The incompressible models for the pressure-strain correlation are unable to correctly predict the turbulence flows evolving with significant compressibility. Huang and Fu use a damping function of the turbulent Mach number to modify two numerical coefficients of the incompressible model for the pressure strain developed by Launder, Reece and Rodi. This model predicts the spreading rate and the shear stress behavior in compressible turbulent mixing well. However, the model does not show the well-known compressibility effects on the compressible homogenous shear flow. In the present work, the model of Huang-Fu is revised, all resulting model coefficients become dependent on the turbulent Mach number, the gradient Mach number and the convective Mach number. The proposed model is tested in different compressible turbulent homogeneous shear flow and mixing layers cases. In general, the predicted results from the proposed model are in an acceptable agreement with DNS and experiment data.
{"title":"A Comparative Study for Compressible Turbulence Models","authors":"H. Khlifi, Adnan Bourehla","doi":"10.4236/wjm.2022.121001","DOIUrl":"https://doi.org/10.4236/wjm.2022.121001","url":null,"abstract":"The incompressible models for the pressure-strain correlation are unable to correctly predict the turbulence flows evolving with significant compressibility. Huang and Fu use a damping function of the turbulent Mach number to modify two numerical coefficients of the incompressible model for the pressure strain developed by Launder, Reece and Rodi. This model predicts the spreading rate and the shear stress behavior in compressible turbulent mixing well. However, the model does not show the well-known compressibility effects on the compressible homogenous shear flow. In the present work, the model of Huang-Fu is revised, all resulting model coefficients become dependent on the turbulent Mach number, the gradient Mach number and the convective Mach number. The proposed model is tested in different compressible turbulent homogeneous shear flow and mixing layers cases. In general, the predicted results from the proposed model are in an acceptable agreement with DNS and experiment data.","PeriodicalId":70106,"journal":{"name":"力学国际期刊(英文)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70874735","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}
{"title":"Relativistic Velocity Addition on a Space-Time Diagram","authors":"A. Ogura","doi":"10.4236/wjm.2022.124004","DOIUrl":"https://doi.org/10.4236/wjm.2022.124004","url":null,"abstract":"","PeriodicalId":70106,"journal":{"name":"力学国际期刊(英文)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70874935","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 fundamental principles of the gyroscope theory contain the system of the inertial torques generated by the rotating mass of the spinning disc that interrelated by the ratio of its angular velocities rotation around axes. The action of the centrifugal, common inertial Coriolis forces and the change in the angular momentum generate the system of inertial torques. These four dynamical components make up the system of the eight torques acting simultaneously on the spinning disc. They manifest their action in gyroscopic effects. The ratio of the precessed motions of the gyroscope presents one of the gyroscopic effects around axes of rotation. The known mathematical model for this ratio contains an error that was corrected in this work.
{"title":"Interrelation of Precessed Motions of the Gyroscope","authors":"R. Usubamatov","doi":"10.4236/wjm.2021.119013","DOIUrl":"https://doi.org/10.4236/wjm.2021.119013","url":null,"abstract":"The fundamental principles of the gyroscope theory contain the system of the inertial torques generated by the rotating mass of the spinning disc that interrelated by the ratio of its angular velocities rotation around axes. The action of the centrifugal, common inertial Coriolis forces and the change in the angular momentum generate the system of inertial torques. These four dynamical components make up the system of the eight torques acting simultaneously on the spinning disc. They manifest their action in gyroscopic effects. The ratio of the precessed motions of the gyroscope presents one of the gyroscopic effects around axes of rotation. The known mathematical model for this ratio contains an error that was corrected in this work.","PeriodicalId":70106,"journal":{"name":"力学国际期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46518596","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}
Rogers Omboga Amenya, J. Sigey, G. Maloiy, D. Theuri
The study investigated the effect of the angular position of the head on the blood flow in the jugular vein of giraffes. The vein considered is elastic and collapsible such that its cross-sectional area is not uniform. Transmural pressure causes the blood to move along the vein. Mathematical equations describing the flow were developed, and the vein was considered to be inclined at an angle φ to the horizontal. A finite-difference scheme was used to solve the equations of motion for the flow. The results are presented via relevant tables and plots. Our findings show that a change in the position of the head causes variation in the external pressure, which in turn causes variation in the cross-sectional area of the vein. Moreover, a drop (or increase) in the inertial pressure of the blood may cause the vein to collapse (or distend), which again triggers a change in the pressure.
{"title":"Effect of Head Position Angles on the Blood Flow in the Jugular Vein of Giraffes","authors":"Rogers Omboga Amenya, J. Sigey, G. Maloiy, D. Theuri","doi":"10.4236/wjm.2021.118012","DOIUrl":"https://doi.org/10.4236/wjm.2021.118012","url":null,"abstract":"The study investigated the effect of the angular position of the head on the blood flow in the jugular vein of giraffes. The vein considered is elastic and collapsible such that its cross-sectional area is not uniform. Transmural pressure causes the blood to move along the vein. Mathematical equations describing the flow were developed, and the vein was considered to be inclined at an angle φ to the horizontal. A finite-difference scheme was used to solve the equations of motion for the flow. The results are presented via relevant tables and plots. Our findings show that a change in the position of the head causes variation in the external pressure, which in turn causes variation in the cross-sectional area of the vein. Moreover, a drop (or increase) in the inertial pressure of the blood may cause the vein to collapse (or distend), which again triggers a change in the pressure.","PeriodicalId":70106,"journal":{"name":"力学国际期刊(英文)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70874945","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}
R. Lombarkia, A. Gakwaya, Denis Nandlall, M. Dano, L. Julie, vesque, Ameur BenKhelifa, P. Vachon-Joannette, Philippe Gagnon
Despite years of governmental and academic institutions’ researches, no experimental standards are established for evaluating crush Specific Energy Absorption SEA for plain weave fabric woven carbon-fiber-reinforced composites used in modern aircraft structures as elements of the boxes to mitigate damage during crush events. At the laboratory scale, this paper proposes a comparative study of energy absorption capability of flat plate coupons made by CFRP plain weave fabric composites. A new fixture design and setup were created with hydraulic pressure and drop tower machines to carry out tests of flat plate composite specimens under quasi-static and low velocity on-axis crash loading. For investigating parameters sensibility of triggers and layups, numerical and experimental results of four trigger types and three stacking sequences were compared. A confrontation between experimental and pre-developed UL-Crush numerical material model results confirms that coupons with 0˚ oriented central plies and saw teeth or corrugated triggers dissipates higher energy during crush, compared to coupons with 90˚ or 45˚ oriented central plies and chamfer 45˚ or steeple triggers. An efficient and simplified experimental methodology was developed to measure and investigate different parameters influencing SEA of composites under crush load. Comparison between experimental and UL-Crush material model confirms the performance of such simulation tool.
{"title":"Comparative Study of Energy Absorption Capability of Flat Plate Coupons Made by CFRP Plain Weave Fabric Composites","authors":"R. Lombarkia, A. Gakwaya, Denis Nandlall, M. Dano, L. Julie, vesque, Ameur BenKhelifa, P. Vachon-Joannette, Philippe Gagnon","doi":"10.4236/wjm.2021.117010","DOIUrl":"https://doi.org/10.4236/wjm.2021.117010","url":null,"abstract":"Despite years of governmental and academic institutions’ researches, no experimental standards are established for evaluating crush Specific Energy Absorption SEA for plain weave fabric woven carbon-fiber-reinforced composites used in modern aircraft structures as elements of the boxes to mitigate damage during crush events. At the laboratory scale, this paper proposes a comparative study of energy absorption capability of flat plate coupons made by CFRP plain weave fabric composites. A new fixture design and setup were created with hydraulic pressure and drop tower machines to carry out tests of flat plate composite specimens under quasi-static and low velocity on-axis crash loading. For investigating parameters sensibility of triggers and layups, numerical and experimental results of four trigger types and three stacking sequences were compared. A confrontation between experimental and pre-developed UL-Crush numerical material model results confirms that coupons with 0˚ oriented central plies and saw teeth or corrugated triggers dissipates higher energy during crush, compared to coupons with 90˚ or 45˚ oriented central plies and chamfer 45˚ or steeple triggers. An efficient and simplified experimental methodology was developed to measure and investigate different parameters influencing SEA of composites under crush load. Comparison between experimental and UL-Crush material model confirms the performance of such simulation tool.","PeriodicalId":70106,"journal":{"name":"力学国际期刊(英文)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43289289","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}
Talaka Dya, B. B. Blaise, G. Betchewe, Mohamadou Alidou
The purpose of this paper is to demonstrate the applicability of Particle Swarm Optimization algorithm to determine material parameters in incompressible isotropic elastic strain-energy functions using combined tension and torsion loading. Simulation of rubber behavior was conducted from the governing equations of the deformation of a cylinder composed of isotropic hyperelastic incompressible materials. Four different forms of strain-energy function were considered based respectively on polynomial, exponential and logarithmic terms to reproduce load force (N) and torque (M) trends using natural rubber experimental data. After highlighting the minimization of the objective function generated in the fitting process, the study revealed that a particle swarm optimization algorithm could be successfully used to identify the best material parameters and characterize the behavior of rubber-like hyperelastic materials.
{"title":"Implementation of Particle Swarm Optimization Algorithm in Matlab Code for Hyperelastic Characterization","authors":"Talaka Dya, B. B. Blaise, G. Betchewe, Mohamadou Alidou","doi":"10.4236/wjm.2021.117011","DOIUrl":"https://doi.org/10.4236/wjm.2021.117011","url":null,"abstract":"The purpose of this paper is to demonstrate the applicability of Particle Swarm Optimization algorithm to determine material parameters in incompressible isotropic elastic strain-energy functions using combined tension and torsion loading. Simulation of rubber behavior was conducted from the governing equations of the deformation of a cylinder composed of isotropic hyperelastic incompressible materials. Four different forms of strain-energy function were considered based respectively on polynomial, exponential and logarithmic terms to reproduce load force (N) and torque (M) trends using natural rubber experimental data. After highlighting the minimization of the objective function generated in the fitting process, the study revealed that a particle swarm optimization algorithm could be successfully used to identify the best material parameters and characterize the behavior of rubber-like hyperelastic materials.","PeriodicalId":70106,"journal":{"name":"力学国际期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45386901","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}
Plastic flow behavior of the SNCM8 steel was investigated by performing hot compression tests within the temperature range of 850˚C to 1200˚C and strain rates of 0.01 s−1 to 10 s−1. Constitutive modeling based on dynamic recrystallization was established, in which Cingara equation was applied to represent work hardening up to peak stress and Avrami equation to describe dynamic softening beyond peak stress up to steady state. It was found that stress-strain responses predicted by the combined model fairly agreed with experimentally resulted curves for the particular conditions. The correlation coefficient (R) of 0.9485 and average absolute relative error (AARE) of 2.3614% was calculated for the modeled flow curves.
{"title":"Investigation of Hot Deformation Behavior of SNCM8 Alloy Steel","authors":"N. Jantepa, S. Suranuntchai","doi":"10.4236/WJM.2021.113003","DOIUrl":"https://doi.org/10.4236/WJM.2021.113003","url":null,"abstract":"Plastic flow behavior of the SNCM8 steel was investigated by performing hot compression tests within the temperature range of 850˚C to 1200˚C and strain rates of 0.01 s−1 to 10 s−1. Constitutive modeling based on dynamic recrystallization was established, in which Cingara equation was applied to represent work hardening up to peak stress and Avrami equation to describe dynamic softening beyond peak stress up to steady state. It was found that stress-strain responses predicted by the combined model fairly agreed with experimentally resulted curves for the particular conditions. The correlation coefficient (R) of 0.9485 and average absolute relative error (AARE) of 2.3614% was calculated for the modeled flow curves.","PeriodicalId":70106,"journal":{"name":"力学国际期刊(英文)","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48247196","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 : 2021-01-01DOI: 10.4236/wjm.2021.1110014
K. Shimada, R. Ikeda, H. Kikura, H. Takahashi
For the purpose of the replacement of Magnetic Fluid (MF) which is effective in the production of an artificial soft and tactile skin for the robot, etc. by utilizing a rubber solidification method with electrolytic polymerization, we proposed a novel magnetic responsive intelligent fluid, Hybrid Fluid (HF). HF is structured with water, kerosene, silicon oil having Polydimethylsiloxane (PDMS) and Polyvinyl Alcohol (PVA) as well as magnetic particles and surfactant. The state of HF changes as jelly or fluid by their rates of the constituents and motion style. In the present paper, we presented the characteristics of HF: the viscosity and the magnetization are respectively equivalent to those of other magnetic responsive fluids, MF and their solvents. For the structure, HF is soluble simultaneously with both diene and non-diene rubbers. The diene rubber such as Natural Rubber (NR) or Chloroprene (CR) has a role in the feasibility of electrolytic polymerization and the non-diene rubber such as silicon oil rubber (Q) has a role in defense against deterioration. Therefore, the electrolytically polymerized HF rubber by mixing NR, CR as well as Q is effective for the artificial soft and tactile skin. It is responsive to pressure and has optimal property on piezoelectricity in the case of the mixture of Ni particles as filler. HF is effective in the production of the artificial soft and tactile skin made of rubber.
{"title":"Development of Novel Magnetic Responsive Intelligent Fluid, Hybrid Fluid (HF), for Production of Soft and Tactile Rubber","authors":"K. Shimada, R. Ikeda, H. Kikura, H. Takahashi","doi":"10.4236/wjm.2021.1110014","DOIUrl":"https://doi.org/10.4236/wjm.2021.1110014","url":null,"abstract":"For the purpose of the replacement of Magnetic Fluid (MF) which is effective in the production of an artificial soft and tactile skin for the robot, etc. by utilizing a rubber solidification method with electrolytic polymerization, we proposed a novel magnetic responsive intelligent fluid, Hybrid Fluid (HF). HF is structured with water, kerosene, silicon oil having Polydimethylsiloxane (PDMS) and Polyvinyl Alcohol (PVA) as well as magnetic particles and surfactant. The state of HF changes as jelly or fluid by their rates of the constituents and motion style. In the present paper, we presented the characteristics of HF: the viscosity and the magnetization are respectively equivalent to those of other magnetic responsive fluids, MF and their solvents. For the structure, HF is soluble simultaneously with both diene and non-diene rubbers. The diene rubber such as Natural Rubber (NR) or Chloroprene (CR) has a role in the feasibility of electrolytic polymerization and the non-diene rubber such as silicon oil rubber (Q) has a role in defense against deterioration. Therefore, the electrolytically polymerized HF rubber by mixing NR, CR as well as Q is effective for the artificial soft and tactile skin. It is responsive to pressure and has optimal property on piezoelectricity in the case of the mixture of Ni particles as filler. HF is effective in the production of the artificial soft and tactile skin made of rubber.","PeriodicalId":70106,"journal":{"name":"力学国际期刊(英文)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70874140","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 : 2021-01-01DOI: 10.4236/wjm.2021.1111015
Abdelraouf M. Sami Alsheikh, D. Rees
This paper is to review the theory of thin-walled beam structures of the open cross-section. There is scant information on the performance of structures made from thin-walled beam elements, particularly those of open sections, where the behavior is considerably complicated by the coupling of tensile, bending and torsional loading modes. In the combined loading theory of thin-walled structures, it is useful to mention that for a thin-walled beam, the value of direct stress at a point on the cross-section depends on its position, the geometrical properties of the cross-section and the applied loading. This applies whether the thin-walled section is closed or open but this study will be directed primarily at the latter. Theoretical analyses of structures are fairly well established, considered in multi-various applications by many scientists. However, due to the present interest in lightweight structures, it is necessary to specify where the present theory lies. It does not, for example, deal with compression and the consequent failure modes under global and local buckling. Indeed, with the inclusion of strut buckling failure and any other unfo-reseen collapse modes, the need was perceived for further research into the subject. Presently, a survey of the published works has shown in the following: 1) The assumptions used in deriving the underlying theory of thin-walled beams are not clearly stated or easily understood; 2) The transformations of a load system from arbitrary axis to those at the relevant centre of rotation are incomplete. Thus, an incorrect stress distribution may result in; 3) Several methods are found in the recent literature for analyzing the behaviour of thin-walled open section beams under combined loading. These reveal cross-section of a thin-walled beam. A general transformation matrix that accounts for a load system applied at an arbitrary point on the cross-section will be published in a future paper.
{"title":"General Stiffness Matrix for a Thin-Walled, Open-Section Beam Structure","authors":"Abdelraouf M. Sami Alsheikh, D. Rees","doi":"10.4236/wjm.2021.1111015","DOIUrl":"https://doi.org/10.4236/wjm.2021.1111015","url":null,"abstract":"This paper is to review the theory of thin-walled beam structures of the open cross-section. There is scant information on the performance of structures made from thin-walled beam elements, particularly those of open sections, where the behavior is considerably complicated by the coupling of tensile, bending and torsional loading modes. In the combined loading theory of thin-walled structures, it is useful to mention that for a thin-walled beam, the value of direct stress at a point on the cross-section depends on its position, the geometrical properties of the cross-section and the applied loading. This applies whether the thin-walled section is closed or open but this study will be directed primarily at the latter. Theoretical analyses of structures are fairly well established, considered in multi-various applications by many scientists. However, due to the present interest in lightweight structures, it is necessary to specify where the present theory lies. It does not, for example, deal with compression and the consequent failure modes under global and local buckling. Indeed, with the inclusion of strut buckling failure and any other unfo-reseen collapse modes, the need was perceived for further research into the subject. Presently, a survey of the published works has shown in the following: 1) The assumptions used in deriving the underlying theory of thin-walled beams are not clearly stated or easily understood; 2) The transformations of a load system from arbitrary axis to those at the relevant centre of rotation are incomplete. Thus, an incorrect stress distribution may result in; 3) Several methods are found in the recent literature for analyzing the behaviour of thin-walled open section beams under combined loading. These reveal cross-section of a thin-walled beam. A general transformation matrix that accounts for a load system applied at an arbitrary point on the cross-section will be published in a future paper.","PeriodicalId":70106,"journal":{"name":"力学国际期刊(英文)","volume":"398 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70874228","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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