Features of modeling of stress and strain waves in an anisotropic medium on the example of a wooden element

This article describes the hypotheses of the occurrence, propagation, and modification of stress and strain waves caused by external loads in isotropic and anisotropic infinite and finite elastic media. A model of an infinite elastic medium experiencing a point external impulse is presented. The model demonstrates the propagation of a longitudinal plane wave. Compaction and rarefaction of the medium are observed in the plane with wave propagation. A graph of changes in the amplitude of a longitudinal plane wave is presented in the same coordinate system. The problem is posed of expanding the numerical model of a finite elastic medium in the form of an anisotropic wooden rod experiencing a plane external impulse. The model should demonstrate the propagation of longitudinal and transverse waves and describe the volumetric deformation of an anisotropic material. Compaction and rarefaction of the medium are shown in the plane, coinciding with the direction of wave propagation. A graph of the change in the shear wave amplitude is presented in the same coordinate system. The combination of these two graphsreveals the difference in wave propagation velocities and the combination of amplitudes. The model will make it possible to identify the presence of Rayleigh waves and to describe the reflection of waves from the boundary of the medium.

Some features of magnetic elements at Trivandrum and Annamalainagar, situated near the geomagnetic equator in the Indian Peninsula

The Sq diurnal variation in H at Trivandrum and Annamalainagar are found to be large compared with those at Alibag. The quiet day range in H at Trivandrum in the month of March is abnormally large. Though the Sq variations in V at Trivandrum are not abnormal they are larger than those at Annamalainagar and Alibag. The response of the H elements to disturbance at Trivandrum, Annamalainagar as well as Alibag are similar in sense. But the V element at Annamalainagar shows a difference in its response to disturbance. When the V elements at both Alibag and Trivandrum show an increase in numerical magnitude the V element at Annamalainagar shows a decrease and vice versa. When the magnitudes of disturbance are examined they are found to be almost the same in the H element at all the observatories (including Alibag) during night hours. But during the day the magnitudes of disturbance in H element at Trivandrum and Annamalainagar are always greater than that at Alibag, a station away from the geomagnetic equator. Effects of disturbance in the V element are greatest at Trivandrum both during the day as well as the night. The lines of force of an average disturbance field in a longitudinal plane over the region of the Indian Peninsula appear to be smooth curves with their concave side turned upwards, their turning points occurring between Annamalainagar and Alibag during the day and close to Alibag in the night.

LOADING ON THE CARRYING STRUCTURE OF A FLAT WAGON IN TRANSPORTATION OF MILITARY EQUIPMENT

The article presents the results of determining the loads on the carrying structure of a flat wagon transported military equipment. The authors suggest that stable fixation of military equipment can be provided with special rings mounted on the flat wagon structure. The results of the strength calculation confirmed the efficiency of this solution. The study deals with the mathematical modelling of the dynamic loads on the carrying structure of a flat wagon with a military tank. The research was made for the plane coordinates. The following oscillations were taken into account: longitudinal plane oscillations, jumping oscillations and galloping oscillations. The differential equations were solved by the Runge–Kutta method in MathCad software suite. The maximum accelerations on the carrying structure of a flat wagon in the longitudinal plane were about 34 m/s2, and in the vertical plane were about 5.0 m/s2. Thus, these accelerations values were within the admissible ones.The study also presents the results of the computer modelling of the dynamic loads on the flat wagon. The calculations were made in SolidWorks Simulation (CosmosWorks) software suite with the finite element method. The study presents the distribution fields of the accelerations relative to the carrying structure of a flat wagon and the numerical values of these accelerations.The models of the dynamic loads on the carrying structure of a flat wagon were verified with an F-test. It has been found that the hypothesis on adequacy is not rejected.The study also included determination of the natural frequencies of the carrying structure of a flat wagon. It was found that the values of the natural frequencies were within the permissible values. This research will contribute to better operation efficiency of the rolling stock with consideration of some military-strategic issues, and will be of help for anyone concerned with development and research into innovative rolling stock structures

Experimental studies of the deflection of the hydraulic cylinder as a result of its operational loading

Two-way hydraulic cylinders with a one-way rod are widely used on Transport and technological machines. During operation, compressive loads act on such a hydraulic cylinder, as a result of which there are deformations of the hydraulic cylinder in the longitudinal plane, i.e., there is an operational deflection. As a result of the appearance of such a deflection, the bending loads and reactions acting on the hydraulic cylinder and its elements significantly increase, which leads to an acceleration of the process of wear of the hydraulic cylinder elements such as the piston and the guide sleeve and an increase in the probability of the hydraulic cylinder failure. Keywords: hydraulic cylinder, deformation, contact, stress, deflection

Determination of the Loading of a Flat Rack Container during Operating Modes

This research deals with determination of the loading of an open container during operating modes. The special feature of this container is its convex walls. This engineering solution increases the useful capacity of a container by 8% in comparison to that of the prototype. The elastic elements in the bearing structure of a container were introduced to decrease the dynamic loads. The dynamic loads in the vertical plane were dumped by means of the dry friction forces between the components of the cross bearers of the container’s base. The dynamic loads in the longitudinal plane were dumped by means of the dry friction forces between the horizontal parts of fittings and fixed lashing components. This study presents the modelling of the dynamic loading of a container in a vertical plane. The dynamic loads of a container in the longitudinal plane were determined with a mathematical model. The authors determined the basic strength characteristics of the bearing structure of a container; and found that the maximum stresses to a container were about 200 MPa, concentrated near the front fittings. The maximum displacements were recorded in the cross bearers of the base and amounted to about 4 mm.

Influence of seed set on apple symmetry assessed by image analysis: an overlooked effect of pollination on fruit shape.

The role of pollination ecosystem service on crop yield and some quality parameters have been largely studied. Nevertheless, the effect of pollination on fruit appearance is still a poorly explored field and it has been assessed by means of oversimplified measurements. Here, we developed an image analysis tool to test the hypothesis that pollination greatly affects the symmetry of one of the most consumed fruit worldwide: the apple. The hypothesis was tested for three commercial classes separately, to understand whether the pollination effect was consistent among classes. We also compared the performance of the image analysis tool with a simplified symmetry measurement that has been previously used. Finally, the effect of pollination on apple symmetry was compared with the effect on weight. We quantified the amount of non-symmetrical area of harvested Gala cultivar apples using two-dimension images of fruits sectioned along the longitudinal plane. We showed that increasing pollination led to significant increase of apple symmetry. The image analysis tool resulted more precise to assess the pollination effect on fruit symmetry than the previously used symmetry measurement, leading to the conclusion that pollination effect on apple shape has been probably overlooked because of the use of oversimplified symmetry measures. The effect of pollination on apple symmetry was not consistent among commercial classes since it resulted significant for little and medium size apples but unimportant for large size apples. Differently from the symmetry, apple weight appeared as not influenced by the pollination. Our findings suggest that the effect of pollination on fruit production should be assessed taking into account different variables and different commercial classes of apple.

Technical solution for providing optimal seeding depth and improving the contact of small seed crops with wet soil when seeding

The article describes an invention that relates to agricultural machinery, namely to seeders for sowing grass seeds and grain crops, in areas with insufficient moisture and soils susceptible to wind erosion. The objective of the invention is to provide the optimum depth of seeding, in particular, of small-seeded crops and herbs, when sowing on treated and untreated backgrounds in soil-protective, minimal and “zero” tillage systems. The technical result of the invention lies in the fact that the distinguishing features of a grain-seeder seeder provide an optimal seeding depth and improved contact of small-seeded crops, in particular grass seeds with moist soil, when sowing in soil-protective, minimal and “zero” tillage systems. The proposed seeder, the coulters are rigidly connected to the frame by means of rods, which allows the coulters to withstand the same predetermined depth on soils of different hardness. The initial formation of sowing grooves is carried out installed before the coulters, in their longitudinal plane of symmetry, at an angle 55-65 degrees to the horizontal, revolving cutter knives with a wear-resistant coating of the working part. There are two packer roller rollers pivotally connected to the frame with a cylindrical rim, while the batteries are spring loaded with the ability to adjust the pressure of the rollers on the soil.

A Refinement Of The Determination Method Of The Linear low-pressure Uv Lamps Radiant Flux

For the measurement of linear low-pressure UV lamps radiant flux the method proposed by the IUVA, which is based on the Keitz method, has become widely used. For deriving the equation that connects the irradiance generated by a lamp at a close distance and its radiant flux, the authors of the method presume that the lamp is the cylinder of equal radiance. According to our estimates, this assumption leads to the inaccuracy of 3 % to 5 % with respect to goniophotometric measurements. In this research, a general formula is derived that connects the irradiance generated by a linear emitter and its radiant flux. This formula does not impose restrictions on the radiant intensity curve in the longitudinal plane. The Keitz equation is its particularcase. To reduce the inaccuracy of the IUVA method, the angular distribution of the radiant intensity of the UV lamps is proposed to be approximated by a cosine polynomial. In order to find the coefficients of the polynomial,clarify the Keitz formula, as well as to estimate the inaccuracy of the refined and classical versions of this formula, the series of goniophotometric measurements of the DB15, DB18, DB30 lamps at various distances was carried out. It was found that at a scanning step Δθ = 5° the first 9 terms of the trigonometric expansion are sufficient to describe the radiant intensity curve with accuracy satisfactory for practical use. It was also shown that the Keitz method needs to be refined only on the basis of goniophotometric data obtained upon condition r / l ≥ 6 where r is the test distance, l is the lamp length. It was identified that in the case of a differentiated approach, the approximation of the low-pressure UV lamps radiant intensity curve by a cosine polynomial makes it possible to provide an inaccuracy of simplified methods that does not exceed 1 % in relation to the goniophotometric method. It is in dicated that in order to find a universal factor applicable for the entire range of linear low-pressure UV lamps, the development and the analysis of statistical data is required.

Technology and machine parameters for preparing the soil for sowing cotton

The study aims to justify the design scheme and main parameters of the combined aggregate for soil preparation for cotton sowing on ridges. The authors have developed the technology of soil preparation for cotton sowing on ridges and the aggregate for its implementation. The technology and design scheme of the developed aggregate are presented. The unit consists of a mouldboard deep loosener with a sloping rack and a ridge maker. The basic principles and methods of classical mechanics, mathematical analysis, and statistics were used in this study. The optimum constructive scheme of combined aggregate is grounded. It was established that to provide formation of new ridges instead of existing ones on fields without stems of cotton with the required degree with minimum power consumption working surfaces of inclined deep looseners equipped with mouldboards and rippers should be turned to each other and shifted relative to each other in a longitudinal plane. The formation of ridges to the required degree with minimal energy input is ensured at a width and length of the subsoiler's chisel, respectively 5 and 20 cm, the width of the wing width 21 cm, wing length between 47 and 49 cm, minimum longitudinal spacing between subsoilers 35 cm.