Plasticity Coefficient Research Articles

Manganese Partitioning and its Effect on Residual Stress

The residual stress in low‐carbon high‐strength steel is not effectively relaxed during alloy carbide precipitation but is fully relaxed during manganese partitioning. The specific microscopic mechanisms responsible for this observed phenomenon have yet to be fully elucidated. This study employs first‐principles calculations in conjunction with experiments to demonstrate that alloy carbide precipitation leads to the formation of dense dislocation tangles that hinder carbon diffusion and carbide precipitation. Conversely, manganese partitioning aids carbon diffusion by altering dislocation morphology while also causing plastic deformation. The simultaneous occurrence of partitioning plasticity and precipitation plasticity during manganese partitioning results in a more significant relaxation of residual stress compared to alloy carbides precipitation: The plasticity coefficient for alloy carbide precipitation is 1.303 × 10−5, while the plasticity coefficient for manganese partition is 2.691 × 10−5. During alloy carbide precipitation, the elastic strain energy decreases to 43.48% of its initial value, whereas it can be further reduced to 25.29% after manganese partitioning.

Estimation of the Reduction Coefficient When Calculating the Seismic Resistance of a Reinforced Concrete Frame Building after a Fire

The consequences of destructive earthquakes show that the problem of analyzing the response of reinforced concrete frames under seismic loads after a fire is relevant. The calculation models used for individual elements and buildings as a whole must take into account the nonlinear properties of concrete and reinforcement. In the spectral calculation method, the nonlinear properties of materials are taken into account by introducing a reduction coefficient to the elastic spectrum. When determining the reduction coefficient, a common deformation criterion is based on the use of the plasticity coefficient. The seismic resistance of a three-span, five-story reinforced concrete frame under four different fire exposure options is considered. The residual strength and stiffness of frame elements after a fire is assessed by performing a thermal engineering calculation in the SOLIDWORKS software for a standard fire. For the central sections of the elements, the highest temperatures were obtained after heating—during the cooling stage. The reduction coefficient is estimated by performing a nonlinear static analysis of reinforced concrete frames in OpenSees and constructing load-bearing capacity curves. Fracture patterns and damage levels in plastic hinges are analyzed. Based on the numerical modeling of reinforced concrete frames after exposure to fire, it was revealed that the most dangerous scenario is the occurrence of a fire on the first floor of the building. Based on the obtained plasticity coefficients, reduction coefficients were determined in the range of 2.62 to 2.44. The influence of fire on the permissible damage coefficient of a reinforced concrete frame is assessed using the coefficient φK—the coefficient of additional damage after a fire, which is equal to the ratio of the reduction coefficients for the control and fire-damaged frames. Depending on the percentage of damaged structures on the first floor, the following values were obtained: 50% or less—φK = 1.09; 100%—φK = 1.17. The obtained coefficients are recommended to be used when assessing the seismic resistance of a reinforced concrete frame after a local fire.

Determination of Transformation Plasticity Coefficient of Structural Steel Sheet by Oil Quenching and Improvement in Prediction Accuracy of Distortion in Heat Treatment

Determination of Transformation Plasticity Coefficient of Structural Steel Sheet by Oil Quenching and Improvement in Prediction Accuracy of Distortion in Heat Treatment

Identifying the effect of low-cycle fatigue of reinforced concrete structures on the properties of the reducing coefficient under the action of a seismic type load

The object of consideration is seismic design, and the subject of the study is the determination of the reduction coefficient. One of the important problems of earthquake-resistant design is to determine the effect of low-cycle fatigue of reinforced concrete on the reduction coefficient and determine its optimal value. This problem is not disclosed and is not specifically taken into account in the standards for earthquake engineering when determining the maximum bearing capacity of types of structures due to the lack of study of the issue. To solve the problem, a series of experimental studies were carried out on low-cycle fatigue of reinforced concrete bending elements and frame units. The range of results of the reduction coefficient values and the degree of influence of monocyclic fatigue on the properties of the reduction coefficient are obtained. A feature and characteristic of the results obtained is that the reduction coefficient Rμ depends on the nature of the hysteresis deformation pattern and the plastic life of structural elements estimated by the plasticity coefficient μ, which is significantly influenced by low-cycle fatigue manifested at peak accelerations of strong seismic impacts. The above test algorithm, the feature and characteristics of the results obtained made it possible to solve the problem under study. The results obtained are accepted for practical use in the action of seismic loads: on the calculation of strength taking into account new low-cycle coefficients, reduction coefficients for determining the spectra of design reactions and seismic loads, taking into account energy absorption. New reduction coefficients are proposed for determining the spectra of calculated reactions and seismic loads

Study and Application of Rock Drilling Resistance Characteristics in the Jiyang Depression Formation

In response to the unclear drilling resistance characteristics of rocks in the Ji’yang Depression, low drilling efficiency of PDC drill bits, and difficulties in drill bit selection, this study selected rock samples from different depths in the area for indoor drilling resistance analysis testing. Based on logging data, a prediction model was established for drilling resistance characteristics parameters of the strata in the area, and a graph of drilling resistance characteristic parameters of the rocks in the area was drawn. The study showed that the uniaxial compressive strength of the strata rocks was 50–110 MPa, with a hardness of 500–1300 MPa, a plasticity coefficient ranging from 1 to 2, a rock drillability grade of 8–20, and an abrasiveness index of 5–20. Combining the analysis of on-site drilling bit failures, PDC drill bits adapted to the strata in the area were selected, and the mechanical drilling speed of the selected bits reached 12.58 m/h, successfully drilling through the target layer. The above research results are of guiding significance for understanding the reasons for the difficulty of drilling into the Jiyang Depression strata and for improving mechanical drilling speed and drill bit selection in this area.

Adaptability of buckwheat varieties in the forest-steppe of the Krasnoyarsk Territory

The article presents the results of the study of eight buckwheat varieties (Dikul (standard), Dasha, Diana, Design, Zhdanka, Zemlyachka, Natasha, Yashlek) for adaptability in the conditions of the Krasnoyarsk forest-steppe. For this purpose, the following indices were determined for each variety: plasticity coefficient, stability measure, intensity, stability index, variety stability level index, homeostaticity, breeding value of the variety, and adaptability coefficient. The hydrothermal coefficient showed that in 2021 the period from the second ten-day period of May to the first ten-day period of September was dry, in 2020 and 2022 – excessively humidified. The index of environmental conditions was with the sign "–" only in 2022 (–2.942). It was with a "+" sign in 2020 and 2021 (+2.821 and +0.121, respectively). This made it possible to determine the ability of the studied buckwheat varieties to adapt under contrasting conditions. Based on the plasticity coefficient in combination with the measure of stability, the conclusion was made about the ability of the varieties Zemlyachka, Diana, Design, Dikul, Yashlek to give high yield in favorable conditions. But Diana, unlike the other three varieties, in unfavorable conditions can noticeably reduce the yield. The varieties Design, Dikul and Yashlek showed slight yield reduction in the same situation. Dasha and Natasha varieties can produce higher yields under the worst conditions. At the same time variety Dasha is able to give both high and low yields in any conditions, which indicates its high meteorological dependence, especially since the value of the yield of this variety varies little from year to year. At the same time, the Zhdanka variety can sharply reduce yields in some years. The adaptability coefficient showed that Yashlek, Design and Diana have a very high degree of adaptability. Dikul can also be attributed to the varieties with a high ability to adapt to stressful conditions. According to the results of the study, Yashlek is the most adaptive variety (sum of the ranks amounted to 22). Diana, Design, Dasha and Dikul were slightly behind (sum of the ranks was 24–33).

OAT ADAPTABILITY TO ENVIRONMENTAL VARIABLES AND TECHNOLOGICAL FACTORS

Global climate changes cause the acceleration of environmental factors changes - temperature, unevenness of precipitation, drought, which has a significant effect on the yield. Food systems need expanded species biodiversity that are multifunctional in use and sufficiently tolerant to growing conditions. One of these cultures is oats which extremely valuable in human nutrition and provision fodder base. The purpose of the research is to establish the adaptability of oat varieties sowing under variable conditions of nutrition, thermal regime and moisture supply during the years of research. Field research with oat varieties was conducted during 2021-2023 in the stationary experiment of the Plant Breeding Department of the National University of Life and Environmental Sciences of Ukraine in a separate subdivision "Agronomic Research Station" (Pshenychne village, Fastivskyi district, Kyiv region ) on typical low humus chernozems. Varieties of oats vary in terms of adaptability due to genetic and environmental characteristics and technological factors of cultivation. The analysis of environmental factors was carried out - thermal units accumulation, sums of active and effective temperatures, GTK for biologically active minima at the level +5C and +10C. It is proved that the ecological factors characteristic for growing oats are used for calculation indicators for the biological minimum of +5С. Sums of thermal accumulation units for the period March - July on average for the years 2021 - 2023 was 2229.7; active temperatures for a biologically active minimum of +5С –2004.2; active temperatures for biologically active minimum +10С–1768.5; effective temperatures for a biologically active minimum of +5С–1361.5; effective temperatures for the biologically active minimum +10C–797.1C. The adaptability of varieties was identified through their plasticity and stability. The plasticity of the varieties increased with an increase of macronutrients in combination with sulfur. Highly plastic and stable varieties are Ivory, Zubr, Legin Nosivskyi - the coefficient of plasticity is equal or exceeds 1 for all fertilizing systems. The Ivory variety is high plastic and stable and responds positively to improvement of nutrition conditions: coefficient of plasticity - 1.00 - 1.32, coefficient of stability - 0.00 - 0.037. The Neptune variety is low-plastic and unstable for almost every rates of fertilizers, except for combinations with sulfur. For the Svitanok variety was established a positive reaction to increasing the rates of macroelements in combination with sulfur - the plasticity coefficient increased from 0.65, the stability coefficient from 0.015 in the control variant to 1.70 and 0.018, respectively, for the introduction N120P120K120S45+N30. There was a similar reaction for the Zakat variety - coefficient increased from 0.86 in the control version to 1.44 with applying N120P120K120S45+ N30.

Selection of watermelon starting material by adaptability for breeding for suitability for intensive and organic growing technologies

Purpose and Objectives. To select watermelon starting materials by major productive indicators (yield, average marketable fruit weight) for the breeding of genotypes suitable for intensive and organic cultivation technologies.
 Materials and Methods. Collection watermelon accessions were studied: 101 cultivars and lines from 9 countries. Cv. ‘Maks Plus’ (Ukraine) was taken as the control accession. The following parameters were determined: Sgi – genotype’s stability, bi – regression coefficient of the genotype's response to changing conditions (plasticity), GBVi – genotype’s breeding value. Plants were grown by traditional technology in the Forest-Steppe of Ukraine (DSTU 3805-98, 1998; DSTU 5045:2008, 2008). Watermelon plants were fertilized and protected in compliance with scientific and practical recommendations. The study was conducted in accordance with routine methods of breeding. Kilchevskiy & Khotylyova’s method, 1997 was used to estimate the genotypes’ stability parameters. The coefficient of environmental plasticity (bi) was calculated by Eberhart & Russel algorithm, 1966. Data were statistically and mathematically processed in Statistica 6.
 Results and Discussion. The adaptive potential of the watermelon collection was evaluated for the following characteristics: total and marketable yields and average marketable fruit weight. The following parameters were determined: bi - coefficient of regression of the genotype’s response to changes in conditions (plasticity), Sgi – genotype’s stability, and GBVi – genotype’s breeding value of the watermelon collection. We established the amplitudes and ranges of variation of the yield indicators. By the coefficient of environmental plasticity bi, the collection watermelon accessions were grouped as showing low, medium or high environmental plasticity for different traits. The collection accessions were categorized as follows: 1 - intensive genotypes with enhanced responses to growing conditions; 2 - with medium environmental plasticity; 3 - highly plastic, which slightly respond to changes in growing conditions. For breeding for various traits, we identified accessions of practical value in terms of stability parameters and genotype’s breeding value (GBVi) for intensive and organic cultivation technologies. Taking into account the environmental variability parameters in collection watermelon accessions to be used in the breeding of cultivars and hybrids suitable for intensive technologies, we selected accessions with enhanced responses to changing growing conditions, which also consistently yielded sufficiently high. As to the yield constituents (productive traits), 5 breeding-valuable accessions were selected by the "total yield" trait, 6 – by the "marketable yield" trait, and 1 – by the "average fruit weight" trait. Analysis of the environmental variability parameters in the watermelon collection to be used as starting materials in the breeding of genotypes suitable for organic cultivation enabled us to select a number of accessions by productive traits: 6 breeding-valuable accessions were distinguished due to the "total yield" trait, 4 – due to the "marketable yield" trait, and 6 - due to the "average fruit weight" trait. The selected accessions optimally responded to year’s conditions and were relatively stable in terms of high levels of expression of these traits under in changing growing conditions.
 Conclusions. For the breeding of genotypes suitable for intensive technologies, accessions with enhanced responses to changing growing conditions were selected; at the same time, they maintained a sufficiently high stability of yields. The breeding-valuable accessions were selected by yield constituents: 5 - by the "total yield" trait; 6 – by the "marketable yield" trait; and 1 – by the "average fruit weight" trait.
 Analysis of the environmental variability parameters in the watermelon collection to be used as starting materials in the breeding of genotypes suitable for organic cultivation enabled us to select a number of accessions: 6 – by the "total yield" trait; 4 – by the "marketable yield" trait; and 6 - by the characteristic "average fruit weight" trait. The selected accessions optimally responded to changing conditions of cultivation and showed relatively stable and strong expression of these traits.

Оценка продуктивности и экологической адаптивности сортов яровой пшеницы в условиях Среднего Предуралья

The article presents the results of scientific research for 2017-2020 on the variety testing of spring soft wheat in abiotic conditions of the Middle Urals. The varieties of spring wheat Iren and Yoldyz, respectively, had relatively higher yields of 490 g/m2 and 488 g/m2 in the competitive variety testing, which is significantly higher by 35 g/m2 and 33 g/m2 yields (455 g/m2) of the control variety Sim-birzit (NSR05 – 25 g/m2). The yield of these varieties was formed with a significantly higher 2% field germination of seeds, 21-60 pcs./m2 of productive plants and 21-37 pcs./m2 of productive stems for harvesting, 0.04-0.05 g of grain weight per ear. The highest average yield in the Yoldyz and Iren wheat varieties was due to a significant increase in the leaf surface area in the tube exit phase by 4.0 and 4.1 thousand m2/ha, in the earing phase – by 2.5 and 2.7 thousand m2/ha and in the phase of the dairy state of grain – by 1.4 thousand m2/ha relative to similar values in the standard Simbircite. The varieties Yoldyz and Iren formed the largest FP of 1275-1284 thousand m2 × day per 1 ha during the growing season, respectively. The varieties Iren and Yoldyz, in which the coefficient of plasticity was equal to 1.03 and 1.04, respectively (bi=1), are plastic, their yield corresponded to the change in growing conditions. The highest indicator of yield stability (0.12) was the spring wheat Iren. Keywords: SPRING WHEAT, VARIETY, YIELD, STRUCTURAL ELEMENTS, PHOTO-SYNTHETIC ACTIVITY OF PLANTS, PLASTICITY, ADAPTABILITY

PLASTICITY AND STABILITY OF THE ELEMENTS OF THE YIELD STRUCTURE OF COMMON BEAN VARIETIES

The article presents the results of long-term studies of the influence of hydrothermal conditions on the elements of the yield structure of common bean forms. It was found that along with genotypic features, the hydrothermal conditions of the years of research have a significant influence on the level of trait manifestation. the most favorable conditions were noted in 2021, 2018 and 2016, it was during the research period of these years that the highest grain productivity of common bean forms was obtained. The lowest grain productivity was observed in the conditions of the least favorable hydrothermal regime, which were in 2015, 2017 and 2020. However, despite the general biological dependence, the research made it possible to rank common bean forms according to their response to changes in the hydrothermal regime of their cultivation. This made it possible to identify forms that respond well to improved growing conditions and those with a lower response to changes in the hydrothermal regime. The highest number of productive nodes during the research period was observed in varieties Great Northern 1140, haricot - 4.55 pcs, Mestnaya 82 - 5.32 pcs, Jamunada, haricot - 5.05 pcs, Mestnaya - 4.95 pcs. mainly these varieties were characterized by an increased response to the improvement of hydrothermal conditions, the coefficient of plasticity (bi˃1). In particular, in the varieties Mestnaya 82 - 1.49, Jamunada, haricot - 1.34, Mestnaya - 1.15, except for the variety Great Northern 1140, haricot, which was characterized by a conservative response to changes in the hydrothermal regime (bi<1). The number of beans per plant is determined by the number of productive nodes, beans per node, and growing conditions. Therefore, as well as by the number of productive nodes, the following varieties stood out: Great Northern 1140, haricot - 18.3 pcs, Mestnaya 82 - 21.5 pcs, Jamunada, haricot - 20.0 pcs, Mestnaya - 19.8 pcs. The highest indices of the number of beans per plant were observed in varieties characterized by a high response to the improvement of hydrothermal conditions. The number of seeds per plant is a derivative of the number of beans. Thus, the best varieties in terms of the number of seeds per plant, as well as the previous trait, were Great Northern 1140, haricot - 55 pcs, Mestnaya 82 - 63.9 pcs, Jamunada, haricot - 60 pcs, Karamtsa - 64 pcs, Mestnaya - 58 pcs. All these varieties, except Great Northern 1140, haricot, belong to highly plastic, the regression coefficient of which was above one. In terms of weight of 1000 grains, the varieties with the national catalog number UD0300658 were distinguished by 330 g, Kharkivs'kii - 256 g, and only Great Northern 1140, haricot, which had slightly higher average values of the number of productive nodes, number of beans per plant and number of seeds per plant, also showed slightly higher average values of weight of 1000 grains - 254 g. Thus, the grain productivity of common bean is determined by the average and above average values of the elements of the crop structure, and not by the maximum complementary combination of each structural element. The highest grain productivity was observed in common bean forms: Karamtsa - 12.2 g, Mistseva 82 - 11.5 g, Great Northern 1140, haricot - 11.3 g. It should be noted that these forms of common bean respond well to the improvement of hydrothermal growing conditions, the plasticity coefficient of these varieties was more than one. In addition, the variant stability of these varieties was as close to zero as possible.

Selection of highly adaptive source material of watermelon for selection for early ripening

In terms of watermelon selection, the issue of stability of obtaining high yields in the conditions of manifestation of abiotic stressors of the external environment is relevant. The purpose of this study was to select a highly adaptive source material of watermelon according to the duration of the growing season and its components for use in breeding for early ripening. 101 collection samples of watermelon from 9 countries of the world were analysed. The study was based on the following methods: general scientific, measurement and weight, calculation, statistical. The watermelon collection was divided into ripeness groups and the sample was ranked according to the “duration of the seedling-ripening period”. The study established the amplitude (Am) and range of variation (Lim) of the signs of the duration of the components of the growing season. Samples with the smallest individual interphase periods were selected for use in selection for early ripening. The study found Vi – general adaptive capacity (GAC), σ2 SACi – specific adaptive capacity (SAC), Sgi – genotype stability, bi – regression coefficient of genotype response to changing conditions (plasticity), SVGi – selection value of the watermelon collection genotype based on the “duration of the growing season period”. According to the general adaptive capacity, the samples with the shortest duration of the “seedling – ripening” period were selected – 19 samples (Vi =-11.72…-6.05). As the most stable genotypes according to the “duration of the growing season” characteristic, 32 collection samples with a low value of the specific adaptive capacity indicator were selected, 23 of which are early ripening. The high stability of the genotype (Sgi) according to the characteristic “duration of the seedling-ripening period” was determined in 31 collection samples, of which 24 were early ripening. Based on the results of determining the regression coefficient (ecological plasticity coefficient), according to the characteristic “duration of the growing season”, the collection samples of watermelon were divided into three groups – with low (bi =0.01-2.20), medium (bi =2.21-4.22), and high (bi =4.23-6.24) ecological plasticity. According to the selection value of the genotype according to the trait “duration of the seedling-ripening period”, 18 collection samples had high indicators (SVGi =110.22-119.92), which are valuable for use in selection work with watermelon as sources of the characteristic “early ripeness”

Reliability analysis of reusable turbine rotor blisk: An application of parametric modelling method under multi-field coupling

As a critical component of reusable rocket engines (RRE), the cyclic life of the turbine rotor blisk often varies due to uncertainties such as machining errors and other factors. However, considering the difficulty of structural reconstruction and the large number of parameters related to the blade configuration, few studies have considered the blade configuration variation due to machining errors in the reliability analysis process. To investigate the influence of factors in reliability analysis, a reliability analysis framework is established by combining parametric modelling methods with finite element analysis methods under fluid-thermal-solid sequential coupling. The influence of blade lattice changes due to machining errors on the reliability of turbine rotor blisks in reusable rocket engines (RRE) is investigated. The effects of machining errors, material, and load variability on the cyclic life reliability of rotor blisks are effectively quantified. With the suggested method, a reliability analysis is conducted for an RRE turbine rotor blisk, and the effect of the machining error range on the analysis results is investigated. It is found that the tolerance level to meet the high reliability requirements is at least medium for the basic cyclic life requirements of the model. In terms of cyclic life reliability, the more influential random factors are blade axial chord, low-cycle fatigue plasticity coefficient, and low-cycle fatigue ductility coefficient, with sensitivity factors of 29.09%, 24.4% and 22.13%, respectively. This study provides an efficient and reliable modelling method for the reliability analysis of reusable turbine rotor blisks based on machining errors, investigates the influence of the range of machining errors, quantifies the ability of the random factors to influence, and provides valuable insights and recommendations for the reliability design and optimization of reusable turbine blisks.

Stress Field Simulation and its Experimental Verification of Carburizing-Quenching Process Performed on 18CrNiMo7-6 Steel

The carburizing and quenching process of 18CrNiMo7-6 steel was performed through simulation methods and experiments. The study was carried out to accurately predict the residual stress distribution of carburized samples after the quenching process. The stress and retained-austenite amount were measured via X-ray diffraction. Similarly, the carbon content was determined using a carbon sulfur analyzer, respectively. A detailed model with the coupling of thermal, metallic, and mechanical fields was built to predict the evolution of the stress field during the quenching process. The carburized “thoroughly” specimens at different carbon potentials were used to obtain the required mechanical property parameters and dilatometric parameters for FEM simulation. According to the results, the martensite transformation kinetic parameters α value of 18CrNiMo7-6 alloy steel should be 0.0202. With the increase of carbon content, the changing trend of the transformation plasticity coefficient K appeared as a 'tick' shape. A compressive residual stress field was generated at the carburized layer surface after the quenching process, and the maximum value of 340 MPa occurred at ~ 0.9 mm below the surface. The carbon profile and residual stress fields predicted from the FEM simulation corresponded closely to the experimentally determined results.

ADAPTIVE VALUE OF SOYBEAN VARIETIES GROWN IN DIFFERENT ECOGRADIENTS

The further expansion of soybean acreage and increase in productivity will be facilitated by the introduction of new modern varieties, which are determined by higher productivity potential and a higher level of resistance to the main fungal and bacterial diseases. However, soybean plants are affected by more than 50 diseases. It is known that pathogenic organisms lead to significant losses of the soybean crop (by 15-20%, and by epiphytotic development – by 50%).The results of studies on the assessment of soybean varieties for adaptability (ecological plasticity and stability) in different soil and climatic conditions for resistance to diseases (ascochitosis, yellow mosaic) are presented. Soybean varieties were ranked according to ecological plasticity and stability according to their response to environmental conditions. Our studies have shown that the intensity of the development of ascochitosis and yellow mosaic depends not only on the genetic characteristics of the genotypes, but also on factors related to the growing area, especially the hydrothermal and edaphic conditions of the region. The varieties Oriana – 93.4% and Hoverla – 93.2% stood out for their resistance to ascochitosis damage under different hydrothermal and edaphic conditions, which were characterized by a low reaction to a change in the hydrothermal growing regime, the coefficient of ecological plasticity (bi) < 1. That is, these varieties soybeans provided high indicators of resistance to ascochitosis despite a deficit or sufficient moisture supply in different ecogradient studies. The following varieties stood out for resistance to yellow mosaic: Hoverla – 85.0%, Oriana – 84.9%, Amethyst – 83.0. It should be noted that according to the parameters of ecological plasticity and stability (adaptability), the listed varieties belong to genotypes with a conservative reaction to changes in the agro-environment of cultivation, the coefficient of ecological plasticity (bi) < 1.

Adaptive potential of a watermelon collection for performance indicators

Purpose and Objectives. To select highly adaptable watermelon starting material by the main indicators of the performance (yield and average marketable fruit weight).
 Materials and Methods. The watermelon collection was investigated: 101 cultivars and lines from 9 countries (55 accessions from Ukraine, 23 - from Russia, 8 - from China, 5 - from the USA, 3 - from Moldova, 2 - from Kazakhstan, Thailand and the Czech Republic each, and 1 - from Italy). A Ukrainian cultivar, Maks Plus, was taken as the check accession. The following parameters were calculated: Vi - general adaptive capacity (GAC), σ2SACi - specific adaptive capacity (SAC), Sgi - genotype stability, bi - regression coefficient of the genotype's response to changing conditions (plasticity), and GBVi – genotype breeding value. AV Kilchevskyi and LV Khotylyova’s method was applied to estimate the parameters of adaptive capacity and stability of the genotypes. The environmental plasticity coefficients (bi) were calculated according to SA Eberhart and WA Russel algorithm. Data were statistically processed, as BA Dospekhov recommended.
 Results and Discussion. The adaptive potential of the watermelon collection was evaluated for the following traits: total yield, marketable yield, and average marketable fruit weight. The variation amplitude (Am) of the "total yield" trait based on the averaged three-year data on the collection was 51.26; the variation range was 15.07 - 66.33 t/ha. In the check accession, Maks Plus, the mean total yield across the 3 years was 64.72 t/ha. For further work, we selected 31 collection accessions, basing on the total yield” trait. The adaptability parameters of the collection watermelon accessions for the "marketable yield" trait differed somewhat from those for the “total yield” trait. From the averaged three-year data, the variation amplitude (Am) of the "marketable yield" trait was 51.15 t/ha; the variation range of this trait was 13.19 - 64.34 t/ha. The variation amplitude of the "average marketable fruit weight" trait based on the averaged three-year data was 3.00 kg. The variation range of this trait was 0.99–3.99 kg. The average fruit weight in the sample across the 3 years was 2.14 kg. In the check cultivar, Maks Plus, the average fruit weight was 2.50 kg. For the breeding for the characteristics under investigation, accessions of practical value, with high values of the general adaptive capacity, stability, and genotype breeding value were selected. By the environmental plasticity coefficient bi, the collection watermelon accessions were categorized as low-, mid- and highly plastic in terms of the characteristics under investigation: intensive accessions with enhanced responses to growing conditions, accessions with moderate levels of the environmental plasticity, and highly plastic accessions, which slightly respond to changes in growing conditions.

Crossbars of frame buildings when changing the sign of forces

A large number of reinforced concrete frame buildings are located in seismically dangerous regions. In case of seismic impacts plastic strains and local destructions occur in elements of such buildings, which influence sufficiently on their bearing capacity and stress-strain state when changing the sign of internal forces. This fact is not taken into account in current Russian norms on earthquake-resistant construction. The numerical research of reinforced concrete beams behavior under action of alternating load with regard to elastic-plastic properties of concrete and reinforcement has been conducted. The evaluation of influence of plastic strain maximum value in tensed reinforcement on the relative bearing capacity of the beam when changing the force sign and on the limit value of coefficient of plasticity corresponding to the destruction of compressed zone of concrete has been made. The comparison of results of numerical simulation with the results of experimental tests of beams with the same parameters has been made, which has demonstrated good convergence of numerical calculations with experimental data both in terms of bearing capacity and deformations for plasticity coefficients less than 2.5. During the experiment it has been found that when changing the sign of internal forces the through cracks form in bending reinforced concrete elements throughout the entire section height, which close afterwards if the coefficient of plasticity for reinforcement deformations does not exceed 2.5. For greater values of coefficient of plasticity the through cracks closing doesn’t take place until the destruction of the specimens due to the rupture of reinforcement bars. According to the results of the study it was concluded, that the decrease by 40% of relative bearing capacity of beams compared with reference samples as the increase of coefficient of plasticity in the first semi cycle of loading takes place. Also with the increase of the coefficient of plasticity the three times decrease of the limit values of coefficients of plasticity, corresponding to destruction of compressed concrete, when changing the sign of forces is observed. The numerical calculations of beams models for 10 and 50 alternating load cycles have been conducted with cycle asymmetry coefficient equal to -1. The conclusion has been made that under the action of alternating load with the number of loading cycles not exceeding 50 and for maximum values of coefficient of plasticity not exceeding 1.62 the insignificant decrease of relative bearing capacity of beams, not exceeding 10%, takes place.

ОСОБЕННОСТИ ДЕФОРМИРОВАНИЯ СЕЧЕНИЙ ИЗГИБАЕМЫХ ЖЕЛЕЗОБЕТОННЫХ ЭЛЕМЕНТОВ ПРИ ДЕЙСТВИИ НАГРУЗОК БОЛЬШОЙ ИНТЕНСИВНОСТИ

Many buildings are exposed to special effects of high intensity. When calculating reinforced concrete constructions both for special emergency loads and for seismic loads, the development of plastic strains in reinforcement is supposed just at the design stage. The experimental investigation of plastic deformations influence of the stress-strain state of normal sections of bending reinforced concrete elements has been made. According to the results of experiments, it has been found, that the hypothesis of plane sections is not observed in all cases. The approximation of deformations graph along the cross-section height by the bilinear function, variable during the load process, i.e hypothesis of bilinear sections, is more accurate. The dependence of coefficient A of the hypothesis of bilinear sections on the coefficient of plasticity for reinforcement deformations has been determined based on the results of numerical calculations of beams with symmetric reinforcement and beams without compressed reinforcement in a finite element software package Abaqus. The comparison of obtained numerical results with experimental data has been made, which has shown their satisfactory convergence. The maximum deviation does not exceed 13 %. The assessment of influence of coefficient of hypothesis of bilinear sections on the limit value of coefficient of plasticity for curvature, corresponding to the beginning of the destruction of compressed area of concrete is given.

Experimental determination of ratio of transverse and longitudinal deformations (Poisson’s ratio) during upsetting of long strips

The dependence of the plasticity coefficient (Poisson’s ratio) on the type of stress-strain state during the upsetting of long rectangular billets is determined. The obtained data differ from the tabulated data for the elastic deformed state and from those accepted in the theory of plasticity.

The limit value of plasticity coefficient of reinforcement under seismic loads

Plastic deformations develop in bending reinforced elements under seismic loads. In calculation of reinforced concrete constructions by spectral method they are taken into account only at the stage of seismic loads determination by introduction of reducing coefficients. But the development of plastic strains in bending elements leads to appearance of cracks, which don’t close after changing the internal forces sign. Due to it the work height of a section decreases, and the strength of elements reduces during subsequent loading cycles. The experimental evaluation of the influence of plastic strains on the stress-strain state of beams under low-cycle alternating effects of high intensity has been carried out. The first group of beams, considered as reference, was loaded with a monotonously increasing load until complete destruction. The other groups of beams were loaded by the monotonically increasing load up to the specified value of plastic deformations was reached. Then they were unloaded and loaded by the force of the opposite sign up to destruction. The stress-strain state of normal sections at all stages of loading was studied. It has been discovered that when changing the sign of load the through cracks are formed which close later if the plastic deformations of reinforcement are not large. The limit value of plasticity coefficient in the first semi cycle of loading preventing the formation of non-closing through cracks when changing the sign of internal forces has been determined.

Оценка продуктивности и адаптивности селекционных номеров ежи сборной в среднетаежной зоне Республики Коми

The aims of the present research were to study selection samples of cocksfoot in the conditions of the middle taiga zone of the Komi Republic with the ecological adaptability parameters, calculated on the basis of green mass yield, with a subsequent selection of the most promising forms for further breeding. The experimental part of the work was carried out in the breeding nurseries laid on the experimental fields of the A.V. Zhuravsky Institute of Agrobiotechnologies FRC Komi SC UB RAS (Syktyvkar) in 2019-2021. We studied 7 cross-pollinated lines from wild-growing populations from the Komi Republic (BN-184, BN-185, BN-186, BN-188), Norway (BN-1817) and Finland (BN-1816) which were given breeding numbers (BNs). Since there were no locally recognized varieties during the study period, BN-1810 was taken as a control. Agroclimatic conditions during the years of research varied. By the environmental conditions’ index, 2020 saw favorable growing conditions (Ij = +14.2) and 2019 – relatively unfavorable (Ij = -18.4). The average yield of green mass of cocksfoot ranged within 22.6-30.3 t/ha in 2019-2021. BN-188 demonstrated the highest result (30.3 t/ha). Almost any breeding number showed a high ecological adaptability: the plasticity coefficient varied within 0.91-1.09. BN-1810, BN-185, BN-184, BN-1816 turned out to be highly adaptive and flexible (bi=1.00-1.09, Si2=0.25-0.75). BN-188 (125.5 %) and BN-185 (115.2 %) were marked through the highest stability level of variety. These numbers also were first by the stability index (0.50 and 0.47, respectively). Four of the studied breeding numbers had the adaptability coefficient of 1.03-1.12 with the highest value of BN-188. The greatest genetic flexibility between genotype and environmental factors was noted for BN-188 (18.1), as well as for BN-185 (17.5), BN-1810 (17.5) and BN-1816 (17.6). BN-185 (Sc=6.9) and BN-188 (Sc=6.4) are classified as having the highest breeding value. In total, according to the set of adaptability parameters, the breeding numbers BN-188 and BN-185 were recognized as highly promising forms by the breeding value (Sc = 6.4 and 6.9, respectively), stable productivity, and homeostatic index (Hom. = 1.4).