Initial Graphics Exchange Specification Research Articles

Effects of Apical Barriers and Root Filling Materials on Stress Distribution in Immature Teeth: Finite Element Analysis Study

PurposeA finite element analysis (FEA) study was performed to determine whether the material of apical barrier used for root apexification and/or the use of canal reinforcement affect the stress distribution in an endodontically treated immature permanent tooth in order to infer in which clinical scenarios a fracture is more likely to occur based on the ultimate tensile strength threshold of dentin. Methods and MaterialsAn extracted human immature mandibular premolar was selected as the reference model and scanned by micro-computed tomography (micro-CT). The digital model was segmented and converted to STL (Standard Tessellation Language) using Simpleware Scan-IP and exported in IGES (Initial Graphics Exchange Specification) to Ansys 19. Six experimental models were designed with different combinations of composite, mineral trioxide aggregate (MTA), and Biodentine (BIO). Using FEA, a static 300 N load at a 135 angle with respect to the axis of the tooth was applied to each model and von Mises stress values (MPa) were measured at the sagittal, apical 8-mm, 5-mm, 2-mm, and 1-mm levels. ResultsIn all regions examined, the control (NT model) had lower stress in the root compared WITH experimental models. At the mid-root level, models with composite, MTA, and BIO reinforcement exhibited lower stresses in the root dentin than those with pulp or gutta-percha. BIO models had equal or greater average von Mises stress values than those of MTA models in all regions. Both, MTA and BIO, caused increases in stress of surrounding root dentin, with BIO causing a greater increase than MTA. ConclusionsStress distribution in immature permanent teeth treated by apexification is affected by the types of materials used. Root dentin's stress was lower when the mid-root canal was reinforced by composite, MTA, or BIO, which provided similar stress reduction to the root dentin. MTA is a more favorable apical barrier material from a mechanical standpoint because it induces less stress on apical root dentin than BIO.

Part point cloud segmentation method based on model registration

In order to analyze the machining errors of parts more accurately, a point cloud segmentation method based on model registration was proposed for mechanical parts. First, the surface information of the standard model of the part is extracted from the Initial Graphics Exchange Specification (IGES) file; then, the part point cloud is registered to the standard model using the method of the moment principal axis method and the Iterative Closest Point algorithm (ICP); then, by calculating the distance between each point in the point cloud and each surface in the standard model, it is used to determine the corresponding relationship between the model surface and the point cloud, and then the point cloud is segmented; finally, the segmentation results are surface-fitted and benchmarked to obtain a segmentation with better alignment quality. The experimental results show that this method can automatically segment the part point cloud according to the surface features of the part when only the IGES model and the point cloud model are input, without setting any empirical parameters, and obtain the segmentation result with clear boundaries.

Construction of a Dual Protease Column, Subzero (-30 °C) Chromatography System and Multi-channel Precision Temperature Controller for Hydrogen-Deuterium Exchange Mass Spectrometry.

This tutorial provides mechanical drawings, electrical schematics, parts lists, stereolithography (STL) files for producing three-dimensional (3D)-printed parts, initial graphics exchange specification (IGS) files for automated machining, and instructions necessary for construction of a dual protease column, subzero, liquid chromatography system for hydrogen-deuterium exchange mass spectrometry (HDX-MS). Electro-mechanical schematics for construction of two multi-zone temperature controllers that regulate to ±0.05 oC are also included in this tutorial.

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

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.

Exchange of parametric assembly models based on neutral assembly constraints

It is difficult to exchange parametric assembly models using conventional neutral formats such as the standard for the exchange of product model data or the initial graphics exchange specification. These formats only support the boundary representation information that leads to the inability to perform parametric re-evaluation, once a model is exchanged. In order to exchange parametric information along with the design intent, a design history-based macro-parametric approach was proposed. Our method is macro-parametrics approach, however, supported only the exchange of individual part models. As most of the products are manufactured in assemblies, where several components are connected with multiple constraints, it is necessary to exchange the assembly model data. To overcome the issue of post-exchange editability, a collection of neutral assembly commands was introduced to extend the capabilities of the macro-parametric approach. A set of neutral assembly constraints was defined and a system for exchanging the parametric assembly models was implemented. An assembly model consisting of coaxial and incidence constraints was successfully exchanged between two commercial computer-aided design systems: CATIA and NX. It was possible to re-evaluate the assembly model parametrically after the exchange. The method can be further extended to exchange the remaining constraint types in different commercial computer-aided design systems.

Large scale layering laser surface texturing system based on high speed optical scanners and gantry machine tool

Abstract A layering laser surface texturing system for large freeform surface workpiece was realized with a reconfigurable structure of usual mechanical gantry machine tool plus laser processing head, which is composed of dual high speed galvanometer optical scanning axes and a mechanical linear axis. The principle of layering processing ability of laser focus point and the method to divide freeform surface into partitions and layers was analyzed. The kinematic of five axes machine tool with three axes laser processing head was derived. A novel computer aided laser texturing software named WnloLaserRobots was designed on visual C++ platform, which provides full function of 3D model data analyzing and real time processing control. The laser head position, the orientation data, and the layering scanning paths for processing a freeform surface were generated through importing and analyzing the universal initial graphics exchange specification (IGES) model file. In the control module, the software sends command to five axes gantry machine tool to position laser head normal to the processing surface partition and control laser processing head to accomplish layering laser texturing. This proposed system is particular suitable for laser ablation of film layer from multilayer materials on large scale free form surface. It has been used in practical application and satisfactory results were obtained.

Determination of The Most Appropriate Surgical Treatment in Syn-desmotic Injury of Ankle Joint: Application of Taguchi Method

Background:Ankle injuries are more frequently observed in youth and athletes, and may lead to permanent disabilities if not treated properly. Approximately 10% of ankle injuries are associated with syndesmotic ligament injuries and fixation with screw is frequently applied as surgical treatment. The present study we aimed to determine the most proper model and model parameters by evaluating the minimum equivalent von Mises stress value developed in syndesmotic fixation of the ankle. Methods: By modeling the normal lower extremity in a healthy subject via the finite element analysis (FEA) method, we compared stress developed in a normal standing position in the models of syndesmotic injuries approached by frequently used cortical screws of various lengths and diameters, and by considering the number of screws and localization of fixation. Tibia, fibula, talus, and calcaneus were modeled as a three dimensional (3D) solid model via images of computerized tomography (CT), using the MIMICS program (version 10.01). The obtained 3D model was saved in the MIMICS program in STL (steriolithography) format, and transferred to the Geomagic Studio (version 10) program. Essential corrections were applied to the bones with the aid of the Geomagic program. The model of lower extremity designed was transferred to the Solidworks (version 2014) program in IGES (Initial Graphics Exchange Specification) format, and thus the meniscus and cartilage were modeled. Tensions that developed in the ankle were calculated after forming a mesh pattern via the ANSYS Workbench (version 15.0) software. Results: Sixteen different models obtained were analyzed by the Taguchi method, and the most appropriate models and model parameters were indicated by determining the minimum equivalent von Mises stress value. Conclusion: Screw diameter was determined to be the most important parameter. When 16 different models were considered, a screw diameter of 4.5 mm and three-cortex fixation with two screws parallel to the tibial joint surface were found to produce the most convenient model.DOI: http://dx.doi.org/10.5755/j01.mech.23.1.14024

Automatic extraction of vertices coordinates for CNC code generation for dental wire bending

This paper reports a new methodology for an automatic extraction of vertices coordinates from a dental wire CAD model in an initial graphics exchange specification (IGES) file format for CNC bending code generation. It has two main components, the first one deals with IGES feature extraction and the second one deals with autonomous CNC code generation based on the Cartesian coordinates using various mathematical formulae. The procedure is carried out in MATLAB environment through some developed functions to support wire design technique in CAD by means of 3D line segmentation. In this approach, the digital design of the wire is constructed from multiple 3D line segments in reference to the 3D teeth scan image (STL file). The developed methodology has three steps consisting of an IGES model pre-processing, automated coordinate extraction and CNC bending code generation. The developed methodology is limited to the CAD design through multiple line segments and has been verified with a case study.

Automatic extraction of vertices coordinates for CNC code generation for dental wire bending

This paper reports a new methodology for an automatic extraction of vertices coordinates from a dental wire CAD model in an initial graphics exchange specification (IGES) file format for CNC bending code generation. It has two main components, the first one deals with IGES feature extraction and the second one deals with autonomous CNC code generation based on the Cartesian coordinates using various mathematical formulae. The procedure is carried out in MATLAB environment through some developed functions to support wire design technique in CAD by means of 3D line segmentation. In this approach, the digital design of the wire is constructed from multiple 3D line segments in reference to the 3D teeth scan image (STL file). The developed methodology has three steps consisting of an IGES model pre-processing, automated coordinate extraction and CNC bending code generation. The developed methodology is limited to the CAD design through multiple line segments and has been verified with a case study.

A tool for ship hull surface healing and domain preparation for downstream applications

This paper presents an automatic ship hull form CAD data repairing and domain preparing tool. The tool is capable to repair commonly found geometrical and topological inconsistencies in and between parametric and triangulated surfaces. Parametric surfaces are read from initial graphics exchange specification (IGES) file format and triangulated surfaces are read from standard tessellated language (STL) file format. Based on the repaired hull form parametric surfaces, automatic domain preparation strategies are implemented for mesh generators such as Numeca HEXPRESS and Open FOAMs SnappyHexMesh. Region identification method is developed to divide the hull form into different regions and export the repaired and consistent geometry in coloured STL file format. The repair, domain preparation, and region identification algorithms are tested against several ship hull form representations to evaluate the tool robustness. The results achieved reveal that the developed tool substantially decreases the time, and therefore cost, required for CAD data repairing and domain preparation for downstream application.

An Analytical Investigation On Design And Structural Analysis Of Cam Shaft Using Solid Works And Ansys In Automobiles

Objectives: This paper reports an investigation that was carried out for modelling and structural analysis of cam shaft. Methods/Statistical Analysis: The modelling of cam shaft is carried out using the software solid works and the structural analysis of the model is carried out by using Ansys software. Initially, the model is designed with Solid works software and then it is converted into Initial Graphics Exchange Specification (IGES) file. Then it is systematically analyzed using the IGES model of cam shaft. Experimental results under static load containing the stresses and deflection are predicted cast iron material. Findings: Testing was carried out for unidirectional different materials like ductile cast iron, nodular iron and carbon epoxy. By considering these materials, it is noted that the ductile cast iron is a good material compared to the nodular iron because the breakage of nodular cast iron is higher than the ductile cast iron. Application Improvements: Ductile cast iron is considered for making the cam shaft in vehicles because the cost of material slightly higher than nodular iron. In the development of modelling and also analyse by software helps to better result in design.

State evaluation of a corroded pipeline

ABSTRACTA submarine pipeline is mainly used to transfer liquid or gas between two land masses and may thus suffer corrosion from the severe subsea environment. Hence, the safety of a corroded pipeline must be evaluated by professionals. In this study, stress analysis of a corroded pipeline is conducted for three situations (i.e. simple defect, complex surface, and interacting defects). A simple defect is modelled using the 3D drawing software CATIA, and ANSYS simulates the stress of the corrosion defect; the effects of the defect were determined using different defect widths and depths. A complex surface involves the use of AUTOCAD VBA to establish the 3D surface based on random data and to generate an Initial Graphics Exchange Specification file. CATIA is used for file opening and geometric modelling and is finally keyed into ANSYS for analysis. ANSYS then is used for the stress analysis. The analysis covers a single rectangular defect, a spherical defect, and interacting effects of both types of defects. Finally, the stress analysis results are explored.

Interoperability of product and manufacturing information using ontology

The communication among different computer-aided design/computer-aided manufacturing/analysis systems usually involves huge amount of information and heterogeneous data formats. Inefficient communication between computer-aided design and computer-aided design/computer-aided manufacturing/analysis systems leads to information loss, which will lead to design and fabrication errors. Therefore, a bridge is needed to be made between the systems so that models can be transported easily and efficiently from the computer-aided design system to another system. To carry out successful manufacturing operation, not only parametric information and machining information but also non-parametric information is needed to be transported. The non-parametric information are geometric dimensioning and tolerance, notes, and other annotation to three-dimensional models which, altogether, are regarded as product and manufacturing information. Exchange of product and manufacturing information is to be done not only syntactically but also semantically. It is necessary to identify ontology and semantics early in the process so that the system is able to view, understand, and define the concepts relating to parametric and non-parametric information to improve interoperability and overcome data sharing problems. Neutral formats such as STEP, Initial Graphics Exchange Specifications, or prominent interoperability-related research works offer integration of other systems with computer-aided design. However, exchange of non-parametric information or product and manufacturing information has not been considered in these research works. To achieve semantic integration of information between computer-aided design and computer-aided design/computer-aided manufacturing/analysis systems, this article proposes a data integration method for both—parametric information of a model and non-parametric information (product and manufacturing information)—by constructing a neutral platform using OWL ontology, and also shows a pilot implementation that verifies interoperability between commercial computer-aided design and computer-aided design/computer-aided manufacturing/analysis systems.

Quick segmentation for complex curved surface with local geometric feature based on IGES and Open CASCADE

Complex curved surface parts with local geometric feature are usually critical parts in high-end equipments. However, the processing for this kind of parts is usually difficult or inefficient due to the adoption of difficult-to-machine material and special structure. Current approaches cannot satisfy the rapid development of high-end equipments. Due to the existence of the local geometric feature for the parts, processing such parts with constant machining parameters is less applicative, restricting the improvement of machining efficiency. By separating the local geometric feature and generating tool path for the local geometric feature and the remaining processing area separately, the more efficient machining with variable machining parameters will be obtained for the complex curved surface with local geometric feature. In this way, the quick segmentation for the complex curved surface with local geometric feature is of great importance to the NC machining with variable machining parameters for this kind of parts, and a quick segmentation system is developed based on Initial Graphics Exchange Specification (IGES) and Open CASCADE (OCC) platform in this study. The complex curved surface model in IGES format is firstly imported into the system and then trimmed into independent surface patches. After computing the feature size of each surface patch, the segmentation for the complex curved surface is achieved by sorting and classifying the surface patches according to their feature sizes. Taking the whole impeller with small splitter blades for an example, the experimental result shows that the segmentation of small splitter blades from the whole impeller is successful and a serialized processing program could be generated, and then the whole impeller could be machined precisely and efficiently with NC equipment. In the machining experiment, it is proved that the machining with various machining parameters can improve the efficiency by 28.18% in the comparison experiment, 20.14% and 12.33% in the estimation. The research provides an important foundation for the high quality and more efficient machining of the complex curved surface with local geometric feature.

Experience using models imported from CAD software for shielding calculations in MCBEND

*Reactor components (e.g. fuel assemblies) and other equipment (e.g. transport flasks) are designed using Computer Aided Design (CAD) packages. The process of converting CAD models into models that can be used in a Monte Carlo simulation is both time consuming and a source of approximations and errors. It is useful to be able to directly use these geometries in Monte Carlo calculations. MCBEND Version 11A Release Update 0 includes several methods of importing CAD geometries. The first method provides full accurate support for the range of geometry capabilities offered by the Initial Graphics Exchange Specification (IGES) model which can be used in combination with the existing geometry capabilities of MCBEND. All the surfaces in the IGES model are used directly with no approximation. This capability is provided by the OiNC software package developed by Sellafield Ltd as part of a Nuclear Code Development collaboration between Sellafield Ltd and the ANSWERS Software Service. A further two methods provide high performance CAD import options, but with a geometry approximation introduced by first converting the CAD file to a tetrahedral mesh representation or polygon surface representation, known as Standard Tessellation Language (STL), before importing them into MCBEND.

Establishment of the craniofacial three-dimensional finite element models with the sutures defined alone

To develop a child craniofacial three-dimensional (3D) finite element model (FEM) with sutures defined alone. The CT data for this study was developed from sequential computed tomography scan images taken at 0.625 mm intervals of an 8 years children skull. Data set was imported into Mimics 10.0 and processed with Geomagic 9.0, and exported as initial graphics exchange specification(IGES) files. The IGES files were then imported into Ansys 13.0 to set up two FEM with or without the median palatine suture being opened. The FEM contained nine craniofacial sutures and eight teeth which were defined alone.For simulating orthopedic maxillary protraction, three forces (F1-F2) were loaded on FEM.F1(1 N) was loaded at 1 cm above the geison. F2(1 N) was loaded at articular fossa of temporal bone. F3(2 N) was directed anteriorly and paralleled with occlusal plane near the canine. The stress distribution and the values distributed in each point gained in the two models were compared. Two craniofacial 3D FEM of the child were developed with the median palatine suture opened or not .With median palatine suture being opened or not, the two models showed the similar von Mises stresses (VMS). The distribution of the VMS was in the bridge of the nose and dextro-ala nasi.When the median palatine suture was opened, the max VMS value was 18916.00×10(-4) MPa which appeared in the nose point and the min VMS value was 1.61×10(-4) MPa which appeared in the maxillary central incisor point. At the same time, the max stress value at the direction Y was -3985.30×10(-4) MPa and appeared in the frontomaxillary suture point, and the min Y value was 0.08×10(-4) MPa which appeared in the maxillary central incisor point. When the median palatine suture was not opened, the max VMS value was 19 244.00×10(-4) MPa and appeared in the nose point. The min VMS value was 1.62×10(-4) MPa and appeared in the maxillary central incisor point. At the same time, the max stress value at the direction Y was -4258.20×10(-4) MPa and appeared in the frontomaxillary suture point, and the min Y value was 0.08×10(-4) MPa which appeared in the maxillary central incisor point. To define the sutures as entities alone contributed to develop child craniofacial 3D FEM which consist nine sutures. There was tiny difference in stress distribution in both the VMS and in Y direction with the median palatine suture being opened or not.

Control of NURBS-Based Surface Error Factor Using a Manufacturing Cost Optimization in Rapid Prototyping Process

Adaptive slicing in Rapid Prototyping Manufacturing (RPM) allows selection of the layer thickness based on the desired quality of the final product. This paper proposes an improved adaptive direct slicing technique for rapid prototyping where Computer Aided Design (CAD) model is directly expressed in standard Initial Graphics Exchange Specification (IGES) format. Using the developed computational platform, the IGES file is sliced based on the user defined allowable surface error factor and the layer thickness range of the RP machine. The total surface error is computed with the developed error function to verify slicing efficiency with respect to cost, production time and accuracy. Variety of experiments was conducted to find the accuracy of the developed procedure and the cost effective surface error factor.

Fast freeform hybrid reconstruction with manual mesh segmentation

In this paper, we presented a method for fitting large B-spline topological surfaces on freeform polygon mesh generated from cloud data of objects. The mesh has been manually segmented and large surfaces are fitted on segments in a hybrid approach, i.e., combination of geometric subdivision and non-uniform rational B-spline (NURBS) interpolation which is an emerging research space. An interpolation method has been proposed to parameterize dense cloud data of any complexity level with capability of handling occluded regions. All junctions are treated with trimming of NURBS surfaces with C0 and C1 continuities between adjacent patches. This scheme amalgamated process knowledge of reconstruction on segmented and subdivided point cloud data, various NURBS geometry options and junction treatment resulting in faster high-quality reconstruction. Apart from manual segmentation, almost the entire process is automatic which generated superior quality surface models. Pawn, Stanford Bunny, and human head clouds with occluded surface zones are used for tryout and resulting shapes are recorded in initial graphics exchange specification (IGES) files.

Evaluation of Design Parameters of Dental Implant Shape, Diameter and Length on Stress Distribution: A Finite Element Analysis

The aim was to evaluate the design parameters of dental implants shape, diameter and length on stress distribution by finite element analysis (FEA).The objectives of the study was to compare the influence of stress distribution in the implants of screw-vent tapered and parallel design by varying the implant diameter with a standard implant length. Six dental implant models have been simulated three-dimensionally. The influence of diameter and length on stress distribution was evaluated by Group I: for screw-vent tapered design (Zimmer Dental Implant Carlsbad, CA, USA) (1) Dental implant model with diameter 3.7mm and length 13mm. (2) Dental implant model with diameter 4.1mm and length 13mm. (3) Dental implant model with diameter 4.7mm and length 13mm. Group II: for parallel design (Zimmer Dental Implant Carlsbad, CA, USA) (4) Dental implant model with diameter 3.7mm and length 13mm. (5) Dental implant model with diameter 4.1mm and length 13mm. (6) Dental implant model with diameter 4.7mm and length 13mm. The 3-D model of the implant was created in the pro-e wildfire 4.0 software by giving various commands. This model was imported to the ANSYS software through IGES (initial graphic exchange specification) file for further analysis. All six models were loaded with a force of 17.1, 114.6 and 23.4N in a lingual, an axial and disto-mesial direction respectively, simulating average masticatory force in a natural oblique direction, to analyze the stress distribution on these implants. The increase in implant diameter in Group I and Group II from 3.7 to 4.1mm and from 4.1 to 4.7mm with constant 13mm length for screw-vent tapered and parallel design implant resulted in a reduction in maximum value of Von Mises stress in the bone surrounding the implant was statistically significant at 5% level done by student "t" test. The overall maximum value of Von Mises stress was decreased in parallel design implant diameter of 4.7mm with constant length of 13mm when compared to screw-vent tapered design implant samples. The results of the FEA computation depend on many individual factors including material properties, boundary conditions interface definition and also on the overall approach to the model. The results depicted that the tapered shape implant design exhibited higher stress levels in bone than the parallel shaped implant design which seemed to be distributing stresses more evenly. The application of a 3-D model simulation with the non-symmetric loading by the masticatory force on a dental implant resulted in a more satisfactory modeling of "clinical reality" than that achieved with 2-D models used in other studies.

Generation and Assessment of Random Surface Texture over a Wide Area

Product surface textures are designed to improve their aesthetic, tactile, and mechanical quality. Surface texture manufactured with microrough patterns over a wide area differs from common geometric product machining. We have proposed generating a surface texture with regular patterns by milling. Here we propose generating a random-pattern surface texture using image processing. Digital surface-texture data consists of “real” three-Dimensional (3D) machining information. Wide-area digital surface-texture data such as scattered point data, Initial Graphics Exchange Specifications (IGES), and Standard Triangulated Language (STL) require humongous memory. The complexity and area of surface texture processed to generate tool paths is limited by computational considerations and generating the tool path for a widearea surface texture is time-consuming, so we propose generating random wide-area-pattern surface texture without the need for wide-area digital texture data. Instead, this uses only wide-area image data and narrowarea digital data. A wide-area tool path is generated by image quilting, which creates a patchwork in which patches represent both image and digital data for narrow-area surface texture, reducing surface distortion for patch boundaries. This paper introduces the generation of random pattern texture and machined samples assessing patch-boundary distortion.