Quantification of mesoscale deformation-induced surface roughness in α-titanium

The phenomenon of mesoscale deformation-induced surface roughening in titanium polycrystals is examined experimentally and numerically. The evolution of the surface morphology under uniaxial tension is analyzed in terms of the standard and ad hoc roughness parameters and the fractal dimension. The statistical estimates are compared to the grain-scale stress-strain fields in order to reveal an interrelation between the in-plane plastic strains and out-of-plane surface displacements. A strong correlation with a determination coefficient of 0.99 is revealed between the dimensionless roughness parameter Rd and the corresponding in-plane plastic strain. The standard roughness parameters Ra and RRMS are shown to correlate linearly with the in-plane strains, but only for moderate tensile deformation, which is due to filtering out low-frequency components in the surface profiles. The fractal dimension DF changes with the subsection strains in a sawtooth fashion, with an abrupt drop in the neck region. The descent portions of the DF dependences are supposedly related to the appearance of low-frequency components in the structure of the surface profiles

A correlation between deformation-induced surface roughness and in-plane plastic strain in an aluminum alloy at the mesoscale

cal studies on deformation-induced surface roughening in a commercial purity aluminum alloy are presented and discussed. Mesoscale surface profiles evolving in the experimental and numerical specimens in the course of tension are processed to reveal a correlation between roughness characteristics and in-plane plastic strains at the mesoscale. A dimensionless parameter calculated as a ratio of the rough profile length to the profile evaluation length has been used for quantitative estimations of the mesoscale roughness patterns. The dimensionless roughness parameter is shown to depend exponentially on the in-plane plastic strains at the mesoscale. The results support an early assumption tha

Mechanical aspects of nonhomogeneous deformation of aluminum single crystals under compression along [100] and [110] directions

The deformation behavior of aluminum single crystals subjected to compression along the [100] and [110] directions is numerically examined in terms of crystal plasticity. A constitutive model taking into account slip geometry in face-centered cubic crystals is developed using experimental data for the single-crystal samples with lateral sides coplanar to certain crystal planes. Two sets of calculations are performed using ABAQUS/Explicit to examine the features of plastic strain evolution in perfectly plastic and strain-hardened crystals. Special attention is given to the discussion of mechanical aspects of crystal fragmentation. Several distinct deformation stages are revealed in the calculations. In the first stage, narrow solitary fronts of plastic deformation are alternately formed near the top or bottom surfaces and then propagate towards opposite ends to save the symmetry of the crystal shape. The strain rate within the fronts is an order of magnitude higher than the average strain rate. The first stage lasts longer in the strain-hardened crystals, eventually giving way to an intermediate stage of multiple slips in different crystal parts. Finally, the crystal shape becomes asymmetrical, but no pronounced macroscopic strain localization has been revealed at any deformation stage. The second stage in perfectly plastic crystals relates to abrupt strain localization within a through-thickness band-shaped region, accompanied by macroscale crystal fragmentation. Stress analysis has shown that pure compression took place only in the first deformation stage. Once the crystal shape has lost its symmetry, the compressive stress in some regions progressively decreases to zero and eventually turns tensile

Modeling of 3D microstructures produced by additive manufacturing

Two approaches to simulating microstructures typical of additively manufactured (AM) materials are presented. First approach relies on the mathematical description of the microstructure evolution during metal AM process, taking into account complex physical processes involved. The numerical solution is based on a combination of the finite difference method for modeling AM thermal processes and the cellular automata method for describing the grain growth. The other approach provides fast generation of artificial 3D microstructures similar to those produced by AM by geometrical characteristics of grains, using the step-by-step packing method

Organization of Professional Retraining and Professional Development of Specialists in Technical Quality Control of Products

Рассматривается проблема низкого уровня квалификации персонала машиностроительного производства в области контроля качества продукции и обосновывается необходимость их повышения квалификации и профессиональной переподготовки. Показана процедура проектирования дополнительной профессиональной программы на основе профессионального и образовательного стандарта. Сформулированы положения успешной организации дополнительного профессионального образования.The problem of the low level of qualification of machine-building personnel in the field of product quality control is considered and the need for their further training and professional retraining is justified. The procedure of additional professional program design based on professional and educational standard is shown. The provisions of the successful organization of additional vocational education are formulated

Influence of insectocompost obtained by cultivation of the during beetle <i>Ulomoides dermestoides</i> on the ecological-trophic composition and development of soil and phytoparasitic nematodes

The purpose of the research is to study the effect of insect compost obtained as a result of the vital activity of insects of the Coleoptera order Ulomoides dermestoides on the quantitative and qualitative composition of soil nematodes of various ecological and trophic groups, as well as on the morphological and physiological state of plants and infection of tomato plants with root-knot nematodes.Materials and methods. Under laboratory conditions, soil containing a diverse fauna of nematodes was treated with 1% dry and 0.5; 0.75 and 1% aqueous solutions of biocompost. Insect compost was obtained by keeping the U. dermestoides on a dry nutrient mixture. Then a mixture of lawn grasses was sown in the ground. After 30 days, the composition of nematodes was analyzed. The ability of insect compost to suppress parasitic nematode species was studied using the tomato-knot nematode model system. Tomatoes were infected with Meloidogyne incognita at a rate of 500 larvae (J2) per plant and simultaneously treated with a 0.5% aqueous biocompost solution.Results and discussion. The insect compost U. dermestoides has an effect on quantitative and qualitative indicators in the community of soil nematodes, increasing the number of predatory and saprobiotic nematodes and displacing parasitic ones. And due to the content of various biologically active compounds, it affects the development of rootknot nematodes in tomato roots. When tomatoes are treated with an aqueous solution of insect compost, the infection score and the number of nematodes that penetrate the roots are reduced. The introduction of compost when growing a mixture of lawn grasses and tomatoes can improve the condition of the plants

High-density genotyping reveals signatures of selection related to acclimation and economically important traits in 15 local sheep breeds from Russia

Domestication and centuries of selective breeding have changed genomes of sheep breeds to respond to environmental challenges and human needs. The genomes of local breeds, therefore, are valuable sources of genomic variants to be used to understand mechanisms of response to adaptation and artificial selection. As a step toward this we performed a high-density genotyping and comprehensive scans for signatures of selection in the genomes from 15 local sheep breeds reared across Russia

Genomic assessment and phenotypic characteristics of F2 resource sheep population

The article presents the results of assessment of genetic diversity and Principal Component Analysis (PCA) in the re-source sheep population, originated from crossing of fast-growing (Katahdin) and slow growing (Romanov) breeds for QTL mapping and search for candidate genes associated with growth rate. The study was conducted on 88 sheep from the resource population, including two unrelated families that have been reared in the Moscow region since 2017. Each family consists of a Katahdin ram (founder), Romanov’s ewes (mothers), F1 hybrids, and two groups of backcrosses. All sheep were genotyped using a high-density DNA chip Illumina Ovine Infinium® HD SNP BeadChip (~ 600 thousand SNP markers). SNP markers were filtered in the PLINK v.1.90. PCA was performed in PLINK v.1.90 and visualized in R package ggplot2. The genetic diversity indices (Ho, uHe, Ar, FIS) were calculated in R package “diveRsity”. It was established that both crosses had higher level of genetic diversity in comparison with the mother breed. F1 hybrids were characterized by the highest level of observed heterozygosity (Ho = 0.409-0.407), while Ho ranged from 0.382 to 0.396 for the backcrosses, respectively. The expected heterozygosity ranged from 0.329 to 0.356 in the groups from the resource population. Allelic richness was high in all studied groups (more than 1.849). PCA showed that the mated parent breeds were highly differentiated, as it should be in successful establishment of the resource population. The phenotypic characteristic of the backcrosses on live weight and nine body measurements at 9, 42 and 90 days is given. The coefficients of variation were the highest by live weight (17.0-19.0%), body length (15.5-22.3%) and oblique body length (16.2% and 22.7%) at 90 days. The results are intermediate and create a geno-typic and phenotypic base to perform GWAS at the next stage of our study