Mechanical Energy Research Articles

Transient Energy Dissipation Control of Energy Storage Devices in Wind Power Generation Systems

The transient stability of power systems with high penetration of wind power generation can be significantly improved through the utilization of variable virtual inertia if the energy source of rotational inertia can be expanded by energy storage devices (ESDs). This paper first establishes the relationship of energy conversion between ESD and mechanical kinetic energy inside a synchronous generator (SG). Then, the impact of the controllable inertia on system frequency characteristics and power angle oscillation is analyzed using the small-signal model corresponding to this system. Based on the analysis of the change of transient energy at different stages in the transient process, the control of transient energy dissipation is proposed employing ESDs for reliable inertia support. Finally, a typical simulation system with high penetration of wind power generation is carried out to demonstrate the viability of the proposed control scheme. The test results show that the fluctuation of SG’s power angle and system frequency can be reduced by regulating the variable inertia in transient events, significantly improving the reliability of the inertia support provided by the ESDs.

Experimental study on the dynamic mechanical and progressive fracture behavior of multi-jointed rock mass under repetitive impact loading

The failure of rock masses is often controlled by structural planes, and the study on the dynamic mechanical behavior of multi-jointed rock masses under repetitive dynamic loading is still few. A series of repetitive impact tests on multi-jointed gabbro (MJG) are conducted with the split Hopkinson pressure bar (SHPB) testing apparatus. The effects of repetitive impact and joint inclination angles (α) on the dynamic mechanical behavior of MJG from the perspectives of impact number, stress equilibrium, dynamic mechanical properties, energy evolution, and macro and micro failure modes are deeply investigated. The results show that the joint inclination angle affects the impact resistance of the MJG. Under repetitive impact loadings, the mechanical behavior of the MJG is consistent, with tensile wing cracks initiating from the joint tips and propagating along the loading direction until specimen failure. During this process, cracks propagate along the weakest paths, thereby consuming the energy generated by the impact and preventing the activation of other minor defects. The macroscopic failure of the MJG undergoes four stages: the appearance of white patch, crack coalescence, crack penetration, and fracture, with the final failure mode being splitting. The microscopic formation stage of white patch is divided into microcrack activation and microcrack widening.

Silk nanoribbon films with enriched silk II structure and enhanced piezoelectricity for self-powered implantable and wearable devices

Piezoelectric biomaterials are intrinsically suitable to convert mechanical energy to electrical output and achieve electricity generation, in vivo/in vitro real-time monitoring, and sensing in biological systems. However, the inability to fabricate piezoelectric bio-materials with excellent piezoelectricity, full biodegradability, and good biocompatibility remains a challenge toward practical applications. As a solution, we present a bio-piezoelectric thin film with macroscopic piezoelectric output, high stability, fast response ability, flexibility, biocompatibility, and biodegradability based on nascent silk nanoribbons (SNRs) with high silk II-type structure. The solvent systems influence the meso/nanostructure and the piezoelectric performance of silk materials. Compared with other silk materials, the SNR fabricated by 2,2,6,6-tetramethylpiperidine-1-oxyl oxidation system (T-SNR) maintains higher silk II-type structure and more stable crystalline structure. The T-SNR film possesses electrostriction effect without electrical poling treatment. It presents an apparent piezoelectric constant (d33) of 7.7 pm/V and a piezoelectric voltage coefficient (g33) of 0.58 Vm/N, such values are superior to most reported bio-films. The piezoelectric T-SNR film can realize in vivo/in vitro real-time monitoring, sensing, and self-power ability. With its natural compatibility and degradability, the T-SNR film exhibits the potential for various implantable and wearable applications and may enable the development of fully biodegradable transient electromechanical devices.

Exploring slip flow of viscoelastic fluid with frictional heating effects: Uncertainty analysis using response surface methodology (RSM)

Viscoelastic fluid flow along a slippery plate finds applications in different fields such as examining friction and wear characteristics of bearing surfaces using viscoelastic lubricants, extrusion, coating and moulding processes, thin film deposition among others. The present article explores boundary layer flow generated by a slippery stretching plate in a viscoelastic fluid and conducts uncertainty analysis of the governing model via response surface methodology. In addition, the analysis includes viscous dissipation mechanism that represents the conversion of mechanical energy into heat induced by viscosity. The inclusion of the wall slip condition results in a non-linear Robin-type condition for the velocity field. A dependable and user-friendly built-in package “bvp4c” of MATLAB is used to provide the computational results. The solution is used to illustrate the implication wall slip phenomenon on the resisting wall shear. One noteworthy finding is that the inclusion of either the frictional heating effect or the elasticity results in a significant decrease in the surface cooling rate. As the contribution of the heat source term grows, the rate of surface cooling decreases. Strengthening the heat sink effect reverses this result. Contour plots for stream function and isotherms are generated and compared in Newtonian and second grade fluid cases.

Mechanochemical and Microwave Multistep Organic Reactions

Abstract: The development of more sustainable chemical reactions and processes has been the focus of recent research activities. Advances in the field of organic synthesis have led to the emergence of new methodologies and techniques involving non-conventional energy sources. These include the applications of mechanical energy (mechanochemistry) and microwave radiation (MW) methods. This article reviews the advances in multistep organic synthesis of biologically relevant organic molecules using mechanochemistry and microwave techniques. Among them, various heterocyclic molecules (with nitrogen, oxygen, and sulphur atoms), amides, and peptides have been synthesized by multistep mechanochemical or MW reactions. Performing multiple synthetic steps using more sustainable methods shows cumulative advantages over multistep processes under conventional conditions in terms of reduced solvent use, shorter reaction times, better turnovers, and reaction yields. Simplification of protocols by carrying out two or more reaction steps in the same reaction vessel is another advantage of multistep syntheses.

Smart Car Parking System and Generation of Piezoelectric Energy

Abstract: In the past few years, parking has become a costly commodity in virtually every major urban region on the earth, and scarcity is a contributing factor to traffic jam and air pollution in urban areas. The most popular method to obtain a parking place is to do it manually, in which the drivers looks for a parking area either through experience or by luck. This method takes time and effort, and it may result in the worst-possible situation of not finding a parking place if vehicle is in a place with a high vehicle density. An effort is made here to park the vehicle as well as to find a parking space for the vehicle with a framework of Smart Parking System(SPS) which is based on the law of conservation of energy in we basically convert the elements from mechanical energy into electrical energy. This document Allow user to Automatically find a free site for parking at low cost without wasting much fuel and time.

Energy Harvesting System

Abstract: This paper presents a novel energy harvesting system designed to harness ambient mechanical energy using piezoelectric sensors, with the Arduino Uno microcontroller serving as the central processing unit. The system's primary objective is to convert mechanical vibrations into electrical energy, storing it for potential use in powering low-energy electronic devices. The proposed setup incorporates piezoelectric materials strategically positioned to capture mechanical vibrations from various sources. The core of the system is an Arduino Uno microcontroller, programmed to efficiently manage the energy harvesting process. The harvested energy is stored in a rechargeable battery, ensuring a consistent power supply for applications with intermittent energy demands. To validate the effectiveness of the system, a light bulb is employed as a demonstrative load, allowing for real-time observation of the energy harvesting capabilities. The paper details the experimental setup, including the placement and configuration of piezoelectric sensors, the Arduino Uno programming logic, and the integration of a light bulb for visual confirmation of the generated current. Performance metrics such as voltage output, current production, and power generation efficiency are thoroughly analyzed under varying environmental conditions and mechanical vibrations. Results demonstrate the feasibility of the proposed energy harvesting system, showcasing its potential as a sustainable power source for low-power electronic devices. The combination of piezoelectric materials, Arduino Uno control, and a practical load application illustrates a promising approach to energy harvesting, paving the way for advancements in self-sufficient and ecofriendly power solutions

Radiative and mechanical energies in galaxies. I. Contributions of molecular shocks and PDRs in 3C 326 N

Atomic and molecular lines emitted from galaxies are fundamental tracers of the medium responsible for the emission and contain valuable information regarding the energy budget and the strength of the different feedback mechanisms. The goal of this work is to provide a new framework for the interpretation of atomic and molecular lines originating from extragalactic sources and a robust method to deduce the mechanical and radiative energy budget from a set of observations. Atomic and molecular lines detected in a given object are assumed to result from the combination of distributions of shocks and photo-dissociation regions (PDRs) within the observational beam. The emission of individual structures is computed using the Paris-Durham shock code and the Meudon PDR code over a wide range of parameters. The total emission is then calculated assuming probability distribution functions for shocks and PDRs. A distance between the observational dataset and the model is finally defined based on the ratios of the observed to the predicted intensities. As a test case scenario, we consider the radio galaxy 3C 326 N. The dataset is composed of 12 rotational and ro-vibrational lines of and the fine structure lines of C$^+$ and O. Our interpretative framework shows that both shocks and PDRs are required to explain the line fluxes. Surprisingly, viable solutions are obtained at low density only ($ n_H < 100 $), indicating that most of the emission originates from diffuse interstellar matter. The optimal solution, obtained for $ n_H = 10 $, corresponds to a distribution of low-velocity shocks (between $5$ and $20$ km s$^ $) propagating in PDR environments illuminated by a UV radiation field ten times larger than that in the solar neighborhood. This solution implies that at least 4<!PCT!> of the total mass carried by the PDRs is shocked. The 0-0 S(0) $28 CII and OI lines originate from the PDR components, while all the other lines are mostly emitted by shocks. The total solid angles sustained by PDRs and shocks imply that the radiative and mechanical energies reprocessed by these structures are $ L UV L_ odot $ and $ L K L_ odot $, respectively, in remarkable agreement with the values of the IR luminosity deduced from the fit of the spectral energy distribution (SED) of 3C 326 N, and consistent with a small fraction of the active galactic nuclei (AGN) jet kinetic power dissipated in the interstellar medium ($ 1$<!PCT!>). This work shows that the radiative and mechanical energy budget of galaxies can be derived from the sole observations of atomic and molecular lines. It reveals the unexpected importance of the diffuse medium for 3C 326 N, in contrast to previous studies. A last-minute comparison of the model to new JWST data obtained in 3C 326 N shows a striking agreement and demonstrates the ability of the model to make accurate predictions. This framework opens new prospects for the prediction and interpretation of extragalactic observations, in particular in the context of JWST observations.

Charge Redistribution in Mechanochemical Reactions for Solid Interfaces.

Mechanochemical strategies are widely used in various fields, ranging from friction and wear to mechanosynthesis, yet how the mechanical stress activates the chemical reactions at the electronic level is still open. We used first-principles density functional theory to study the rule of the stress-modified electronic states in transmitting mechanical energy to trigger chemical responses for different mechanochemical systems. The electron density redistribution among initial, transition, and final configurations is defined to correlate the energy evolution during reactions. We found that stress-induced changes in electron density redistribution are linearly related to activation energy and reaction energy, indicating the transition from mechanical work to chemical reactivity. The correlation coefficient is defined as the term "interface reactivity coefficient" to evaluate the susceptibility of chemical reactivity to mechanical action for material interfaces. The study may shed light on the electronic mechanism of the mechanochemical reactions behind the fundamental model as well as the mechanochemical phenomena.

Stepless Transmission Optimization for Green Micromobility

Small, electrified vehicles are becoming possible for urban environmental mobility due to their environmental performance, including zero-emission driving. Vehicles of this type use electric motors as sources of mechanical energy. Today, two types of transmission are most used in electrical micromobility vehicles (skateboards, scooters, tricycles, quadricycles, mopeds, motorcycles, go-karts, etc.): chain transmission and belt transmission. This transmission types provides a constant gear ratio that can only compromise between the maximum speed and the starting torque values, thus reducing the usage efficiency of the engine. This reduces vehicle manufacturers’ choice of less powerful drive and control elements, as well as balancing performance and efficiency at low and high speeds as well as on terrain.A novel design of a continuously variable transmission (CVT) for an electric go-kart is presented in this paper. The CVT consists of an inertial driving pulley mounted on an electric motor shaft, a timing V-belt, a gear wheel on the drive axle and 2 pressure rolls, which are moved by a servo motor for tensioning the V-belt. Gear ratio of a transmission can change seamlessly in the range of 1.5 - 2.2. The CVT has been tested under real conditions. The top speed of the electric go-kart with the given CVT and motor power 24.7 kW is 133km/h; time to accelerate to the top speed is 25 s. Total efficiency of the transmission (motor shaft, CVT, drive axle and wheels) is 65-72 % now, but there exist a lot of possibilities to improve it in the future. The conditions under which the novel CVT has an advantage over belt and chain transmissions with constant gear ratios have been studied. The developed mathematical model, the method for determination its constants, the algorithm for numerical calculations and the optimization criterion makes it possible to determine the optimal gear ratio for a vehicle with various CVT (not only belt) at any point in time in different racing modes. The model has been proved experimentally during acceleration and deceleration tests of the go-kart; it describes precisely the motion of the go-kart within the speed measurement error.The developed solution is applicable in urban micromobility. An optimized and stable transmission system focused on energy efficiency, resource saving, using less powerful drive and zero-emission.

Self-Powered Hybrid Motion and Health Sensing System Based on Triboelectric Nanogenerators.

Triboelectric nanogenerator (TENG) represents an effective approach for the conversion of mechanical energy into electrical energy and has been explored to combine multiple technologies in past years. Self-powered sensors are not only free from the constraints of mechanical energy in the environment but also capable of efficiently harvesting ambient energy to sustain continuous operation. In this review, the remarkable development of TENG-based human body sensing achieved in recent years is presented, with a specific focus on human health sensing solutions, such as body motion and physiological signal detection. The movements originating from different parts of the body, such as body, touch, sound, and eyes, are systematically classified, and a thorough review of sensor structures and materials is conducted. Physiological signal sensors are categorized into non-implantable and implantable biomedical sensors for discussion. Suggestions for future applications of TENG-based biomedical sensors are also indicated, highlighting the associated challenges.

Influence of the Heated-Bed Material on PLA Mechanical Properties and Energy Consumption in the FDM Process

Influence of the Heated-Bed Material on PLA Mechanical Properties and Energy Consumption in the FDM Process

Mechanical Characteristics and Energy Evolution of Limestone Under the Action of Acid Corrosion

Mechanical Characteristics and Energy Evolution of Limestone Under the Action of Acid Corrosion

Enhanced performance of hybrid piezo/triboelectric using BaTiO3/polymer composite film modified with rGO

ABSTRACT Hybrid piezo/triboelectric technology is an emerging energy source that can continuously power small electronic devices by harvesting ambient mechanical energy and converting it into electricity. In this work, a high-performance hybrid piezo/triboelectric device was presented. The composite film was synthesized that co-doped BaTiO3 powders (BT) and reduced graphene oxide (rGO) embedded within a host material made of polydimethylsiloxane (PDMS). The hybrid device is made by mixing BT powders into the PDMS to form a series of composite films, ranging from 10% to 45% by wt.%. Additionally, 1–5 wt.% of rGO was loaded into fabricates 40BT/PDMS. The results show that the addition of rGO can improve the uniform dispersion of BT powder in the PDMS matrix. The 4 wt.% of rGO for 40BT/PDMS exhibited the optimal energy harvesting performance among all compositions, achieving notable output voltage and current. This work demonstrates a facile, low-cost approach for obtaining high-performance hybrid piezo/triboelectric by utilizing a composite film BaTiO3 and polymer (PDMS) modified with rGO.

Strength and durability performance of acid-mechanically treated recycled aggregate concrete with metakaolin, lime powder, and A-fine

This study examines the effectiveness of lime powder (LP) and metakaolin (MK) in concrete containing acid-mechanically treated recycled concrete aggregate (RCA). The acid-mechanically produced recycled fine, i.e., A-Fine (AF), is also evaluated as a supplementary cementitious material (SCM). According to the strength activity index (SAI) for AF, it has a low pozzolanic reactivity in comparison to MK and a higher pozzolanic reactivity in comparison to LP. An optimal dosage of AF (15 %), LP (17 %), and MK (22 %) improves the physical properties of recycled aggregate concrete (RAC). The compressive strength of RAC with AF (RAC-AF) is closer to that of RAC with LP (RAC-LP), and RAC with MK (RAC-MK). As a result of their partial or complete chemical inertness, AF, LP, or MK decrease the self-cementing capability of RCA and reduce the mechanical properties and fracture energy of RAC. While the split tensile and flexural strength of RAC-AF is greater than that of RAC-LP, it is smaller than that of RAC-MK. As a result of their higher elastic modulus, RAC-AF and RAC-MK are more ductile than RAC and RAC-LP. As a result of low ion penetration and high electrical resistance, RAC, RAC-AF, RAC-LP, and RAC-MK are classified as low permeability materials. AF or MK as a cement substitute does not alter the sorptivity of RAC despite improvement. In contrast, RAC has higher initial and final absorption when LP substitutes for cement. According to their pozzolanic reactivity and filler effect, RAC sorptivity varies with these SCMs. There is a strong correlation between the compressive strength and UPV of RAC, RAC-AF, RAC-LP, and RAC-MK with R2 = 0.94. The sorptivity and electrical resistivity are also correlated with R2 = 0.94. Due to the formation of Si-rich C-S-H gels, SEM and EDS show a more uniform and denser microstructure in RAC-AF, RAC-LP, and RAC-MK.

Mechanical Properties, Energy Absorption, and Shape Memory Behavior of 3D Printed PLA‐MXene Nanocomposites and Gyroid Lattices

This work investigates the influence of MXene content on the mechanical and functional response of PLA‐MXene composites fabricated additively using fused deposition modeling. The mechanical, thermal, and microstructural properties of the fabricated samples are investigated considering dense and architected triply periodic minimal surfaces (TPMS) gyroid specimens. Overall, the addition of 0.25–0.5 wt% MXene is found to improve the stiffness, fracture strength, and energy absorption capabilities of the PLA. However, further increasing MXene content to 1 wt% becomes detrimental to the general performance of the composite. In terms of functional behavior, the PLA‐MXene blends developed in this work are shown to display a shape memory effect, wherein deformed samples are shown to recover their shape when submerged in hot water. The reported results provide insights into the use of PLA‐MXene in engineering applications, namely those involving impact shielding or energy absorption.

A mechanical manipulated electromechanical coupling design with stretchable electret film: mechanical sensing, energy harvesting, and actuation

Electrical and mechanical energy converts around the nature, and electromechanical coupling effect is applied in various conditions such as mechanical sensing, electrical actuation, and self-powering. During the energy type conversion, electromechanical parameters are among the key issues, such as enlarging the sensitivity and range of mechanical sensing, and energy harvesting efficiency. In this work, a mechanical manipulated approach with stretchable electret is proposed to continuously manipulate the electromechanical parameters. An electromechanical coupling demonstration with pre-stretched electret films and non-contact electrodes are applied, verifying high and regulable electromechanical coupling parameters, and it is advantaged from large deformable and overload permissible capability. This mechanical manipulation approach proposes a new possibility on simplifying the structural and mechanical design of various electromechanical devices, and further enhancing the general applicability with certain geometry and material with ultra-high and tunable electromechanical coupling parameters.

Tuning ZnO-based piezoelectric nanogenerator efficiency through n-ZnO/p-NiO bulk interfacing

ZnO based piezoelectric nanogenerators (PENG) hold immense potential for harvesting ambient vibrational mechanical energy into electrical energy, offering sustainable solutions in the field of self-powered sensors, wearable electronics, human–machine interactions etc. In this study, we have developed flexible ZnO-based PENGs by incorporating ZnO microparticles into PDMS matrix, with ZnO concentration ranging from 5 to 25 wt%. Among these, the PENG containing 15 wt% ZnO exhibited the best performance with an open-circuit output voltage/short-circuit current of ~ 42.4 V/2.4 µA. To further enhance the output performance of PENG, p-type NiO was interfaced with ZnO in a bulk hetero-junction geometry. The concentration of NiO was varied from 5 to 20 wt% with respect to ZnO and incorporated into the PDMS matrix to fabricate the PENGs. The PENG containing 10 wt% NiO exhibits the best performance with an open-circuit output voltage/short-circuit current of ~ 65 V/4.1 µA under loading conditions of 30 N and 4 Hz. The PENG exhibiting the best performance demonstrates a maximum instantaneous output power density ~ 37.9 µW/cm2 across a load resistance of 20 MΩ under loading conditions of 30 N and 4 Hz, with a power density per unit force and Hertz of about ~ 0.32 µW/cm2·N·Hz. The enhanced output performance of the PENG is attributed to the reduction in free electron concentration, which suppresses the internal screening effect of the piezopotential. To assess the practical utility of the optimized PENG, we tested the powering capability by charging various commercial capacitors and used the stored energy to illuminate 10 LEDs and to power a stopwatch displays. This work not only presents a straightforward, cost-effective, and scalable technique for enhancing the output performance of ZnO-based PENGs but also sheds light on its underlying mechanism.

ML Assisted Foot Step Power Generation using Piezoelectric Sensors

In our rapidly evolving world, the escalating demand for energy coupled with the finite nature of traditional resources underscores the imperative for sustainable, pollution-free, and inexhaustible energy solutions. This paper introduces a pioneering approach to harnessing the kinetic energy expended during human locomotion through the innovative use of piezoelectric sensors. Leveraging the piezoelectric effect, these sensors efficiently convert mechanical energy generated by footstep pressure into electrical energy, thereby mitigating wastage and addressing the increasing energy needs. Our model advocates for the deployment of an extensive sensor network along footpaths, complemented by an RFID-based mobile charging system for enhanced convenience and functionality. Moreover, we introduce an innovative method integrating Machine Learning (ML) techniques to enhance power generation efficiency through intelligent modulation of piezoelectric element resistance. Additionally, we leverage ML algorithms to enhance the requisite daily footstep count necessary to fulfill the energy demands of specific areas. This proactive approach ensures optimal deployment of footstep power generation devices based on actual foot traffic patterns. Our research underscores the significance of this technology in the context of urban energy sustainability, particularly in densely populated regions like China and India, where foot traffic is abundant. By harnessing mechanical energy and leveraging advanced ML algorithms, our approach promises to revolutionize energy harvesting paradigms, paving the way for greener and more efficient power generation systems

Smart materials for sustainable energy

In the new era of technologies, different smart or responsive materials are used which can respond to external stimuli, such as a specific amount of mechanical stress, pressure, temperature, pH, or sunlight radiations, by modifying their shape or dimensions or mechanical properties. As global temperatures rise and weather patterns become more erratic and severe. The risk to communities with energy-passive structures is growing, smart materials such as smart rooftops, thermoelectrics, photovoltaics, pyroelectrics, chromoactive, photoluminescent, as well as other innovations, help to conserve renewable energy smartly and sustainably. This review paper reflects on the applications of different smart materials as renewable smart resources. Intelligent quantum dot solar cells, Schottky solar cells, organic thin-film photovoltaic cells, dye-sensitized solar cells (DSSCs), and organic-inorganic heterojunction solar cells have high conversion efficiency, low cost, and possess wide absorption spectra that reach the near-infrared range. Biomechanical energy can be transformed into green energy using triboelectric and piezoelectric-based smart nanogenerators such as zinc oxide nanowires. Shape memory materials such as Nitinol (NiTi) have been embedded in the wind turbine blades to enhance aerodynamic efficiency. Piezoelectric nanogenerators can convert mechanical energy directly into electrical energy by using wireless sensors to harvest energy from moving water in hydroelectric power plants. Thermoelectric materials such as silver antimony telluride (AgSbTe2) offer a sustainable energy option, which employs industrial waste heat to produce power. Smart materials like graphene are more reliable and effective than carbon nanotubes for storing green hydrogen. Smart non-enzymatic biofuel cells are used in biomedical gadgets such as anesthesia machines and pacemakers, which are self-powered and have great sensitivity. Shape memory materials (SMM) are introduced in natural gas and oil reservoirs because they offer exceptional qualities such as the shape memory effect (SME), lightweight, corrosion resistance, and superelasticity, which enhance the performance and robustness of offshore industries. These new advancements, challenges, and applications of smart materials for renewable energy are covered in this review paper.