Moment Diagrams Research Articles

On buckling of compact I-section beams subjected to biaxial bending

This paper aims at providing a new insight into the lateral-torsional buckling behavior of compact I-section steel beams subjected to biaxial bending, without axial force, a subject seldom treated in the literature. This investigation is based on both analytical and numerical results, the latter obtained using a two-node geometrically exact beam finite element developed by one of the authors (Gonçalves, 2019), which has all the required features. Several geometrically non-linear analysis (GNA) types are used to characterize the buckling behavior, namely with geometric imperfections (GNIA), with material non-linearity (GMNA) and combining material non-linearity and imperfections (GMNIA). Different boundary conditions along the two principal planes are allowed and particular attention is paid to cases which involve the same first-order bending moment diagrams but different support schemes. As a consequence, it is shown that the buckling behavior depends not only on the slenderness and the first-order moment diagrams, but also on the supports. On the basis of results obtained concerning the application of the Eurocode 3 provisions for different support conditions, it is shown that unsafe results can be obtained but may be resolved using the recommendations presented in the paper.

Mechanical Behaviour Assessment and Optimization of Construction Sequence for an HSS Vierendeel Truss

Long-span Vierendeel trusses in construction are challenged by smooth force transfer and critical stress control concerns. In this article, construction sequences characterized by loading/unloading due to various assemblies of the branches and/or temporary lattice column supports are focused on to reproduce their related mechanical behaviours in finite element modelling. Typical bending moment and shear force diagrams for hollow structure section (HSS) chords are analysed first, and then combined with a corrected assessment index in the development of an optimized construction scheme through effective discussion. It is observed that the branch assembly sequence has significant but reversed influences on either the bending moments or the shear forces of the interior support and the midspan of the HSS chords. The influence of the branch assembly sequence on the bending moment and shear force are compromised with the introduction of a temporary support. The corrected assessment index superimposed by the internal force and the deflection is demonstrated properly to represent the strength and the serviceability requirements, especially for characterizing the removal of a temporary support after the completed construction of a twelve-panel Vierendeel truss for the roof of an assembly hall.

Application of Artificial Intelligence Technology for Prompt Diagnosis of Cast Iron Mechanical Properties

Kinetic indentation is widely used to measure physical and mechanical properties of materials as one of the most universal methods for non-destructive testing. This paper uses the latest advances in artificial intelligence and capabilities of the Python programming language libraries allowing to carry out accurate measurements of cast iron hardness based on the data of the material’s micro-impact loading diagram. It has been shown that use of machine learning allows eliminating gross errors and reducing the error of indirect hardness evaluation in several times – down to 10 units according to Brinell HB. It has also been established that formation of additional features for training models (based on traditionally used characteristics: penetration depths, indenter movement speed and contact forces at certain points in time) has a positive effect on the accuracy of measurements, but amount of measurements should also be optimized. Feasibility of effective use of machine learning to evaluate hardness has been demonstrated by comparing of calculated hardness values with data obtained with standard testing methods. Advantage of the developed testing method is the fact that the developed algorithms can be used for prompt diagnostics of cast iron hardness using existing equipment. It is appropriate to extend the proposed approach for determination of other mechanical properties of cast iron: yield strength, strain hardening index, creep, relaxation, determined by indentation methods.

Determination of Load Forces on the Upper Part of Orthopedic and Postoperative Shoes

Determined patterns of force load on the sole and upper of orthopedic and postoperative shoes when bending the foot while walking. To determine the force of the load on the top of the postoperative orthopedic shoes, the frictional forces between the lateral surfaces of the shoes and the outer lateral sides of the foot can be neglected. Thus, the task will be reduced to the compilation of equilibrium equations of a plane system of forces. As can be seen from the load diagram of the top of the shoe, we have a flat arbitrarily located system of forces. To determine the unknown forces, it is necessary to compile a system of two equilibrium equations, which will represent the algebraic sums of the projections of all forces on the horizontal and vertical axes. To automate the design process of orthopedic and postoperative shoes, a computer program was developed that allows you to perform calculations of the corresponding forces and tension depending on the design and types of material of individual elements, as well as obtain regression equations for determining the effect of tension on the magnitude of the detachment force.

Numerical study of the influence of the parameters of statistical distribution of the structural elements’ ultimate strength on deformable bodies’ fracture processes

This work is dedicated to the numerical study of the influence of the parameters of statistical distribution of the structural elements’ ultimate strength on fracture processes of deformable bodies with stress concentrators. The loading diagrams, the macro level behavior and the damaging process kinetics have been studied using various probability distribution laws and their standard deviations. The main types of the damage accumulation process have been identified. The approach basing on the analysis of the solutions of the boundary value problems within the elasticity theory has been proposed in order to predict the fracture process kinetics, the corresponding parameters have been introduced. Advantages, limitations and potential practical use of the proposed methodology have been discussed. It has been concluded that the statistical distribution of the structural elements’ strength properties should be taken into account in the numerical modeling of the fracture processes to ensure the reliability and safety of critical structures.

Justifying and Implementing Concept of Object-Oriented Observers of Thermal State of Rolling Mill Motors

Implementing the IIoT concept in industry involves the development and implementation of online systems monitoring the technical state of electromechanical equipment. This is achieved through the use of digital twins and digital shadows (object state observers). The tasks of mastering new rolling profiles and optimizing plate mill rolling programs require improved methods for calculating equivalent motor currents and torques. Known methods are generally based on calculations using smoothed load diagrams, which are assumed to be identical for the upper and lower main drive (UMD and LMD) rolls. These methods do not consider the differences in actual loads (currents or torques) in steady rolling states. Experiments performed on the 5000 plate mill have shown that due to speed mismatches, the UMD and LMD torques differ three times or more. This causes overheating of the more heavily loaded motor, insulation life reduction, and premature failure. Therefore, the problem of developing and implementing techniques for monitoring the load and thermal regimes of motors using digital observers is relevant. The paper’s contribution is the first justification of the concept of object-oriented digital shadows. They are developed for specific classes of industrial units using open-source software. This research justifies a methodology for assessing motor load and temperature by processing arrays of motor currents or torques generated during rolling. An equivalent load observer and a temperature observer were proposed and implemented using Matlab-Simulink resources. The algorithm was implemented on the mill 5000 and tuned using an earlier-developed virtual commissioning methodology with digital twins. Thermal regimes were studied, proving that torque alignment ensures equal motor temperatures. The proposed considerations contribute to the development of the theory and practice for creating digital systems to monitor the technical condition of electromechanical and mechatronic systems and implementing the Industry 4.0 concept at industrial enterprises.

A novel method to determine the critical buckling load for plates from load versus in-plane displacement diagram

Based on the literature, the load vs. in-plane displacement diagram (P-u curve) is not sufficiently indicative to provide a reliable determination of the critical buckling load, Pcr. This attitude is rooted in three issues. First, the P-u curve often exhibits very gradual slope changes, second, it concerns unavoidable graph fluctuations caused by imperfections in specimens or boundary conditions, and third, the P-u curve behavior during the buckling phenomenon is not fully understood. In the present work, a narrative review is conducted to gain a better understanding of the location of Pcr on the P-u curve. Accordingly, a novel method is introduced to correctly extract Pcr from the load vs. in-plane displacement diagram as the most accessible buckling test output, compared to out-of-plane displacement and strain monitoring data, which require additional equipment. The proposed method is highly sensitive to changes in the slope of the graph while significantly reducing the adverse effects of undesired fluctuations. This method is applied to several experimental buckling data for composite laminates as well as sandwich panels, and its reliability and accuracy are confirmed by comparison with other well-known methods.

Power consumption profiles of the main fans at coal mines

Purpose. To determine the main indicators of the power consumption profiles of the main ventilation fans of coal mines under the condition of regulating their performance using controlled electric drive systems based on semiconductor elements. The methods. The methods of operations research were used to analyse technological processes in terms of compliance of the actual power consumption profiles of the main fans with their expected operating modes. The methods of mathematical statistics were used to determine the statistical parameters of the electrical loading diagrams of the main ventilation fans of coal mines. Findings. A statistical analysis of typical power consumption profiles of the main fans of coal mines with different electric drive systems has been carried out: a synchronous motor with a high-voltage frequency converter, an induction motor based on the asynchronous-thyristor cascade system, and a synchronous motor with ‘classical’ rotor excitation control without semiconductor elements. The feasibility of using adjustable electric drive systems to control the performance of main ventilation fans in terms of reducing active power consumption has been confirmed. However, at the same time, the consumption of a significant amount of reactive power is shown, which is inherent for systems based on semiconductor elements, regardless of the motor type (synchronous or asynchronous). Originality. The statistical analysis of the actual daily power consumption profiles of the main fans of coal mines with different controlled electric drive systems has shown that the standard deviation of the active load does not exceed 1% of the rated power of the drive motor and does not depend on its type (synchronous or asynchronous). Practical implementation. The practical value of the work is in determining the actual consumption of reactive power by the systems of controlled electric drive based on semiconductor elements. It shows its significant level, which should be provided by appropriate filter-compensating devices on the power supply buses of the motors of the main ventilation fans.

Design and Analysis of General Hospital Building Using STAAD Pro

Abstract: Structural design is the primary aspect of the civil engineering. The foremost basic in structural engineering is the design of simple basic components and members of a building viz., Beams, Columns and Footings. The principal objective of this project is to analyze and design a general hospital using Staad pro. The design involves manual load calculations, analysis and design of the whole structure using STAAD Pro. The design methods used in STAAD-Pro analysis are Limit State Design conforming to Indian Standard Code of Practice. Structure considered for analysis and design is 21m high hospital building located in the seismic zone III. In this project, we study the effect of various load combinations on the structure by analysing the bending moment diagrams in post processing mode. The project involves detailed drawings of column layout, column detailing and beam detailing

Vibration Analysis of Uniform Flexible Beams under Large Deformation with Uniformly Continuous Mass Elements Using the Equivalent Pseudolinear System

This paper analyses vibration of uniform flexible simply supported rectangular isotropic beam under large deformation with uniformly distributed mass elements. The method of equivalent pseudolinear systems was employed. The deformation of the beam was assumed to be large and the beam was also assumed to be inextensible. The expressions for elastic and nonlinear bending moments were determined. The numerical values of horizontal displacements of the movable support, and the equivalent lengths at various depth-to-breadth (aspect) ratios were determined. The corresponding equivalent pseudolinear systems for various nonlinear bending moment diagrams at various aspect ratios were determined. Consequently the concentrated loads yielding the equivalent pseudolinear systems were converted to point masses using the gravitational acceleration; and subsequently a unit load system was applied successively and independently at each mass point. The Vereshchagin’s method was applied to determine the displacements for canonical equations of motion. Non-trivial solution of the canonical equations at each aspect ratio was sought for the desired eigenvalues. The first mode frequencies at aspect ratios, β = 1.00 and β = 1.25 are complex eigenvalues. Also the natural frequencies exhibit hard-spring type with aspect ratios; and the fundamental frequencies for all the aspect ratios are at seventh mode. Conclusively, the dynamic stability of the flexible rectangular beam of 0.25m-breadth and 15m-undeformed length is not guaranteed when the aspect ratio is less than or equal to 1.25. It is also concluded that deepness of the flexible rectangular beam loaded with uniformly distributed mass elements influences the vibratory characteristics.

Study of the Dynamics and Strength of the Detachable Module for Long Cargoes under Asymmetric Loading Diagrams

This article highlights the structural features of the detachable module for the transportation of long cargoes. The choice of profiles for the detachable module was based on the resistance moments of its components. The detachable module was considered a rod structure on four supports. To determine the longitudinal loads acting on the detachable module, mathematical modeling of its longitudinal dynamics was carried out, provided they were placed on a flat car during a shunting impact. The accelerations obtained were used for the calculations of the detachable module. This article presents the results of the strength calculation of the detachable module under asymmetric loading diagrams, i.e., the action of longitudinal and lateral forces on the detachable module structure. The results of the calculations show that the maximum stresses in the structure of the detachable module when it receives longitudinal loads are 7.7% lower than the permissible ones, and when it receives lateral loads, they are 5.8% lower. Thus, the strength of the detachable module is maintained under the loading diagrams considered. This study also included a modal analysis of the detachable module structure. The first natural frequency of oscillations is found to be 20 Hz. Thus, the safety of the detachable module movement in terms of frequency analysis is ensured. This research will help to create recommendations for the design of modern modular vehicles and improve the efficiency of the transport industry.

Fracture processes numerical modeling of elastic-brittle bodies with statistically distributed subregions strength values

This work is devoted to the fracture processes numerical modeling of elastic-brittle bodies taking into account the statistical distribution of subregions strength values and stress concentration. The novel formulation of the boundary value problem and its solution algorithm are developed. The loading diagrams obtained in computational simulations, the corresponding growth curves of the destroyed elements relative number and the damaging process kinetics are analyzed. The presence of the postcritical deformation stage at the macro-level is noted. The influence of the strength properties distribution range and the depth of the concentrator on the maximum load value and the damage evolution is determined. The significant influence of the finite elements’ properties distribution on the fracture processes modeling results is concluded.

Using the wavelet transform to process data from experimental studies of the discontinuous plastic deformation effect

Vast number of theoretical and experimental works has been devoted to the study of discontinuous plastic deformation (the Portevin-Le Chatelier effect), which manifests itself for most widely used alloys in certain ranges of both temperatures and strain rates. Due to the statistical nature of this phenomenon, difficulties arise in processing, qualitative analysis and quantitative comparison of test results and calculations. Using of statistical methods for these purposes makes it possible to get only some averaged characteristics of the obtained data (usually - moments of the first and second orders in amplitudes and frequencies). A possible alternative for processing of experimental and theoretical results of this effect research is wavelet analysis using. The results of experimental studies of the Portevin–Le Chatelier effect, realized during the deformation of thin-walled tubular specimens made of aluminum alloy AMg6M at certain strain rates at room temperature are presented. Diagrams of deformation under uniaxial tension, shear, proportional and disproportionate loading of specimens were obtained. The inhomogeneity of strain fields and their rates is shown, illustrating the manifestation of the Portevin – Le Chatelier effect under conditions of complex loading of thin-walled tubular specimens made of AMg6M alloy. A brief overview of existing methods and means of non-destructive testing is presented that make it possible to non-contactly record the spatial heterogeneity of plastic yielding. Some possibilities of using the wavelet transform to process certain types of non-monotonic stress-strain diagrams obtained for the specimens made of the aluminum alloy in question are discussed. Using wavelet analysis, a compact presentation of data from field experiments in the form of amplitude-frequency characteristics was obtained. The scalograms analysis of specimen loading diagrams was carried out.

Assessing the implementation of the plan and the rhythm of production of the crusher based on the dynamics of power consumption

The relevance of this study is driven by the growing interest in developing and implementing effective local development strategies that encompass comprehensive measures for the formation and development of the financial-economic potential of territorial communities. In the context of changing economic realities and contemporary challenges, the EU experience is significant for creating adaptive and innovative development models capable of ensuring local communities' long-term viability and prosperity. The article aims to increase the efficiency of diagnosing the intra-shift hourly arrhythmia of crusher product output, making it possible to manage the rhythm of product output during production quickly. The article discusses the methodology for assessing the implementation of the plan and the rhythm of production of the crusher based on the dynamics of power consumption. Existing methods for assessing the rhythm and implementation of the production plan involve assessing the rhythm and fulfilling the plan over a sufficiently long period (days, months, years) after the end of the production process and calculating the volume of products produced. However, for operational production management, it is necessary to evaluate the rhythm and implementation of the plan in the production process, considering hourly and intra-shift operating modes. To substantiate the method for assessing the implementation of the production plan based on indicators of arrhythmicity of power consumption, proven methods for measuring and economic analysis of the rhythmicity of product production were used. The connection between indicators of arrhythmia in output and in power consumption was established based on the theory of crushing minerals and methods of analysing electrical loads in the power supply theory to industrial enterprises. Operational methods have been developed to determine the rhythm and fulfilment of the production plan for fractional factories by analysing intra-shift hourly diagrams of the electrical load of technological equipment. It is shown that existing methods for assessing production rhythm allow us to conclude only after the release of products. The proposed methods for assessing rhythm allow us to evaluate the process of implementing the plan and the production rhythm during the production process by the time of shipment of the finished product. For the first time, methods have been developed to indirectly assess the rhythm and implementation of the production plan based on the dynamics of the factory's power consumption. The developed methodology for quickly assessing the production rhythm and fulfilling the crusher’s production plan allows us to reduce energy costs for ore crushing and increase the economic efficiency of crushing factories. Keywords: rhythm of production, crushers, energy consumption, enterprise economics, mining and transport complex, energy saving.

Energy Household Forecast with ANN for Demand Response and Demand Side Management

This paper presents a short term load forecasting with artificial neural networks. Despite the great imprevisibility, it is possible to forecast the electricity consumption of a household with some accuracy, similarly to that the electricity utilities can do to an agglomerate of households. Nowadays, in an existing electric grid, it is important to understand and forecast household daily or hourly consumption with a reliable model for electric energy consumption and load profile. Demand response programs required this information to adequate the profile of energy load diagram to generation. In the short term load forecasting model, artificial neural networks were used, with a consumption records database. The results show that the artificial neural networks approach provides a reliable model for forecasting household electric energy consumption and load profile. To do so and using smart devices such as cyber-physical systems monitoring, gathering and computing in real time a database with weekdays and weekend, can improve forecasts results for the next hours, a strong tool for Demand Response and Demand Side Management.

Optimizing production of electric energy from renewable sources by differential evolution

This work deals with a general procedure for optimizing operational diagrams of electric energy production units that use alternative energy sources. The goal of optimization is to supply given load at minimal use of conventional energy sources. In order to perform the optimization, simplified mathematical models of different production units that use alternative energy sources are introduced. These units are based on solar cells, wind turbines, fuel cells and electrolysis. The optimization is performed for given weather forecasting and forecasted load diagram by the Differential Evolution, which is a stochastic search algorithm.

COMPLEX RESISTANCE OF A COMPRESSED-BENT ROD TAKINGINTO ACCOUNT ELASTIC COMPLIANCE OF ITS SUPPORT

This work deals with the urgent problem in the mechanics of a deformable solid: studying factors of the stress-strain state of a single-span statically indeterminate beam with complex boundary conditions that is under conditions of complex resistance (axial compression with plane transverse bending). To solve the problem, both analytical methods (the method of forces in the form of “five” support moments, the method of initial parameters) and the numerical finite difference method with a “linear” grid with density n=8 were used. The necessary resolving equations and matrices are given to take into account changes in the rigidity parameter of the right hinged support and variations in concentrated and uniformly distributed loads, both along the axis of the beam and across it. In the final form, diagrams of deflections, bending moments and shear forces were constructed for specific values of bending rigidity and the degree of elastic compliance of the right hinge-yielding support. Reliability of the theoretical principles and applied results obtained by the authors is confirmed on the basis of the given alternative calculation methods.

ПОСТРОЕНИЕ УПРУГОЙ ЛИНИИ БАЛКИ И ОПРЕДЕЛЕНИЕ ВЕЛИЧИНЫ И НАПРАВЛЕНИЯ ГЛАВНЫХ НАПРЯЖЕНИЙ В СЕЧЕНИИ БАЛКИ

The paper uses the data from diagrams of I-beam transverse forces and bending moments to calculate the values and directions of primary stresses at three points of the beam cross-section – on the neutral axis, above and below it. To calculate the values of primary stresses, the graphic analytical method with the construction of Mohr's circles is used. Further, the article presents an algorithm for constructing a beam deflection line and calculating cross-section deflections. To determine deflections, the universal beam deflection line equation is used. After determining the largest deflection value, conclusion is made that the hardness condition of a steel I-beam is met.

A Framework Study on the Application of AIGC Technology in the Digital Reconstruction of Cultural Heritage

Abstract AIGC is currently a hot field and a future trend in AI applications, and addressing the challenge of digitally reconstructing cultural heritage under the influence of AI technology is a pressing issue that requires immediate resolution. The article proposes an application framework for AIGC technology that is based on refining its meaning and designing a specific process for applying it to the digital reconstruction of cultural heritage. A high-definition camera is used to acquire relevant images of cultural heritage. The image features are extracted by the SIFT algorithm optimized by the PROSAC algorithm. The color features are acquired by combining the color histogram, color moment, and color correlation diagram. The 3D laser scanning technology is used to obtain the 3D point cloud data of the cultural heritage; the KD-tree improved ICP algorithm is introduced to improve the efficiency of point cloud alignment; the dense reconstruction of the 3D point cloud data of the cultural heritage is realized based on CMVS/PMVS; and the immersive 3D experience system of the cultural heritage is constructed by combining with platforms such as Unity3D. The average matching rate of the optimized SITF algorithm to the image features of cultural heritage is about 74.91%, and the maximum alignment time of the ICP algorithm to the cultural heritage point cloud data based on KD-tree is 9.241 s. The cultural heritage immersive 3D experience system has a satisfaction rate of 56.75%, and the density reconstructed model’s surface has an average deviation of only 0.34 mm from the real surface. The user satisfaction rating for the immersive 3D experience system for cultural heritage is 56.75%. Based on AIGC technology, it can revitalize cultural heritage and achieve digital reconstruction and inheritance innovation of cultural heritage.

A Novel Approach Extracting Extreme Points Combining Multidirection Phase Superposition and Weighted Moment Diagram for Matching Multi-Modal Images

A Novel Approach Extracting Extreme Points Combining Multidirection Phase Superposition and Weighted Moment Diagram for Matching Multi-Modal Images