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Analysis of the Dimensional Accuracy of Point Clouds Created by Photographic Scanning

Kwieciński Karol, Paluch Maciej, Lisowska Aleksandra

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 6

121--132

EN

The article concerns the analysis of the dimensional accuracy of point clouds reproducing spatial objects made by photographic scanning in the Agisoft Metashape program. Due to the lack of available scientific literature describing the results of research on the accuracy of this type of objects created in the Metashape program, analyzes were carried out to determine it. In order to demonstrate the possibilities of wide application of point clouds also in opinion-making practice, three examples of objects with dimensions typical for the area of road accident research are described: a tread trace, a car and a fragment of a road. The obtained point clouds were compared with real objects in terms of dimensional accuracy. It was found that the method is able to provide very good accuracy, with a margin that meets the requirements of typical accident analysis.

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Simulation method for measuring the impact energy of rail vehicles equipped with a soft absorber

Lisowska Aleksandra, Sanecki Henryk, Szkoda Maciej

Transport Problems

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2023

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T. 18, z. 3

15--28

EN

This paper presents a simulation method for testing the energy absorbed by the absorption systems of rail vehicles equipped with a soft absorber. The method makes it possible to verify the actual behavior of the absorption system during the impact of two vehicles. The first part of this paper describes the structural elements of a railway vehicle performing the function of an energy absorber during an impact according to the EN 15227 standard. A soft absorber, the so-called honeycomb, is analyzed in detail. It is a multicellular structure often used in rail vehicles due to its properties of controlled deformation. The literature review describes the research conducted on this element. The analytical part of this paper describes a general mathematical model of a rail vehicle collision according to Scenario 1, in which the collided vehicles are of the same type, and Scenario 2 for vehicles of different types. A computational impact simulation for the two scenarios has been carried out using the specialist software Mathcad, and the results are presented in graphs. The paper ends with conclusions presenting the application possibilities of the developed tool.

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Measurements of Tensile Strength and Elongation of 3D Printed Polylactide Solids Produced with Different Temperatures of Extruder Using Coordinate Measuring Technique and Finite Element Method

Gaweł Anna Magdalena, Ostrowska Ksenia, Lisowska Aleksandra

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 6

356--366

EN

In order to determine the largest and smallest deformations during 3D printing, measurements were made for pure polylactide (PLA) using a coordinate measuring technique using a measuring arm. The additive manufacturing process was carried out using four nozzle temperatures: 190℃, 200℃, 210℃ and 220℃. The model was properly selected to check the cylindricity, angles of inclination and dimensional deviations from the nominal value of the cuboid. FEM analysis was used to confirm the obtained results. The cylindricity and shape tolerances were shown to be the best at 190℃. The smallest deviations from the angle of 90 ° have solids made at 200 ℃ and 220 ℃. In the case of dimensional tolerances of the centers of the holes relative to each other, the best deviations were obtained for the temperature of 190 ℃ and 220 ℃. The highest stress values during uniaxial stretching using FEM analysis were obtained for samples made with nozzle temperatures of 200°C and 210°C, which are about 31 MPa. For the temperature of 190°C and 220°C, the deviations are the closest to the reference model and are equal to about 30 MPa. In the case of the FEM analysis for single-point bending, the element made at 190°C had a maximum deformation of 0.203 mm, which was the same for the reference model. The largest deviation is noticeable for the printing temperature of 200°C and is 0.211 mm.