. The system is development by using Visuall C++ compiler in the environment of pentium PC. Operating system is Windows NT workstaion from Micro-Soft.

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Investigation for effect of the specimen location on sound transmission loss measurement (차음성능시험에서 시편설치위치에 대한 실험적 고찰)

  • 김상렬;강현주;김재승;김현실;김봉기
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1234-1237
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    • 2002
  • When measuring sound transmission loss (STL) in a laboratory, the specimen location in test aperture affects considerably the measuring accuracy through the influence of so-called “tunneling effect” In this paper, for a single panel and a double panel with air cavity, experimental STL evaluations on various specimen locations on test aperture were carried out to explain the phenomenon. It is shown that the difference of STL is more than 2dB especially at the low frequency region and the case of the center-located panel yielded the lower STL than that of flushing with the end of tunnel, which confirms that the tunneling effect plays an important role in STL measurement.

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A study on conversion of cross-sectional information form STL file for Stereolithography (Stereolithography를 위한 STL파일로부터 단면정보 변환에 관한 연구)

  • 최홍태;김준안;이석희;백인환
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.445-450
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    • 1995
  • This paper deals with conversion from STL file to Slice cross-sectional information for Stereolithography. The STL file consist of three vertices of triangle and normal vectors in order to represent three dimension shape, but It is very difficult to convert STL file intoSlice file directly, because of file size from one Mbyte to tens of Mbytes. So, The system is accomplished data flow such as neutral.dat, .SL1, .SL2, .SL3, and .SLC file. The data processing is as follows: 1. Create a neutral file including common information. 2. Modify STL file within effective scope of SLA. 3. Calculate a point of intersection between plane equation and line equation. 4. Sort z values by increasing order. 5. Search closed loop by method of singlylinked linear list. The system is developed by using Borland C++ 3.1 compiler in the environment of Pentium PC. We get a satisfactory prototype as a result of application about a lot of household electrical appliances.

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Triangle Based Geometric modeling for rapid Prototyping CAM system (고속시작 시스템을 위한 삼각형 기반 형상모델링)

  • 채희창
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.587-591
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    • 1996
  • Usually triangular patches are used to transfer geometric shape in Rpaid Prototyping CAM system. STL, a list of triangles, is de facto in RP industry. Because STL has no topology data, it can cause errornous results. So, STL should be verified before using. After adding support structures to anchor the part to the platform and to prevent sagging or distortion, slicing and layer by layer manufacturing process are done. But triangular patch is surface model and cannot provide dufficient information on geometry in the above processes. So, geometric modeling is necessary in verifying STL, adding support structures, and slicing. It is natural that triangle based modeling is the best when traingular patches are used as input. Considering support structures, solid and faces coexist in RP process. Therefore non-manifold modeler is required. In this study, triangle based non-manifold geometric modeling is proposed for RP system consitent with STL input.

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Generating FE Mesh Automatically from STL File Model (STL 파일 모델로부터 유한 요소망 자동 생성)

  • Park, Jung-Min;Kwon, Ki-Youn;Lee, Byung-Chai;Chae, Soo-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.7
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    • pp.739-746
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    • 2007
  • Recently, models in STL files are widely used in reverse engineering processes, CAD systems and analysis systems. However the models have poor geometric quality and include only triangles, so the models are not suitable for the finite element analysis. This paper presents a general method that generates finite element mesh from STL file models. Given triangular meshes, the method estimates triangles and makes clusters which consist of triangles. The clusters are merged by some geometric indices. After merging clusters, the method applies plane meshing algorithm, based on domain decomposition method, to each cluster and then the result plane mesh is projected into the original triangular set. Because the algorithm uses general methods to generate plane mesh, we can obtain both tri and quad meshes unlike previous researches. Some mechanical part models are used to show the validity of the proposed method.

Bridging the gap between CAD and CAE using STL files

  • Bianconi, Francesco
    • International Journal of CAD/CAM
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    • v.2 no.1
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    • pp.55-67
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    • 2002
  • In many areas of industry, it is desirable to have fast and reliable systems in order to quickly obtain suitable solid models for computer- aided analyses. Nevertheless it is well known that the data exchange process between CAD modelers and CAE packages can require significative efforts. This paper presents an approach for geometrical data exchange through triangulated boundary models. The proposed framework is founded on the use of STL file specification as neutral format file. This work is principally focused on data exchange among CAD modelers and FEA packages via STL. The proposed approach involves the definition of a topological structure suitable for the STL representation and the development of algorithms for topology and geometry data processing in order to get a solid model suitable for finite element analysis or other computer aided engineering purposes. Different algorithms for model processing are considered and their pros and cons are discussed. As a case study, a prototype modeler which supports an exporting filter for a commercial CAE package has been implemented.

STL mesh based laser scan planning system for complex freeform surfaces (STL 메쉬를 이용한 자유곡면의 레이저 측정경로 생성 연구)

  • 손석배;김승만;이관행
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.595-598
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    • 2002
  • Laser scanners are getting used more and more in reverse engineering and inspection. For CNC-driven laser scanners, it is important to automate the scanning operations to improve the accuracy of capture point data and to reduce scanning time in industry. However, there are few research works on laser scan planning system. In addition, it is difficult to directly analyze multi-patched freeform models. In this paper, we propose an STL (Stereolithography) mesh based laser scan planning system for complex freeform surfaces. The scan planning system consists of three steps and it is assumed that the CAD model of the part exists. Firstly, the surface model is approximated into STL meshes. From the mesh model, normal vector of each node point is estimated. Second, scan directions and regions are determined through the region growing method. Also, scan paths are generated by calculating the minimum-bounding rectangle of points that can be scanned in each scan direction. Finally, the generated scan directions and paths are validated by checking optical constraints and the collision between the laser probe and the part to be scanned.

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An Analysis of the Sound Transmission through a Plate Installed inside an Impedance Tube (임피던스 튜브 내에 설치된 평판의 음파투과해석)

  • Kim, Hyun-Sil;Kim, Bong-Ki;Kim, Sang-Ryul;Lee, Seong-Hyun
    • The Journal of the Acoustical Society of Korea
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    • v.34 no.3
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    • pp.219-226
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    • 2015
  • In this paper, derivation of the STL (Sound Transmission Loss) of a square plate installed in an impedance tube is discussed using an analytic method. Coupled motion of the plate vibration and acoustic field is considered. Vibration of the plate and pressure field inside the tube are expressed in terms of the infinite series of modal functions. Under the plane wave assumption, it is shown that consideration of the first few modes yields sufficiently accurate results. When the boundary of the plate is clamped, vibration mode is assumed as a multiplication of the beam modes corresponding to the crosswise directions. The natural frequencies of the clamped plate are calculated using the Rayleigh-Ritz method. It is found that the STL shows a dip at the lowest natural frequency of the plate, and increases as the frequency decreases below the natural frequency. Comparison of the result in this paper with the STL obtained by measurements and FE computations in the reference shows an excellent agreement.

Sound transmission of multi-layered micro-perforated plates in a cylindrical impedance tube (원통형 임피던스 튜브 내 다중 미세천공 판의 음향투과)

  • Kim, Hyun-Sil;Ma, Pyung-Sik;Kim, Bong-Ki;Lee, Seong-Hyun;Seo, Yun-Ho
    • The Journal of the Acoustical Society of Korea
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    • v.39 no.4
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    • pp.270-278
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    • 2020
  • In this paper, sound transmission of Micro-Perforated Plates (MPPs) installed in an impedance tube with a circular cross-section is described using an analytic method. Vibration of the plates is expressed in terms of an infinite series of modal functions, where modal function in the radial direction is given by the Bessel function. Under the plane wave assumption, a low frequency approximation is derived, and a formula for the sound transmission coefficient of multi-layered MPPs is presented using the transfer matrix method. The Sound Transmission Losses (STLs) of single and double MPPs are computed using the proposed method and compared with those done by the Finite Element Method (FEM), which shows an excellent agreement. As the perforation increases, the STL is degraded, since the STL becomes dominated by the perforation ratio rather than by vibration of the plate. The STL shows dips at natural frequencies as well as at the mass-spring-mass resonance frequency. The proposed model for the STL prediction in this study can be applied to an arbitrary number of MPPs, where each MPP may or may not have a perforation.