Papers by Keyword: Mechanical Characteristic

Abstract: In fracture mechanics, there is a rather complex theory associated mainly with the choice of model and the correct choice of fracture criteria. There may be models and criteria for the fracture mechanics of bodies with stable and unstable properties, or the choice of a fracture model for an viscoelastic material. When calculating, you can choose the critical crack opening criterion or the local energy criterion. But in practice, it is possible to carry out more simplified initial theoretical calculations, which can be performed by an engineer who has the necessary theoretical knowledge and practical experience, for example, in the operation of pipelines. If the material is considered completely solid, then the interatomic bonds are destroyed. On this basis, the theoretical strength limit of the material is introduced. In this article we study normal tensile cracks, since this is the most dangerous situation (when the tensile stress is perpendicular to the plane of the crack). The main goal is to reduce a real crack detected on an object to simple standard solutions. That is, to imagine it as a crack that has a solution. This means that we must calculate the load with a margin and all our assumptions must be related to the safety margin. In reality, cracks are the most unpredictable (unpredictable shape, unpredictable location).

Abstract: At present, the introduction of only organic or inorganic binder is not always sufficient for the practical application of stabilized soils. The research investigated the effect of the stabilizing additives Chimston, Baustab and Dorstab on changing a number of parameters over time, such as: average density, water saturation, ultimate compression and tensile strength, and frost resistance. All the researched parameters were determined at intermediate and target age — 7, 14 and 28 days respectively. Tests to assess the effectiveness of various stabilizing additives in strengthening loamy soil have shown the feasibility of using Baustab and Chimston-3 additives (in the dosage of 2%). Introduction of additives into the soil composition allowed obtaining soil with high strength characteristics and higher frost resistance as compared to the control composition. Composition No.2 has the compressive strength of 5.1 MPa and the tensile strength of 1.6 MPa. Composition No.7 has the limit of compression strength of 5.4 MPa, and the limit of tensile strength of 1.27 MPa. Thus, both compositions have the strength grade M40. Such soil will be subject to minimal subsidence and loss of strength.

Abstract: The article shows results of the influence of "DORLUK" impregnation on physical and mechanical characteristics of asphalt concrete pavement. "DORLUK" impregnation is produced by "Scientific-Production Enterprise" Plant Innovation Industrial Equipment" ("SPE "PIIE"). The impregnation was tested on the section of road «1P-193 from Voronezh to Tambov». The research of the additive’s effectiveness was carried out according to the following characteristics of asphalt-concrete samples: density, water saturation, water resistance, water permeability, fatigue strength. According to the findings the application of the "DORLUK" impregnation results in a significant decrease in the water saturation of asphalt concrete samples by 36%, and also in water permeability decrease under the pressure by 3-4 min. Reducing the water saturation and water permeability of asphalt concrete with impregnation will reduce the negative impact of water on the strength characteristics of asphalt concrete. It is important to note that the impregnation has no negative effect on the fatigue strength of asphalt concrete samples, since the amount of cycles of samples with impregnation and without it is the same.

Abstract: In this paper, the results of experimental and analytical investigations pertaining to the structural behavior of glass fiber reinforced polymer plastic (GFRP) pipes are presented. GFRP is assumed as an orthotropic material. Mechanical properties along the longitudinal and hoop direction of the pipes are determined by the tension and compression tests. The parallel plate loading tests for the GFRP pipes were conducted to findthe relation between load and ring deflection. Inaddition, the finite element analysis (FEA) for the GFRP pipes was conducted using the material properties obtained from test in the study. The numerical results obtained by the finite element method show good agreement with the parallel plate loading test results for GFRP pipes.

Abstract: Planetary transmissions used as speed amplifiers in wind/hydro conversion systems typically rely on the conventional concept of mechanism with one input and one output. This concept is found in the most of the high power wind turbines; however, the need to implement in the built environment smaller wind turbines with speed amplifiers led to new turbine concepts such as counter-rotating rotors and classical generator. The paper presents a comparative analysis of two wind turbines with one rotor and respectively two counter-rotating rotors, which contain identical electrical generators and the same type of mechanical amplifier used as a 1 DOF mechanism and differential one respectively. With the assumption of maintaining the same electrical generator running point for both wind turbines, the steady-state behaviour of the considered turbines is identified and a comparative kinematic and static performance analysis is performed, aiming at highlighting the impact on efficiency and on constructive design and development of the two turbines.

Abstract: The fiber is considered the most important element in fiber reinforced composite materials, as it generally occupies the largest volume in a composite material; further, delivers the heaviest loads. therefore, it is important to select types, quantity and proper stacking angles of the fiber. In this study, the fiber directions were arranged in different orientation angles, i.e. in symmetric (0°/0°,15°/15°,30°/30°,45°/45°,90°/90°) and asymmetric (0°/15°,0°/30°,0°/45°,0°/90°), to analyze the tensile strengths depending on the fiber orientation angles through the tensile test. In addition, a thermal imaging camera was used to investigate the thermal characteristics of the test specimens generated during the tensile test. the tensile strength showed a tendency of decreasing while the orientation angle increased. the maximum temperature generated when the fracture occurred increased at the fiber orientation angle of 30°, and showed a tendency of decreasing as the orientation angle increased.

Abstract: Downstream sinking technology of flexible mattress has wide application in erosion protection、berth firm and bank protection. During sinking of flexible mattress, the distance get gradually between the landing position of the mattress and the laying mattress ship, then the suspense length and mattress’s self-weight are also increase because of the ship’s move. Therefore the tension in mattress is also change continuously, so the calculation of the tension becomes difficult. By using lumped mass method, the mattress can be separated into several lumped mass which are connected using non-mass springs, with the laying distance increase, the length and self-weight of the mattress can be increase gradually, and according to forces equilibrium equation, the tension and profile of the mattress can be obtained.

Abstract: This paper simulates the separate lock with shear keys or with flat joints under different design conditions using the ANSYS programme, analyze the mechanical effect of the shear keys. The variation law of the joint opening，the vertical displacement and foundation stress of lock chamber in different working condition are investigated. The research shows that the joint opening is biggest under high water-level condition, but simultaneously, the influences of shear keys on the lock chamber structures is small. The vertical displacement and foundation stress of separate lock chamber with trapezoidal shear keys or with flat joints show the similar variation law. Under overhaul condition and built up lock chamber condition, the joint opening of lock with shear keys is smaller than that of lock with flat joints. Under the same conditions, the biggest vertical displacement of the lock with shear keys is smaller than that of lock with flat joints, and the foundation stress distribution of the former is more uniform.

Abstract: In order to improve the safety and stability of dredger crane (DC), three dimensional finite element models for the DC were established. By applied loads and boundary conditions, the area of stress concentrations, the axis force of jib cylinder and the reaction force of the king structure was obtained under four typical working conditions. Meanwhile, the related theoretical calculations were accomplished to comparing finite element results and at last some suggestions were given. The conclusions can provide a theoretical reference for the further structure design and optimization of DC.

Abstract: The functional relationship is analyzed between three-phase asynchronous motor electromagnetic torque and some factors; Mechanical characteristic curve of motor performance is drawn; The inherent mechanical properties and human mechanical properties are explored in a specific application. Facts prove that mechanical characteristic analysis of three-phase asynchronous motors, to reduce the failure rate of the three-phase induction motor, to improve the running capacity and production efficiency are important.