Industries that rely on additive manufacturing of metallic parts, especially biomedical companies, require material science-based knowledge of how process parameters and methods affect the properties ...of manufactured elements, but such phenomena are incompletely understood. In this study, we investigated the influence of selective laser melting (SLM) process parameters and additional heat treatment on mechanical properties. The research included structural analysis of residual stress, microstructure, and scleronomic hardness in low-depth measurements. Tensile tests with specimen deformation analysis using digital image correlation (DIC) were performed as well. Experiment results showed it was possible to observe the porosity growth mechanism and its influence on the material strength. Specimens manufactured with 20% lower energy density had almost half the elongation, which was directly connected with the porosity growth during energy density reduction. Hot isostatic pressing (HIP) treatment allowed for a significant reduction of porosity and helped achieve properties similar to specimens manufactured using different levels of energy density.
In the article the results of comparative research of eight types of polymers, used in sliding pairs, are presented. For the selected polymersmechanical properties and then also their tribological ...characteristics were examined with UNMT (UNMT -Universal Nano/Micro Tester) to select the best material. Friction coefficient and wear measurements were performed with reciprocating ball-on-disk pairof UNMT under dry lubrication conditions. The usefulness of UNMT was confirmed as a quick and precise method. Presented results showed also that the best antifriction and anti-wear properties were observed for polymer with small hardness and elasticity module.
The purpose of this paper is to study the tribiological behavior of (steel/porous iron), (steel/steel) and (steel/bronze) tribopair with micellar copper oxide, hexagonal boron nitride (h-BN), Lithium ...grease Liten LT43 and base oil, transformer mineral oil, and mineral oil SN650 as lubricants. The results are discussed in the form of performance such as wear surface, friction coefficient, weld point, limiting load wear and load-carrying capacity. It is found that (steel/bronze) friction pair contacts develop into a (copper/copper) contact along the sliding time. Worn surfaces were examined using XPS to determine the friction mechanism. The lower friction by additives is based on the formation of metallic copper tribofilm, and lamellar h-BN lubrication mechanism is discussed.
In this article we use artificial neural networks (ANN) in durability analysis of porous bearings. First, we present briefly the results of durability tests of porous sleeves impregnated with ...synthetic ester oil under different duration of the tests (100, 500, and 1000 h) and bearing temperature (60, 80, and 130 degree C) at a rotational speed of 1000 rpm. After each durability test oil samples were removed from the bearings and some chosen parameters were checked (Fourier Transform Infrared spectra and total acid number). In the second stage, the collected data were used in the design of ANN, i.e. work parameters as the inputs and oil properties as the outputs. The tests of various ANN types were performed to achieve the smallest training error and the best performance. The best parameters were achieved for multilayer perceptrons neural networks, and also quite good prediction of oil parameters after the test was observed. The achieved results, i.e. the ANN designed, algorithms, and oil parameters used, were compared with those observed in the previous tests for mineral oil.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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