Transformation Of Mechanical Energy Research Articles

THE CONTENT OF EDUCATIONAL MATERIAL ON MECHANICAL SCIENCE IN THE TRAINING OF FUTURE LABOR AND TECHNOLOGY TEACHERS

The article deals with the solution to the problem of the low level of machine science knowledge of pre-service teachers of labor education and technology. It has been found out that it is based on a contradiction between the real content of mechanical training of students and the content of technological education of schoolchildren. The goal of the article is to reveal the peculiarities of students' knowledge of mechanical engineering, based on the study of the technology of transformation of mechanical energy of rotational movement. The methods of analysis and synthesis of achievements of machine science and scientific achievements of technological education have been used. It has been found that in the work of researchers of mechanical science, as well as researchers of technological education of schoolchildren, there are enough guidelines for a well-founded choice of the subject of study. It is described that it should meet a number of different level requirements, for example to contribute to the formation of the technical outlook of schoolchildren; correspond to the content of technological education of schoolchildren; have a polytechnic character; simultaneously belong to different types of working machines. Technical knowledge about it must be integrated with knowledge of mathematics and physics. It must be used in educational projects of schoolchildren being a model of implementation of natural and scientific knowledge in practice, and suitable for technical construction of schoolchildren. The machine drive as a subject of the study meets all the specified requirements. It has been revealed that the subject of study for the formation of students' general idea about machines should provide a large amount of knowledge about the types of working machines and at the same time a moderate content. It has been established that such contradictory requirements are met by the drive of the machine as a subject of study. It is described that the concept of drive has the property of fractality as far as it enables a free transition from the study of the drive of any mechanism to the study of the drive of any working machines. It is described that the condition for choosing the content of educational material for the formation of students' general idea about machines is the use of the mental operation of abstraction and the corresponding transition from the level of description of the morphology and functions of technical objects to the level of energy conversion technology. It has been substantiated that the didactic value of the basic technical phenomena of the machine drive is the transmission of mechanical motion to a distance, the change of the kinematic parameters of the mechanical motion and the change of the power parameters of the mechanical motion. There has been revealed the importance of the results of this study for the disclosure of approaches to the use of the project method, as well as the use of technical construction for the visual presentation of the basic technical phenomena

Influence of the number of carded non-woven layers on mechanical and acoustic performance

Acoustic absorption consists basically of the transformation of mechanical energy into thermal energy, carried out through the interaction of the fibers with the sound wave through the breaking of such waves and their meeting with the surface of the fibers. Among the various materials that may be employed to this end, the use of non-woven fabrics has stood out. This study aimed to evaluate the influence of the number of carded non-woven web layers on the mechanical and sound absorption capacity. For this purpose, three groups of non-woven fabrics were produced with different numbers of web layers (24, 40, and 58 layers) of equal thickness and density, composed of a mixture of polyester fibers. Standard test procedures were used to measure the physical properties of the non-woven fabrics, the linear density of the fibers used as raw material, the tensile strength, and air permeability and to assess the sound absorption capacity. In addition, to identify a balance point between sound absorption and equipment productivity, the relationship between the acoustic performance of the non-woven fabrics produced and their production speed was evaluated. The greater the number of web layers is, the higher the absorption coefficient of the non-woven. However, the variation was not significant when the various sound absorption frequencies were observed. In this regard, developing a non-woven fabric with fewer layers was more productive and cost-effective without losing technical performance.

THE CONTENT OF EDUCATIONAL MATERIAL ON MECHANICAL SCIENCE IN THE TRAINING OF FUTURE LABOR AND TECHNOLOGY TEACHERS

The article deals with the solution to the problem of the low level of machine science knowledge of pre-service teachers of labor education and technology. It has been found out that it is based on a contradiction between the real content of mechanical training of students and the content of technological education of schoolchildren. The goal of the article is to reveal the peculiarities of students' knowledge of mechanical engineering, based on the study of the technology of transformation of mechanical energy of rotational movement. The methods of analysis and synthesis of achievements of machine science and scientific achievements of technological education have been used. It has been found that in the work of researchers of mechanical science, as well as researchers of technological education of schoolchildren, there are enough guidelines for a well-founded choice of the subject of study. It is described that it should meet a number of different level requirements, for example to contribute to the formation of the technical outlook of schoolchildren; correspond to the content of technological education of schoolchildren; have a polytechnic character; simultaneously belong to different types of working machines. Technical knowledge about it must be integrated with knowledge of mathematics and physics. It must be used in educational projects of schoolchildren being a model of implementation of natural and scientific knowledge in practice, and suitable for technical construction of schoolchildren. The machine drive as a subject of the study meets all the specified requirements. It has been revealed that the subject of study for the formation of students' general idea about machines should provide a large amount of knowledge about the types of working machines and at the same time a moderate content. It has been established that such contradictory requirements are met by the drive of the machine as a subject of study. It is described that the concept of drive has the property of fractality as far as it enables a free transition from the study of the drive of any mechanism to the study of the drive of any working machines. It is described that the condition for choosing the content of educational material for the formation of students' general idea about machines is the use of the mental operation of abstraction and the corresponding transition from the level of description of the morphology and functions of technical objects to the level of energy conversion technology. It has been substantiated that the didactic value of the basic technical phenomena of the machine drive is the transmission of mechanical motion to a distance, the change of the kinematic parameters of the mechanical motion and the change of the power parameters of the mechanical motion. There has been revealed the importance of the results of this study for the disclosure of approaches to the use of the project method, as well as the use of technical construction for the visual presentation of the basic technical phenomena

МЕХАНИЧЕСКИЙ ГЕНЕРАТОР ВЫСОКОНАПРАВЛЕННОЙ ПЕРИОДИЧЕСКОЙ СИЛЫ

The article concerns theoretical basics for generation of highly-directed mechanical oscillations based on the principle of inertial force transformation. The problem of formulation and analysis of the general principle of transformation of mechanical energy in order to generate periodic force directed preferably along chosen axis is considered also from dynamic and kinematic points. As an example of application for described principle the paper represents generator of highly directed periodic force. Detailed kinematic and dynamic analysis of the device is presented in the article. Perspectives of possible device’ technological application are also discussed.

Using the energy of the amortization system in the organization of the movement of an electric vehicle

Problem. One of the areas of developing energy saving when using machines and mechanisms is the recovery of used energy for the purpose of reuse. At the same time, potential energy accumulated by massive mechanisms or kinetic energy of moving machine elements is used. Goal. The purpose of the work is to reveal the main advantages and principle of operation of the pneumatic damping system for energy recovery and generation. Methodology. The methodological basis of the work is the analysis, comparison and generalization of existing scientific research and inventions. The ever-increasing interest of domestic and foreign researchers in the direction of energy saving in road transport, the steady expansion of the list of inventions related to energy saving, such as the conversion of mechanical vibrations into electrical, thermal, hydraulic and other types of energy with subsequent accumulation and useful use, were noted. Results. When the car is moving, as a result of the deformation of the suspension springs, there are transverse and longitudinal vibrations of the frame or body, which are damped by shock absorbers. The most widely used are hydraulic and gas shock absorbers, which use the resistance of a viscous liquid or gas when passing through calibrated holes or limited valve diameters. The very process of dampening oscillations is reduced to the transformation of mechanical energy into thermal energy with subsequent removal of heat to the environment. Originality. As part of energy saving, the authors of the work propose to accumulate the energy of oscillating movements in the form of pneumatic energy of compressed air with the possibility of further use in various systems of automobile transport. They also show the effectiveness and expediency of introducing similar measures, especially in hybrid schemes of cars in which the transformation of thermal and electrical energy takes place at the same time, point out the problems that arise when introducing energy accumulation in the form of compressed air, and propose measures to overcome negative phenomena that characteristic of this process. Practical value. The results of the study indicate the perspective and expediency of implementing new schemes in the direction of increasing the efficiency of newly created recuperation systems in car suspensions, expand the list of methods of providing energy-efficient technologies to increase reliability and durability depending on operating conditions.

Computational study of temperature and density perturbations on atmospheric dynamics

This study examines the perturbation effect of temperature and density of moist air on atmospheric variables at 9°1’48″N, 38°44’24″E and 6.324 km above the Earth’s surface. The atmosphere is a compressible neutral moist air flowing on a rotating Earth as a model and it’s basic atmospheric parameters such as gas constant, transport coefficients, mixing ratio and specific heat capacities are considered to be temperature dependent and the Earth’s gravity changes with latitude and altitude. To describe the dynamics, we carried out a numerical computation using finite difference method on an unstaggered grid. Our results revealed that the response of all the variables have a plane wave pattern, in which specific heat capacities (SHCs), resultant wind speed (RWS) and water vapor mixing ratio (MR) increase with time at each latitude but vertical wind speed (VWS), specific enthalpy (SE) and pressure decrease with time at each latitude. The increase of MR with time is the result of water vapor flux into the air parcel and the decrease of SE and increase of RWS with time is the result of thermal energy to mechanical energy transformation. The decrease of VWS with time is the effect of the viscous force due to temperature dependence of viscosity.

Enhancement of Piezoelectric Properties of Flexible Nanofibrous Membranes by Hierarchical Structures and Nanoparticles.

Piezoelectric nanogenerators (PENGs) show superiority in self-powered energy converters and wearable electronics. However, the low power output and ineffective transformation of mechanical energy into electric energy l limit the role of PENGs in energy conversion and storage devices, especially in fiber-based wearable electronics. Here, a PAN-PVDF/ZnO PENG with a hierarchical structure was designed through electrospinning and a hydrothermal reaction. Compared with other polymer nanofibers, the PAN-PVDF/ZnO nanocomposites not only showed two distinctive diameter distributions of uniform nanofibers, but also the complete coverage and embedment of ZnO nanorods, which brought about major improvements in both mechanical and piezoelectric properties. Additionally, a simple but effective method to integrate the inorganic nanoparticles into different polymers and regulate the hierarchical structure by altering the types of polymers, concentrations of spinning solutions, and growth conditions of nanoparticles is presented. Further, the designed P-PVDF/ZnO PENG was demonstrated as an energy generator to successfully power nine commercial LEDs. Thus, this approach reveals the critical role of hierarchical structures and processing technology in the development of high-performance piezoelectric nanomaterials.

Nanogenerators integrated self-powered multi-functional wings for biomimetic micro flying robots

Under rigorous weight and power constraints, improving the energy systems and the onboard sensing approaches for flapping-wing micro air vehicles (FWMAVs) are monumental challenges. Mechanical energy transformation and integrated self-powered sensing hold great promising features to improve the flying performance of FWMAVs. Herein, we introduce novel triboelectric nanogenerators (TENGs) integrated multi-functional wings to address these challenges. Synthetically, The TENGs integrated wings can realize the mechanical energy transformation, the motion monitoring of flapping wings, and the pneumatic functions for FWMAVs. Firstly, a lightweight and ultra-thin sandwich structure integration technique with silk-fibroin film as the coated friction layer is realized for the TENGs integrated wings. Secondly, the wind tunnel test verifies the feasibility of the mechanical transformation and reveals the effects of the operating conditions of the FWMAVs on the triboelectric energy performance. The triboelectric energy performance of the TENGs integrated wings, whose entire thickness and the weight increases are less than 20 µm and 0.2 g respectively is verified to achieve 468.7 V voltage, 100.6 μA current, and 379.8 μW power. Likewise, as an attractive potential application, it is demonstrated to provide an accurate self-powered measurement of the flapping mechanism frequency based on the triboelectric principle. The aerodynamic measurements verify that the TENGs integrated wings maintain the pneumatic functions, which guarantee flight stability, and they positively enhance 29.89% of the onboard load of the FWMAV.

On the correlation of temperature harmonic content with energy dissipation in C45 steel samples under fatigue loading

Fatigue damage onset involves a transformation of mechanical energy. This is in part spent into work of plastic deformation and fracture and in part transformed into heat. Therefore, different thermomechanical heat sources are activated during a fatigue loading cycle, resulting in a temperature modulation that can be characterized by its frequency content. Several studies have monitored the temperature on samples undergoing high-cycle fatigue, measuring specific thermomechanical metrics which could serve as indicators of damage evolution. The present work evaluates the harmonic content of temperature, to investigate its correlation with the material dissipation. The harmonic terms investigated are the amplitude and phase of temperature at the loading frequency (First Harmonic) and at twice the loading frequency (Second Harmonic). The paper reviews the mechanisms linking the evolution of heat dissipation to changes in these four parameters. The theoretical analysis is supported by an experimental campaign carried out on C45 steel tensile specimen subject to R=−1 and R=0.1 loading ratios. The harmonic metrics are evaluated analyzing both their spatially averaged value and their spatial dispersion, to check for the formation of localized heat dissipation zones in early fatigue life. The study shows that the phase of the Second Harmonic signal has a peculiar bimodal distribution that can be correlated to either a thermoelastic or dissipative prevailing effect. This behavior evolves towards a unimodal dissipative behavior when the load amplitude is increased, thus proposing the Second Harmonic phase parameter as an effective indicator for monitoring internal intrinsic dissipation in the material.

Energy analysis of transfer processes and their main characteristics in thermo mechanical damping systems

The article discusses the energy analysis of transfer processes in the damping system. The basic theoretical foundations based on the equations of the energy balance of the hydraulic shock absorber and the law of conservation of energy are presented. The proposed approach is associated with the development of a methodology and scheme for calculating the technical system of vibration damping. The schemes of interaction of the system through the phenomena of transfer and functioning of the vibration protection system with the environment are presented. It is shown that damper systems are based on the physical process of transformation of mechanical energy into thermal energy with subsequent dissipation into the environment. The total energy distribution in damping problems takes the following form the mechanical energy of motion is absorbed due to the hydraulic resistance of the liquid and turns into a dissipative component, which can reach 80% of the total energy. A mathematical model of the law of conservation of energy is presented which includes a dissipative function. The analysis of how it is possible to design work processes in a shock absorber due to energy dissipation and similarity criteria: Euler, Froude, Reynolds, etc. As a result of physical experiments, it was found that the movement of a fluid in hydraulic calibrated throttles gives rise to cavitation and various physical phenomena and accompanying processes, in which there is a significant change in the energy balance and energy dissipation in non-stationary modes of fluid movement.
 The dependence of the total power loss of the shock absorber under changing operating conditions, and the diagram of physical processes and energy transformations in the problems of damping, which are in dissipative processes, are given. The article describes the principles that can be used for the design of devices and modules of damper systems of a wide class with the possibility of energy recovery and accumulation by introducing a damper into the system, for example, a motor generator, an inductor with permanent magnets or a peso element in the design of a traditional telescopic shock absorber.

Atomistic mechanisms for frictional energy dissipation during continuous sliding

After more than a century of detailed investigations into sliding friction, we have not arrived yet at a basic understanding of energy dissipation, even for the simple geometry of a rigid slider moving over a perfectly periodic counter surface. In this article, we use a first-principles-based analysis to establish the atomistic mechanisms of frictional energy dissipation for a rigid object that moves continuously in the periodic surface potential landscape of a solid with vibrational degrees of freedom. We identify two mechanisms that can be viewed as (i) the continuous pumping of energy into the resonant modes, if these exist, and (ii) the destructive interference of the force contributions introduced by all excited phonon modes. These mechanisms act already in a purely dynamic system that includes independent, non-interacting phonon modes, and they manifest irreversibility as a kind of “dynamical stochastization”. In contrast to wide-spread views, we show that the transformation of mechanical energy into heat, that always takes place in real systems due to the coupling between phonon modes, can play only a minor role in the appearance of friction, if any. This insight into the microscopic mechanisms of energy dissipation opens a new, direct way towards true control over friction.

Generation and Capture of Electric Energy Using Piezoelectric Materials: A Review

Piezoelectricity comes as a principle of transformation of mechanical energy into electrical energy, it is limited in terms of investment, time and research, due to this fact, the need arises to be able to innovate with data collection on the most used models to collect and generate electrical energy. In this research, the literature regarding the generation and collection of electrical energy using piezoelectric materials was analyzed, from this analysis, fifty innovative articles were determined in the last three years, which were reflected in a data matrix, in which It presents the generation and collection element, the applications, and shows the performance in terms of power or voltage that the prototypes supply. With the results of the table, a condensed panorama of current data is obtained, about the most used and outstanding of this form of little-used energy, but which is a competent and efficient alternative for the generation of electricity.

Wake structure and mechanical energy transformation induced by a horizontal axis tidal stream turbine

The horizontal axis turbine is one of the most promising energy extractors for tidal stream energy utilization. However, there is no widely accepted model for describing the wake structure of a tidal stream turbine. Besides, the flow velocity variation in wakes is accompanied by energy transformation and has hardly been investigated to date. In this paper, a brief review of existing laboratory tidal stream turbine experiments is first presented, followed by a discussion about the controlling variables that includes cross-comparisons between different results from physical laboratory tests. Theoretical derivation and experimental data analysis are conducted to enable a better understanding of the energy transformation and wake development processes, and tidal stream energy extraction. It has been found that part of the flow kinetic energy has been converted into potential energy before reaching the rotor, commonly used power coefficients are not equivalent when quantifying energy extraction, and it is possible to reconstruct turbine wakes using 3 independent data-based parameters.

Energy Analysis of the Propulsion Shaft Fatigue Process in a Rotating Mechanical System Part II Identification Studies – Developing the Fatigue Durability Model of a Drive Shaft

Abstract The article presents a continuation of research carried out concerning identification of energy consequences of mechanical fatigue within a propeller shaft in a rotating mechanical system, while working under conditions of the loss of the required alignment of shaft lines. Experimental research was carried out on a physical model reflecting a full-sized real object: i.e., the propulsion system of the ship. It is proven, by means of an active experiment, that changes in propeller shaft deflection are reflected in the amount of dissipated kinetic energy of masses in rotational motion and the accumulated internal energy in its construction material. Adoption of a high-cycle fatigue syndrome, consisting of diagnostic symptoms determined from the action of the propeller shaft associated with the transformation of mechanical energy into work and heat, as well as with the generation of mechanical vibrations and elastic waves of acoustic emission, is proposed. To assess the diagnostic information quantity brought about by the defined features of propeller shaft fatigue, an experimental research program was developed and implemented, in which two statistical hypotheses are verified: the significance of the impact of the values enforcing the fatigue process, presented in the first part of the article, and the adequacy of the regression equation describing the fatigue durability of the propeller shaft in the energy aspect, constituting the second part of the article. This finally gives us the opportunity, after the appropriate translation of the model test results into full-sized real objects, to develop a methodology to diagnose marine propeller shaft fatigue in operating conditions. The third part of the article is devoted to this issue

Granular metamaterials for seismic protection. Hyperelastic and hypoelastic models

The hyperelastic potentials along with hypoelastic models applicable to describe dynamic behaviour of the granular metamaterials at wave propagation in their structure under seismic activity are studied. The specially constructed potentials suitable for bimodular materials are analysed. Effects of possible mechanical energy transformation due to formation and propagation of the shock wave fronts are discussed.

EXPERIMENTAL METHOD OF JOULE’S EXPERIMENT IN PHYSICS FOR SECONDARY SCHOOL

Energy remains a problematic topic in the pedagogic sphere. One main issue in high-school teaching is the lack of practical examples. Such demonstrations are the most effective way of imparting knowledge. This article discusses a new modern version of the Joule’s experiment as a practical demonstration for Physics classes. It models the specific thermal capacity and the transformation of mechanical energy into heat energy. As such, it represents an approach for teaching thermodynamics. The goal of this research is to verify the functionality of the new apparatus and its optimization for use in practical experiments during high-school classes. One main acquisition is the application of the Joule’s experiment in teaching Physics within a lesson and to provide a methodical procedure on how to operate the experiment in a school. This practical example may help teachers incorporate other experiments and use inquiry-based science education in their teaching programs.

Bioinspired Electrically Activated Soft Bistable Actuators

AbstractMovement and morphing in biological systems provide insights into the materials and mechanisms that may enable the development of advanced engineering structures. The nastic motion of plants in response to environmental stimuli, e.g., the rapid closure of the Venus flytrap's leaves, utilizes snap‐through instabilities originating from anisotropic deformation of plant tissues. In contrast, ballistic tongue projection of chameleon is attributed to direct mechanical energy transformation by stretching elastic tissues in advance of rapid projection to achieve higher speed and power output. Here, a bioinspired trilayered bistable all‐polymer laminate containing dielectric elastomers (DEs) is reported, which double as both structural and active materials. It is demonstrated that the prestress and laminating strategy induces tunable bistability, while the electromechanical response of the DE film enables reversible shape transition and morphing. Electrical actuation of bistable structures obviates the need for continuous application of electric field to sustain their transformed state. The experimental results are qualitatively consistent with our theoretical analyses of prestrain‐dependent shape and bistability.

A Study of Significant Factors Affecting Viscoelastic Damping Properties of Polymer Materials

Viscoelastic behaviour of materials is connected with transformation of mechanical energy into heat, which is a measure of a material structural damping. Viscoelastic properties of materials are described by different quantities, e.g. by loss modulus, storage modulus and loss factor. They depend on material type, its structure, excitation frequency, temperature, relative humidity etc. Damping properties were experimentally measured by means of the forced oscillation method. The purpose of the paper was to investigate viscoelastic damping properties of different polymer materials like PE, PP, ABS or rubber. There were studied different factors that have an influence on viscoelastic damping properties of the investigated polymer materials under dynamic loading, mainly the effect of operating temperature, excitation frequency, sample deformation and rubber composition.

Thermo-visco-elasticity for Norton–Hoff-type models with homogeneous thermal expansion

In this work we study a quasi-static evolution of thermo-visco-elastic model with homogeneous thermal expansion. We assume that material is subject to two kinds of mechanical deformations: elastic and inelastic. Inelastic deformation is related to a hardening rule of Norton–Hoff-type. Appearance of inelastic deformation causes transformation of mechanical energy into thermal one, hence we also take into the consideration changes of material’s temperature.The novelty of this paper is to take into account the thermal expansion of material. We are proposing linearization of the model for homogeneous thermal expansion, which preserves symmetry of system and therefore total energy is conserved. Linearization of material’s thermal expansion is performed in definition of Cauchy stress tensor and in heat equation. In previous studies, it was done in different way. Consideration of such linearization leads to system where the coupling between temperature and displacement occurs in two places, i.e. in the constitutive function for the evolution of visco-elastic strain and in the additional term in the heat equation, in comparison to models without thermal expansion. The second coupling was not considered previously. For such system of equations we prove the existence of solutions. Moreover, we obtain existence of displacement’s time derivative, which has not been done previously.

Merkel cells and Meissner's corpuscles in human digital skin display Piezo2 immunoreactivity.

The transformation of mechanical energy into electrical signals is the first step in mechanotransduction in the peripheral sensory nervous system and relies on the presence of mechanically gated ion channels within specialized sensory organs called mechanoreceptors. Piezo2 is a vertebrate stretch-gated ion channel necessary for mechanosensitive channels in mammalian cells. Functionally, it is related to light touch, which has been detected in murine cutaneous Merkel cell-neurite complexes, Meissner-like corpuscles andlanceolate nerve endings. To the best of our knowledge, the occurrence of Piezo2 in human cutaneous mechanoreceptors has never been investigated. Here, we used simple and double immunohistochemistry toinvestigate the occurrence of Piezo2 in human digital glabrous skin. Piezo2 immunoreactivity was detected in approximately 80% of morphologically and immunohistochemically characterized (cytokeratin 20+ , chromogranin A+ and synaptophisin+ ) Merkel cells. Most of them were in close contact with Piezo2- nerve fibre profiles. Moreover, the axon, but not the lamellar cells, of Meissner's corpuscles was also Piezo2+ , but other mechanoreceptors, i.e. Pacinian or Ruffini's corpuscles, were devoid of immunoreactivity. Piezo2 was also observed in non-nervous tissue, especially the basal keratinocytes, endothelial cells and sweat glands. The present results demonstrate the occurrence of Piezo2 in cutaneous sensory nerve formations that functionally work as slowly adapting (Merkel cells) and rapidly adapting (Meissner's corpuscles) low-threshold mechanoreceptors and are related to fine and discriminative touch but not to vibration or hard touch. These data offer additional insight into the molecular basis of mechanosensing in humans.