Papers by Keyword: Force

Abstract: The development of drag and lift balance aimed to modify and creating a measuring instrument that may be used in the field of aerodynamics or in testing aerodynamic properties. This measurement is in the form of wind speed on an object model such as airfoils, building models and automotive technology. This design uses an open circuit wind tunnel with a low turbulence subsonic type, with a maximum air speed of 30 m/s. The exsisting wind tunnel still uses an analogue measuring instrument which is then modify in a digital arduino-based for drag and lift balance measuring instrument with a drag and lift sensor maximum load of 1kg (v=30m/s) and maximum air speed of 50m/s. The Measuring instrument is calibrated using a 1kg weight test equipment for testing with the test object model (spherical, hemispherical, cylindrical, cube) and three types of airfoil models. The test results are in the form of drag coefficient (C_d) and lift coefficient (C_L). The coefficient of drag is greatest in the cube shape and lowest in the sphere, but will decrease in value at a speed of 20 m/s. In the airfoil, the values ​​of C_d and C_L have the same trend with the literature with an uncertainty value of less than 10%. The value of C_L / C_d will increase as the angle of attack increases, but can very significantly depending on the fluid, airfoil, and aircraft type.

Abstract: Adapter parts are common in hydraulic pipelines. They can connect pipes of different cross-sections. The article discusses the crimping of pipes. Its peculiarity is that the pipe section to be crimped undergoes thinning, which is ensured by the gap between the tools. This process was studied to determine the deformation forces and the influence of various parameters of the operation on its value.

Abstract: This paper presents the methodology of designing a transducer for the experimental measurement of forces. For this purpose, an elastic element of the shape of the letter "S" is designed and manufactured. The elastic element designed in SolidWorks is subjected to virtual testing, using the finite element method in ANSYS. After validating the results obtained considering the maximum values ​​of the stresses that appear for the nominal load, the experimental model of the transducer is realized. The central part of the elastic element behaves like a fixed double beam subjected to bend by the measuring force. On this beam are bonded strain gauge transducers, which measure the deformations produced by bending. The transducer is calibrated, in order to obtain the calibration constant, based on the obtained characteristic, that is, the dependence of the specific strain-deformation and force. The transducer thus constructed can be used in force measurement applications.

Abstract: The article is devoted to the study of energy-force parameters of combined process "rolling-equal-channel angular pressing". The objectives of the work were to determine the forces of rolling and pressing in the deformation by this combined method. The strength calculation of the matrix and the experiment on deformation of AISI 6063 aluminum samples were carried out. During the experiment, the force values were recorded using a tensometric station. The results of the strength analysis showed that this matrix design is suitable for creating an experimental stand of combined process "rolling – equal-channel angular pressing", since the calculated safety margin is sufficient to implement the pressing under extreme conditions. Analysis of the results of force measurement showed that rolling forces at all stages of deformation exceed the corresponding pressing forces, which is a necessary condition for the implementation of this combined process. The obtained results can be used in the design of experimental stands that implement investigated combined process. At the same time, the used tensometric technique for studying strength characteristics is suitable for the case of calibrated rolls.

Abstract: The article describes a new technology in milling of the flat surfaces - Inverse Cutting Technology. The theoretical basics of the inverse cutting are formulated. The boundary conditions of the process depending on the cutting parameters are presented. The chip formation and chip flow by inverse milling are simulated. The comparison of cutting forces by conventional and inverse face milling is shown. Finally, cutting experiments were conducted to confirm the results of the 3D-FEM-simulation.

Abstract: For the process design of a cutting process, the knowledge of the cutting force is of fundamental importance. The cutting force influences the dimensioning of machine components and process parameters [1]. A precise interpretation of those process elements enables for high manufacturing and component accuracy. Due to the complexity of the chip geometries, the cutting force in gear hobbing is calculated by using a penetration calculation. The applied cutting force models have been developed by BOUZAKIS [2] and GUTMANN [3] in the 1980s. These models are based on data from longitudinal turning processes. Advancements in machine tool technology of the past decades have led to more efficient processes. The use of new cutting materials allows for higher speeds and feeds. This led to larger chip thicknesses. The bases of the models by GUTMANN and BOUZAKIS covers today's usual hobbing parameters not extensive enough. The influence of tempered levels on the cutting force is not included in the models. Therefore, the aim is to create a cutting force model and adjust the calculation base after GUTMANN. A radial turning process with interrupted cutting is used as analogy process. The influence of the heat treatment at 42CrMo4 is to be examined for the cutting force. This will be compensated in three different tensile strengths. The investigated process parameters are extended beyond the current state of the art.

Abstract: The deformation and internal forces of beams on tensionless foundation materials were studied. The reaction force between the beam the foundation was fitted as a cubic polynomial about the deflection based on the experimental data, and the corresponding control equations of beams were derived by the finite difference method. Results show there are significant differences between tensionless and tensional foundation materials for the deformation and internal forces of beams. The difference is varying with the length of beams. Both the relative errors of the maximum of deflection and slope can be over 20%, and the relative errors of the maximum of shearing force and bending moment are smaller comparatively, so the tensionless effect of foundation materials can not be neglected for the stiffness verification and the strength verification of beams.

Abstract: The deformation and internal forces of beams on non-linear elastic foundation materials were studied. The reaction force between the beam and the foundation was fitted as a cubic polynomial about the deflection of beams by experimental data, and the corresponding control equations were derived by the finite difference method. MATLAB program with the Newton iteration method was used to obtain numerical results. Results of the numerical example show the deformation and internal force of short non-linear and linear elastic Winkler beams are same, but the relative errors can reach 10%-20% for moderate and long beams, so the non-linear foundation effect on the settlement of beams should be considered in engineering; the relative errors of the deformation and internal force between moderate non-linear and linear elastic Winkler beams vary with the length of beams, but keep invariant for long beams.

Abstract: Provided is a mathematical model of stretching operation involving wall thinning of axisymmetric blanks of anisotropic materials. Obtained were correlations which can be used to evaluate the kinematics of the material flow, the stress and strain states of the blank, the force conditions and the limit possibilities of drawing involving wall thinning of thick-walled anisotropic axisymmetric blanks. Comparison of results of theoretical calculation against experimental data have shown satisfactory similarity. The maximal difference between the theoretical and experimental data does not exceed 10 percent. The research results were used in developing the technological process to manufacture thick-walled cylindrical blanks for critical axisymmetric items made of steel 11YUA.

Abstract: Shown are results of theoretical and experimental research of force modes and limit possibilities of the first and subsequent operations of combined isothermal drawing of axisymmetric parts made out of anisotropic materials through conic and radial matrixes in the mode of short-time creeping. Studied was straining of anisotropic material under conditions of short-time creeping. We ignore the elastic components of strain. We introduced potential straining speeds for an anisotropic body under conditions of short-time creeping. Found was the effect of technological parameters, anisotropy of mechanical properties, and of age-hardening upon the stress condition, the force modes of the operation, and upon the design margin of strain during the first and subsequent operations of combined drawing. Experimental research was carried out for the force conditions and possible limits of straining during the first and second operations of combined isothermal drawing with convex-face and conic matrices in the mode of short-time creeping. Comparing the results of theoretical and experimental research for force modes and strain limits during the first and subsequent operations of combined drawing has shown their satisfactory similarity (up to 5% - 10%).