Papers by Keyword: Dynamic Force

Abstract: Dynamic-error caused by the mass attached to the sensing part of a force transducer is experimentally investigated using the Levitation Mass Method (LMM), in which the dynamic-force applied to the force transducer is measured based on the definition of force, i.e. the product of mass and acceleration. It is experimentally proved that the change in the dynamic correction coefficient (DCC) is proportional to the additional mass as expected by the theory. The effective mass and the effective spring constant of the transducer with the additional mass are estimated from the experimental result. It is experimentally proved that the DCC for the transducer with the additional mass can be calculated using the estimated properties, i.e. the effective mass and the effective spring constant, and the dynamic-error can be corrected with the calculated DCC.

Abstract: Bamboo shinai is a practice sword for kendo which is the Japanese traditional fencing. The effectiveness of the shock absorption of the bamboo shinai has been shown in our previous study. Although shinai is usually made of bamboo, it is also made of carbon fiber reinforced plastic (CFRP). The impact response of bamboo shinai and CFRP shinai is compared. As a result, the difference of peak value of impact force between bamboo shinai and CFRP shinai against similar initial velocity is small. Impact response measurement of each shinai has been carried out using the Levitation Mass Method (LMM) which has been proposed by us. In this method, a mass, which is levitated with a pneumatic linear bearing and hence affected by negligible friction, is made to collide with a shinai under test. Because bamboo is natual product, resource of suitable bamboos for shinai is limited. On the other hand, carbon-fiber-reinforced-plastic (CFRP) can be designed to be suitable for a shinai, which has a fixed shock absorption characteristic for an application to the structure of robot arms. Therefore, if the shock absorption characteristic of CFRP shinai is the same as that of bamboo shinai, CFRP shinai is more suitable for the structure of robot arms.

Abstract: This paper presents the results of the investigation of the causes of the occurrence and the influence of the dynamic effects in the couplers of the remotely controlled electric shunting locomotives and a set of fully loaded rail cars. These are typical rail-road sets, working at the logistic area of the central ore trans-shipment of large steelworks with heavy rail traffic. The stated effects lead to excessive deterioration of the supporting structure of the locomotives, axle gripping, drive mechanisms and braking systems. To achieve the desired goal, the methods and means of numerical and experimental modelling have been used. Based on the performed numerical and experimental analyses were then specified the recommended design and operational measures to prevent the failures mentioned above.

Abstract: The efficiency of applying electrophysical impacts in technological methods of machine part cutting to a great extent depends on the understanding of the processes forming the basis of these impacts. As a rule a specific nature of these processes is characterized by their high intensity, locality of the impact and an impulse mode.The understanding of a certain process is necessary both for its efficient use in technological processes and for the development of new technologies based on the combination with other electrophysical impacts. The paper presents the results of mathematical modeling of deformation processes under ultrasonic frequency impulse plastic impact of a deformer on the surface layer of metals and alloys. Based on the mathematical modeling of the process of ultrasonic deformation of materials, operating parameters of the impact defining the field of application of this method are found. Quantitative relationships between basic characteristics of the deformation process and operating parameters of an ultrasonic impact are established.

Abstract: The article presents the results of the mathematical modelling of the strain and deformation conditions in the steel-cord conveyor belt of the ST 2000 and ST 2500 types, applying the Finite Element Method. The output of the model is identification of the maximum magnitude of the activated dynamic force in the conveyor belt on the basis of the analysis of vertical shifts of the loaded point, vertical strains in the area of supporting rollers, and the maximum principal strains.

Abstract: In order to grasp the microcosmic mechanism of abrasive flow machining (AFM), find out the real law of grain cutting workpiece surface, make out a reasonable process parameters and improve the abrasive flow processing efficiency. The process of grain (near to workpiece surface, called as active grains) cutting workpieces material has been analyzed and the cutting force model has been established in present work. Firstly, at the beginning of the present work, the general process of grain cutting, wearing or deburring workpiece surface has been researched. Theoretical analysis shows that the cutting force not only derives from static force, such as abrasive medium viscoelasticity and grain squeezing, but also dynamic force, such as grain impacting load on the workpiece surface. In ordering to prove the dynamic force exists, one or two main dynamic process parameters (such as abrasive viscosity, extrusion pressure, piston velocity) are chosen, dynamic force is most sensitive to the variation of which, meantime, static force is not, and then the effects of main dynamic process parameters on cutting force value have been compared with the effects of others process parameters by several experiments in the present work. The experimental results show that with the same proportion of variation of process parameters, the change in cutting force (mainly axial cutting force) consists with theoretical results very well in some degree.

Abstract: A violin bridge kept in place by the pressure of the four strings has a powerful effect on the tone of the instrument. Its dynamic mechanical behaviors are investigated using finite elemental modeling and experiments in this paper. Modal and frequency response analysis of an isolated bridge are carried out. Numerical results show that the frequency responses are related to the vibration modes of the bridge. Particularly, the bridge hill is due to the bridge itself, and linked to the in-plane rocking mode of the bridge near the bridge hill peak. Three-dimensional dynamic forces exerted to the violin plates by the strings and bridge are then experimentally measured using a dynamometer. The experimental results are then analyzed and correlated to the simulation. The frequency response analysis of an isolated bridge is demonstrated to be a potential tool to study the mechanical behaviors of the violin bridge.

Abstract: In this paper, the vibration of a three screw pump was studied. Firstly the vibration response of the pump was tested. Then the FE model of the pump was constructed and the modals of it were calculated. The exactness of the result was confirmed by the testing modals and the reasonable of the FE model was verified at the same time. Finally, the force acted on rotors due to pressure was calculated by the mathematical method of surface integral. The force was loaded on the FE model and the force response was predicted, which represented the basic vibration of the screw pump. Based on the work above, the vibration spectrum of the screw pump was analyzed.

Abstract: Due to the larger workflow, more complex foundation and special structure and with the 8° design seismic intensity, it is necessary to analyze this sedimentation basin in the static and dynamic by 3D finite element method. This paper describes the structural model and the selected parameters for calculation of static and dynamic properties, and states the stress analysis results under the various conditions.

Abstract: This paper reviewed the present status and the future prospects of a method for precision mass and force measurement based on levitation mass method (LMM). The LMM has been proposed and improved by the author The mass which levitated using a pneumatic linear bearing in LMM is used to producte a inertial force which used as the reference force applied to the objects under test, such as to force sensor calibration, material and structure test. The inertial force is calibrated only from Doppler shift frequency. The stability of laser’s wavelength has improved in the LMM. The futhure work and the method to improve the precision have described.