Evaluation Of Stress-Strain State Of Vehicles’ Metal Structures Elements

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Specific features in operation of road construction equipment in the Far North

The development of the Far North goes hand in hand with the use of road construction equipment. The article addresses the main factors that affect the operation of this equipment in extremely cold climates. The effect of low temperatures on the operation of machines and individual units is examined. In particular, information is provided on the effect of low temperatures on operation of the hydraulic drive, power plants, and metal structures. The influence of the requirement to observe the methodological recommendations regarding the ergonomics and physiology of workers on increasing the cost of works with the use of road construction machinery has been noted.

Theoretical Comparison of the Methods of Surgical Treatment of Deforming Arthrosis of the Knee Joint

Comparison of the techniques of valgus osteotomy with resection osteotomy of the fibula in combination with sanitation arthroscopy. Resection of the fibula, debridement arthroscopy is characterized by minimally invasiveness, targeted therapeutic effect on the focus of destruction of the cartilaginous cover, removal of inflammatory mediators with abundant lavage, low-trauma intervention. Abrasive chondroplasty, subchondral tunneling during arthroscopy make it possible to create conditions for reparative processes, and the formation of hyaline-like cartilage in the defect zone. Corrective osteotomy may result in fractures of the tibial plateau, fractures of the cortical loop (instability of fixation), false joints, and fractures of metal structures.

Power Spectral Density Analysis for Optimizing SERS Structures

The problem of optimizing the topography of metal structures allowing Surface Enhanced Raman Scattering (SERS) sensing is considered. We developed a model, which randomly distributes hemispheroidal particles over a given area of the glass substrate and estimates SERS capabilities of the obtained structures. We applied Power Spectral Density (PSD) analysis to modeled structures and to atomic force microscope images widely used in SERS metal island films and metal dendrites. The comparison of measured and calculated SERS signals from differing characteristics structures with the results of PSD analysis of these structures has shown that this approach allows simple identification and choosing a structure topography, which is capable of providing the maximal enhancement of Raman signal within a given set of structures of the same type placed on the substrate.

Some Evaluations on the Technical State of Metal Products and Determination of their Safe Operation Period on the Basis of Criterial Control

Over a long period of operation, under the influence of corrosion and stresses from the acting forces, metal structures lose their strength. There is a need for their periodic non-destructive testing. The development of new methods is relevant in the field of control of building metal structures, such as bridge structures, structures of building cranes and other mechanical engineering products. The applied methods should be reliable and should not require huge material and labor costs. In this work, informational relationships between acoustic characteristics and parameters of metal microstructure are established. The proposed method can be useful for specialists and experts in the field of monitoring the technical condition of metal products requiring non-destructive testing. The safety of the operated objects depends on the accuracy of the applied criteria, as well as the degree of resource saving due to the full use of the product resource.

Evaluation of crack resistance of welded joints with soft interlayers

Introduction. Welded joints in large-sized metal structures (e.g., in the structures of ship hulls) subject to low-cycle fatigue are considered. The characteristic appearance of soft interlayers, which are significantly plastically deformed under working loads, was noted. Deformation of the metal structure with damage, especially in the form of cracks, reduces the strength and reliability of structural elements and joints. Pre-deformation negatively affects plasticity; therefore, much depends on the residual plasticity of the cracking material. At the same time, with a decrease in residual plasticity, such an important reliability indicator as the resistance of the material to crack propagation — the fracture toughness – decreases. The paper is devoted to the development of a model that includes analytical dependences for assessing the crack resistance of metal structures and their welded joints with soft interlayers according to the crack resistance limit for all crack sizes.Materials and Methods. The theory and methods of linear mechanics of materials destruction, structural-mechanical approach are used. The calculation results were analyzed and compared to the experimental data and other analytical solutions. The numerical experiment was performed for the ferrite-perlite steel grades of 10, 50, 22K, St3sp, etc., widely used in industry, as well as for alloy steels hardened to medium and high strength of 30KhGSA, 37KhN3A, etc. Results. Analytical dependences are obtained for calculating the relative crack resistance limit according to three main known mechanical characteristics of the state of the material of the soft interlayer of the welded joint.Discussion and Conclusions. The results obtained can be used to assess the crack resistance of pre-deformed structural elements and welded joints (including those with soft interlayers) operating under a transverse load. The results of experimental data and analytical calculations are shown in dimensionless form, which enables to obtain invariant results with respect to the fracture toughness limit.

Surface-nitridized 3D nickel host for lithium metal anodes with long cycling life at high-rate

Three dimensional (3D) metal structures such as nickel (Ni) and copper (Cu) frames have long been regarded as a good host for lithium (Li) metal. However, the Li deposition on...