Bend with compression of thin-layer rubber-metal elements

For efficient application of thin-layer rubber-metal elements (TLRME) in modern mechanical engineering, including vibration insulation, it is necessary to determine ruggedness characteristics of TLRME. Numerous experimental studies have demonstrated that at tension and compression this characteristic is influenced essentially by value of specific load, compliance of non-elastomeric layers and way of fastening of elastomeric layers in the TLRME package. In the present article the calculation method of ruggedness constant of TLRME is presented at static load, tension - compression, in the field of small deformations taking into account the deformation of a glutinous layer. The solution is obtained by the method of Ritz using the principle of the minimum complete potential energy of deformation. The obtained solution allows to obtain asymmetrical ruggedness constant of TLRME at tension - compression without the assumption regarding dissimilar modularity of rubbe

Motion control optimization of robotic fish tail

"In the daily life people, animals, fishes, birds and insects constantly interact with continuous media such as air or water. It means that synthesis of new robotic systems inside this continuous media and imitation of motion of real objects must be investigated together with media surrounding them. In this report motion of robotic fish tail vibration and simplified interaction with water flow is investigated. The study comprises: (a) preliminary analysis of main goal that is given to scientist to solve the problem; (b) optimization of a main fundamental system; (c) analysis of ideal control actions; (d) synthesis a new structural schemes; (e) calculation of optimal parameters. The preliminary analysis includes 5 steps: analysis of technological processes, choice of base system, choice of control actions, clarification of criteria for optimization and selection of limits. In this report criterion of optimization (for robotic fish tail model inside water) is maximal positive impulse of water forces in the fish tail and hull contact pivot. The main idea is to find out optimal control law for variation of additional area of vibrating tail within limits. The limits are maximal and minimal area of tail interaction with water. For task solution the maximum principle of Pontryagin is used [5 – 14]. It is demonstrated that optimal control action is on bounds of area limits. Examples of synthesis of real mechatronic systems are provided. One example of synthesis is a system with time harmonic moment excitation of tail in the pivot. The other example is a system with adaptive force moment as function of phase coordinates. In both systems area exchange (from maximal to minimal values) has control action as a function of phase coordinates. It is demonstrated that real tail vibration motion is highly stable and provides satisfactory real criterion in the hull contact point

Analysis of non-stationary flow interaction with simple form objects

ArticleThe paper is devoted to the analysis of a non-stationary rigid body interaction in a fluid flow. Initially, an approximate method for determining the forces due to fluid interaction with the rigid body is offered. For this purpose, the plane movement of a mechanical system with an infinite DOF (degrees of freedom) is reduced to 5 DOF motion: 3 DOF for the body and 2 DOF for the areas of compression and vacuum in fluid flow. Differential equations of non-stationary motion are formed by the laws of classical mechanics. The use of an approximate method has been quantified by computer modelling. The average difference in results was found to be small (< 5%). The analysis of the fluid (air) interaction is carried out for a rigid body of two simple geometries - flat plate and diamond. The results obtained are used to refine the parameters of the proposed approximate method that is addressed in the present study for fluid interaction with the non-stationary rigid body. Theoretical results obtained in the final section are used in the analysis of the movement of prismatic bodies in order to obtain energy from the fluid flow

Investigation of dual varying area flapping actuator of a robotic fish with energy recovery

Autonomous under-water vehicles (AUV) performing a commanded task require to utilize on-board energy sources. At the time when on-board power source runs low during operation, the vehicle (AUV) is forced to abort the mission and to return to a charging station. The present work proposes the technique of an energy recovery from surrounding medium. This effect is studied for dual action actuator movement that obtains energy from fluid. It is realized that a flapping or vibrating actuator can be used for energy extraction phenomenon apart from the non-traditional propulsive technique. In the present work a simple dual flapping actuator that can switch between simple flat plate and perforated plate at extreme end positions (angles) by using an efficient mechatronic mechanism that would help in overcoming viscous forces of the operating medium is extensively studied. The main objective of the present article is to develop a new approach for energy gain and recharge power pack of on-board sources from the surrounding medium and to create a robotic fish that would work autonomously by using unconventional drive along with the possibility of energy restoration by using dual varying area type vibrating actuator. At the time of recharge, the robotic fish would project its tail (actuator) out of water and use surrounding medium (air) to scavenge the energy. All the equations describing the process are formed according to classical laws of mechanics. The mechatronic system is explained and the results obtained are discussed in detail for air as the operating fluid to scavenge energy

Cargo pendulum vibration damping inside vehicle hull

"A model is proposed to study the dynamic response of cargo pendulum vibrations. Equations of motion are obtained by Lagrange equations using Lagrange multiplier. Two independent bumpers of the securing cargo are considered in the model. Bumpers forces are represented by a special stiffness and damping as a function of phase coordinates. Investigation was performed for: a) transient motion from free initial conditions; b) stationary motion excitation from constrained string or hull bumpers vibrations; c) joint transient and excitation motion take into account random parameters. Results of investigations may be used for cargo fastening inside trailer, ship or airplane

Fiberconcrete non-linear fracture control through fresh concrete flow numerical simulation

The use of fiber (steel or synthetic) reinforced concrete (FRC) had a considerable increase during the last decades mainly due to its higher resistance to crack formation and simplified casting technique. At the same time fiberconcrete strength properties are non-linear with a high scatter. The paper presents results for fiberconcrete post-cracking behavior control by means of fresh FRC flow numerical simulations and prediction of internal structure (fiber orientation and distribution) formatio

Nonlinear optimal synthesis of the vibrator with flow excitation

In the daily life and techniques people all time have interaction with continue media like air or water. In report motion of vibrator with constant air or water flow excitation is observed. In first part of report motion of a vibrator with constant air or water flow velocity excitation is investigated. The main idea is to find out optimal control law for variation of additional area of vibrating object within limits. For solution of the high-speed problem the maximum principle is used. It is shown that optimal control action is on bounds of area limits. Examples of synthesis real mechatronic systems are give

Vibration characteristics of miniature stirling electric coolers

We present the investigation results of vibration characteristics of miniature stirling electric coolers, which can be used for compact HPGe spectrometers for space applications. Comparative assessment between three Stirling cycle coolers – two Ricor model K508 coolers and one Thales model RM3 cooler were done. In spite of the limited number of the coolers tested, the following conclusions can be made, that there are significant differences in the vibration characteristics between the various types of coolers and between coolers of the same type. To categorize the vibration characteristics of the coolers we carried out our tests by different methods in certified Vibroacoustic laboratory and BSI laboratory. The results obtained in our laboratory follow the same trends and give the same ranking as the test results obtained in the Vibroacoustic laboratory

Optimization of vibrator motion with air flow excitation

In the daily life and techniques people constantly interact with continuous media such like air or water. In this paper motion of a vibrator with constant air or water flow excitation is considered. Firstly, motion of the vibrator with constant air or water flow velocity excitation is investigated. The main idea is to determine optimal control law for variation of additional area of vibrating object within limits. The criterion of optimization is time required to move object from initial position to the final one. The maximum principle is used for solution of the high-speed problem. It is demonstrated that optimal control action is on bounds of area limits. Examples of synthesis of real mechatronic systems are give

Cargo pendulum vibration damping inside vehicle hull

"A model is proposed to study the dynamic response of cargo pendulum vibrations. Equations of motion are obtained by Lagrange equations using Lagrange multiplier. Two independent bumpers of the securing cargo are considered in the model. Bumpers forces are represented by a special stiffness and damping as a function of phase coordinates. Investigation was performed for: a) transient motion from free initial conditions; b) stationary motion excitation from constrained string or hull bumpers vibrations; c) joint transient and excitation motion take into account random parameters. Results of investigations may be used for cargo fastening inside trailer, ship or airplane