The article solves the problem of theoretically determining the deformable characteristics of railway ballast, considering its condition through mathematical modeling. Different tasks require mathematical models with different levels of detail of certain elements. After a certain limit, excessive detailing only worsens the quality of the model. Therefore, for many problems of the interaction between the track and the rolling stock, it is sufficient to describe the ballast as a homogeneous isotropic layer with a vertical elastic deformation. The elastic deformation of the ballast is formed by the deviation of individual elements; the ballast may have pollutants, the ballast may have places with different levels of compaction, etc. To be able to determine the general characteristics of the layer, a dynamic model of the stress–strain state of the system based on the dynamic problem of the theory of elasticity is applied. The reaction of the ballast to the dynamic load is modeled through the passage of elastic deformation waves. The given results can be applied in the models of the railway track in the other direction as initial data regarding the ballast layer.
{"title":"Determining the Deformation Characteristics of Railway Ballast by Mathematical Modeling of Elastic Wave Propagation","authors":"D. Kurhan, M. Kurhan, B. Horváth, S. Fischer","doi":"10.3390/applmech4020041","DOIUrl":"https://doi.org/10.3390/applmech4020041","url":null,"abstract":"The article solves the problem of theoretically determining the deformable characteristics of railway ballast, considering its condition through mathematical modeling. Different tasks require mathematical models with different levels of detail of certain elements. After a certain limit, excessive detailing only worsens the quality of the model. Therefore, for many problems of the interaction between the track and the rolling stock, it is sufficient to describe the ballast as a homogeneous isotropic layer with a vertical elastic deformation. The elastic deformation of the ballast is formed by the deviation of individual elements; the ballast may have pollutants, the ballast may have places with different levels of compaction, etc. To be able to determine the general characteristics of the layer, a dynamic model of the stress–strain state of the system based on the dynamic problem of the theory of elasticity is applied. The reaction of the ballast to the dynamic load is modeled through the passage of elastic deformation waves. The given results can be applied in the models of the railway track in the other direction as initial data regarding the ballast layer.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"29 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2023-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83685306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Wardach-Świȩcicka, S. Polesek-Karczewska, D. Kardaś
In the face of threats related to energy supply and climate change, the use of biomass is gaining importance, particularly in distributed energy systems. Combustion of biomass, including residue biomass, is considered one of the routes to increase the share of renewables in energy generation. The modeling of gaseous phase reactions remains crucial in predicting the combustion behavior of biomass and pollutant emissions. However, their simulation becomes a challenging task due to the computational cost. This paper presents a numerical analysis of the combustion process of a gas mixture released during biomass decomposition in a domestic 25 kW coil-type boiler. Three types of biogenic fuels were taken into consideration. The work aimed at examining the available tools for modeling gas burning, thus the geometry of the system was limited only to the 2D case. The thermodynamic equilibrium composition of pyrolysis gas was determined and implemented in Ansys to simulate the process. The computational results showed the potential of detailed, but reduced, combustion mechanisms of CH4/CO/H2 mixtures in predicting the main process features. The mechanism involving 85 reactions appeared to be more reliable compared to that comprising 77 reactions, particularly for volatiles with higher H2 content, whilst offering an acceptable calculation time. The burning characteristics obtained for volatiles with less CH4 and more H2 are in good agreement with the real operation conditions reported for the boiler.
{"title":"Biomass Combustion in the Helically Coiled Domestic Boiler Combined with the Equilibrium/Chemical Kinetics CFD Approach","authors":"I. Wardach-Świȩcicka, S. Polesek-Karczewska, D. Kardaś","doi":"10.3390/applmech4020040","DOIUrl":"https://doi.org/10.3390/applmech4020040","url":null,"abstract":"In the face of threats related to energy supply and climate change, the use of biomass is gaining importance, particularly in distributed energy systems. Combustion of biomass, including residue biomass, is considered one of the routes to increase the share of renewables in energy generation. The modeling of gaseous phase reactions remains crucial in predicting the combustion behavior of biomass and pollutant emissions. However, their simulation becomes a challenging task due to the computational cost. This paper presents a numerical analysis of the combustion process of a gas mixture released during biomass decomposition in a domestic 25 kW coil-type boiler. Three types of biogenic fuels were taken into consideration. The work aimed at examining the available tools for modeling gas burning, thus the geometry of the system was limited only to the 2D case. The thermodynamic equilibrium composition of pyrolysis gas was determined and implemented in Ansys to simulate the process. The computational results showed the potential of detailed, but reduced, combustion mechanisms of CH4/CO/H2 mixtures in predicting the main process features. The mechanism involving 85 reactions appeared to be more reliable compared to that comprising 77 reactions, particularly for volatiles with higher H2 content, whilst offering an acceptable calculation time. The burning characteristics obtained for volatiles with less CH4 and more H2 are in good agreement with the real operation conditions reported for the boiler.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"74 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2023-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85784467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In recent years, the hybridization of natural fibers with synthetic fibers has received much attention. This paper conducted an experimental study on the tensile and flexural behavior of unidirectional carbon/flax fiber reinforced epoxy composites and single flax fibers. Four hybridization rates were considered for 16 reinforced layers in a symmetric staking sequence, with the carbon ply at the surface. The damage evolution under load increase was monitored using the acoustic emission (AE) technique. The Davies–Bouldin index and the K-means clustering algorithm were used to correlate the hybridization rates to the contribution of each damage mechanism to overall failure. AE monitoring of tensile and flexural behaviors showed that delamination and fiber breakage mechanisms dominate the composite failure, regardless of the hybridization rate.
{"title":"Effects of Hybridization on Tensile, Flexural, and Damage Behaviors of Flax/Carbon Epoxy Composites","authors":"M. Habibi, L. Laperrière","doi":"10.3390/applmech4020039","DOIUrl":"https://doi.org/10.3390/applmech4020039","url":null,"abstract":"In recent years, the hybridization of natural fibers with synthetic fibers has received much attention. This paper conducted an experimental study on the tensile and flexural behavior of unidirectional carbon/flax fiber reinforced epoxy composites and single flax fibers. Four hybridization rates were considered for 16 reinforced layers in a symmetric staking sequence, with the carbon ply at the surface. The damage evolution under load increase was monitored using the acoustic emission (AE) technique. The Davies–Bouldin index and the K-means clustering algorithm were used to correlate the hybridization rates to the contribution of each damage mechanism to overall failure. AE monitoring of tensile and flexural behaviors showed that delamination and fiber breakage mechanisms dominate the composite failure, regardless of the hybridization rate.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"36 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2023-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88833224","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Flax fiber/shape memory epoxy hygromorph composites are a promising area of research in the field of biocomposites. This paper focuses on the tensile modulus of these composites and investigates how it is affected by factors such as fiber orientation (0° and 90°), temperature (20 °C, 40 °C, 60 °C, 80 °C, and 100 °C), and humidity (50% and fully immersed) conditions. Machine learning algorithms were utilized to predict the tensile modulus based on non-linearly dependent initial variables. Both decision tree (DT) and random forest (RF) algorithms were employed to analyze the data, and the results showed high coefficient of determination R2 values of 0.94 and 0.95, respectively. These findings demonstrate the effectiveness of machine learning in analyzing large datasets of mechanical properties in biocomposites. Moreover, the study revealed that the orientation of the flax fibers had the greatest impact on the tensile modulus value (with feature importance of 0.598 and 0.605 for the DT and RF models, respectively), indicating that it is a crucial factor to consider when designing these materials.
{"title":"Machine Learning-Assisted Tensile Modulus Prediction for Flax Fiber/Shape Memory Epoxy Hygromorph Composites","authors":"T. Sadat","doi":"10.3390/applmech4020038","DOIUrl":"https://doi.org/10.3390/applmech4020038","url":null,"abstract":"Flax fiber/shape memory epoxy hygromorph composites are a promising area of research in the field of biocomposites. This paper focuses on the tensile modulus of these composites and investigates how it is affected by factors such as fiber orientation (0° and 90°), temperature (20 °C, 40 °C, 60 °C, 80 °C, and 100 °C), and humidity (50% and fully immersed) conditions. Machine learning algorithms were utilized to predict the tensile modulus based on non-linearly dependent initial variables. Both decision tree (DT) and random forest (RF) algorithms were employed to analyze the data, and the results showed high coefficient of determination R2 values of 0.94 and 0.95, respectively. These findings demonstrate the effectiveness of machine learning in analyzing large datasets of mechanical properties in biocomposites. Moreover, the study revealed that the orientation of the flax fibers had the greatest impact on the tensile modulus value (with feature importance of 0.598 and 0.605 for the DT and RF models, respectively), indicating that it is a crucial factor to consider when designing these materials.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"69 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2023-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79155125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Straightening has to be carried out in order to ensure the straightness of a shaft, as distortions exceed the tolerance limit. Since the straightening load is typically large enough to produce plastic and residual deformation, repeated straightening loading cycles are very likely to induce cracks or fractures on the case-hardened shaft surface. In this study, in order to minimize repeated straightening cycles, an analytical straightening model is developed which calculates optimum stroke displacements corresponding to measured straightness errors so as to achieve the desired residual deflections and eliminate straightness errors. First, the hardness variation in the shaft radial direction is considered in the analytical model. Then, the proposed theoretical model is validated by numerical simulations. The results suggest that the analytically predicted stroke displacements and residual deflections agree very well with the numerical results when using induction-hardened SAE 4140 steel, and this signifies that the analytical straightening model developed in this study is capable of providing predictions of straightening stokes.
{"title":"Analytical Modeling for Mechanical Straightening Process of Case-Hardened Circular Shaft","authors":"S. Xing","doi":"10.3390/applmech4020036","DOIUrl":"https://doi.org/10.3390/applmech4020036","url":null,"abstract":"Straightening has to be carried out in order to ensure the straightness of a shaft, as distortions exceed the tolerance limit. Since the straightening load is typically large enough to produce plastic and residual deformation, repeated straightening loading cycles are very likely to induce cracks or fractures on the case-hardened shaft surface. In this study, in order to minimize repeated straightening cycles, an analytical straightening model is developed which calculates optimum stroke displacements corresponding to measured straightness errors so as to achieve the desired residual deflections and eliminate straightness errors. First, the hardness variation in the shaft radial direction is considered in the analytical model. Then, the proposed theoretical model is validated by numerical simulations. The results suggest that the analytically predicted stroke displacements and residual deflections agree very well with the numerical results when using induction-hardened SAE 4140 steel, and this signifies that the analytical straightening model developed in this study is capable of providing predictions of straightening stokes.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"2 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84060952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Advances in applied mechanics have facilitated a better understanding of the recycling of heat and work in the troposphere. This goal is important to meet practical needs for better management of climate science. Achieving this objective may require the application of quantum principles in action mechanics, recently employed to analyze the reversible thermodynamics of Carnot’s heat engine cycle. The testable proposals suggested here seek to solve several problems including (i) the phenomena of decreasing temperature and molecular entropy but increasing Gibbs energy with altitude in the troposphere; (ii) a reversible system storing thermal energy to drive vortical wind flow in anticyclones while frictionally warming the Earth’s surface by heat release from turbulence; (iii) vortical generation of electrical power from translational momentum in airflow in wind farms; and (iv) vortical energy in the destructive power of tropical cyclones. The scalar property of molecular action (@t ≡ ∫mvds, J-sec) is used to show how equilibrium temperatures are achieved from statistical equality of mechanical torques (mv2 or mr2ω2); these are exerted by Gibbs field quanta for each kind of gas phase molecule as rates of translational action (d@t/dt ≡ ∫mr2ωdϕ/dt ≡ mv2). These torques result from the impulsive density of resonant quantum or Gibbs fields with molecules, configuring the trajectories of gas molecules while balancing molecular pressure against the density of field energy (J/m3). Gibbs energy fields contain no resonant quanta at zero Kelvin, with this chemical potential diminishing in magnitude as the translational action of vapor molecules and quantum field energy content increases with temperature. These cases distinguish symmetrically between causal fields of impulsive quanta (Σhν) that energize the action of matter and the resultant kinetic torques of molecular mechanics (mv2). The quanta of these different fields display mean wavelengths from 10−4 m to 1012 m, with radial mechanical advantages many orders of magnitude greater than the corresponding translational actions, though with mean quantum frequencies (v) similar to those of radial Brownian movement for independent particles (ω). Widespread neglect of the Gibbs field energy component of natural systems may be preventing advances in tropospheric mechanics. A better understanding of these vortical Gibbs energy fields as thermodynamically reversible reservoirs for heat can help optimize work processes on Earth, delaying the achievement of maximum entropy production from short-wave solar radiation being converted to outgoing long-wave radiation to space. This understanding may improve strategies for management of global changes in climate.
{"title":"Applying the Action Principle of Classical Mechanics to the Thermodynamics of the Troposphere","authors":"I. Kennedy, M. Hodzic","doi":"10.3390/applmech4020037","DOIUrl":"https://doi.org/10.3390/applmech4020037","url":null,"abstract":"Advances in applied mechanics have facilitated a better understanding of the recycling of heat and work in the troposphere. This goal is important to meet practical needs for better management of climate science. Achieving this objective may require the application of quantum principles in action mechanics, recently employed to analyze the reversible thermodynamics of Carnot’s heat engine cycle. The testable proposals suggested here seek to solve several problems including (i) the phenomena of decreasing temperature and molecular entropy but increasing Gibbs energy with altitude in the troposphere; (ii) a reversible system storing thermal energy to drive vortical wind flow in anticyclones while frictionally warming the Earth’s surface by heat release from turbulence; (iii) vortical generation of electrical power from translational momentum in airflow in wind farms; and (iv) vortical energy in the destructive power of tropical cyclones. The scalar property of molecular action (@t ≡ ∫mvds, J-sec) is used to show how equilibrium temperatures are achieved from statistical equality of mechanical torques (mv2 or mr2ω2); these are exerted by Gibbs field quanta for each kind of gas phase molecule as rates of translational action (d@t/dt ≡ ∫mr2ωdϕ/dt ≡ mv2). These torques result from the impulsive density of resonant quantum or Gibbs fields with molecules, configuring the trajectories of gas molecules while balancing molecular pressure against the density of field energy (J/m3). Gibbs energy fields contain no resonant quanta at zero Kelvin, with this chemical potential diminishing in magnitude as the translational action of vapor molecules and quantum field energy content increases with temperature. These cases distinguish symmetrically between causal fields of impulsive quanta (Σhν) that energize the action of matter and the resultant kinetic torques of molecular mechanics (mv2). The quanta of these different fields display mean wavelengths from 10−4 m to 1012 m, with radial mechanical advantages many orders of magnitude greater than the corresponding translational actions, though with mean quantum frequencies (v) similar to those of radial Brownian movement for independent particles (ω). Widespread neglect of the Gibbs field energy component of natural systems may be preventing advances in tropospheric mechanics. A better understanding of these vortical Gibbs energy fields as thermodynamically reversible reservoirs for heat can help optimize work processes on Earth, delaying the achievement of maximum entropy production from short-wave solar radiation being converted to outgoing long-wave radiation to space. This understanding may improve strategies for management of global changes in climate.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"35 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90808405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Akshansh Mishra, V. Jatti, Eyob Messele Sefene, Shivangi Paliwal
Structural integrity is a crucial aspect of engineering components, particularly in the field of additive manufacturing (AM). Surface roughness is a vital parameter that significantly influences the structural integrity of additively manufactured parts. This research work focuses on the prediction of the surface roughness of additive-manufactured polylactic acid (PLA) specimens using eight different supervised machine learning regression-based algorithms. For the first time, explainable AI techniques are employed to enhance the interpretability of the machine learning models. The nine algorithms used in this study are Support Vector Regression, Random Forest, XGBoost, AdaBoost, CatBoost, Decision Tree, the Extra Tree Regressor, the Explainable Boosting Model (EBM), and the Gradient Boosting Regressor. This study analyzes the performance of these algorithms to predict the surface roughness of PLA specimens, while also investigating the impacts of individual input parameters through explainable AI methods. The experimental results indicate that the XGBoost algorithm outperforms the other algorithms with the highest coefficient of determination value of 0.9634. This value demonstrates that the XGBoost algorithm provides the most accurate predictions for surface roughness compared with other algorithms. This study also provides a comparative analysis of the performance of all the algorithms used in this study, along with insights derived from explainable AI techniques.
{"title":"Explainable Artificial Intelligence (XAI) and Supervised Machine Learning-based Algorithms for Prediction of Surface Roughness of Additively Manufactured Polylactic Acid (PLA) Specimens","authors":"Akshansh Mishra, V. Jatti, Eyob Messele Sefene, Shivangi Paliwal","doi":"10.3390/applmech4020034","DOIUrl":"https://doi.org/10.3390/applmech4020034","url":null,"abstract":"Structural integrity is a crucial aspect of engineering components, particularly in the field of additive manufacturing (AM). Surface roughness is a vital parameter that significantly influences the structural integrity of additively manufactured parts. This research work focuses on the prediction of the surface roughness of additive-manufactured polylactic acid (PLA) specimens using eight different supervised machine learning regression-based algorithms. For the first time, explainable AI techniques are employed to enhance the interpretability of the machine learning models. The nine algorithms used in this study are Support Vector Regression, Random Forest, XGBoost, AdaBoost, CatBoost, Decision Tree, the Extra Tree Regressor, the Explainable Boosting Model (EBM), and the Gradient Boosting Regressor. This study analyzes the performance of these algorithms to predict the surface roughness of PLA specimens, while also investigating the impacts of individual input parameters through explainable AI methods. The experimental results indicate that the XGBoost algorithm outperforms the other algorithms with the highest coefficient of determination value of 0.9634. This value demonstrates that the XGBoost algorithm provides the most accurate predictions for surface roughness compared with other algorithms. This study also provides a comparative analysis of the performance of all the algorithms used in this study, along with insights derived from explainable AI techniques.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"38 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91378835","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. A. De Rosa, M. Lippiello, Antonella Onorato, I. Elishakoff
Carbon nanotubes with their outstanding mechanical, physical and electrical properties have stimulated a significant amount of scientific and technological research due to their uniqueness compared to conventional materials. As a result, an extensive study on their mechanical properties has been conducted, and the static and dynamic behavior of single- walled and multi-walled carbon nanotubes has been examined using Euler-Bernoulli and Timoshenko beam models. The main objective of this paper is to study the free vibration behaviour of single-walled carbon nanotubes (SWCNT) using the nonlocal truncated Timoshenko beam theory. According to the Hamilton principle, the equation of motion of Timoshenko single-walled carbon nanotubes is calculated taking into account the truncated theory; and the general corresponding boundary conditions are derived. Finally, some numerical examples are performed to evaluate the effects of the nonlocal coefficient and the length of the nanotube. The obtained results are validated by comparing them with those found in the literature, and they show the accuracy and efficiency of the developed model. Particularly, the results demonstrate that the present formulation is highly efficient and capable of satisfactorily describing the behavior of nanobeams.
{"title":"Free Vibration of Single-Walled Carbon Nanotubes Using Nonlocal Truncated Timoshenko-Ehrenfest Beam Theory","authors":"M. A. De Rosa, M. Lippiello, Antonella Onorato, I. Elishakoff","doi":"10.3390/applmech4020035","DOIUrl":"https://doi.org/10.3390/applmech4020035","url":null,"abstract":"Carbon nanotubes with their outstanding mechanical, physical and electrical properties have stimulated a significant amount of scientific and technological research due to their uniqueness compared to conventional materials. As a result, an extensive study on their mechanical properties has been conducted, and the static and dynamic behavior of single- walled and multi-walled carbon nanotubes has been examined using Euler-Bernoulli and Timoshenko beam models. The main objective of this paper is to study the free vibration behaviour of single-walled carbon nanotubes (SWCNT) using the nonlocal truncated Timoshenko beam theory. According to the Hamilton principle, the equation of motion of Timoshenko single-walled carbon nanotubes is calculated taking into account the truncated theory; and the general corresponding boundary conditions are derived. Finally, some numerical examples are performed to evaluate the effects of the nonlocal coefficient and the length of the nanotube. The obtained results are validated by comparing them with those found in the literature, and they show the accuracy and efficiency of the developed model. Particularly, the results demonstrate that the present formulation is highly efficient and capable of satisfactorily describing the behavior of nanobeams.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"1 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82202056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The management of an intracranial hemorrhage in patients receiving anticoagulant therapy presents a significant challenge for medical professionals. Anticoagulant treatment is intended to prevent blood clotting, but it can worsen active brain bleeds. Despite this risk, avoiding the prothrombotic state caused by mechanical heart valves remains crucial. Guidelines on managing this issue are currently lacking, prompting a review that delves into embryonic development and anatomical functions of heart valves, valve replacement therapy for diseased valves, and the need for anticoagulants. Ultimately, recent literature and cases inform discussion regarding how best to manage intracranial hemorrhages in patients with mechanical heart valves. The expectation is that this examination will offer valuable perspectives on the handling of intracranial bleeding among individuals with mechanical heart valves and stimulate additional investigations in this intricate domain, particularly through the lens of applied mechanics.
{"title":"Management of Intracranial Hemorrhage in the Setting of Mechanical Heart Valve Replacement Therapy","authors":"Sahar Khan, Faiz Syed, Milan Toma","doi":"10.3390/applmech4020033","DOIUrl":"https://doi.org/10.3390/applmech4020033","url":null,"abstract":"The management of an intracranial hemorrhage in patients receiving anticoagulant therapy presents a significant challenge for medical professionals. Anticoagulant treatment is intended to prevent blood clotting, but it can worsen active brain bleeds. Despite this risk, avoiding the prothrombotic state caused by mechanical heart valves remains crucial. Guidelines on managing this issue are currently lacking, prompting a review that delves into embryonic development and anatomical functions of heart valves, valve replacement therapy for diseased valves, and the need for anticoagulants. Ultimately, recent literature and cases inform discussion regarding how best to manage intracranial hemorrhages in patients with mechanical heart valves. The expectation is that this examination will offer valuable perspectives on the handling of intracranial bleeding among individuals with mechanical heart valves and stimulate additional investigations in this intricate domain, particularly through the lens of applied mechanics.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"1 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2023-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79908896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effect of elastic constants, cij, on the nature (easy or difficult) of a cleavage system in mono-crystalline YBa2Cu3O7−δ is investigated by employing a novel three-dimensional eigenfunction expansion technique, based in part on the separation of the thickness variable and partly on a modified Frobenius-type series expansion technique in conjunction with Eshelby–Stroh formalism. Out of the three available, complete sets of elastic constants, only the experimental measurements using resonant ultrasound spectroscopy merit serious attention, despite reported values of c12 and, to a lesser extent, c66 being excessively high. The present investigation considers six through-thickness crack systems weakening orthorhombic mono-crystalline Yttrium barium copper oxide (YBCO) plates. More importantly, the present investigation establishes sufficient conditions for crack path stability/instability, which entail a cleavage system being easy or difficult, i.e., whether a crack would propagate in its original plane/direction or deflect to a different one. This criterion of fracture mechanics is then employed for accurate determination of the full set of elastic constants of superconducting mono-crystalline YBCO. Finally, heretofore unavailable results pertaining to the through-thickness variations of stress intensity factors and energy release rates for a crack corresponding to symmetric and skew-symmetric hyperbolic cosine loads, which also satisfy the boundary conditions on the plate surfaces, bridge a longstanding gap.
{"title":"Employment of Fracture Mechanics Criteria for Accurate Assessment of the Full Set of Elastic Constants of Orthorhombic/Tetragonal Mono-Crystalline YBCO","authors":"R. Chaudhuri","doi":"10.3390/applmech4020032","DOIUrl":"https://doi.org/10.3390/applmech4020032","url":null,"abstract":"The effect of elastic constants, cij, on the nature (easy or difficult) of a cleavage system in mono-crystalline YBa2Cu3O7−δ is investigated by employing a novel three-dimensional eigenfunction expansion technique, based in part on the separation of the thickness variable and partly on a modified Frobenius-type series expansion technique in conjunction with Eshelby–Stroh formalism. Out of the three available, complete sets of elastic constants, only the experimental measurements using resonant ultrasound spectroscopy merit serious attention, despite reported values of c12 and, to a lesser extent, c66 being excessively high. The present investigation considers six through-thickness crack systems weakening orthorhombic mono-crystalline Yttrium barium copper oxide (YBCO) plates. More importantly, the present investigation establishes sufficient conditions for crack path stability/instability, which entail a cleavage system being easy or difficult, i.e., whether a crack would propagate in its original plane/direction or deflect to a different one. This criterion of fracture mechanics is then employed for accurate determination of the full set of elastic constants of superconducting mono-crystalline YBCO. Finally, heretofore unavailable results pertaining to the through-thickness variations of stress intensity factors and energy release rates for a crack corresponding to symmetric and skew-symmetric hyperbolic cosine loads, which also satisfy the boundary conditions on the plate surfaces, bridge a longstanding gap.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"72 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2023-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83728721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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