Vibration dampers for transmission of mechatronic systems

The paper reviews original torsional vibration dampers retaining their efficiency in a wide disturbing frequency band. Some potential design alternatives are considered. The basic structural element of the damper is a rotary flexible ring. The mathematical model of the system estimates inertia, flexible and gyroscopic terms. The equations to calculate the system motion are derived and stability conditions for the system dynamic balance are formulated, proper consideration is given to other possible stability loss forms and regions of the flexible ring. The analysis of the system natural frequencies is made. Efficiency estimation of the damper versus various parameters is effected following the expression of the equivalent inertia moment and its limit value

Research of dynamics of lifting equipment

In the recent years, girder bridge cranes are replaced by double-beam overhead cranes with beams of rectangular cross-section. In addition, new materials are used for their fabrication, characterized by different values of allowable loads and deformations. In the paper, two overhead cranes from JSC "Vilniaus kranai" are considered. A mathematical model is proposed that enables assessment of the impact of the hydraulic damper built in the cargo suspension system upon the dynamic features of the crane in the beginning of the lifting process. It was determined that in such a way the period of vibration damping is reduced. However, the impact of the damper upon the dynamics of the metal structure of the crane is limited because of high mobility of the rope as compared to the mobility of the total structure

Investigating possibilities of a table vibrator with controlled damping

This paper considers the possibility of ensuring a desired regime of vibrations of the table vibrator with a support, where a damping element with a magnetorheological fluid is used. A feedback system is employed for control of the damping element. The system receives signals from the accelerometer that measures the vibrations of the table vibrator. Solution of the equations describing vibrations of the table vibrator demonstrated that double integration of signals of the accelerometer ensures a stable regime of vibrations for varying mass of a product. If the signal of the accelerometer is integrated once and then passes through a frequency detector, a dangerous increase of the vibrations in the resonance zone is avoide

Research of Cargo Delivery Errors by Conveyance using Lifting Mechanism

The mechanical properties of the rope - stiffness and internal friction changes during the movement of cargo. For this reason, under the influence of gravity and inertial forces in the rope having varying tension. Thus, the lift mechanism further exposed to dynamic loads. The highest value of this load is obtained at the beginning of lifting and lowering in place. The mathematical model of the lift mechanism was investigated using the original software package and found dynamic load. In modern control system used cranes lifting mechanism, taking into account the deviation from the vertical rope. Dynamic load on the rope can distort the signals. Results are used to improve the control system of the lifting mechanism

Investigating possibilities of a table vibrator with controlled damping

This paper considers the possibility of ensuring a desired regime of vibrations of the table vibrator with a support, where a damping element with a magnetorheological fluid is used. A feedback system is employed for control of the damping element. The system receives signals from the accelerometer that measures the vibrations of the table vibrator. Solution of the equations describing vibrations of the table vibrator demonstrated that double integration of signals of the accelerometer ensures a stable regime of vibrations for varying mass of a product. If the signal of the accelerometer is integrated once and then passes through a frequency detector, a dangerous increase of the vibrations in the resonance zone is avoide

Vibration dampers for transmission of mechatronic systems

The paper reviews original torsional vibration dampers retaining their efficiency in a wide disturbing frequency band. Some potential design alternatives are considered. The basic structural element of the damper is a rotary flexible ring. The mathematical model of the system estimates inertia, flexible and gyroscopic terms. The equations to calculate the system motion are derived and stability conditions for the system dynamic balance are formulated, proper consideration is given to other possible stability loss forms and regions of the flexible ring. The analysis of the system natural frequencies is made. Efficiency estimation of the damper versus various parameters is effected following the expression of the equivalent inertia moment and its limit value

Couplings with variable characteristics of vehicles

Couplings abruptly changing their torsional rigidity and carrying capacity when the transmitted torque reaches a particular value are considered. This state is achieved either changing the conditions of the deformation of a flexible member or by excluding it from torque transmission. In the presented paper the conditions of mode variation are determined and some relationships for determining major parameters of couplings are given

Dragendorff’s reagent: Historical perspectives and current status of a versatile reagent introduced over 150 years ago at the University of Dorpat, Tartu, Estonia

The well-known Dragendorff’s reagent (DR) was introduced by an Estonian-German Professor Johann Georg Noel Dragendorff (1836–1898) in the middle of the 19th century (1866). Dragendorff, who was a full-time professor in pharmacy at the university of Dorpat (Tartu) used his reagent originally for the rapid screening of herbal products to find traces of alkaloids. DR is a solution of potassium bismuth iodide composing of basic bismuth nitrate (Bi(NO3)3), tartaric acid, and potassium iodide (KI), and when contact with alkaloids DR produces an orange or orange red precipitate. In this review article, we make a short historical overview on the biography and scientific research work of Professor Dragendorff at the University of Dorpat. The chemistry, method of preparation, mechanism of action, and practical uses of DR in various disciplines in various European countries including the Baltic countries (Estonia, Latvia, Lithuania), Finland, Ukraine, Moldova, and in Asia (Vietnam), are also discussed. Over several decades, DR and its modifications have found uses in many new applications and disciplines, and a number of commercial DRs are also currently available on the market. Today, DR is used for example in the production of surfactants, where non-ionic surfactant is precipitated in water solution with modified DR (KBiI4+BaCl2+glacial acetic acid). Total six different potassium iodobismuthate (DR) solutions are also presented in the European Pharmacopoeia. In conclusion, DR (after more than 150 years of its invention in Estonia) has still an important role in pharmaceutical and related sciences all over the world