Experimental studies of the operation of a frameless building made of thin-gauge structural sections

Light metal structures (LMS) are widely spread in domestic construction industry. A promising direction for the development of LMS includes prefabricated shell structures made of thin-gauge structural sections. The scope and operating conditions of such structures are quite extensive. In this regard, the development of a competent engineering methodology for calculating buildings using thin-gauge structural sections is required. The present paper describes a method for a full-scale testing of a shell building fragment and provides the results of forces and deformations calculated using the experimental model. In addition, an approach to modeling and dimensioning of finite elements for the profiles under consideration is described. The comparative analysis of numerical data and experimental results is performed. The results of the study can be used both for developing recommendations and engineering methods for calculating similar shell buildings and for determining the actual operational scheme for units and elements of the considered structure.

Friction Stir Welding of Thick Plates of 4Y3Gd Mg Alloy: An Investigation of Microstructure and Mechanical Properties

Applications of non-ferrous light metal alloys are especially popular in the field of aerospace. Hence it is important to investigate their properties in joining processes such as welding. Solid state joining process such as friction stir welding (FSW) is quite efficient for joining non-ferrous alloys, but with thick plates, challenges increase. In this study, Mg alloy plates of thickness 11.5 mm were successfully welded via single-pass FSW. Due to the dynamic recrystallization, grain size in the stir zone was reduced to 16 µm which is ≈15 times smaller than the parent material. The optimized rotational speed and traverse speed for optimum weld integrity were found to be 710 rpm and 100 mm/min, respectively. A sound weld with 98.96% joint efficiency, having an Ultimate Tensile Strength (UTS) of 161.8 MPa and elongation of 27.83%, was accomplished. Microhardness of the nugget was increased by 14.3%.

Evaluation of Prestrain Annealing Impact on Nanomaterial Sensitization

Light metal alloys are extensively used in automotive, aerospace, aircraft, and military sectors since their lightweight leads to reduced energy consumption, increased fuel efficiency, and better environmental protection. In the present situation, nanomaterials are the potential candidate for weight saving in the structural application and can meet stringent government norms. Nanomaterial was heat-treated in the furnace to about a certain temperature and time and then normalized for strengthening. The heat-treated nanomaterial undergoes different forging processes, namely, hot forging and cold forging, using a certain capacity’s hydraulic press. Hence, in this work, an extensive study on the influence of the prestrain annealing, the corrosion rate on differently treated samples, and the effect of sensitization heat treatment on the nanomaterial was done.

DEFORMATION OF ALUMINUM ALLOYS IN ISOTHERMAL CONDITIONS

It has been scientifically proven that aluminum, more than other materials, meets the requirements of production, storage and processing of various foods. Therefore, the prospects for its use in the agro-industrial complex are quite high. At the same time, the process of developing such materials should be improved and promoted. Aluminum alloys are widely used in the aviation industry, in mechanical engineering and in agricultural production, due to their properties and light metal consumption. Alloys are resistant to water, they are not afraid of corrosion, sunlight, easily disinfected. All these properties are best suited for the use of aluminum in the storage of both cereals and livestock products. Moisture, dangerous molds, rodents and various insects are released and absorbed in storage. Aluminum has a high thermal conductivity and reflectivity, which reduce the risk of moisture condensation, which normalizes storage. The smoothness of this material suggests that the walls of aluminum structures collect much less dust. The proposed isothermal method of hot deformation of aluminum alloys in the processing of metals by pressure, differs from traditional deformation, and the temperature of the heated workpiece and the deforming tool is kept constant, close to the upper limit of forging temperatures, throughout the process. The deformation of the metal under isometric conditions and approximate deformations is characterized by an increase in ductility compared with ductility when machined in a cold tool. This is due to the lower rate of deformation, the lower limit of which is limited only by the productivity of the process. As a result, the "filling time" of defects that occur during metal deformation increases, the temperature stress in the workpiece volume decreases, the deformation becomes more uniform.

Advanced Corrosion Protection of Additive Manufactured Light Metals by Creating Ceramic SurfaceThrough CERANOD® Plasma Electrolytical Oxidation Process

Lightweight structures produced by additive manufacturing (AM) technology such as the selective laser melting (SLM) process enable the fabrication of 3D structures with a high degree of freedom. A printed component can be tailored to have specific properties and render possible applications for industries such as the aerospace and automotive industries. Here, AlSi10Mg is one of the alloys that is currently used for SLM processes. Although the research with the aim improving the strength of AM aluminum alloy components is rapidly progressing, corrosion protection is scarcely addressed in this field. Plasma electrolytic oxidation (PEO) is an advanced electrolytical process for surface treatment of light metals such as aluminum, magnesium, and titanium. This process produces an oxide ceramic-like layer, which is extremely hard but also ductile, and significantly improves the corrosion and wear behavior. The aim of this study is to understand the corrosion behavior of 3D-printed AlSi10Mg alloy and to improve its corrosion resistance. For this reason, the properties of CERANOD®—PEO coating on an AlSi10Mg alloy produced by SLM were investigated on different AM surfaces, i.e., as-built, polished and stress relieved specimens. The corrosion performance of these surfaces was analyzed using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and long-term immersion tests. Moreover, the microstructure and morphology of the resulting coatings were characterized by SEM/EDS, taking into account the corrosive attacks. The results exhibited a high amount of localized corrosion in the case of the uncoated specimens, while the PEO process conducted on the aluminum AM surfaces led to enclosed homogeneous coatings by protecting the material’s pores, which are typically observed in AM process. Thereby, high corrosion protection could be achieved using PEO surfaces, suggesting that this technology is a promising candidate for unleashing the full potential of 3D light metal printing.

Application of Industrial Computer Tomography to Determine Wood Porosity

The main objective of this research was to analyse the limitations of iCT - industrial computer tomography for measuring the wood pores characteristics as a new non-destructive method which is primarily intended to measure and inspect complete components primarily made of plastics or light metal. The subject matter of this paper are wood samples of paulownia (Paulownia tomentosa) and ash (Fraxinus excelsior) before and after thermal treatment. Porosity, pore volume and distribution of pores on the wood samples before and after the heat treatment were measured by iCT Metrotom 1500. The total porosity of the samples before thermal treatment was 5.28 % (paulownia) and 14.90 % (ash), while after thermal treatment, porosity increased to 9.50 % (paulownia) and to 30.78 % (ash). Changes in the porosity of the samples before and after heat treatment show an increase in porosity of 3.87 % (paulownia) and 15.88 % (ash).

Investigation of the Deformation Behaviour and Resulting Ply Thicknesses of Multilayered Fibre–MetalFibreM Laminates

Multilayered fibre–metal laminates (FMLs) are composed of metal semifinished products and fibre-reinforced plastics, and benefit from the advantages of both material classes. Light metals in combination with fibre-reinforced thermoplastics are highly suitable for mass production of lightweight structures with good mechanical properties. As the formability of light metal sheets is sometimes limited at room temperature, increasing the process temperature is an appropriate approach to improve formability. However, the melting of thermoplastic materials and resulting loss of stiffness limit the processing temperature. Since single-ply layers have different through-thickness stiffnesses, the forming process changes the ply thickness of the multilayered laminate. In the present study, the deformation behaviour of multilayered FMLs was investigated using a two-dimensional finite-element model assuming plane strain. The thermoelastic-plastic finite-element analysis made investigation of the variation in thickness made possible by incorporating sufficient mesh layers in the thickness direction. The results indicate that a thermoelastic-plastic finite-element model can predict the delamination of plies during deformation, as well as in the final product. Additionally, the predicted changes in thickness of the plies are in good agreement with experimental results when a temperature-dependent friction coefficient is used.

Hydrogen Production via Hydrolysis and Alcoholysis of Light Metal-Based Materials: A Review

As an environmentally friendly and high-density energy carrier, hydrogen has been recognized as one of the ideal alternatives for fossil fuels. One of the major challenges faced by “hydrogen economy” is the development of efficient, low-cost, safe and selective hydrogen generation from chemical storage materials. In this review, we summarize the recent advances in hydrogen production via hydrolysis and alcoholysis of light-metal-based materials, such as borohydrides, Mg-based and Al-based materials, and the highly efficient regeneration of borohydrides. Unfortunately, most of these hydrolysable materials are still plagued by sluggish kinetics and low hydrogen yield. While a number of strategies including catalysis, alloying, solution modification, and ball milling have been developed to overcome these drawbacks, the high costs required for the “one-pass” utilization of hydrolysis/alcoholysis systems have ultimately made these techniques almost impossible for practical large-scale applications. Therefore, it is imperative to develop low-cost material systems based on abundant resources and effective recycling technologies of spent fuels for efficient transport, production and storage of hydrogen in a fuel cell-based hydrogen economy.