The problem of control of strength characteristics of agricultural machine parts by dynamic non-destructive methods of impact indentation of conical shape is considered. The quality of the most important parts is considered in terms of the set of mechanical characteristics that determine the strength, hardness, wear resistance and deformability. These characteristics should be known and be able to quickly and accurately control all parts both during production and during operation. The mechanical properties of metals are stochastic. For this purpose, a device for impact indentation was developed and a method based on the probabilistic laws of dispersion of mechanical characteristics was developed.

Keywords: agricultural machines, reliability, quality control, mechanical characteristics, Weibull law, non-destructive testing, impact indentation

The paper deals with statically determinate and statically indeterminate reinforced beams of a rectangular cross-section of bimodule material loaded with a uniformly distributed load. Since for heterogeneous materials, the elastic modulus for tension and compression are different, the work aimed to study the influence of different boundary conditions in statically indeterminate beams on SSS. It is shown that the magnitude of the maximum normal stresses is less than the stresses found without taking into account the bimodule nature of the beam material, both in statically determinate and in statically indeterminate beams. The maximum normal stress and maximum deflection decrease with the transition to a statically indeterminate beam from a similarly statically determined beam by replacing the supports. The method used in work makes it possible to clarify the calculation of strength and rigidity, taking into account the bimodule nature of the material of the reinforced beams, and also to select the optimal fastening of the beams that ensure the bearing capacity of the structure with material saving.

Keywords: reinforced beam, heterogeneity, bimodule material, stress-strain state, normal stresses, deflection, statically indeterminate scheme, bearing capacity, strength, deformability

The paper considers the actual problem of an assessment of mechanical characteristics of two-layer materials by nondestructive methods (a method of conical indentation). The calculation of the process of indentation into two-layer medium by the finite element method with ANSYS program. The influence of layer thickness on the parameters of the indentation is considered.

Keywords: conical indenter, nondestructive testing, mechanical properties, strength tests of metal, finite element method, hardness, surface hardening

The paper considers arbitrarily supported arbitrarily loaded reinforced plate.on an elastic Foundation. Reinforced rods are parallel to the sides of the plate.. the Location and number of terminals is arbitrary. The shape and size of the rods is arbitrary. Plastro is considered as structurally orthotropic. To determine the deflection of the plate used in the method of Bubnov - Galerkin. The obtained expression-x) for the governing equations relative to the deflection plates.

Keywords: reinforced plate, elastic Foundation, structural orthotropism, the method of Bubnov - Galerkin

The question of the diagnosis of the state of building structures using non-destructive testing. These methods allow to predict the condition of structures to prevent accidents and, therefore, increase the service life of structures. The main objective of the study - assessment of changes in the vibration mode shapes method for the detection of structural damage , in the absence of forced uploading. The article describes the implementation of a mathematical method of vibration identification and localization of lesions of metal trusses . The results of the calculation for fault location triangular steel truss.

Keywords: Vibration diagnostics, fault detection, diagnosis, construction construction spans, trusses, trusses, defect, damage, vibration, localization, identification

The last ten years have seen a rapid growth of research related to the development of methods of localization of defects and assessment of technical condition of metal structures based on dynamic analysis. This paper presents the results of a study on the localization of defects arched steel truss. The main purpose of this article is to analyze the results of the damage index method and the development of the software module to localize structural damage. The results of numerical experiments presented in this article have shown the effectiveness of this method of localization of damage. The use of this method in practice will reduce the time of inspection by pre- defining a site design that are necessary to pay special attention during the field study.

Keywords: Vibration diagnostics, fault detection, diagnosis, construction construction spans, trusses, trusses, defect, damage, vibration, localization, identification

The problem of stress concentration near step junction of sections in constructional elements and machine elements has been solved in this article by means of one singular integral equation. The formula for determination of stress concentration factor depending on fillet radius has been submitted.

Keywords: Step plate, singular integral equation, conjugation line, stress concentration factor

Considered the questions connected with estimation of mechanical properties of steel elements of metal construction. The measurements are performed in a non-destructive method on the basis of the analysis of the characteristics of the implementation of the conical indenter in surface materials. This method allows you to get the values of all mechanical characteristics of metal. The measurement of mechanical characteristics can be made to anywhere in the design. At the same time, when large amounts of construction and large volumes of measuring works, you need to evaluate a sufficient number of measurements in a particular place. Proposed and implemented the Bayesian method of consideration of a priori information to reduce the number of dimensions and complexity of the process of receiving mechanical characteristics.

Keywords: nondestructive control, mechanical characteristics, durability, diagnostics, aprioristic information, metal tests.

Discusses the calculation of stress-strain State of glued structural sheathing to the test to determine the calibration of the test stand

Keywords: Finite elements method, Stress concentration, Skin, Test, Prediction.

The possibilities of the vibration method changes the curve oscillation localization damage concrete structural elements with prestressed reinforcement. This article discusses a method for curve oscillation example concrete slab in terms of spatial, complex stress state under the action of vertical force Q.

Keywords: Vibration diagnostics, fault detection, diagnosis, design, construction span, reinforced concrete, concrete, reinforcement, prestressing.

The paper considers arbitrarily supported arbitrarily loaded reinforced, beam with an aggregate of bimodulus of elasticity material. Formulas for determination of the tangential stresses arising in the aggregate, subject to the reinforced elements. Formulas are obtained for principal stresses occurring at an arbitrary point in the aggregate, as well as the equation for determining the point where major stresses reach extreme values. Are terms of strength as the classical theories of strength, and strength criteria applied for calculation of constructions made of bimodulus of elasticity material.

Keywords: reinforced beam, bielastic modulus, stress, normal concrete, strength criteria.

Information about authors of issue №4 (2013)

Keywords: authors

The article investigates the impact on the normal stresses of inequality of the young modulus for tension and compression in the bending of reinforced beams. Obtained formulas for determination of the bending moments that arise in the fixture, compressed and stretched zone of the aggregate. Found the formula for the normal stresses arbitrarily supported reinforced beams, arbitrary cross section and arbitrarily loaded bending loads. For example, reinforced beams of rectangular cross-section shows the determination of the neutral line and maximum stresses.

Keywords: reinforced beam, elastic modulus, stress, normal concrete

Cracking of reinforced-concrete elements with holes is examined. Comparison of theoretical and experiment moments of crack’s  formation during torsion, and during intensive torsion with twist. Formula for practical calculations of cracking of reinforced-concrete elements with holes during torsion and formula for estimate of cracking of reinforced-concrete elements with holes during intensive torsion with twist is suggested.

Keywords: Crack, twist, torsion, reinforced-concrete, elements, hole, beam

The resolving equations for the calculation of the stability of polymer compressed rods with the creep using Galerkin method are obtained. The problem is solved in the case of a simply supported pivotally-rod having an initial bending in the plane of the lower stiffness, and in the case of off-center application of force. Galerkin method used in combination with the finite element method, that is the shape functions are taken as the basis functions . The solution is made numerically, using the software package Matlab. There are two variants considered: a variant of the rod with constant and variable in length stiffness. It is shown that for rods with variable cross-sections and the same mass, a critical time has increased by almost 4.5 times. The solution for the rods of constant cross section agrees well with the solutions obtained by the method of finite differences. This may indicate the reliability of the proposed method  

Keywords: polymer rod, creep, Galerkin method, stability, variable stiffness