Papers by Keyword: Computer Tomography

Abstract: The article is about manufacturing a component with a precision circular hole by Digital Light Processing (DLP) additive technology for inserting another part. The accuracy of the hole itself depends on the choice of production technology and the appropriate material. Deformation of the inner wall of the hole prevents correct insertion of the part - nut of trapezoidal threaded rod. This article analyzes the feasibility of manufacturing a component using Digital Light Processing (DLP) additive technology and the use of liquid resin „Proto GRY“ for the manufacture a component. Among additive technologies processes, digital light processing (DLP) is typically seen as the technology capable of reaching the highest standards in terms of part complexity and precision. DLP technology rely on the use of light, typically in the UV region of the spectrum (380 – 405 nm), to cure a photosensitive viscous resin. This resin, typically composed of epoxy or acrylic and methacrylic monomers, will polymerize and harden when exposed to light. As light shines on the vat to create specific shapes or patterns that compose each layer, a solid object can be formed and extracted from the otherwise liquid resin.

Abstract: Industrial tomography is currently the fastest growing sector of non-destructive research. Until recently, the use of computed tomography in industry has been limited mostly to defects in materials due to lack of accuracy. Modern measuring machines combining metrology and tomography can extract information about the external geometry and volume of the part with high precision from a single scan. This article deals with the transmission gearing scanning, which is a functional component used in the mechanical transmission design. It is imperative that it does not contain internal defects that can largely render the transmission ineffective due to the strain caused by stress. The component is produced by Digital Light Processing (DLP) additive technology. The chosen production method ensures greater strength of the part. The part will be made of material call as „Proto GRY “on a FabPro1000 printer from the company 3D Systems, Inc. The production process of the model will depend on the change in the orientation of the part.

Abstract: Impurities and resulting inclusions are an issue when processing higher amounts of scrap during steel making. To increase the recycling rate, the removal of impurities from the scrap in form of inclusions is of great interest. In previous studies was found that inclusions attach primarily on carbon containing refractories, especially if on their surface an interfacial layer (1–3 µm thickness) was formed in-situ. This study investigates the formation mechanism of this in-situ layer in detail by application of computer tomography (CT) measurements on two scales. The large scale CT scans visualized the general appearance whereas the small scale measurement regarded the in-situ formed layer and the attached inclusions in detail. Based on these measurements, previous results and a literature review it was concluded that the layer formed mainly due to carbothermally reduced impurities which moved to the decarburized surface of the refractory in gaseous form and enhanced sintering of the surface region to develop the layer.

Abstract: Ceramic freeze cast preforms based on alumina show an anisotropic behavior due to directional freezing during preform production. Beside the specific characteristics such as alumina content and lamellae spacing also the distribution of the so-called domains – regions with a relatively homogeneous orientation of alumina lamellae – play an important role considering stiffness and strength. The gas pressure infiltration process was used for infiltrating the freeze cast preforms with a eutectic aluminum/silicon alloy with a low melting point. Selected regions taken from the freeze cast preform have been analyzed via X-ray micro computed tomography (µCT) prior to the infiltration due to a higher contrast in comparison to the infiltrated preforms. The orientation of the lamellae has been determined from the three dimensional data with an algorithm which is based on the structure tensor. The mechanical stability - in terms of the strength - of the infiltrated preforms has been quantified via quasi static compression tests on cuboid samples. The results show a good agreement between the orientation of the lamellae distribution and the maximum strength of the preform which could also be verified using an analytical model.

Abstract: The Development of Fiber Reinforced Plastics (FRP) offers a great opportunity for applications in automobile industry, aeronautics and consumer goods to achieve light weight structures. However, the connection technology between FRP and mainly metallic based structures is the key to use the full potential of the FRP. Out of this motivation recent developments address this aspect.Using the powder metallurgical approach to generate a metal/ FRP connection module by spark plasma sintering a great variety is possible by integration of different metal and/ or fiber components. In this work aluminum and stainless steel was chosen for the upper and lower metallic side. The fibers integrated into the metal were glass, basalt and carbon fiber in one layer, two layer and mixed layer configuration. To connect the sintered module to greater CF weaves an infiltration process with a room temperature curing resin was used in a modified vacuum infusion (MVI) setup. In not optimized configuration the shear test after infiltration indicated an initial value for module shear strength above 20 MPa which can be enhanced in future developments by optimized armor between the upper and lower metal side and the number of integrated fiber layers of the connection module. A model is predicted to calculate the module shear strength in sintered state by multiplication of the armor area with the shear strength of the armor material. First experiments additionally show the possibility to weld the connection module directly to metallic structures.

Abstract: Until the present days, in discontinuous conveyor systems, e.g. cranes and elevators, steel wire ropes and steel chains are the exclusively used tension members. Nevertheless, these tension members are exhibiting essential disadvantages, e.g. high dead weight, low bending flexure and high susceptibility to corrosion. For fulfilling the steadily increasing requirements especially in running ropes, alternative tension members have to be developed and approved concerning their series-production readiness by utilization of new technologies and new materials. High-strength fiber ropes are demonstrating promising mechanical properties, regarding tensile strength, vibration behavior and bending fatigue life. Still, the application of such high-strength fiber ropes is limited, due to unavailable systematic investigations and insufficient guidelines for dimensioning and processes for determination of discard criteria. With the help of new technologies and procedures, e.g. multi-zone cyclic bend-over-sheave (CBOS) test machinery and computer-assisted tomography, new knowledge concerning the wear behavior of fiber ropes is to be gained and new discard criteria are to be developed.

Abstract: This Paper Designs the Intelligent Automatic Processing System of Precision Complex Work pieces by using the computer scanning technology and PLC control technology, and the use of computer scanning can capture the physical map, and then according to the physical map to divide into finite element grid, we can get the mechanical processing node path. The intelligent machine drive system is designed, and the system equip with MD32207 signal driver, 220V single-phase AC, power supply and using the pulse and direction signals common anode connection terminal, Finally, the system is applied to the computer college students' ideological and political education public opinion monitoring system, and the Meta search and intelligent information event extraction idea are also put forward, to provide the technical reference for the college students’ internet ideological and political online education.

Abstract: Traditional dental impression approach is not applicable to most of the oral and craniofacial trauma patients. Without a physical model, it is not easy to evaluate a patients fracture and occlusion, limiting the treatment process. Especially, the accuracy of the maxillofacial model for occlusion evaluation needs to meet strict clinical demands. Therefore, in this research, we attempted to use computed tomography (CT), without damaging the oral and craniofacial tissues of patients, together with image processing and Rapid Prototyping (RP) technique to obtain physical oral and maxillofacial models with high accuracy. Initially, a set of procedures of generating maxillofacial model was developed. CT images were segmented and converted to a CAD file by a commercial medical image processing software. RP technique was used to fabricate maxillofacial model. After comparison, the deviations were greater than clinical demands of less than 1 mm. After analyzing the sources of errors, issues of CT slice thickness, images threshold selection and editing, and RP fabrication were investigated to improve the accuracy. As a result, updated standard procedures were suggested to obtain RP maxillofacial models with higher accuracy. The improved average deviation can be reduced to 0.22 mm. The biological RP models with high accuracy generated in this research can be used to improve success rate and safety in a surgery, to reduce complications after the surgery, and to decrease the time and cost of treatment.

Abstract: We consider in this paper the Projective Computer Tomography (PCT) as an instrument for image reconstruction of objects with the internal simple discrete structure that consists of some separate elements inside of the homogeneous (or quasi homogeneous) substance in the considered domain. PCT consists in localization of intersections of prolongation of some known projections, obtained as images by some concrete tomography. Developed scheme is constructed as algorithms and MATLAB program package, which quality and rapidity is demonstrated on simulated numerical examples.

Abstract: This article is focused on computational modeling of an interaction of malleable lumbar spine fixation device with ambient bone tissue focusing on solving problems of clinical practise. It describes creation of computational model including model of geometry, materials, loads and constraints. There is a comparative stress strain analysis of spinal segment after fixation device application with its physiological state. Computations are performed with use of FEM method. To simulate natural way of loading we used the compression of motional spinal segment. Results show the difference between the system including intervertebral disc in between vertebras and the system with applied lumbar spinal fixation device.