Damping Of Mechanical Vibrations Research Articles

Investigation of Physical Properties of Polymer Composites Filled with Sheep Wool.

Sheep farmers are currently facing an oversupply of wool and a lack of willing buyers. Due to low prices, sheep wool is often either dumped, burned, or sent to landfills, which are unsustainable and environmentally unfriendly practices. One potential solution is the utilization of sheep wool fibers in polymer composites. This paper focuses on the study of mechanical vibration damping properties, sound absorption, light transmission, electrical conductivity of epoxy (EP), polyurethane (PU), and polyester (PES) resins, each filled with three different concentrations of sheep wool (i.e., 0%, 3%, and 5% by weight). It can be concluded that the sheep wool content in the polymer composites significantly influenced their physical properties. The impact of light transmission through the tested sheep wool fiber-filled polymer composites on the quality of daylight in a reference room was also mathematically simulated using Wdls 5.0 software.

Matching the output voltage level of the energy recovery device and the voltage of the on-board network

This article deals with the possibilities of applying magnetic dampers for damping of mechanical vibrations, both of car body and of radio-electronic equipment. An electronic device is proposed to adapt the output voltage of the energy recovery device to the voltage of the car’s onboard network or to the power supply voltage of the radio-electronic equipment. In addition, the developed device can be used in conjunction with an energy recovery system for vehicle braking.

STUDY OF FACTORS INFLUENCING VIBROISOLATING PROPERTIES OF MATERIALS FOR PASSIVE ELASTIC BEARING OF MACHINES

Machinery or instruments are subjected to external forces from a base in many cases. It can have a negative influence on manufacturing accuracy, tightness, wear of machine parts, work safety etc. Therefore, it is necessary to perform suitable passive elastic bearings of machinery to eliminate external vibration from the base. An application of suitable vibroisolating materials is one way of the vibration elimination. The aim of the paper is to study vibration damping properties of different materials by means of a non-destructive method of forced mechanical oscillations. Different factors influencing transfer damping of mechanical vibration were investigated in this work, e.g., material type and its thickness, excitation frequency of mechanical oscillations, size of mass load and effect of material composition. These factors were subsequently evaluated. Finally, suitable recommendations for passive damping of mechanical vibration were described.

The effect of homogenization and addition of polysaccharides on the viscoelastic properties of processed cheese sauce

This study was conducted to determine the effect of 1-stage homogenization (OSH) and 2-stage homogenization (TSH) and the addition of polysaccharides [κ-carrageenan (CR) or furcellaran (FR) at levels ranging from 0.000 to 1.000% (wt/wt)] on the physicochemical, viscoelastic, and mechanical vibration damping properties of processed cheese sauces (PCS) after 30 d of storage (6 ± 2°C). The basic chemical properties (pH, dry matter content) were similar for all tested samples. Viscoelastic measurements indicated that PCS rigidity was directly proportional to increasing CR or FR concentration and to the application of homogenization. The interactions between the application of homogenization and the concentration of polysaccharides used were also significant. Compared with OSH, TSH did not lead to any further increase in the rigidity. The preceding results were also supported by data obtained from a nondestructive method of mechanical vibration damping. No changes in water activity were observed in any PCS sample. Overall, the addition of FR or CR appeared to be highly suitable for increasing the emulsion stability of PCS. If PCS products with softer consistency are desired, then a concentration of CR/FR ≤0.250% (wt/wt) could be recommended together with OSH/TSH. For products for which a firmer PCS consistency is required, the addition of CR in concentrations of ≥0.500% (wt/wt) or FR in concentrations of ≥1.000% (wt/wt) together with OSH is recommended. Finally, as the concentration of polysaccharides increased, a darker PCS color was observed.

Mechanical Vibration Damping and Compression Properties of a Lattice Structure.

The development of additive technology has made it possible to produce metamaterials with a regularly recurring structure, the properties of which can be controlled, predicted, and purposefully implemented into the core of components used in various industries. Therefore, knowing the properties and behavior of these structures is a very important aspect in their application in real practice from the aspects of safety and operational reliability. This article deals with the effect of cell size and volume ratio of a body-centered cubic (BCC) lattice structure made from Acrylonitrile Butadiene Styrene (ABS) plastic on mechanical vibration damping and compression properties. The samples were produced in three sizes of a basic cell and three volume ratios by the fused deposition modeling (FDM) technique. Vibration damping properties of the tested 3D-printed ABS samples were investigated under harmonic excitation at three employed inertial masses. The metamaterial behavior and response under compressive loading were studied under a uniaxial full range (up to failure) quasi-static compression test. Based on the experimental data, a correlation between the investigated ABS samples’ stiffness evaluated through both compressive stress and mechanical vibration damping can be found.

The effect of furcellaran or κ-carrageenan addition on the textural, rheological and mechanical vibration damping properties of restructured chicken breast ham

The aim of the study was to investigate the dependence of selected textural, rheological and mechanical vibration damping properties of restructured chicken breast ham (RCBH) on the concentration of furcellaran (FRC1 or FRC2) or κ-carrageenan (KC) during a 14-days storage period (at 4 ± 2 °C). The above-mentioned polysaccharides were used in concentrations of 0.25 g/100 g, 0.50 g/100 g, 0.75 g/100 g and 1.00 g/100 g. Control sample (CS) without any polysaccharide addition was also produced. The textural, rheological and mechanical vibration damping properties of RCBH samples were affected by the type and concentration of the polysaccharide used (p < 0.05) and the storage period (p < 0.05). Samples prepared with KC and FRC1 at a concentration level of 1.00 (g/100 g) presented the highest values of hardness, G′, G″ and G*. Values of G* and δ (in all tested frequency ranges) indicated a solid-like behavior for all the samples over the experimental range. It was found that the first resonance frequency peak position increased with an increase in the RCBH stiffness leading to lower vibration damping properties of the samples (p < 0.05).

Evaluation of various emulsifying salts addition on selected properties of processed cheese sauce with the use of mechanical vibration damping and rheological methods

The scope of the study was the employment of an innovative method beneficial to evaluate the impact of various emulsifying salts (ES) addition on selected properties of processed cheese sauces (PCS). The ES applied were disodium hydrogenphosphate (DSP), tetrasodium disphosphate (TSPP), pentasodium triphosphate (PSTP), sodium salt of polyphosphate n ˜ 20 (POLY) and trisodium citrate (TSC). Moreover, the examined effect was observed in two groups of samples, (i) PCS with non-adjusted pH and in (ii) PCS with adjusted pH. The hardness of the samples was influenced by the type of the applied ES, pH, and storage period. The PCS produced with DSP:TSPP (1:1; without pH adjustment) exhibited the higher hardness which was also confirmed by the increasing samples viscosity and storage modulus. The results obtained by the mechanical vibrations damping analysis were analogous to rheological analysis. Generally, it was found that more viscous PCS exhibited “better” vibration damping properties, which was reflected by a shift of the first resonance frequency peak position to lower frequencies. In case of all investigated samples it was verified that the increasing storage period caused increasing stiffness and led to a shift of the first resonance frequency peak position to higher frequencies.

Vibration damping of Ni-Mn-Ga/silicone composites

Ferromagnetic shape memory alloy (FSMA)/polymer composites are promising materials for mechanical vibration damping. One of the main issues is that mechanically active FSMA particles from different types of viable sources for large quantities of these particles have not been compared under the same conditions. In this paper we compare the dynamic mechanical response of NiMnGa/silicone composites, made of different types of mechanically active particles, using the same matrix and experimental conditions. The study reveals a strong influence of both volume fraction of FSMA in the composite and morphology of the particles used as fillers on the vibration damping of composites.

THERMOPLASTIC POLYMER MACHINE GUARDS – EXPLOITATION SAFETY

The machine construction sector uses from 2 to 5% of thermoplastic polymer produc-tion. This material is used to make small elements and big parts of equipment, includ-ing guards. The latter have mechanical vibration damping capacity, do not require any maintenance, are cheap and look attractive. Moreover, polymer guards are an essen-tial element of machines as they improve workplace safety. They are used in such ma-chines as lathes, milling machines, drills, extruding machines, presses and grinders. Pursuant to the Ordinance of the Minister of Labour and Social Policy on general provi-sions for safety and health at work, protective devices used in machines should be strong and durable so as to ensure the appropriate level of occupational safety. This is why the selection of the right material to make such devices is essential. Most fre-quently guards used in the market are steel frames with a polycarbonate screen or lam-inated safety glass. Other materials used to manufacture guards are poly(methyl methacrylate) (PMMA) and polystyrene (PS). Thermoplastics are characterised by high visual light transmittance (even up to 98% in the case of PMMA), easy treatment, pos-sibility to form any shape and resistance to atmospheric factors. However, they are also characterised by limited high temperature resistance, low fire resistance and high speed of fire propagation on their surface which may be dangerous for employees in case of fire. The article discusses the selection of appropriate material for the produc-tion of guards in the context of their exploitation in higher temperature conditions and examines threats posed by thermoplastics in fire conditions.

Forced Monoharmonic Vibrations and Self-Heating of Viscoelastic Flexible Circular Plates with Piezoelectric Layers

The coupled problem of the forced axially symmetric vibrations and self-heating of clamped and hinged flexible circular plates with viscoelastic piezoelectric layers as sensors and actuators is solved. The mechanical and electric excitation of vibrations and the damping of mechanical vibrations by applying the appropriate potential difference to the electrodes of the actuators are studied. The effect of geometrical nonlinearity on the frequency-dependence of the deflection, self-heating temperature, and sensor voltage of a plate under harmonic electromechanical loading at principal bending resonance is analyzed

Research of the Nonlinear System Identification Based on the Volterra RLS Adaptive Filter Algorithm

This paper mainly research a kind of nonlinear system modeling method based on the Volterra series RLS adaptive filter algorithm. Through the modeling second order Volterra nonlinear system, and adapting Volterra RLS algorithm to apply in the first order and second order item, under the gaussian noise condition, iterations times is not more than fifty times, the algorithm can realize convergence, which prove the algorithm accuracy. Volterra RLS adaptive filter algorithm can be effectively applied into the mechanical vibration damping and de-noising in active control, which has a broad application prospect. DOI: http://dx.doi.org/10.11591/telkomnika.v11i5.2261

Damping of mechanical vibrations by free electrons in metallic nanoresonators

We investigate the effect of free electrons on the quality factor ($Q$) of a metallic nanomechanical resonator in the form of a thin elastic beam. The flexural and longitudinal modes of the beam are modeled using thin beam elasticity theory, and simple perturbation theory is used to calculate the rate at which an externally excited vibration mode decays due to its interaction with free electrons. We find that electron-phonon interaction significantly affects the $Q$ of longitudinal modes, and may also be of significance to the damping of flexural modes in otherwise high-$Q$ beams. The finite geometry of the beam is manifested in two important ways. Its finite length breaks translation invariance along the beam and introduces an imperfect momentum conservation law in place of the exact law. Its finite width imposes a quantization of the electronic states that introduces a temperature scale for which there exists a crossover from a high-temperature macroscopic regime, where electron-phonon damping behaves as if the electrons were in the bulk, to a low-temperature mesoscopic regime, where damping is dominated by just a few dissipation channels and exhibits sharp nonmonotonic changes as parameters are varied. This suggests a scheme for probing the electronic spectrum of a nanoscale device by measuring the $Q$ of its mechanical vibrations.

Energy Harvesting Using an Analog Circuit under Multimodal Vibration

The efficiency of harvesting energy from a vibrating structure using a piezoelectric transducer and a simple analog circuit is investigated experimentally. This analog circuit was originally invented for a synchronized switch damping on inductor (SSDI) technique, which enhances the damping of mechanical vibration. In this study, the circuit is used to implement a synchronized switch harvesting on inductor (SSHI) technique. A multiple degree of freedom (MDOF) structure is excited by single sinusoidal forces at its resonant frequencies and by random forces. The piezoelectric transducer converts this mechanical energy into electrical energy which is harvested using a standard rectifier bridge circuit with and without our analog circuit. Experimental results show that our analog circuit makes it possible to harvest twice as much energy under both single sinusoidal and random vibration excitations.

Forced resonant vibrations and self-heating of a flexible circular plate with piezoactuators

The problem of the forced axisymmetric vibrations and self-heating of a clamped flexible circular plate with piezoelectric actuators is solved. The aspects of mechanical and electric excitation of vibrations and damping of mechanical vibrations with actuators are discussed. The effect of geometrical nonlinearity on the frequency dependence of deflections and self-heating temperature under electromechanical harmonic loading at the principal resonance of bending vibrations of the plate is studied

Velcro-like fasteners based on NiTi micro-hook arrays

A recently developed Velcro-like fastener utilizes superelastic deformation of twointerlocked NiTi hooks when pulled apart. This work focuses on experimentalanalysis (evaluation of normal detachment force at different temperatures) andmodeling (simulation by a finite element implemented SMA model) of theunhooking process. It is claimed that nonlinear superelastic deformation of NiTileads to unique properties of the NiTi hook fasteners such as high strength (∼15 000 kg m − 2), a significant increase of strength with increasing temperature, absorption of impactloads, damping of mechanical vibrations, forceless contact or silent release and betterfunctioning in dirty environments compared to conventional Velcro fasteners.

Development of Mathematical Model of a Mechatronic System

This paper is a continuation of earlier publications of the authors related to the analysis of mechatronic systems including piezoelectric materials used as sensors or actuators for stabilization and damping of mechanical vibration. It was demonstrated that only very accurate mathematical model of the system with the piezoelectric transducers and external electric circuit attached to a mechanical system like a beam or a shaft by a glue layer allows the engineers to design the system with required dynamic parameters. Geometrical and material parameters of all the components have to be taken into account because neglecting the influence of one of them results in erroneous analysis results [1-4]. The paper presents the improved mathematical model of the considered mechatronic system. The assumption of pure shear of the connection layer is rejected during modeling and deformation of the layer is taken into consideration. The purpose of the reported enhancement of the mathematical model of the considered mechatronic system is to improve accuracy of computational results.

Selection of Parameters of External Electric Circuit for Control of Dynamic Flexibility of a Mechatronic System

This paper deals with the analysis of mechatronic systems including piezoelectric materials used as sensors or actuators for stabilization and damping of mechanical vibration. This work presents the analysis of the flexural vibrating one-dimensional mechatronic system – a cantilever beam and the piezoelectric transducer bonded on the beam surface by means of a glue layer. The external RC circuit is connected to the transducer clamps. Dynamic equations of motion of the considered mechatronic system were written down using the discrete-continuous mathematical model, taking into consideration the influence of the connection layer and the external electric circuit. Dynamic flexibility of the mechatronic system was assigned on the basis of the approximate Galerkin method.

Damping of Mechanical Vibrations Using Piezoelements, Including Influence of Connection Layer’s Properties on the Dynamic Characteristic

The paper presents analysis of flexural vibrating machatronic system. Considered system is compounded of a cantilever bending beam and a strip-like piezoelectric transducer. The transducer is bonded with the beam surface by means of connection layer which has homogeneous properties in whole length. External RC circuit is adjoined to the transducer’s clamps. This mechatronic system is loaded with harmoniousness variable force. Beam’s vibrations affect piezoelectric transducer through the agency of connection layer which generates electric charge and produces additional stiffness. Dynamic equations of considered mechatronic system were determined on the basis of elementary beam and transducer’s section dynamic equilibrium. Transducer’s dynamic equation was assigned using transducer’s piezoelectric properties. Dynamic flexibility of considered mechatronic system was assigned on the basis of approximate Galerkin’s method. Solution of beam’s differential motion’s equation was defined as a product of time and displacement’s eigenfunctions which satisfy defined boundary conditions. Dynamic characteristic of considered mechatronic system, including pure shear of the connection layer was assigned on the end of the beam and illustrated on the chart at the same time taking into account beam and transducer’s geometrical and material parameters.

Vibration Damping Using CCII-Based Inductance Simulators

In this paper, we present an application of second- generation current-conveyor (CCII)-based active inductance simulators to mechanical vibration damping. The oscillation amplitude of a metallic beam, which is near some resonant frequencies, can be reduced by converting mechanical energy into electrical energy through a piezoelectric transducer that is bonded to the beam. An electric circuit, which is made up of the piezoelectric transducer, a resistance, and an inductance, accomplishes the task of dissipating the energy. To this end, the natural frequency of the circuit should be close to the natural frequency of interest of the mechanical system. The high value that is requested for the inductance (thousands of Henrys) can only be achieved through an inductance-simulator circuit. In the literature, the circuit implementations of the inductance simulators are typically based on operational amplifiers, such as the Antoniou circuit. In this paper, we make use of the CCIIs, which allow us to obtain both grounded and floating equivalent inductances that work within a regulated frequency range from three to four decades. The effectiveness of the traditional inductance simulators and CCII-based simulators is discussed, comparing the responses of an experimental mechanical-electrical system, with different circuit implementations, through experimental results. The use of series-resistance compensation, which is obtained through the use of a suitable topology based on the CCIIs, in the implementation of the equivalent inductance, allows one to obtain the best vibration damping, as confirmed by measurements, for all the natural mechanical frequencies of the realized system.

Voltage amplification transfer function analysis of the operational amplifier in the negative capacitance circuits for vibration control with piezoceramics

AbstractPiezo elements due to their ability of converting mechanical energy into electrical energy and vice versa can be found in numerous mechanical vibration damping and absorbing applications. A desired effect may be customized by an external impedance shunt branch connected to the plates of the piezo element. The negative capacitance connected in serial with the passive shunt significantly improves the damping and absorbing performance of such systems. Negative capacitance circuit is built of an impedance converter realized by the operational amplifier. Since the amplifiers are not the ideal elements, the performance of the proposed systems is limited. This is due to the maximum voltages and currents that the operational amplifiers are able to generate. This effect causes instabilities and limits the operational area of the impedance converter. In the paper, the amplification transfer function of the non‐ideal operational amplifier in the negative impedance converter is studied, and the necessary modification with the additional passive elements is proposed. The influence of the certain imperfections in the design, and its improvements are shown on the system consisting of the 1DOF mechanical oscillator, and a shunted piezo element. (© 2008 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)