Advanced Materials Research Vols. 1025-1026

Abstract: This study aimed to produce and determine physical and mechanical properties of three layers particleboards produced with Eucalyptus sp. particles, in outer layers, and Eucalyptus urograndis e Eucalyptus saligna bark, in internal layer. Recommendations of the Brazilian Code ABNT NBR 14810-3:2006 were adopted to fundament physical and mechanical tests. Properties considered were modulus of rupture (MOR) and modulus of elasticity (MOE) in static bending; internal adhesion; thickness swelling; water absorption; moisture content and density of the panels. Four different panel compositions were studied, with 5, 10, 15 and 20% of bark (related to particle mass) the internal layer. Results were compared with the requirements of: Brazilian Code ABNT NBR 14810-2; European Code EN 312 and related literature. The produced panels were adequate to all the values stipulated the cited codes and also superior to similar studies found in the literature, for all compositions of bark in internal layer, except for the moisture content test, in which only the composition of 5 % hull met the normative specifications.

Abstract: – Welding defects can create a major threat in industrial equipments and pressure vessels can during operation. Detecting and identifying of existing welding defects has a great role in the assessment of the probability of failure in different situations. Acoustic emission (AE) is only a nondestructive technique that can be used as in-service testing and used on large structures. This paper examines the changes in the properties of AE source generated from Pencil Lead Break (PLB). AE is recorded across different seam welds with pre-identified welding defects. Series of experiments are carried out on three certified standard Carbon Steel plates. Each plate has different pre-identified defect such as lack of fusion, porosity and slag. Different AE parameters such Energy, Amplitude and number of counts have been used to identify quantitatively the type of defects. The results are showing that AE technique is capable to identifying the different defects types which can be upgraded for higher productivity and accuracy for welding inspection.

Abstract: This study aimed to investigate the possibility of using castor-oil based polyurethane resin (PU), formulated with 30 % solids and 70 % solvent, in production of Medium Density Fiberboards (MDF) with Pinus caribaea fibers and two percentages of adhesive (5 and 10%). Six panels were fabricated under 4MPa pressing pressure, 190°C temperature. Initial moisture content of fibers was 9%. Properties investigated were: density of the panels; modulus of elasticity (MOE) and modulus or rupture (MOR) in static bending; and internal adhesion. Requirements of European Code EMB/IS-2 were used for comparison of results. Panels made with 10% of resin presented problems due gases expansion, disrupting the plates. For 5% resin content, mechanical properties investigated were above the requirements of the European Coded values. However, an undesirable odor prevented handling of the resin, in conditions here considered, which motivates the suggestion of new research in order to investigate different ratios between of solids and solvent contents, to completely enable the use of castor-oil based polyurethane resin MDF manufacture.

Abstract: Fatigue tests for full-scale orthotropic steel decks were conducted to evaluate and validate the fatigue performance of welded and bolted splice joints of longitudinal ribs. The test results indicated that the fatigue properties of two splice joints met the design requirements. The bolted splice joints whose principal tensile stress was largely lower than welded splice joints under the same loading conditions appeared to have superior fatigue resistance to the welded one. No fatigue cracks were detected among all the specimens and the principal tensile stress of measuring points had few changes during the whole fatigue tests. Systematic analysis of test data showed that bolted splice joints appeared to be more reasonable for improving the fatigue performance of longitudinal ribs.

Abstract: The problem of calculating the diameter of a pressurized vaulted rectangular conduit is solved explicitly through two methods which are based on an referential rough model whose geometric and hydraulic characteristics are well defined. The first method provides a highly reliable approximate relation which gives very accurate results for all practical applications. The second method consists in introducing into the calculations a rectangular rough model whose geometric and hydraulic properties were judiciously chosen. The theoretical development leads to an equation of third degree whose resolution has been made possible by the hyperbolic and trigonometric functions. Practical examples are presented to explain the procedure of calculation.

Abstract: This paper presents the performance characteristics of thermo-elastohydrodynamic lubrication (TEHL) in line contact with non-Newtonian liquid–solid lubricant. The time independent Reynolds equation, energy equation, elastic equation and load carrying with solid particle equation were formulated for compressible fluid. Newton-Raphson method and multigrid technique were implemented to obtain film thickness, film pressure, film temperature, friction coefficient and load carrying with solid particle equation in the contact region at various concentrations of solid lubricant and applied loads. The simulation results showed that film thickness and film temperature increase but film pressure decreases when solid particles are added into liquid lubricant. The maximum film temperature and load carrying of solid particle increased but friction coefficient decreased when concentration of solid particle increased. For increasing applied loads, the minimum film thickness decreases but maximum film temperature and friction coefficient increase for all liquid lubricant and liquid-solid lubricants.

Abstract: The article deals with the influence of production technology on mechanical properties of rubber testing samples. In practice, rubber testing samples are cut out from a compression molded sheet, also in case of testing of rubber compounds appointed for injection molding. However, the different way of the preparation of testing samples and the production itself may have a negative effect on the mechanical properties of the final product. Thus the article judges, to what extent the mechanical properties (tensile strength, extension, tear strength and microhardness) of testing samples from selected rubber materials are influenced by injection molding, and evaluates the possible divergence.

Abstract: This study aimed, with the aid of analysis of variance (ANOVA), to investigate and quantify the influence of moisture ranging between 12% and over 30% (fiber saturation) on the mechanical properties: strength and modulus of elasticity in compression and in tension parallel to grain; modulus of rupture and modulus of elasticity in static bending; shear strength parallel to grain considering wood species Ipê (Tabebuia sp) and Angelim Araroba (Vataireopsis araroba). Tests were performed according to the assumptions and calculating methods Brazilian standard ABNT NBR 7190, Anexx B, totalizing 400 tests. Results of ANOVA revealed a significant reduction (16% on average) for mechanical properties wood due to the increase in moisture content from 12% to over 30% (fiber saturation). The same behavior also occurred when assembly containing the two species was considered.

Abstract: The aim of this work is to determine the main mechanical properties, related to timber structures design, of the Brazilian tropical wood specie: Dipteryx odorata (Aublet) Willd. Tests were conducted according to the guidelines of the Brazilian Code ABNT NBR 7190: 1997 "Design of Timber Structures". Specimens were obtained from a so-called homogeneous clear wood lot, with moisture content around 12% . Mean values ​​of strength and stiffness properties confirmed Dipteryx odorata (Aublet) Willd as a good alternative for structural uses.