Application of the Computed Tomography to Control Parts Made on Additive Manufacturing Process

AbstractThe article presents possibilities of application computed tomography to study elements made with additive methods. 3D printing is currently growing very rapidly and already allows to execute ready-to-use, structurally complex elements consisting of one or more parts. Similarly, computed tomography (CT), as the youngest measurement technique and methods to control the geometrical size of the parts, allows to control through any element and evaluate both the quality of each individual components and their assembly.This technique is especially valuable for the evaluation of additive methods. What is more, the evaluation of porosity on the individual sections of the parts might be conducted. It is also possible to obtain information about the location and thickness of each of the outer wall and inaccessible by any other techniques of non-destructive quality control of construction elements filling the various parts of the printed parts

Modelling of the injection and combustion processes in the gasoline direct injection engine

Rad prikazuje modeliranje procesa ubrizgavanja pomoću KIVA programa. Složeni matematički modeli koji se koriste u izračunima i koji opisuju procese koji se odvijaju unutar cilindra motora omogućuju generiranje kompliciranih virtualnih modela koji odražavaju stvarne uvjete na zadovoljavajući način. Točnost rezultata proračuna određena je kvalitetom ulaznih podataka, koji se mogu dobiti na temelju ispitivanja s modelom. Na temelju modeliranja procesa ubrizgavanja i izgaranja u GDI motoru, predstavljenih u radu, dobivena je osnova za širu analizu plinsko-dinamičkih pojava.The paper presents modelling of the injection process by means of KIVA program. The elaborate mathematical models used in calculations describing the processes occurring inside the engine cylinder make it possible to create complicated virtual models reflecting real conditions in a satisfactory way. The accuracy of calculation results is determined by the quality of input data, which can be obtained based on model investigations. Based on the modeling of injection and combustion processes in the GDI engine, presented in the work, the basis for a broader analysis of the gas-dynamic phenomena was obtained

Numerical analysis of the engine with spark ignition and compression ignition

U radu se prikazuju istraživanja simulacije izgaranja u testiranom motoru s četiri cilindra, na osnovu motora Toyote Yaris 1,3 dm3 s paljenjem iskrom i opremljenim s dva sustava napajanja energijom: osnovnim i paljenjem. Primijenjene su dvije metode pokretanja postupka izgaranja: paljenje iskrom i ponovo, poslije isključenja, ubrizgavanje zapaljive doze. Cilj je istraživanja bilo utvrđivanje razlika u postupku izgaranja i radu motora, prije svega promjena tlaka do kojih je došlo u cilindru te vrste motora s dva sustava napajanja energijom. Zapaljiva doza uštrcana u cilindar bila je jednaka otprilike 5 ÷ 8 % ukupne mase goriva u motoru. Gorivo je direktno ubrizgavano tijekom nekoliko desetaka stupnjeva rotacije koljenaste osovine prije dostizanja gornje mrtve točke. Pripremljena je prostorna mreža modela motora (predprocesor), a napravljena je i modifikacija izvornog KIVA 3V programa kako bi se uzela u obzir dva sustava ubrizgavanja. Treba spomenuti da standardni KIVA 3V program ima, po defaultu, samo jedan izvor ubrizgavanja goriva.The article presents simulation researches on the combustion process in the four-cylinder testing engine, based on the spark ignition engine Toyota Yaris 1,3 dm3 which was equipped with two systems of power supply i.e.: fundamental and ignition. Two methods of initiating the combustion process were applied: by spark ignition and, after it was turned off, by means of the ignition dose injection. The researches aimed at revealing the differences in the combustion process and engine performance, above all the changes in pressure that occurred in the cylinder for that kind of two-fuel power supply of the engine. The ignition dose injected into the cylinder was equal to about 5 ÷ 8 % of the general mass of the fuel supplied to the engine. The mass of the fuel injected into the approach collector determined the remaining part, and the direct injection of the fuel took place over several dozen of rotation degrees of the crankshaft before TDC (Top Dead Centre). A spatial grid of the engine’s model (pre-processor) was prepared, and also a modification to the source KIVA 3V program was made consisting in taking into account of two systems of injection. It is necessary to mention that the standard KIVA 3V program contains, as a default, only one source of fuel injection

Classification of Deflections of Thin-Walled Elements Made of EN AW-7075A Aluminum Alloy During Milling

The aim of the research is to classify and evaluate the size of deformations appearing during milling of thin-walled elements representing a pocket form made of aluminum alloy AW-7075A. Finishing, which is the purpose of the research, was carried out at the full depth of cut ap = 15 mm, milling the entire height of the wall in one pass. Deformations during machining were correlated with the geometric accuracy of the workpieces after machining. During the tests, deformations were measured with a laser displacement sensor, and the temperature of the samples was measured using a resistance temperature sensor. The tests made it possible to identify deformations occurring during the milling of thin-walled elements. The course of deformation during milling was analyzed, from which the value of deformation caused by milling, the reaction to this deformation and its time were extracted, additionally, permanent distortion of the workpiece was detected. The results show the effect of the ratio of the height to the thickness of the thin-walled element on its geometric accuracy after machining in the form of straightness and flatness of the samples. The test results were compared to the tests carried out on the Ti6Al4V titanium alloy, which confirmed the influence of the material selection on the course of deformations during milling

Multiscale Evaluation of Jaw Geometry Reproduction Obtained Via the Use of Selected Orthodontic Materials in Dental Implants and Orthodontics—In Vitro Case Study

In this paper, the multiscale analysis of the reproduction accuracy of jaw geometry obtained via the use of selected orthodontic materials is discussed. Impressions were made from two types of impression material. An accuracy assessment of the model geometry mapping was performed using noncontact systems, including a fringe projection optical 3D scanner, computed tomography, and a focus variation microscope. Measurements were made in three modes for comparison, as were the silicone and polyether impression materials. These modes were a jaw model and impression, an impression and plaster model, and plaster and jaw models. The research results are presented as colorful maps of deviations. Data analysis showed that deviations were the smallest in the case of silicone and that the best fit occurred between the silicone impression and the plaster model. The conducted research confirmed the validity of the assumptions considering the use of multiscale analysis for geometric analysis. The use of modern multiscale measurement methods allows for shorter and more efficient prosthetic operations. At present, these devices are expensive and complicated to use, but developments in technology should simplify the process, and prosthetic professionals should be aware of the possibilities described in the paper

Analysis of Tool Geometry for the Stamping Process of Large-Size Car Body Components Using a 3D Optical Measurement System

The paper presents a method for checking the geometry of stamped car body parts using a 3D optical measurement system. The analysis focuses on the first forming operation due to the deformation and material flow associated with stall thresholds. An essential element of the analysis is determining the actual gap occurring between the forming surfaces based on the die and punch geometry used in the first stamping operation. The geometry of car body elements at individual production stages was analyzed using an optical laser scanner. The control carried out in this way allowed one to correctly position the tools (punch and die), thus introducing the correction of technological parameters, having a fundamental influence on the specific features of the final product. This type of approach has not been used before to calibrate the technological line and setting of shaping tools. The influence of the manufactured product geometry in intermediate operations on the final geometry features was not investigated