Applied Mechanics and Materials Vol. 762

Abstract: This paper presents a method to build the forward kinematics model of a bucket excavator’s digging equipment. The applied method is the one used for the industrial robots’ mechanisms and uses Denavit-Hartenberg convention.

Abstract: This paper presents a method to build the inverse kinematics model of a bucket excavator’s digging equipment. The model is determined by using two different methods, the matrix method applied on the decoupled forward kinematics model and respectively the geometric model.

Abstract: The paper presents works carried out by the authors in the field of NC axes’ structural and functional optimization. This paper includes the results obtained by using a MathCAD application (developed in the doctoral thesis of the second author) for the servomotor's thermal behavior computer assisted evaluation. The analyzed servomotor is included in the driving system of a linear motion NC axis experimental testing stand, (existing in MMS department from EMTS Faculty). The NC axis of the experimental stand integrates a FAGOR brushless servomotor, a 1:1 ratio belt drive intermediary transmission, a ball screw - bearings assembly (lead screw - ball nut - bearings) and a driven element guided through a ball rail system. The MathCAD application was developed in order to perform specific calculation for servomotor's thermal energy dissipation and maximum operating temperature evaluation, and allows to perform the assisted final check and optimum selection of the electrical driving servomotors based on these results. The paper presents, through some screenshots from running the MathCAD application, the computer assisted evaluation procedure and results of the brushless servomotor's thermal behavior analysis corresponding to analyzed NC axis (included in the experimental stand).

Abstract: In the precision engineering field, a large number of applications require precise and micro-level manipulation. In the last decade the demand of micro products and miniaturization has seen a wide spread growth. The microfactories concept was first developed in In the precision engineering field, a large number of applications require precise and micro-level manipulation. In the last decade the demand of micro products and miniaturization has seen a wide spread growth. The microfactories concept was first developed in the late twentieth century in Japan. With the development of the microfactories field has evolved the compliant mechanisms field. In this paper a microrobotic cell with an original manipulator for microassembly with a compliant gripper is designed, simulated and analyzed. The compliant gripper is mounted on a five bar mechanism with conventional joints in order to achieve a larger workspace. The vertical motion is produced by the linear actuator. The kinematics of the five bar mechanism and the workspace boundaries are analyzed based on the input parameters. For the compliant gripper is realized a 3D model and FEM analysis is conducted based on input displacement by the piezoelectric actuator. late twentieth century in Japan. With the development of the microfactories field has evolved the compliant mechanisms field. In this paper a microrobotic cell with an original manipulator for microassembly with a compliant gripper is designed, simulated and analyzed. The compliant gripper is mounted on a five bar mechanism with conventional joints in order to achieve a larger workspace. The vertical motion is produced by the linear actuator. The kinematics of the five bar mechanism and the workspace boundaries are analyzed based on the input parameters. For the compliant gripper is realized a 3D model and FEM analysis is conducted based on input displacement by the piezoelectric actuator.

Abstract: In a previous paper of the authors, a general method was presented for the reduction of a rigid plane plate to a discrete system of material points, with equivalent inertial properties (mass, center of mass, tensor of inertia). The present paper generalizes the method for rigid bodies of arbitrary shape, i.e. for material volumes, as well as for curved shells. It is shown that a homogenous ellipsoid can be reduced to a system of seven material points placed in significant geometrical points of the body. Next, starting from the concept of ellipsoid of inertia, an equivalent homogenous ellipsoid is determined for an arbitrary body. The method simplifies considerably the calculation of various mechanical quantities, such as moments and products of inertia with respect to rotated Cartesian coordinate systems, angular momentum and kinetic energy, of rigid bodies part of all types of mechanical devices or structures.

Abstract: — This document contains experimental data regarding operational stats and thermal stats of an automatic gearbox. Experimental data regarding the operating pressure and the command of the solenoid actuators is being expressed in percentage and current and is being recorded on the hydraulic test rig for establishment and optimization of the clutches and brakes operations from an automatic gearbox.

Abstract: The study of the bending vibrations of Euler-Bernoulli beams is typically performed based on pure elastic material models, which neglect the damping. However, in practice, due to the internal friction of the material, the vibrations are damped. This phenomenon can be taken into account by using a viscoelastic material model, in which supplementary strains, dependent on the strain rates, are considered. In the paper, free bending vibrations of homogeneous viscoelastic Euler-Bernoulli beams are studied by developing generalized forms of an exact and of an approximate method, respectively, used regularly in the study of pure elastic Euler-Bernoulli beams. The developed methods are applied and compared on a numerical example, highlighting their advantages and limitations.

Abstract: This paper presents the works carried out by the authors in the field of structural and functional optimization of industrial robot's numerically controlled (NC) axes. The study includes the results obtained in the research stage of the experimental measurements performed to evaluate the electrical servomotor's thermal behavior using a thermal (infrared) imaging camera. The analyzed servomotor is a brushless servomotor integrated in an experimental stand for linear motion NC axis experimental research, existing in the MMS department from EMTS faculty. Supplementary to the driving servomotor, the experimental stand includes a belt drive transmission, a ball screw - bearings assembly and a driven element guided by ball rail system. This experimental research phase is part of the doctoral thesis of first author and was conducted in order to validate the mathematical models developed in the PhD thesis. Thus, experimental results presented in the paper have been used to validate first mathematical models for electric motor's preliminary selection and checking, (performed by determining the total reflected inertia of the mechanical system on motor shaft level) as well as the mathematical models for final selection and checking (by evaluating the servomotor's thermal energy dissipation, and servomotor's internal and external maximum operating temperature). Second, the experimental results have been used to validate the assisted simulation for structural and functional optimization of industrial robot's NC axes based on both servomotor and drive's thermal behavior analysis, performed in the thesis by means of a dedicated commercial software package.

Abstract: The paper presents the works performed by the authors in the field of structural and functional optimization numerically controlled (NC) axes. The study includes two computing applications developed by second author of the paper in a PhD thesis related on NC axes’ structural and functional optimization. The first computing application is used for calculating the total reflected inertia of a linear motion NC axis (total inertial loads' reducing on the driving motor's shaft level). The second computing application is used for both preliminary selection of the driving servomotor (by checking first the accomplishment of the kinematic criterion) and a secondary selection of the electric motor (by checking in a second stage the accomplishment of the static and dynamic criterion). By mean of both software applications optimal matching of servomotor driving system with available NC axis mechanical structure may be determined. The analyzed linear motion NC axis is part of an experimental stand (existing in the MMS department from EMTS faculty), that supplementary to the driving servomotor, includes a belt drive transmission, a ball screw - bearings assembly and a driven element guided by ball rail system.