Physical-mechanical Parameters Research Articles

Influence of physical–mechanical properties on SPF in sunscreen formulations on ex vivo and in vivo skin

The sun protection factor (SPF) is related to the selected UV filters. The objective of this study was to evaluate and compare the rheological behavior and texture profile of two sunscreen formulations and to correlate these data with the obtained SPF values. Two formulations (F1 and F2) were developed with the same type and amount of UV filters – whereby one of them also contained ethoxylated lanolin as additional film former (F2). Their rheological behavior, texture profile and in vitro and in vivo SPF were analyzed. The film-forming properties were evaluated by skin profilometry and diffuse reflectance spectroscopy. The structures of the formulations were examined by two-photon tomography combined with fluorescence lifetime imaging, and the penetration profile into the stratum corneum was investigated by tape stripping. The formulation with lanolin presented lower and constant values for physical–mechanical parameters, with a higher and better reproducible SPF. Both formulations did not penetrate the viable epidermis. In conclusion, formulations with better surface deposition on the skin surface can influence the film formation and, consequently, improve the SPF. These findings are important to improve the efficacy of sunscreen formulations and reduce the addition of UV filters.

Simulation of Granular Organic Fertilizer Application by Centrifugal Spreader

There is no specialized equipment designed to spread granular cylindrical organic fertilizer in the soil. There are also no rational recommendations available on how to spread this type of fertilizer. Mineral fertilizer spreaders are most often used for spreading granulated organic fertilizer. However, these fertilizers are significantly different from mineral fertilizers. Due to these differences, organic granular fertilizers often are spread unevenly, and the fertilizer does not reach the required working width. Furthermore, the rate of spreading is not accurate, and the fertilizer is often crushed too much. The objective of this research is to develop a simulation model for granular organic fertilizer applications with a centrifugal spreader in EDEM (extended distinct element method) software. It is possible to develop a numerical model that corresponds to a real spreader, and to determine the key physical–mechanical parameters for the application of granular organic fertilizer. This model can also be used for evaluating the transverse uniformity of the fertilizer in the field (along the trajectory normal to the machine). The results of this research show that the distance traveled by the fertilizer granules partially depends on the particle size, initial speed, type of fertilizer and the parameters of the spinning discs of the spreader.

Three-dimensional deformation monitoring and simulations for the preventive conservation of architectural heritage: a case study of the Angkor Wat Temple, Cambodia

ABSTRACT Architectural heritage has important historical, artistic, and technological value. However, these sites are subject to long-term degradation and are sensitive to disturbances from the surrounding landscape, resulting in the potential deterioration of the architecture. Deformation is a quantitative indicator of the vulnerability of architectural heritage. The extraction of three-dimensional (3D) deformation via existing geodetic approaches, such as global navigation satellite systems (GNSS) and interferometric synthetic aperture radar (InSAR), proves to be a challenging task. In this study, we proposed an adaptable methodology for the preventive monitoring of architectural heritage by integrating differential SAR tomography (D-TomoSAR) and a finite element method (FEM) to overcome the limitations of current geodetic approaches in cultural applications (i.e., sparse measurements in space; time- and labor-intensive). The Angkor Wat Temple, a well-known monument at the Angkor World Heritage site, Cambodia, was selected as the investigation target. We used D-TomoSAR to calculate the deformation, height, and thermal dilation of the structure using 46 TerraSAR-X images acquired during 2011–2013. InSAR deformation measurements were used as the constraint for the 3D deformation simulation and structural monitoring using an integrated approach to diagnose the soundness of the architectural structure. The experimental results demonstrate the following: 1) the integration of InSAR measurements prevented the underestimation of structural instabilities and linked the simplified physical model and mechanical parameters to the FEM simulation. 2) The Angkor Wat Temple appeared stable; however, structural instabilities were detected with an absolute deformation rate of up to 3 mm/yr. 3) Daily changes in thermal-related deformations caused by incoming frontal and posterior solar radiation-induced the bending of the architecture and the risk of structural defects. Our study reveals the defect mechanism of the Angkor Wat Temple and demonstrates the potential of the proposed method for the health diagnosis and preventive safeguarding of architectural heritages across the globe.

ASONIKA-BD: reference database of electrical and radio products and materials by geometric, physical-mechanical, thermophysical, electrical and reliability parameters

Information about the ASONIKA-BD subsystem — a database of electrical radio products (ERP) and materials — is given. The following sections are considered in detail: data base of materials, radiators, vibration isolators, classes of ERP, ERP installation variants, operating mode maps, ERP infallibility models, synchronization of the reference database. The interface of the program according to these sections is described. Keywords radio engineering device; modeling; database; electrical radio product

An Analysis of Deformations during Wave Propagation through the Contact Layer of Elastic Media

The stress-strain state at the interface between elastic media, which represents a contact layer characterized by the size and a set of physical-mechanical parameters, is investigated. The interface is described using the models of stratified and block media, within which the problem of a plane wave propagating through the interface is considered. The analytical expressions for the interface reflection and refraction coefficients are obtained, which allow determining the deformations at the interface and the strain distribution in the contact layer. The respective relationships for the dependence of deformation on the layer thickness at different elastic parameters of the contacting media and the interface are calculated. The regularities of deformation at the interface, described by the models of layered and block media, are analyzed. The areas of equivalent applications of these models are determined for the analysis of deformations at the interface and their distribution in the contact layer.

Modeling throttle bridge measuring transducers of physical-mechanical parameters of Newtonian fluids

The paper proposes a measuring transducer of the physical-mechanical parameters of a Newtonian fluid based on a throttle bridge measuring diagram with identical turbulent and laminar throttles in opposite arms. A mathematical model is built for the throttle bridge transducer of the combined parameter, which depends on the kinematic viscosity and density of the fluid. The problem of parametric optimization of the proposed measuring transducer is formulated and analytically solved in the paper. The authors calculated the transform function of the measuring transducer of the combined parameter of jet fuel.

Factors Affecting the Dynamic Rail Canting of the Railway Track

The article discusses the change in the canting of the rail track under the influence of vertical and horizontal forces transmitted from the wheel to the rails and further to the underlying elements of the track. A quantitative assessment of the change in the canting with deviations from the maintenance regulations of rail fastenings was made and with various options for wheel-rail contact. The calculations were carried out in a finite element modeling environment using three-dimensional models that are completely identical to the actual structure operating on the network of Russian Railways. The physical-mechanical parameters of the elements when modeling various types of materials of the upper and lower track superstructure completely repeat the properties of real materials, including bulk ones used on the road network of Russian Railways. The developed models are capable to evaluate the change of the rail canting – a deviation from the initial position, for any combination of loads and deviations from the maintenance regulations. The results of the study are quantitative values of the change in the position of the rail relative to the initial state at axial loads from 20 to 30 tons, lateral force up to 10 tons, and when the position of the wheels of the rolling stock on the rails changes. Numerical modeling made it possible to identify the factors that adversely affect the rail canting, which subsequently can lead to a broadening of the rail track, as well as a significant increase in contact stresses in the wheel-rail system.

Specific problems of engineering geological survey of sewer constructions

Sewerage constructions, unlike other types of constructions, require a certain specific methodological approach based on the fact that we have to deal primarily with the issue of earthworks related to the extraction of soils. Furthermore, it is necessary to deal with the hydrogeological conditions that affect the implementation of sewerage structures from multiple angles. The presence of water changes, for example, the physical-mechanical parameters of soils. The actual implementation of sewerage structures can change the flow of groundwater in the case of poor implementation of the backfill. All these specifics are pointed out in the presented publication.

Unsteady vibrations of a three-layer plate with an asymmetric structure

This article discusses the problem of symmetric vibrations of a three-layer plate pivotally supported along the edges in the longitudinal direction is solved. The materials of the plate layers are assumed to be elastic and isotropic. It is believed that the plate is not symmetrical in thickness, i.e. different thicknesses of layers. A brief review of scientific papers on theories of calculation of three-layer and multilayer plates is given. The equations of vibration of a three-layer plate, previously developed by the authors, are accepted as resolving equations. The stress and displacement components are expressed, as well as the oscillation equations, through the main parts of the longitudinal and transverse displacements of the points of the “intermediate” plane of the middle layer, which is at some distance from the middle plane of the plate. The conditions of the articulated plumage are formulated with respect to the displacements of the points of the middle layer. The initial conditions are assumed to be zero. The formulated problem is solved by an analytical-numerical method using a software package. The obtained numerical results are presented in the form of graphs of the dependences on time and the longitudinal coordinate of the displacements and voltages of the points, both the middle and the bearing layers of the plate. The calculations were performed for steel materials of the bearing layers, and for the middle layer the physic-mechanical parameters of the polymer material were adopted. The corresponding conclusions are made according to the results of numerical calculations. It was established that slight transverse displacements of the plate points appear due to the action of longitudinal external loads. Moreover, due to the insignificance of these displacements with symmetric vibrations of a three-layer plate, transverse displacements can be neglected. With symmetrical vibrations of the plate, longitudinal normal voltages are also excited despite the fact that the edges of the plate are free of external loads. These voltages are generated by the action of external tangential and normal voltages on the boundary surfaces.

Nonlinear problem of structural deformation in interaction with elastoplastic medium

The use of numerical methods in the calculation of machines and structures, taking into account their interaction with the elastic-plastic medium is largely determined by the complexity or even impossibility of analytical calculation due to the complexity of structural schemes, heterogeneity of material features, uneven soil layers, implementation of step-by-step work execution technologies and so on.
 Compatible calculations of structures and nonlinear basis, which are described by modern mechanical and soil models in one problem is a significant technical problem. And neither the existing “problem-oriented” software packages, nor the “universal” ones - do not fully contain such models.
 The tasks solution is possible only within the framework of numerical methods, the most common of which is the finite element method (FEM). The construction of the calculated finite element model raises many complex questions that require additional detailed study. In addition, the compliance with the state building norms and regulations is an important factor for further practical use.
 The combination of the latest achievements in the field of structural mechanics and soil mechanics is a promising direction for the development of effective approaches for building discrete models of spatial systems “structure-nonlinear base” for solving applied problems.
 On the basis of modern numerical implementations of the finite element method the article presents the theoretical foundations of the analysis of deformation processes of machines and structures in their contact interaction with the elastic-plastic nonlinear soil medium within the three-dimensional spatial problem taking into account the previous stress state and load history. The methodology of construction of computational models of joint deformation and mutual influence of rigid structures and essentially plastic external medium is developed, new special heterogeneous finite elements of SAFEM of general form with variable geometrical and physical-mechanical parameters and arbitrary boundary conditions for approximation of arrays of hardly connected reinforced soils are developed.

Thermodynamics and Mechanics of Thermal Spraying of Steel EN 10060 Substrate with NiCrBSi Alloy after Milling.

The objective of this paper is to present a new way of identifying and predicting the relationship between thermodynamic and physical-mechanical parameters in the formation of a layer after spraying on a substrate with NiCrBSi alloy and its subsequent processing by milling. The milling of the spherical surface of the EN 10060 material after spraying was performed on the DMU 40 eVolinear linear milling centre. The experimental part of the article is focused on investigating the influence of cutting parameters when machining a selected combination of materials (substrate-coating: EN 10060 steel-NiCrBSi alloy). The experiment is based on the results of direct measurements of three basic cutting parameters, namely: cutting speed vc (m∙min−1), feed per tooth fz (mm), and the depth of cut ap (mm). The new distribution functions of selected cutting parameters were derived. The analytical results of the thermodynamic calculations performed on nickel-based alloy can be used for accurate predictions of the technological parameters of milling a spherical substrate made of EN 10060 steel after HVOF spraying, and also for both sample preparation and the subsequent production of high-quality coatings.

Application of AHP and GRA methods in energy efficiency potential’s assessment of envelopes from natural materials

The best choice of energy efficient envelope from variety of available materials is still the challenge. Therefore, the attempt of thermal performance multi-criteria evaluation of some building materials of natural origin for energy-efficient envelopes is conducted in present paper. Such types of walls from natural energy-efficient materials are considered in comparison assessment: hempcrete, adobe, strawbale panel, earthbag, cordwood, SIP (plywood+ecofiber), hempcrete+straw and energy efficient block. The influence of thermal inertia time, internal areal heat capacity, as well dimensionless index of thermal inertia D, the total thermal resistance of the walls Rtot-value, mass of the wall assembly and its cost have been taken into consideration as important influence factors. The multi-criteria numerical assessment of envelope’s energy efficiency potential was performed by two popular methods – Analytic Hierarchy Process (AHP) as the subjective weighting method and Grey Relation Analysis (GRA) as the objective weighting method. Both of methods allow to arrange the alternatives and could be applied as decision support tools in decision making (DM) process of choosing the best alternative in terms of multi-criteria assessment. For more objective analysis, by taking into account the variety of physical and physical-mechanical parameters of the wall assembly material, the concept of generalized index of the envelope energy efficiency potential is proposed. Conducted research has shown that the best envelope type in terms of of generalized index of energy efficiency potential has the hempcrete wall and hemcrete+straw wall, almost three times smaller has the wall of the earthbags. The walls from adobe, cordwood and strawbale panels have practically the equal value of generalized index of energy efficiency potential. It could be observed that AHP method shown more inhomogeneous results, than GRA. The possible reason for that is the difference in evaluation attitude in techniques - AHP is considered as the subjective method with pairwise comparison matrixes, while GRA is objective method of comparison.

Justification of the possibility of cooking eggs without water in an ultra-high frequency electromagnetic field

Rejected hatching eggs after ovoscoping can be used as protein feed for chickens after they have been heat-treated by exposure to an ultra-high frequency electromagnetic field. In this regard, the dielectric and physical-mechanical parameters of the components of a chicken egg are analyzed, the heat treatment modes and structural designs of resonators of ultra-high-frequency continuous-flow installations are justified. Studies show that the yolk is endogenously heated two to three times faster than the protein, which is coagulated mainly by heat transfer from the yolk. This is due to the mass difference and the dielectric loss factor of the egg components. Unconventional resonators have been developed that allow controlling the heating rate of raw material components not only by smoothly regulating the generator power. In a quasi-toroidal resonator, this is done by changing the capacitance in the capacitor part; in mobile hemispherical resonators that provide a downhole technological process of less than 0.5 due to the resonant beam electrodynamic system-by changing the speed of movement of the hemispheres; in a biconic resonator - by changing the downhole process.

Substantiating the choice and optimizing the parameters for the technology of hot recycling of asphalt concrete road coating

The method of expert assessments has been used to substantiate that the most significant factors that significantly influence the mechanism and kinetics of technological processes of the regenerated mixture preparation are the temperature of its preparation and the content of the regenerating additive. We have investigated their influence on the physical-mechanical parameters of regenerated asphalt concrete, obtained using the technology of hot recycling of asphalt concrete pavement applying the «in place» method. The experimental research has established the dependences of the physical and mechanical parameters (water saturation, compressive strength at 0 °С and 50 °С) of regenerated asphalt concrete on the content of an additive and stirring temperature. The mathematical models have been constructed in the form of second-degree polynomials that describe the dependence of water saturation and strength at the compression of regenerated asphalt concrete on the temperature of preparation and the content of a regenerating additive. It has been established that increasing the stirring temperature increases compressive strength at 0 °С; at the same time, compressive strength at 50 °С and the measure of water saturation decreases. The increase in the regenerating additive reduces all the examined physical and mechanical indicators. Based on an analysis of the results obtained, we have determined the regions of rational values of the stirring temperature of loose asphalt-concrete crumbs (125‒135) °С, as well as the content of an additive (0.26‒0.28) %, when preparing hot asphalt concrete mixture. In terms of physical-technical indicators, the resulting mixture meets the requirements set by DSTU B V.2.7-119:2011 «Asphalt concrete mixes and road and airfield asphalt concrete. Technical specifications» for hot fine-grained asphalt mixtures. The reported results could prove useful when devising a technology of hot recycling of asphalt concrete pavement by the «in place» method and for studies related to its improvement

Experimental Study and Computer Simulation of Compression Characteristics and Crushing of Chinese Cabbage Seeds

HighlightsBasic physical properties and mechanical parameters related to moisture content and compression orientation.A discrete model of cabbage seed was established by discrete element method.Crushing simulation has high consistency and small deviation compared with physical experiment.Abstract. To reduce the mechanical damage to cabbage seeds during combined harvesting, storage, and processing and to explore the mechanism of grain breakage, the basic physical parameters, such as the 1000-grain weight and the triaxial size under different moisture content (6.38%~15.30%), and the compressive mechanical properties under different loading methods (ventral loading and lateral loading) were studied. The discrete element method was used to establish a BPM model of cabbage seed. The distribution law underlying macroscopic cracks, evolutionary mechanism of internal damage and the micromechanical response during the compression of cabbage seeds were simulated. The results showed that the triaxial size, 1000-grain weight, arithmetic mean diameter and geometric mean diameter of cabbage seeds were related to the moisture content. The crushing force and apparent elastic modulus were related to the moisture content and the loading method. The distribution law of macroscopic cracks during the simulation processing was consistent with the physical experiment, and it was accompanied by increases in cracks and changes in the internal stress. In comparing the crushing force-displacement curves under the two compression modes, the law of curves between physical and virtual experiments was similar, and the peak values were very close, which indicated the feasibility of using the discrete element method to simulate the crushing of cabbage seeds during the compression process. Keywords: Cabbage seeds, Compression test, Cracks, DEM, Stress.

ОЦЕНКА КОНТАКТНЫХ НАПРЯЖЕНИЙ ПРИ ВНЕДРЕНИИ УДАРНИКА В ПРОЧНЫЙ ГРУНТ

Finite formulas have been derived for evaluating contact stresses in a rigid impactor penetrating a soil, taking into account the friction in the framework of the local interaction model. In analyzing dynamic deformation of the soil, its volumetric compressibility, shear resistance and initial strength are accounted for. The obtained evaluations of resistance to penetration of an impactor into the soil are based on a quadratic relation between the stress normal to the impactor surface and impact velocity. The authors have pioneered in deriving finite expressions for coefficients of a trinomial approximation as a function of experimentally determined physical-mechanical parameters of the soil - a dynamic compressibility diagram (a shock adiabat) and a yield strength - pressure diagram. Impact compressibility of soils is described based on Hugoniot's adiabat - a linear relation between shock wave velocity and mass velocity of the medium particles behind the shockwave front. Plastic deformation obeys the Mohr - Coulomb yield criterion with a constraint on the limiting value of maximal tangential stresses according to Tresca's criterion - the Mohr - Coulomb - Tresca plasticity condition. An earlier obtained analytical solution of a one-dimensional problem of a spherical cavity expanding at a constant velocity from a point in a half-space occupied by a plastic soil medium is used. A formula for determining critical pressure (a minimal pressure required for the formation of a cavity, accounting for internal pressure in the framework of Mohr - Coulomb's yield criterion) is also used, which generalizes a known solution for an elastic ideally plastic medium with Tresca's criterion. The derived formulas have been verified by comparing their results with the available data from experiments on the penetration of a steel conical impactor into a frozen sandy soil. It is shown that the disagreement between the numerical and experimental results is within 10%.

Алгоритм комбінованого технологічного процесу утворення мікронаправляючих на поверхнях поліграфічного обладнання

An algorithm for controlling the technological process of microrelief guides formation by the method of thin surface plastic deformation on flat surfaces of printing equipment parts has been developed. The proposed technology allows to increase the wear resistance of flat guides and improve the positioning of printed products when passing on the surface of the microguides of printed products.The algorithm takes into account a set of indicators related to the material, geometric and physic-mechanical parameters of the surface of the flat guide, the modes of surface plastic deformation.Depending on the hardness of the material and the geometry of the regular microrelief in the algorithm, the geometry and parameters of the molding tool are selected. The hardness of the material is used to calculate the indentation force of the tool.The influence of regular microrelief on the operational properties of the microrail and on the positioning of paper and cardboard is consistently determined. When implementing the technological process on the surface form a partially regular microrelief of a curved shape. The following geometrical parameters of the microrelief are introduced into the algorithm: depth, width and height of the microguide inflows, and its area. The calculation of the area of the microrelief guide is offered. The geometrical parameters of the partially regular microrelief are taken into account at each combined stage of the technological process.The implementation of the algorithm allows to accelerate the preparatory and final work, purposefully in the automated mode to form a combined microrelief on a flat surface, to improve the positioning of printed products, as well as to assign optimal modes of guides and determine the geometric parameters of regular microrelief.

ВИЗНАЧЕННЯ ТА ПОРІВНЯННЯ ВЛАСТИВОСТЕЙ ВЖИВАНОЇ ДЕРЕВИНИ ОСНОВНИХ ХВОЙНИХ ПОРІД

The physical-mechanical properties of post-consumer wood (PCW) coniferous wood, namely pine fir, larch, spruce, were investigated. Tabular data of post-consumer wood of individual coniferous species are compiled: larch, pine, spruce and fir. The following physico-mechanical indices of used coniferous wood are investigated: density, impact hardness of fibers, static hardness, static flexural strength, chipping strength along fibers, compressive strength. Nomograms based on the research results have been constructed, which made it possible to efficiently carry out a comparative analysis of indicators for all breeds – physical-mechanical parameters of primary wood and post-consumer wood of some coniferous species. It is established that the characteristics of freshly chopped and used timber of separate coniferous species, namely pine, fir, larch, spruce, differ within acceptable limits and not more than 10-15%. Post-consumer wood coniferous timber meets the standards in terms of their physico-mechanical characteristics. On the basis of the obtained experimental researches the possibility of using used wood of separate coniferous breeds of post-consumer wood coniferous, namely pine, fir, larch, spruce for the production of wood products with satisfactory physical and mechanical properties was established. The economic feasibility of using some coniferous wood is analyzed. It is substantiated that the processing of used wood is of great environmental and social importance – the benefits of material processing of this resource. In addition, the used wood stores carbon dioxide, because after burning it will be released into the air, which is important in terms of environmental ecology. It is established that post-consumer wood of individual coniferous species is a suitable resource for material use in woodworking. It has been found that the research and recommendations will be useful for the production of products and the training process in the training of technologists.

Model of fuzzy ultra-acoustic diagnostics of nanocomposite functionally graded plate constructions in mechanical engineering

A description of a numerical-analytical technique for obtaining fuzzy estimates of the physical-mechanical parameters of plates that are exponentially inhomogeneous in thickness from functionally gradient transversely isotropic nanocomposite materials intended for use in mechanical engineering and aerospace technologies is given. The technique is based on the use of uncertain experimental data of measuring the lengths of normal shear elastic waves with different frequencies for different modes of the dispersion spectrum of the plate under consideration having interpretation in form of fuzzy sets. For obtaining fuzzy estimates of physical-mechanical parameters the transition to fuzzy-multiple arguments in the analytical relationships between the physical-mechanical parameters of functionally gradient transversely isotropic nanocomposite materials and the characteristics of ultrasonic measurements are used.

THEORETICAL RESEARCH OF THE VIBROACOUSTIC DYNAMICS OF THE CUTTING TOOLS FOR MILLING RECESSING AND CHAIN MORTISE WOODWORKING MACHINES

Milling recessing machines are designed to select mortises with end mills of the rectangular-shaped sockets. To the characteristic features of these machines, distinguishing them from the machines of the milling group is the additional oscillatory movement of the milling cutter on the chain ridged machines. The sockets are selected with the rectangular shape of the milling chain. These machines are operated at constant spindle speeds. Therefore, in these machines there are no multistage gear boxes with a large number of the spindles. These features lead to the fact that the vibrations of the cases of the speed boxes of woodworking machines (unlike metal-cutting machines) are much less and, accordingly, the intensity of their sound radiation is also less. The frequency of the rotation of the cutting tool is significantly higher. Therefore, it can be assumed that the main source of the noise that exceeds sanitary standards is the workpiece cutting tool system. The purpose of theoretical studies with obtained results show the analytical dependencies of the active sound pressure levels created by the cutting tool of the milling recessing and chain mortise machines providing for geometrical, physic-mechanical parameters of the tool and technological cutting conditions. The used acoustic source models are monocle for the tool of the milling recessing machines and a linear source for the milling chain and the noise levels obtained on their basis showed that for engineering calculation it is necessary to determine the oscillation velocities of the sources on their own oscillation modes. The speeds of the oscillations are determined from the differential oscillation equations; the solutions are obtained taking into account the cleat boundary conditions. The calculation of the noise spectra makes it possible at the design stage of both similar equipment and technological processes of the wood processing to determine the magnitudes over the maximum allowable values and in fact at the same stage to design noise protection systems.