Pub Date : 2020-07-07DOI: 10.46300/9104.2020.14.14
Z. Kala
This article presents a stochastic computational model for the analysis of the reliability of a drawn steel bar. The whole distribution of the limit state function is studied using global sensitivity analysis based on Cramér-von Mises distance. The algorithm for estimating the sensitivity indices is based on one loop of the Latin Hypercube Sampling method in combination with numerical integration. The algorithm is effective due to the approximation of resistance using a threeparameter lognormal distribution. Goodness-of-fit tests and other comparative studies demonstrate the significant accuracy and suitability of the three-parameter lognormal distribution, which provides better results and faster response than sampling-based methods. Global sensitivity analysis is evaluated for two load cases with proven dominant effect of the long-term variation load action, which is introduced using Gumbel probability density function. The Cramér-von Mises indices are discussed in the context of other types of probability-oriented sensitivity indices whose performance has been studied earlier.
{"title":"Limit States of Structures and Global Sensitivity Analysis Based on Cramér-von Mises Distance","authors":"Z. Kala","doi":"10.46300/9104.2020.14.14","DOIUrl":"https://doi.org/10.46300/9104.2020.14.14","url":null,"abstract":"This article presents a stochastic computational model for the analysis of the reliability of a drawn steel bar. The whole distribution of the limit state function is studied using global sensitivity analysis based on Cramér-von Mises distance. The algorithm for estimating the sensitivity indices is based on one loop of the Latin Hypercube Sampling method in combination with numerical integration. The algorithm is effective due to the approximation of resistance using a threeparameter lognormal distribution. Goodness-of-fit tests and other comparative studies demonstrate the significant accuracy and suitability of the three-parameter lognormal distribution, which provides better results and faster response than sampling-based methods. Global sensitivity analysis is evaluated for two load cases with proven dominant effect of the long-term variation load action, which is introduced using Gumbel probability density function. The Cramér-von Mises indices are discussed in the context of other types of probability-oriented sensitivity indices whose performance has been studied earlier.","PeriodicalId":39203,"journal":{"name":"International Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43406844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-30DOI: 10.46300/9104.2020.14.12
Z. Murčinková
Composites are known for their significant damping, however, both reinforcement type or layered arrangement influence the response of material: mechanical, thermal, electrical etc. The paper provides the dynamic time analysis of glass fiber reinforced polymer samples of various layups. The mechanical response to dynamic excitation was tested by numerical simulation and experiment. The excitation function was the unit impulse force generating free damped vibrations. Experimental results were evaluated in time domain to obtain damping parameters. For numerical simulation, the commercial software was used to visualize deformed model in individual damping phases, Mises stress distribution in individual laminate layers, and comparison of that for different layups.
{"title":"Dynamic Time Analysis of Glass Fiber Reinforced Polymer – Numerical Simulation and Experiment","authors":"Z. Murčinková","doi":"10.46300/9104.2020.14.12","DOIUrl":"https://doi.org/10.46300/9104.2020.14.12","url":null,"abstract":"Composites are known for their significant damping, however, both reinforcement type or layered arrangement influence the response of material: mechanical, thermal, electrical etc. The paper provides the dynamic time analysis of glass fiber reinforced polymer samples of various layups. The mechanical response to dynamic excitation was tested by numerical simulation and experiment. The excitation function was the unit impulse force generating free damped vibrations. Experimental results were evaluated in time domain to obtain damping parameters. For numerical simulation, the commercial software was used to visualize deformed model in individual damping phases, Mises stress distribution in individual laminate layers, and comparison of that for different layups.","PeriodicalId":39203,"journal":{"name":"International Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45518010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-30DOI: 10.46300/9104.2020.14.13
A. Pezzutti, G. Araujo
The process of formation of new morphologies by confinement in nano-droplets, created from a dewetting process, was simulated. The obtained structures showed a great similarity with the experimental results present in the literature. The developed model captures the fundamental interactions that determine the dynamics of the phase separation process of a copolymer system confined between a rigid substrate and a free surface. Furthermore, its numerical resolution is highly efficient as a result of the implementation of Eyre algorithm.
{"title":"Droplet Formation of an Anisotropic Liquid","authors":"A. Pezzutti, G. Araujo","doi":"10.46300/9104.2020.14.13","DOIUrl":"https://doi.org/10.46300/9104.2020.14.13","url":null,"abstract":"The process of formation of new morphologies by confinement in nano-droplets, created from a dewetting process, was simulated. The obtained structures showed a great similarity with the experimental results present in the literature. The developed model captures the fundamental interactions that determine the dynamics of the phase separation process of a copolymer system confined between a rigid substrate and a free surface. Furthermore, its numerical resolution is highly efficient as a result of the implementation of Eyre algorithm.","PeriodicalId":39203,"journal":{"name":"International Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45143668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-25DOI: 10.46300/9104.2020.14.10
K. Santhosh, P. Mohanthy
Performance of any system is identified through the observation of significant system parameters. Required parameters have to be measured using suitable sensors. But in some scenarios, it is difficult to measure some of the parameters due to issues in the placement of sensors. In such cases, estimators are developed to measure the parameters indirectly. In this paper, an attempt is made to develop an estimator to monitor the value of pitch and yaw of a twin-rotor multi input multi output system. The observer is developed using two methods one using Luenberger’s equations and the other using an Artificial Neural Network (ANN). For training the neural network model, the backpropagation algorithm is used. Tests have been conducted to analyze and compare the behavior of both observers. From the results, it is evident that a Luenberger observer performs better when sufficient system information is available and ANN observer performs better when inadequate system information is available
{"title":"Design of Estimator for Computing Yaw and Pitch for a Twin Rotor MIMO system","authors":"K. Santhosh, P. Mohanthy","doi":"10.46300/9104.2020.14.10","DOIUrl":"https://doi.org/10.46300/9104.2020.14.10","url":null,"abstract":"Performance of any system is identified through the observation of significant system parameters. Required parameters have to be measured using suitable sensors. But in some scenarios, it is difficult to measure some of the parameters due to issues in the placement of sensors. In such cases, estimators are developed to measure the parameters indirectly. In this paper, an attempt is made to develop an estimator to monitor the value of pitch and yaw of a twin-rotor multi input multi output system. The observer is developed using two methods one using Luenberger’s equations and the other using an Artificial Neural Network (ANN). For training the neural network model, the backpropagation algorithm is used. Tests have been conducted to analyze and compare the behavior of both observers. From the results, it is evident that a Luenberger observer performs better when sufficient system information is available and ANN observer performs better when inadequate system information is available","PeriodicalId":39203,"journal":{"name":"International Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47462864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The contribution of the fill to the global behavior of masonry vaulted bridges may be primarily significant. Nevertheless, ordinary analyses conducted on masonry bridges usually consider only the main structural vaulted elements. The paper reports some results obtained through a numerical simulation developed on a FEM model of an ancient bridge, the Devil’s bridge on Sele river at Barrizzo, in the Campania region. The study is aimed at showing how the fill may be contributing with a significant static action , changing the real carrying capacity of the bridge as regards applied loads. The study allows to highlight the spatial behavior of the single components and of the overall structure as well, in terms of stresses and deformed configurations under the self- weight and the accidental loads.
{"title":"Analysis of the Spatial Behaviour of Masonry Bridges Via Hierarchical FEM Modelling: the Devil’s Bridge","authors":"I. Corbi, O. Corbi","doi":"10.46300/9104.2020.14.9","DOIUrl":"https://doi.org/10.46300/9104.2020.14.9","url":null,"abstract":"The contribution of the fill to the global behavior of masonry vaulted bridges may be primarily significant. Nevertheless, ordinary analyses conducted on masonry bridges usually consider only the main structural vaulted elements. The paper reports some results obtained through a numerical simulation developed on a FEM model of an ancient bridge, the Devil’s bridge on Sele river at Barrizzo, in the Campania region. The study is aimed at showing how the fill may be contributing with a significant static action , changing the real carrying capacity of the bridge as regards applied loads. The study allows to highlight the spatial behavior of the single components and of the overall structure as well, in terms of stresses and deformed configurations under the self- weight and the accidental loads.","PeriodicalId":39203,"journal":{"name":"International Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41991704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper discusses the approximations with the local basis of the second level and the sixth order. We call it the approximation of the second level because in addition to the function values in the grid nodes it uses the values of the function, and the first and the second derivatives of the function. Here the polynomial approximations and the non-polynomial approximations of a special form are discussed. The non-polynomial approximation has the properties of polynomial and trigonometric functions. The approximations are twice continuously differentiable. Approximation theorems are given. These approximations use the values of the function at the nodes, the values of the first and the second derivatives of the function at the nodes, and the local basis splines. These basis splines are used for constructing variational-difference schemes for solving boundary value problems for differential equations. Numerical examples are given
{"title":"Approximations of the Sixth Order with the Polynomial and Non-polynomial Splines and Variational-difference Method","authors":"","doi":"10.46300/9104.2020.14.8","DOIUrl":"https://doi.org/10.46300/9104.2020.14.8","url":null,"abstract":"This paper discusses the approximations with the local basis of the second level and the sixth order. We call it the approximation of the second level because in addition to the function values in the grid nodes it uses the values of the function, and the first and the second derivatives of the function. Here the polynomial approximations and the non-polynomial approximations of a special form are discussed. The non-polynomial approximation has the properties of polynomial and trigonometric functions. The approximations are twice continuously differentiable. Approximation theorems are given. These approximations use the values of the function at the nodes, the values of the first and the second derivatives of the function at the nodes, and the local basis splines. These basis splines are used for constructing variational-difference schemes for solving boundary value problems for differential equations. Numerical examples are given","PeriodicalId":39203,"journal":{"name":"International Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49288411","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Controlling the discharge through a gravity dam by means of sluice gate is quite common technique. Although extensive theoretical and experimental studies on discharge parameters are available, most of these studies reported sedimentation and river-bed conditions resulting in reduced discharge through a dam, although limited research has focused on controlling and adjusting the discharge considering practical scenario. This paper presents a simplified analytical model applied to a typical case study on a typical dam in western India which was used the lift irrigation technique for improving the discharge. The approach focuses on the parametric studies for predicting the variations in discharge ratio employing a range of geometrical parameters such as area and aspect ratio of the individual sluice gates and their total number. It was found that the discharge is largely affected by minor alteration in these parameters. A set of important conclusions was drawn from the entire study.
{"title":"Analysis and Control of Flow Parameters through Sluice Gate in Dam","authors":"","doi":"10.46300/9104.2020.14.3","DOIUrl":"https://doi.org/10.46300/9104.2020.14.3","url":null,"abstract":"Controlling the discharge through a gravity dam by means of sluice gate is quite common technique. Although extensive theoretical and experimental studies on discharge parameters are available, most of these studies reported sedimentation and river-bed conditions resulting in reduced discharge through a dam, although limited research has focused on controlling and adjusting the discharge considering practical scenario. This paper presents a simplified analytical model applied to a typical case study on a typical dam in western India which was used the lift irrigation technique for improving the discharge. The approach focuses on the parametric studies for predicting the variations in discharge ratio employing a range of geometrical parameters such as area and aspect ratio of the individual sluice gates and their total number. It was found that the discharge is largely affected by minor alteration in these parameters. A set of important conclusions was drawn from the entire study.","PeriodicalId":39203,"journal":{"name":"International Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49554939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Computation fluid dynamics (CFD) modelling of laminar heat transfer behaviour of three types of nanofluids over flat plate are studied. In the modelling the two dimensional under laminar model is used. The base fluid is pure water and the volume fraction of nanoparticles in the base fluid is 0, 1, 2, 3, and 4%. The applied Reynolds number range considered is 997.1 ≤ Re ≤ 9971. For modelling of the physical properties of the nanofluid, single phase approach is used. The effect of the volume fraction and the type of nanoparticles on the physical properties has been evaluated and presented. Then, the analysis the flow behaviour of these three nanofluids is conducted by presenting the effect of increasing the nanoparticles concentration on the velocity profile, wall shear stress, skin friction coefficient, and average heat transfer coefficient. The results show that the type of nanoparticles is an important parameter for the heat transfer enhancement as each type has shown dissimilar behaviour in this study. Moreover, a polynomial correlation has been obtained to present the relation of the wall shear stress, skin friction coefficient and average heat transfer coefficient as a function of the volume fraction for the three nanofluids.
{"title":"CFD Study for the Flow Behaviour of Nanofluid Flow over Flat Plate","authors":"M. Klazly, G. Bognár","doi":"10.46300/9104.2020.14.6","DOIUrl":"https://doi.org/10.46300/9104.2020.14.6","url":null,"abstract":"Computation fluid dynamics (CFD) modelling of laminar heat transfer behaviour of three types of nanofluids over flat plate are studied. In the modelling the two dimensional under laminar model is used. The base fluid is pure water and the volume fraction of nanoparticles in the base fluid is 0, 1, 2, 3, and 4%. The applied Reynolds number range considered is 997.1 ≤ Re ≤ 9971. For modelling of the physical properties of the nanofluid, single phase approach is used. The effect of the volume fraction and the type of nanoparticles on the physical properties has been evaluated and presented. Then, the analysis the flow behaviour of these three nanofluids is conducted by presenting the effect of increasing the nanoparticles concentration on the velocity profile, wall shear stress, skin friction coefficient, and average heat transfer coefficient. The results show that the type of nanoparticles is an important parameter for the heat transfer enhancement as each type has shown dissimilar behaviour in this study. Moreover, a polynomial correlation has been obtained to present the relation of the wall shear stress, skin friction coefficient and average heat transfer coefficient as a function of the volume fraction for the three nanofluids.","PeriodicalId":39203,"journal":{"name":"International Journal of Mechanics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41665268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The interlocking concrete pavement blocks are quite commonly used to construct the pedestrian walkways and parking lots of transport infrastructure. Such blocks need adequate compressive strength to withstand the design live loads. In this paper, the influence of admixtures on the compressive strength of the blocks are studied through a series of laboratory investigations. The M35 grade of concrete conforming to the Indian Standard code of practice has been used with a standard superplasticizer as admixtures added at specified weights. The study implied that the use of admixtures alters the compressive strength of concrete blocks significantly.
{"title":"Compressive Strength of Interlocking Concrete Pavement Block influenced by Admixtures","authors":"","doi":"10.46300/9104.2020.14.7","DOIUrl":"https://doi.org/10.46300/9104.2020.14.7","url":null,"abstract":"The interlocking concrete pavement blocks are quite commonly used to construct the pedestrian walkways and parking lots of transport infrastructure. Such blocks need adequate compressive strength to withstand the design live loads. In this paper, the influence of admixtures on the compressive strength of the blocks are studied through a series of laboratory investigations. The M35 grade of concrete conforming to the Indian Standard code of practice has been used with a standard superplasticizer as admixtures added at specified weights. The study implied that the use of admixtures alters the compressive strength of concrete blocks significantly.","PeriodicalId":39203,"journal":{"name":"International Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45777309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
O. Koubaiti, A. Elkhalfi, J. EL-Mekkaoui, N. Mastorakis
In this work, we propose a new boundary condition called CA;B to remedy the problems of constraints due to the Dirichlet boundary conditions. We consider the 2D-linear elasticity equation of Navier-Lam´e with the condition CA;B. The latter allows to have a total insertion of the essential boundary condition in the linear system obtained without going through a numerical method like the lagrange multiplier method, this resulted in a non-extended linear system easy to reverse. We have developed the mixed finite element method using the mini element space (P1 + bubble, P1). Finally we have shown the efficiency and the feasibility of the limited condition CA;B.
{"title":"Solving the Problem of Constraints Due to Dirichlet Boundary Conditions in the Context of the Mini Element Method","authors":"O. Koubaiti, A. Elkhalfi, J. EL-Mekkaoui, N. Mastorakis","doi":"10.46300/9104.2020.14.2","DOIUrl":"https://doi.org/10.46300/9104.2020.14.2","url":null,"abstract":"In this work, we propose a new boundary condition called CA;B to remedy the problems of constraints due to the Dirichlet boundary conditions. We consider the 2D-linear elasticity equation of Navier-Lam´e with the condition CA;B. The latter allows to have a total insertion of the essential boundary condition in the linear system obtained without going through a numerical method like the lagrange multiplier method, this resulted in a non-extended linear system easy to reverse. We have developed the mixed finite element method using the mini element space (P1 + bubble, P1). Finally we have shown the efficiency and the feasibility of the limited condition CA;B.","PeriodicalId":39203,"journal":{"name":"International Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48986118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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