Engineering calculations and numerical modeling of composite adhesive plywood panels

The global construction industry is witnessing a surge in production volumes, particularly in residential construction. To address the growing demand for prefabricated and cost-effective housing, the proposition is to employ glued plywood panels as construction components for building floors and roofs. These panels, comprising a timber frame, plywood skins, and insulation, offer numerous advantages, including low weight and a high strength-to-weight ratio. The objective of this study was to diminish the material consumption of panels by comparing calculations using both the traditional engineering method and the finite element method within a software package. The methodology for calculating and designing glued plywood panels, when employing the engineering method, involves determining the geometric characteristics of the panel sections, accounting for variations in the elastic moduli of wood and plywood. In the numerical calculation, the design method of plate elements of the "ReGridQuad" type was chosen, with the assignment of the required plate thickness. The outcomes of all calculations revealed comparable stress and deflection patterns in structures. The values obtained from both calculations were found to be below the standard ones. Research in this domain underscores the significance of numerical calculation methods in enhancing the quality of glued plywood panels, rendering them more competitive in the building materials market

Effect of Melt Overheating on Structure and Mechanical Properties of Al-Mg-Si Cast Alloy

The paper discusses the complex effect of melt overheating with subsequent fast cooling down to the pouring temperature on the crystallization process, microstructure and mechanical properties of Al-Mg-Si aluminum alloy. The results obtained facilitated the establishment of rational modes of melt overheating, leading to a significant change in the dispersion and morphology of structural components. In particular, with an increase in the melt overheating temperature to 900 °C with holding and subsequent rapid cooling to the casting temperature, a decrease in the average size of dendritic cells of the aluminum solid solution from 39 μm to 13 μm was observed. We also noticed the refinement of eutectic inclusions of the Mg2Si phase with compact morphology. An increased level of mechanical properties was noted; the maximum values of tensile strength and elongation reached 228 MPa and 5.24%, respectively, which exceeded the initial values by 22.5% and 52.3%, correspondingly. The microhardness of the aluminum solid solution sequentially increased from 38.21 to 56.5 HV with an increase in the temperature during melt overheating. According to the EDS linear scanning, an increase in the superheat temperature of the melt is accompanied by an increase in the degree of saturation of the solid solution with magnesium

Application of variable-height beams with wooden sub-rafter elements in the roof structures of industrial buildings

The investigation pertains to the coating utilized in single-story industrial buildings. Frame constructions with spans of 24, 30, and 36 meters are examined, employing wood-based elements as rafter structures. The reinforced concrete rafter structures exhibit a pitch of 2-3 meters and are configured in the shape of an I-beam. The truss structures along their length are subdivided into seven sections, featuring variable lengths, flange widths, rib thicknesses, and cross-section heights. Deflection calculations consider the nonlinearity of concrete and reinforcement deformations, adhering to prevailing building codes. The elastic solutions method is employed in conjunction with the finite difference method. The proposed coating designs are distinguished by their ease of manufacturing, transportation, and element installation. The wood-composite rafter structure boasts a lower mass compared to reinforced concrete elements, facilitating installation with a lightweight crane and overall diminishing the coating's weight without compromising its structural integrity. Several beam characteristics for spans of 24, 30, and 36 meters include respective mid-span heights of 1.2 meters, 1.4 meters, and 1.5 meters; volumes of 8.23 cubic meters, 9.25 cubic meters, and 10.6 cubic meters; and weights of 19.8 tons, 22.2 tons, and 25.4 tons. The proposed solution allows for the integration of bending moment and stiffness diagrams for the rafter beam configuration

Design evaluation and material selection of a mulch milling cutter working bodies

Working bodies of agricultural machinery and equipment are operated in harsh conditions. Mulching cutters shred various types of vegetation, including stumps, trees, bushes, their roots and mix wood residues with soil, which acts as an abrasive. Therefore, great attention is paid to the scientifically based selection of materials for the manufacture of the working parts of the mulching cutter. This study presents a systematic analysis of the operating conditions and design features of the working parts of the mulching cutter. The results of chemical and metallographic analysis, and hardness measurements of materials used for parts that make up the mulching cutter’s working body, as well as for obtaining permanent connections between structural elements, are given. Practical recommendations for material selection that meet the required operational characteristics of the working parts in the operating conditions have been formulated

Synthesis of Complex-Alloyed Nickel Aluminides from Oxide Compounds by Aluminothermic Method

This paper deals with the investigation of complex-alloyed nickel aluminides obtained from oxide compounds by aluminothermic reduction. The aim of the work was to study and develop the physicochemical basis for obtaining complex-alloyed nickel aluminides and their application for enhancing the properties of coatings made by electrospark deposition (ESD) on steel castings, as well as their use as grain refiners for tin bronze. The peculiarities of microstructure formation of master alloys based on the Al–TM (transition metal) system were studied using optical, electronic scanning microscopy and X-ray spectral microanalysis. There were regularities found in the formation of structural components of aluminum alloys (Ni–Al, Ni-Al-Cr, Ni-Al-Mo, Ni-Al-W, Ni-Al-Ti, Ni-Cr-Mo-W, Ni-Al-Cr-Mo-W-Ti, Ni-Al-Cr-V, Ni-Al-Cr-V-Mo) and changes in their microhardness, depending on the composition of the charge, which consisted of oxide compounds, and on the amount of reducing agent (aluminum powder). It is shown that all the alloys obtained are formed on the basis of the β phase (solid solution of alloying elements in nickel aluminide) and quasi-eutectic, consisting of the β′ phase and intermetallics of the alloying elements. The most effective alloys, in terms of increasing microhardness, were Al-Ni-Cr-Mo-W (7007 MPa) and Al-Ni-Cr-V-Mo (7914 MPa). The perspective is shown for applying the synthesized intermetallic master alloys as anode materials for producing coatings by electrospark deposition on steel of C1030 grade. The obtained coatings increase the heat resistance of steel samples by 7.5 times, while the coating from NiAl-Cr-Mo-W alloy remains practically nonoxidized under the selected test conditions. The use of NiAl intermetallics as a modifying additive (0.15 wt. %) in tin bronze allows increasing the microhardness of the α-solid solution by 1.9 times and the microhardness of the eutectic (α + β phase) by 2.7 times

Strengthening Mechanisms in CoCrFeNiX0.4 (Al, Nb, Ta) High Entropy Alloys Fabricated by Powder Plasma Arc Additive Manufacturing

In high entropy alloys (HEAs), the addition of large-size atoms results in lattice distortion and further leads to solid solution strengthening or precipitation strengthening. However, the relationship between atomic radius, solid solution strengthening and precipitation strengthening has not been discerned yet. In this work, CoCrFeNiX0.4 (X = Al, Nb, Ta, with an equi-atomic radius) HEAs were prepared by powder plasma arc additive manufacturing (PPA-AM) and evaluated for their mechanical properties. Compression and nano-indentation hardness tests showed that the HEA with Ta showed the best properties. The influence of atomic radius and solid solubility on solid solution strengthening was investigated and the main strengthening mechanism that determines the mechanical properties of the developed HEAs was analyzed. The results showed that (i) the CoCrFeNiAl0.4 alloy did not show any solid solution strengthening effect and that a clear relation between solid solution strengthening and atomic size was not observed; (ii) in both CoCrFeNiTa0.4 and CoCrFeNiNb0.4 HEAs, precipitation strengthening and grain boundary strengthening effects are observed, wherein the difference in mechanical properties between both the alloys can be mainly attributed to the formation of fine eutectic structure in CoCrFeNiTa0.4; and (iii) from the microstructural analyses, it was identified that, in the CoCrFeNiTa0.4 HEA, the location containing a fine eutectic structure is accompanied by the formation of low-angle grain boundaries (LAGBs), which is also the region where deformed grains gather, giving rise to improved mechanical strengthening