Different Types Of Loads Research Articles

LOCAL INDENTATION AS METHOD OF REDUCING FATIGUE CRACK GROWTH RATE

The possibility of a significant decrease in the growth rate of a fatigue crack is studied. The goal can be attained by creating a local field of residual stresses near the crack tip which arises due to the indentation of a spherical indenter. A methodology and program algorithm (in ANSYS) have been developed for numerical simulation of the problem in a three-dimensional formulation of the process of fatigue crack growth in the field of residual stresses. Considering the prospects of developing the technique with regard to the use of dynamic indentation, the ANSYS Explicit STR solver fully integrated into the calculation module was used in the macro. Proceeding from the solution of the elastoplastic problem the program provides determination of the fields of residual stresses (RS) at the first stage of the calculation and numerical simulation of the fatigue crack growth on the second stage. The effect of the indentation parameters (magnitude of the force applied to the indenter and the location of the indentation point, conditions of fixing) on the crack growth rate is considered. Methods for a significant reduction in the crack growth rate based on multiple preliminary indentation are substantiated. Using the developed program, we managed to solve a series of problems regarding the effect of different types of loading and fastenings on the growth rate of a fatigue crack in a plate with a through crack. The use of one-sided indentation of thin-walled objects with cracks, which are installed on the support surface, greatly simplifies the practical application of the technique for creating a residual stress field in the vicinity of the crack tip. It is shown that with multiple indentation along the crack propagation line, the fatigue crack growth rate is significantly lower than that when using a single indenter.

Heuristic Optimization of a New Type of Prestressed Arched Truss.

This paper represents new approaches for calculating, designing, and optimizing prestressed arched trusses with a tie member. Structural systems with long spans, such as trusses, beams, frames, etc., are subjected to a considerable/substantial risk of losing load-carrying capacity because of the different types of loads used. Some traditional design methods define the values of prestressing force in the tie member and internal forces in the truss elements to avoid this load capacity loss. However, the accuracy and limits of the determination of the forces are not necessarily known. The authors offer a new type of prestressed arched truss and some new approaches in the design and calculation process to solve these disadvantages. The study's main objectives were to design an innovative and new geometric form of prestressed arched truss, which allows the development of high-value prestressing force, to optimize a new truss for reducing self-weight, increasing load-carrying capacity compared to its analogs. The force, stiffness matrix, and simulated annealing methods were used during the study. A new advance to the optimization of prestressed arched truss suggested by the authors reduces the self-weight and improves the load capacity of the truss by 8-17%, depending on the span.

Optimal fuzzy logic controller based PSO for photovoltaic system

In this study, an off-grid photovoltaic (PV) inverter generates three-phase power to supply the local load and is controlled using an optimized fuzzy logic controller (FLC) using particle swarm optimization (PSO) to control the photovoltaic system’s output. The PSO improves the three-phase inverter’s membership functions (MFs) by using the objective function as mean square error (MSE) for voltage at the output. The best-obtained outcome of the PSO is used to trigger the gate drives of the PWM inverter. The system has been simulated and modeled using MATLAB/Simulink to validate the performance of the proposed method and shows the best control output from the inverter and has been tested in a different types of loads. The motivation for using FLC to control the shape of MFs was about saving time consumed in trial and error. The results present an output of three-phase voltage and current waveform subjected to different loading conditions.

Research on source-load coordinated dispatching of flexible DC distribution network based on big data

In this new round of power network development, the concept of coordinated and optimized operation of power network interconnection and smart grid “source network load” has gradually attracted attention. Based on the analysis of the impact of the flexible DC distribution network on the complex energy system with multiple data sources and large data volume under the big data platform, the coordinated dispatching of the source and load of the big data flexible DC distribution network is studied. Therefore, a source-load matching index that can evaluate the impact of different types of loads on the stability of the flexible DC grid is constructed and incorporated into the load recovery optimization model. First, use the scene reduction method to process all generated scenes; next, take the reduction technology and the scene generation method into account of the uncertainty caused by the prediction error and incorporate them into the multi-objective function optimization model; finally, the membership function of fuzzy numbers is used to model uncertainty. So as to construct a load recovery model that can coordinate the load recovery amount, importance and system dynamic response. The actual meaning of the matching index is explained through model solving and actual case analysis.

3D printing of flexible strain sensor based on MWCNTs/flexible resin composite

The flexible strain sensor is an indispensable part in flexible integrated electronic systems and an important intermediate in external mechanical signal acquisition. The 3D printing technology provides a fast and cheap way to manufacture flexible strain sensors. In this paper, a MWCNTs/flexible resin composite for photocuring 3D printing was prepared using mechanical mixing method. The composite has a low percolation threshold (1.2% ωt). Based on the composite material, a flexible strain sensor with high performance was fabricated using digital light processing technology. The sensor has a GF of 8.98 under strain conditions ranging between 0% and 40% and a high elongation at break (48%). The sensor presents mechanical hysteresis under cyclic loading. With the increase of the strain amplitude, the mechanical hysteresis becomes more obvious. At the same time, the resistance response signal of the sensor shows double peaks during the unloading process, which is caused by the competition of disconnection and reconstruction of conductive network in the composite material. The test results show that the sensor has different response signals to different types of loads. Finally, its practicability is verified by applying it to balloon pressure detection.

A Multi-Objective Fuzzy Optimization Model for Electricity Generation and Consumption Management in a Micro Smart Grid

This manuscript proposes an intelligent supply and demand management system in a complete network of electricity production and consumption. A micro smart grid (MSG), which includes a solar cell, a wind turbine, a diesel generator, and battery storage system capable of trading energy with the smart gride (SG), connected to smart buildings with different types of loads is modelled. Different types of intelligent fuzzy controllers for distributed management were proposed and optimized via the non-dominated sorting genetic algorithm-II (NSGAII), which is a multi-objective optimization method. Maximum user comfort, the amount of renewable energy employment, minimum total power consumption cost, total energy consumption at peak time, and MSG loss of power supply probability are the five objective functions of the optimization process. Various uncertainties of the real world have also been considered. The most crucial distinguishing feature of this proposed method is the design of controllers to manage the demand and supply of electricity without the need for daily optimization. Comparison experiments with other methods presented in the field of electricity supply and demand management are conducted to show the superiority of this method in terms of optimality of the results, low processing volume required to implement real controllers, and its resilience to changing conditions.

Embedded real-time and in-situ fatigue life monitoring sensor with load types identification

Structural fatigue failure has always been a widely concerned research in mechanical equipment. It requires more and more real-time monitoring of structural damage before cracks appear for the intelligent development of modern equipment. Based on embedded technology, a real-time fatigue in-situ fatigue life monitoring sensor (FLMS) is proposed, which has the function of load spectrum identification and linear cumulative damage calculation. The sensor can realize wireless communication through LoRa integration module. After experimental verification, the number of remaining cycles, residual damage and remaining time life can be calculated quickly for different types of loads. The fatigue life prediction error for cycle load is basically within 22%. The maximum and minimum calculation error under random load of the FLMS are 2.27 times and 1.01 times, respectively. And they can be displayed in real time and stored regularly. The integrated sensor can realize the real-time fatigue life prediction of the structure and promote the intelligent development of fatigue life monitoring of the equipment. • This paper proposes a real-time monitoring method for identification of load types based on embedded processor. • The real-time fatigue life monitoring of the FLMS is realized through algorithm integration. • The life error for cycle load is basically within 22%, and it is kept at 2.3 times for random load.

Economic and environmental analysis of coupled PV-energy storage-charging station considering location and scale

The coupled photovoltaic-energy storage-charging station (PV-ES-CS) is an important approach of promoting the transition from fossil energy consumption to low-carbon energy use. However, the integrated charging station is underdeveloped. One of the key reasons for this is that there lacks the evaluation of its economic and environmental benefits. Based on the electricity load of different types of buildings and the data of electric vehicle charging stations in Beijing, this paper analyzes the economic and environmental benefits of integrated charging station developed over different scales by the capacity optimization model. Said benefits are shown to differ considerably with different locations (building types): the construction of the integrated charging station in places where the electricity load is high at night, and where the curve of daytime electricity consumption is consistent with the PV generation curve (e.g., hospitals), shows maximal economic benefits and carbon dioxide emissions reduction. In other (e.g., residential) areas, where power consumption is lower across both day and nighttime hours, the economic benefits and carbon dioxide emissions reduction are lowest. The economic and environmental benefits of the integrated charging station also markedly differ on different scales: with scale expansion, the rate of return on investment and the carbon dioxide emissions reduction first increase and then decrease. A decline in energy storage costs increases the economic benefits of all integrated charging station scales, an increase in EVs increases the economic benefits of small-scale investments, and expansion of the peak-to-valley price difference increases the economic benefits of large-scale investments.

Designing a voltage control system of the magnetoelectric generator with magnetic flux shunting for electric power systems

The object of research in this work is a three-phase magnetoelectric generator with magnetic flux shunting based on industrial induction electric motors. The presence of a magnetic shunt makes it possible to control the voltage of the generator by changing the excitation current in the non-contact electrical winding of the magnetic shunt, which is powered by direct current. Thus, the problem of stabilization of the output voltage of the generator with permanent magnets is solved when the speed of rotation and load change. This paper reports the construction of a three-dimensional field mathematical model of the generator, which allows for electromagnetic calculations of the generator with specified parameters, taking into consideration the influence of final effects, magnetic scattering fields, as well as their radial-axial nature. The results of the calculation of the electromagnetic field are the initial parameters for building a simulation model in the MATLAB-Simulink environment. A simulation model of a magnetoelectric generator with magnetic flux shunting under conditions of changing rotational speed and load has been constructed in the MATLAB-Simulink environment. On the basis of the built models, the performance characteristics of a magnetoelectric generator with magnetic flux shunting were established, which show the limits of control of the output voltage. Adjusting characteristics were determined at zero and rated shunt current for different types of load. The adjusting characteristics of the generator are presented at the rated voltage of the generator for different types of load and with an increase to 150 % of the rated value. The study's results show the high efficiency of the voltage control system of a magnetoelectric generator with a magnetic shunt at different speeds of rotation and load

Experimental study on dynamic response of aluminum film under two spark bubbles coupling loading

The interaction of two or more bubbles with various structures is involved in many engineering problems, a clear understanding of the dynamic response process of the target under different coupling forms of bubbles loading is helpful to give full play to the value of bubbles in engineering application and avoid relevant harm. In the paper, the dynamic response process of aluminum (Al) film under the loading of a single bubble is first studied, and the deformation modes of the Al film under different bubble sizes and loading distances were considered. Then, two spark bubbles with different phase differences and initial distances are generated by a high-voltage power supply that can delay discharge, and different coupling types of two spark bubbles with different parameter combinations are given. Furthermore, the dynamic response process of the Al film with the loading of different types of coupled jets generated by bubble pairs is studied. In addition, the influence of the bubbles’ loading direction is considered. Finally, the center deflection of Al film with the loading of spark bubble pairs with different phase differences and initial distances is statistically analyzed. It is found that the piercing jet with forward loading is the most likely to cause holes in the Al film, while the relatively moving jet has the weakest damage power. The research results of this paper have a certain reference value for some engineering problems such as ship damage and ice breaking.

Prediction of Corrosion-Induced Longitudinal Cracking Time of Concrete Cover Surface of Reinforced Concrete Structures under Load.

Reinforced concrete (RC) structures suffer from different types of loads during service life, and the corrosion characteristics of steel bars embedded in concrete under load are different from those under non-load. In this paper, when the interface between steel bars and concrete (IBSC) cracked and the concrete cover surface (CCS) cracked, the effects of load on the critical corrosion depth of steel bars were analysed based on the thick-walled cylinder model, and a prediction model for the corrosion-induced longitudinal cracking (CLC) time (i.e., initiation cracking time) of the CCS of RC structures under load was proposed. Finally, the influence of load on the CLC time of CCS was discussed on the basis of the proposed prediction model. The results showed that the load had a significant effect on the critical corrosion depth of steel bars when the IBSC cracked induced by corrosion, while the influence of load on the critical corrosion depth of steel bars when the CCS cracked induced by corrosion was not obvious. When the CCS cracks induced by corrosion under load, the influence of the rust-filling layer on the critical corrosion depth of steel bars was larger than that of the load. With the increase in load, the CLC time of CCS decreased. The calculated values of the proposed prediction model were in reasonable agreement with the experimental values, which can provide a reference for durability evaluation and service life prediction of RC structures and lay the foundation for the investigation of the corrosion depth of steel bars in concrete under load.

An event-based flexible load modelling method for optimising residential demand response

With widely deployed electrical heating appliances and electrical vehicles (EVs), community-level demand response will provide great benefits for reducing renewable power generation (RPG) curtailment and flattening demand profile through peak clipping and trough filling, especially through coordinated integration and regulation. It is desirable to characterise real-time power demand of the aggregated system and operating status of targeting appliances simultaneously for effective coordinated control. An event-based aggregated demand modelling method is proposed in this paper to integrate the power demand profiles with status information of electrical appliances, on which advanced analytical approaches could be applied for control design optimisation and system performance evaluation. The concept of event is adopted to characterise thermostatically controlled loads (TCLs) and EVs in a unified way. Thus, same queue-theory based structure with different parameters is used to model different types of loads. Ideally, the parameters identifying the non-homogeneity and periodicity of each load type are estimated from real measurements. However, to overcome the difficulties in obtaining real measurements of TCLs, a physical-statistical data acquisition approach is used. A hypothesis test is conducted to validate that the proposed model can capture the operating status of all electrical appliances.

Ultimate Load of Different Types of Reinforced Self-Compacting Concrete Columns Attacked by Sulphate

In this study, the effects of the partial immersion of sulphate attack on the ultimate load capacity of reinforced self-compacting concrete (SCC) columns and the sulphate attack resistance improvement using silica fume, steel fibres, and the combination of silica fume and steel fibres were assessed. Twelve short circular self-compacting reinforced concrete columns (0.150 m in diameter and 0.7 m long) were cast and divided into groups according to (1) the three acid-attack groups. The first group was tested without an acid attack (control). The second group was tested after 1 month of exposure to 2% acid. The final group was tested after 1 month of exposure to 4% acid and was then (2) subdivided according to the type of casted concrete. The first group was cast with SCC. The second group was cast with SCC and silica fume (0.1% of the cement weight). The third group was cast with SCC and 1% volume fraction steel fibres. The fourth group was cast with SCC silica fume and 1% volume fraction steel fibre. All columns were tested by axial loading. The ultimate load was increased by 42% with silica fume, 190% with steel fibres, and 238% with silica fume and steel fibres. Exposure to 2% and 4% acid reduced the ultimate loads of the columns casted with SCC by 23% and 47%, the columns casted with SCC and silica fume by 34% and 37%, the columns casted with SCC and steel fibres by 69% and 78%, and the columns casted with SCC, silica fume, and steel fibres by 72% and 79%, respectively. Based on the results, using silica fumes improved sulphate resistance, and using steel fibres enhanced sulphate resistance at an acceptable ratio. Furthermore, the mix with silica fume and steel fibres improved sulphate resistance at a good ratio. We encountered several problems in this study. The partial immersion of sulphate affected the strain in both concrete and steel. Future studies using different immersion ratios are recommended. Doi: 10.28991/CEJ-2022-08-10-04 Full Text: PDF

Analysis of Blended Concrete Cubes under Impact loading using ANSYS

Blended concretes, with the partial replacement of the cement with secondary cementitious material like fly ash, rice husk ash, GGBS (Ground Granulated Blast Slag), silica fume etc. are gaining a wide range of applications in civil engineering nowadays. The behaviour of concrete structures has been studied by many researchers under different types of loads like impact load, wind load, earthquake load etc. Impact loading analysis has applications like ship impact resistance design for marine structures, impact-resistant structural design against military and terrorist attacks etc. This study aims to perform a FEM analysis of blended concrete cubes under impact load. Deformation and stress response has been obtained from the velocity impact simulations in ANSYS Explicit dynamics module. Parametric analysis has been done by changing the height of the impactor, shape of the impactor, boundary conditions and partial replacement of cement in the blended concrete with different supplementary cementitious material. It is observed that the strength of the blended concrete cube decreases with an increase in height of the impact.

A NEW ANALYTICAL REPRESENTATION FOR CREEP CURVES OF PLASTICS

In order to have the best prediction of the non-linear viscoelastic behaviour of solid polymers, a new constitutive relationship has been obtained by inserting the stress invariants ( 1 I ) and ( 2 I ) into the formulation of multiple integral representation (MIR). The analytical part for the uniaxial tensile loading, it was found that creep could be separate into three components. First and second components, represent the contributions of the hydrostatic and deviatoric stresses respectively, while the third component represent the contribution of the synergistic effect of the hydrostatic and deviatoric stresses. Also, for the case of pure shear loading it was found that all components of creep are dependent on the deviatoric stress. Thus, new kernels have been obtained which called the hydrostatic, deviatoric and synergistic kernels, in terms of power law. Good agreement has been obtained from the comparisonbetween the experimental of other studies and theoretical results of MIR under different types of loading for PP, PE and PMMA. This comparison proved that MIR gives the prediction with an average error of 0.05%.

Deformation Behavior of Two-Phase Gradient Nanograined Fe95Ni5 Alloys under Different Types of Loading

In this paper, we used molecular dynamics simulations to study the atomic mechanisms of phase transformations, plasticity features, and mechanical properties of two-phase Fe95Ni5 (at. %) samples with a gradient nanograined structure under uniaxial deformation and shear. The simulated samples with a uniform distribution of Ni atoms are composed of fcc grains from 10 to 30 nm in size, which in turn contain bcc interlayers in the form of lamellae of various distribution and size. It was shown that uniaxial loading or shear causes the bcc-fcc phase transformation in the lamellae. In the vast majority of cases, phase transformations are initiated at the junction of lamellae and grain boundaries. Deformation-induced phase transformations in lamellae occur at the front of bands propagating from grain boundaries. Grains larger than ~15 nm can have several bands or regions with differently orientated fcc lattices, whose meeting results in grain fragmentation. It was found that the atomic volume increases abruptly during the bcc-fcc structural phase transformation. The Kurdyumov–Sachs orientation relation is valid between the initial bcc and formed fcc structures. It was shown that the volume fraction and spatial distribution of the bcc phase significantly affect the yield stress of the sample. The yield stress can be increased by forming the bcc phase only in large-grained layers. This behavior is associated with the fragmentation of large grains, and consequently with grain refinement, which, in accordance with the Hall–Petch relation, improves the strength of the material.

An Assumed Strain Finite Element for Composite Plates Analysis

This paper deals with the formulation of a novel four-node quadrilateral finite element based on the first-order shear deformation theory and using the strain-based approach for static and free vibration responses of composite plates. The developed element has five degrees of freedom per node and its displacement functions contain higher-order terms that satisfy the rigid body modes and are based on assumed strains satisfying compatibility equations. The efficiency of the present element is demonstrated by applying it to sandwich and symmetric/antisymmetric laminated composite plates with various shapes, boundary conditions, side-to-thickness ratios, stacking sequences, fiber orientation angles, and different types of loads. The obtained results are compared with published analytical and numerical solutions that have proved excellent accuracy and efficiency in predicting bending and free vibration of laminated composite plates and have shown that this element is free of shear locking.

A Review on Certainty of load monitoring and analysis for Home Energy Systems

One important aspect of energy management is energy monitoring. Consequently, before planning some technical measures to reduce energy use, premises must be monitored for power consumption. Through Load Monitoring (LM), the most recent advancements in appliance energy management is presented in this paper. Various methods of Home Energy Management (HEM) using LM have been analyzed and categorized in an effort to investigate the most recent trend in energy management for researchers in the field. The researchers' various contributions have been highlighted, as have some methods for lowering a building's power consumption to save money and improve the environment. According to the findings of this study, there are problems with load management and monitoring that require attention; issues like the need for a surveillance system capable of that can recognize as many different types of loads as possible and more accurate recognition. Additionally, additional efforts are required to implement LM in appliance energy management. Last but not least, it is necessary to promote a culture of energy management among those who use electricity, whether in businesses, offices, or homes. The study will assist local researchers in gaining a clear understanding of the area's most recent trends.

Lightweight design with displacement constraints using graded porous microstructures

A multi-scale approach of topology optimization is proposed to design lightweight components for given loads and displacement limits. Hexagonal close-packed arrangements of circular/spherical holes allow defining 2D/3D isotropic/transversely isotropic microstructures whose macroscopic elastic properties depend on the radius of the cavities, namely the density of the porous material. An interpolation law is implemented to handle two-material structures with void, distributing both solid and graded material within a certain density range. An Augmented Lagrangian approach is adopted to handle multiple displacement constraints, along with the enforcement of a minimum amount of graded porous microstructure to be used in the optimal design. The proposed method defines: (i) boundaries of the component, and, (ii) possible internal arrangements of circular/spherical holes with graded radius. Also, when boundaries of a hollow component are prescribed, the method can be used to equip it with an optimal infill. Numerical examples are presented, concerning two- and three- dimensional problems, for different types of loads. Features of the proposed procedure are discussed, as well as peculiar properties of the optimal solutions, with special regard to coated structures. Fabrication of the porous layouts by means of additive manufacturing techniques is outlined.

Displacement response estimation of a cable-stayed bridge subjected to various loading conditions with one-dimensional residual convolutional autoencoder method

Displacement is an essential indicator of the functioning and safety of long-span cable-supported bridges under operational conditions. However, displacement estimation is challenging as these bridges are simultaneously subjected to various loading conditions such as temperature, wind, and vehicles. This article investigates an approach for estimating bridge displacement responses under multiple loads using a residual autoencoder model. Monitoring data of a cable-stayed bridge are collected to validate the proposed approach, including comprehensive measurements of the various loads and the displacement responses. Characteristics of temperature, wind, and vehicle loads are taken as the input, and the displacement responses at the mid-span of the main girder and top of the two pylons are taken as the output. The results showed the effectiveness of the proposed approach with an accuracy higher than 95%, which clearly outperformed other models such as long short-term memory networks in accuracy and efficiency. The effects of different types of loads are also investigated, and the wind load is found to be the most influential. Furthermore, multistep ahead prediction is carried out using the proposed approach, and good accuracy is achieved even 5 min ahead. The proposed approach can shed light on early warning of the malfunction of the bridge.