The stress-strain state of reinforced concrete elements is rather complicated issue of scientific research, which integrates different factors, such as the load type, atmospheric conditions, various defects, damages, geometric deviations. It is commonly known that corrosion of reinforced concrete elements affects both the strength and deformation parameters of the structure significantly; thus, internal stresses` parameters are also influenced. Therefore, detailed theoretical investigation of this issue is the main goal of this article. The detailed literature review and thorough analysis was conducted concerning previous experimental and theoretical studies of the corrosion defects` influence on the reinforced concrete elements` stress-strain state. Existing data and results were systematized and analyzed. On the basis of provided research it could be concluded that the reinforced concrete elements` stressstrain state greatly depends on existing damages and impurities. The stress-strain state could be complicated on micro-scale due to material chemical and mechanical peculiarities; simultaneously on macro-scale the bearing capacity is of the structure could be reduced in general. In the articles existing methods for this issue simulation and evaluation are described and perspective fields for further research are identified. The practical significance of the article is due to complex approach to the research and multilateral identification of the main issue key points.
Purpose: To ensure an adequate level of accuracy, it is rational to study the ponderomotor forces of the ring, which drive a hollow disk of variable thickness, hung on the ring. Design/methodology/approach: The solution of the motion problem of a hollow disk of variable thickness suspended on a force ring of rectangular cross section is based on the method of solving the equations of the theory of thermoelasticity. The stress-strain state, as well as the motion of the specified body of rotation, the disk, in studies in a cylindrical coordinate system, under the action of ponderomotor forces. Findings: The motion equation of a hollow disk hung on a force ring-torus is made, exact solutions of the motion equations of a ring in the torus form of rectangular cross section are found. New component expressions of ponderomotor forces, which appear from the action of the ring's own electromagnetic field and cause the motion of a hollow disk, have been found on the basis of Maxwell's equations. It is proved that at high speeds and low natural accelerations the stress - strain state of the disk material does not cause the destruction of the structure. Research limitations/implications: Calculations of ponderomorphic forces are valid for the ring, which drives a hollow disk of variable thickness, hung on the ring. Practical implications: It is proved that at high velocities and small natural accelerations the stress-strain state of the disk medium does not cause structural damage. It is determined that the rotation in the direction of movement at an angle of 90 degrees changes only the direction of the acceleration vector without increasing its value. Originality/value: The dependences between own time and coordinate time are formulated. It is proved that a small change in the natural time for the studied disk can significantly change the coordinate time, and the pulsed electromagnetic field provides the ability to cover infinitely large distances over finite periods of time.
Purpose: Development of a computational model of stress-strain state bearing elements of trailer frames for preliminary assessment and identification of areas with increased risk of failure. Design/methodology/approach: The object of the study is the processes of loading the load-bearing metal structures of trailers - fertilizer spreaders. The stress-strain state of the spreader bearing system is investigated for the established three typical cases of external load. To refine the values obtained as a result of modelling, they were determined in SOLIDWORKS. Findings: Computational models of load have been compiled by improving the method of minimum potential deformation energy for its effective correct use in analytical studies of a similar type of metal structures. It is proved that for a flat closed frame structure made of thin-walled profiles, loaded with forces perpendicular to the plane of the frame, the levelling of compression and shear energies, as well as axial and transverse forces and bending moments in the horizontal plane does not significantly affect the calculation results. Research limitations/implications: Horizontal components of the shear forces as well as the normal forces and as a consequence the corresponding potential deformation energy are neglected, which has some effect on the accuracy of the calculations. Practical implications: An effective tool for strength analysis with preliminary assessment and diagnostics of load-bearing metal structures based on the constructed calculation models of stress strain state load-bearing frames of typical geometry with an arbitrarily given distribution of external load. Originality/value: A universal algorithm for recording additive functions of bending and torques, as well as the potential deformation energy of welded frames of trailers.
One of the main elements of control over wells in the process of their construction is the blowout equipment, which includes annular preventers. This also applies to wells that provide degassing of coal veins to reduce their gas dynamic activity. Modern technology of work requires expansion of the functionality of the sealing unit of the annular preventers with the simultaneous provision of its operational characteristics. Determining the necessary durability of seals for different operating modes is the study of their stress-strain state. The paper deals with the possibility of using simulation modeling in the annular preventers design situations and within the study of the armature geometry influence of the sealant fittings on its stress-strain state. The method of determining the material constants to realize the Mooney-Rivlin model has been proposed. The behavior of low-density rubber in software product has been described by the finite element method. The aggregation error of experimental and theoretical studies is 5%. Therefore, the preconditions and the possibility of using simulation modeling in the design of annular preventers devices with increased operational characteristics have been created and confirmed.
The article deals with the work under load of a bent reinforced concrete girder element with a fixed formwork made of cement-bonded particleboard reinforced with. The main strength and deformation parameters of a multi component structure are determined, the main pre-purpose of which is to use overlap for monolithic structures with the inclusion of non-removable formwork of cement-bonded wood board in collaboration.
PL
Artykuł dotyczy pracy wygiętego elementu dźwigara żelbetowego z szalunkiem stałym wykonanym z płyty cementowo-drzazgowej zbrojonej pod obciążeniem. W ramach badań określono główne parametry wytrzymałościowe i deformacyjne konstrukcji wieloskładnikowej, której głównym celem wstępnym jest zastosowanie zakładki dla konstrukcji monolitycznych z włączeniem we współpracy nieusuwalnego szalunku z płyt cementowo-drewnianych.
The paper presents the results of experimental and numerical studies of contact interaction of rubbing bodies after technological processing – discrete hardening. Experimental studies were carried out on the example of the contact pair "crankshaft of an internal combustion engine - liners". Numerical simulation was carried out using generalized parametric modeling of complex mechanical systems. To determine the stress-strain state of the elements being studied, the finite element method was chosen. Based on the results of the conducted studies, the efficiency of the proposed method of technological processing of contacting bodies – discrete hardening - was demonstrated.
PL
W pracy przedstawiono wyniki eksperymentalnych i numerycznych badań kontaktu ciał trących po obróbce technologicznej - dyskretnym utwardzaniu. Badania eksperymentalne przeprowadzono na przykładzie pary kontaktowej "wał korbowy silnika spalinowego - wkładki". Symulacja numeryczna została przeprowadzona przy użyciu uogólnionego parametrycznego modelowania złożonych układów mechanicznych. Aby określić stan naprężenie-odkształcenie badanych elementów, wybrano metodę elementów skończonych. Na podstawie wyników przeprowadzonych badań wykazano skuteczność proponowanej metody technologicznej obróbki ciał stykowych - dyskretne utwardzanie.
The article is devoted to the overall view of experimental research of reinforced concrete beams with the simultaneous influence of the corrosion environment and loading. The tests have been carried out upon the reinforced concrete specimens considering the corrosion in the acid environment, namely 10 % H2SO4 that have been taken as a model of the aggressive environment. The beams are with span equalling to 1,9m with different series of tensile armature, concrete compressive strength and different length of impact of corrosion (continuous and local). The influence of simultaneous action of the aggressive environment and loading on strength of reinforced-concrete beams has been described. For a detailed study of the effect of individual components there was suggested additional experimental modelling of the only tensile armature damage without concrete damage. It will investigate the influence of this factor irrespective of the concrete.
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W artykule zaprezentowano wyniki badań wytrzymałości górotworu w zależności od prędkości robót górniczych. Pokazano również zależności pomiędzy zniszczeniem górotworu (z pomiarów in situ) a zniszczeniem próbek laboratoryjnych. W opracowanym modelu uwzględniono zmiany wytrzymałości w zależności od szybkości obciążania oraz wykorzystano fenomenologiczne kryterium zniszczenia. Modelowanie stanu naprężenie - odkształcenie w górotworze wykonano stosując symulację numeryczną. Jako rezultat analiz podano strefy zniszczenia w zależności od prędkości robót w różnych przestrzeniach przodkowych.
EN
Research results of rock mass strength depending on rate of mining are presented in the article. The connection between rock mass failure (in situ measurements) and the destruction of rock samples (laboratory tests) is shown. The statistical model considering change of rock mass strength depending on loadingrate effect is resulted. The phenomenological failure criterion is developed taking into account the created statistical model. This criterion is used at numerical simulations of rock mass stress strain state. Outcomes of numerical modelling for "workings - rock mass - longwall" system are presented. Failure zones in rock mass at various working speed and the various coalface spaces are resulted as well.
The paper presents a survey of available joints of the clamped type (CJ), which are of crucial importance in view of the design safety level. A numerical analysis has been carried out to estimate the efficiency of a given shape of the CJ. A digital database of material parameters most often employed in CJs has been presented as well.
PL
W pracy dokonano przeglądu stosowanych złącz zaciskowych. Złącza mają istotny wpływ na poziom bezpieczeństwa całej konstrukcji. Przeprowadzono analizę numeryczną oceniającą efektywność stosowanych kształtów połączeń zaciskanych. Zaprezentowano cyfrową bazę danych parametrów materiałowych stosowanych do budowy złącz zaciskanych.
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