Applied Mechanics and Materials Vol. 162

Abstract: On the basis of a five bar linkage it is possible to generate actinomorphic coupler curves if certain conditions, related to the kinematic dimensions and the gear ratio between the two cranks, are fulfilled. These symmetric coupler curves can then be used to realize a step mechanism by adding two additional links, taking advantage of the typical curvature characteristics of the generated coupler curve The following article starts with a short literature survey about five bar linkages in general and their use as dwell or step mechanisms in particular. Then it will be shown how the curvature properties of the coupler curves generated by five bar linkages can be determined by graphical means. It will be shown how this procedure can be advantageously applied with the help of an interactive geometry program, using the geometric determination of the curvature properties, such that an optimal step mechanism can be derived.

Abstract: The paper proposes two methods for kinematic analysis of a belt mechanism with circular eccentric output element (link). One of them is based on the mechanisms geometry and the second on its kinematics in order to obtain the transmission functions of different order. Both approaches are based on a imaginary cam mechanism instantaneous isokinetic with the given belt mechanism. The transmission functions obtained by means of proposed procedures are in a numerical form due to the finite incremental method used in solving the problem.

Abstract: Fast wheeled motion on unstructured grounds requires highly efficient suspensions that damp shocks vertically but also horizontally, which is an original contribution of the author. This work describes nine 2D and 3D kinematics, most of them with parallel structure, that are suitable for guiding a wheel and providing simultaneous damping in two directions. Steering and power transmission are also included in the most advanced variants, that were previously patented. Both structural and dimensional synthesis are presented, with a kinematic description of each system. A real implementation at a small scale is also described.

Abstract: The conventional engine cannot start alone. The engine needs a special device to turn it on. This device is usually an electric motor that is called starter. Any other engine that uses another working cycle then Otto cycle or Diesel cycle could accede to a self-starting ability. The paper tries to use ancient ideas in order to develop a true thermal engine able to use solar and other renewable energy. This unconventional engine inherits some ideas from the perpetual motion machine solutions.

Abstract: In the last two decades most information sources both old and new were digitized or prepared directly in digital form. This process allows a better accessibility and visibility of information throughout the world. In order to find useful information easily and quickly, it is important to have a coordinated search engine. The paper deals with the development of a demonstrative digital technical library. The controlled search engine is based on the multilingual illustrated micro-thesaurus in the technical field of mechanisms science according to the librarian indexation rules. Some search possibilities are presented.

Abstract: To improve the efficiency of printing or coating processes for paper products the velocity of the web and the roller width can be increased. However, these measures cause deformations of the rollers, heating effects and streak print defects due to undesirable oscillations. The vibration characteristic is significant for the quality and efficiency of the printing or coating processes. Approved methods like balancing of the rollers and maximizing the bending stiffness have come to technical limits. This paper describes a new promising technology for further optimization of printing and coating machines. Piezoelectric actuators are integrated in the bearings of a roller of a flexographic printing machine and generate counterforces to compensate undesired bending vibrations. Strain gauges applied on the roller measure the vibrations. A simulation model of the mechatronic overall-system has been developed to design the control strategy. The oscillations of roller systems in printing machines and other industrial applications are mainly stimulated by disturbances that occur periodically with each rotation. A feedback control strategy combined with a feed forward compensation of predictable disturbances has shown promising results in simulation and experiments. Due to the fact that the excitations of the oscillations are periodically with the rotation of rollers, another approach for vibration reduction has been developed. The forces for vibration reduction are not generated by an active mechatronic system but by passive profile rings.

Abstract: We present a study of the feasibility of controlling the pitch angle of a high velocity ground vehicle in ballistic phase by accelerating or decelerating its wheels. The vehicle performed several jumps, and various wheel acceleration commands were sent to it while it was airborne. Images were recorded using a high-speed video camera, and the trajectories of markers placed on the vehicle were analyzed in order to measure the relationship between the changes in angular velocities of the chassis and the wheels. It appeared that it was possible to achieve pitch righting through the modification of the angular velocities of the wheels with adequate performance, thus opening the road towards automated control of pitch, then later yaw and roll angles.

Abstract: An axial clutch is one in which the mating frictional members are moved in a direction parallel to the shaft. One of the earliest of these is the cone clutch, which is simple in construction and quite powerful. However, except for relatively simple installations, it has been largely displaced by the disk clutch employing one or more disks as the operating members. Advantages of the disk clutch include the freedom from centrifugal effects, the large frictional area that can be installed in a small space, the more effective heat-dissipation surfaces, and the favorable pressure distribution. Modeling methods typically implement mathematical models that can be used to simulate steady-state and transient performance under various commanded conditions, loads, and operational regimes. In the case of drive-train systems, these models should be dynamic to simulate the transient interaction among speeds, loads, and power sources. These dynamic simulation models enable the identification of diagnostic indicators. .

Abstract: The spline joints transmit torque from shafts to rotors by multiple contact surfaces. The joint's mechanical system is, therefore, undetermined, i.e. the number of contact points is much larger than the number of restricted degrees of freedom. Thus, the actual load distribution is greatly influenced by the joints elements elastic properties and their geometrical errors and surface profile. In this paper, an analytical and experimental study for the load distribution on the in joints length caused by the finite rigidity of the joints elements is presented.