In gas turbines, the blade vibration caused by aerodynamic excitation or by self-excited vibration and flutter leads to high cycle fatigue that represents the main cause of damage in turbomachinery. Turbine operators have resorted to assess the blade vibrations using non-contact systems. One of the well-known non-contact methods is Blade Tip Timing (BTT). BTT is based on monitoring the time history of the passing of each blade tip by stationary sensors mounted in a casing around the blades. The BTT method evaluates the blade time of arrival (ToA) in order to estimate the vibration. To perform the BTT technique, optical sensors were widely used by industry due to their high accuracy and performance under high temperatures, but the main drawback of these systems is their low tolerance to the presence of contaminants. To mitigate this downside, Eddy Current Sensors (ECS) are a good alternative for health monitoring application in gas turbines due to their immunity to contaminants and debris. This type of sensor was used by many researches, predominantly on the experimental side. The focus was to extract response frequencies and therefore the accuracy of the timing measurement was ignored due to the lack of modeling. This paper fills the gap between experiments and modeling by simulating a BTT application where detailed finite element modeling of active and passive ECS outputs was performed. A test rig composed of a bladed disk with 12 blades clamped to a rotating shaft was designed and manufactured in order to validate the proposed models with experimental measurements. Finally, a comparison between these different types of sensor output is presented to show the effect of the blade tip clearance and rotational speed on the accuracy of the BTT measurement.
{"title":"Simulating Eddy Current Sensors in Blade Tip Timing Application: Modeling and Experimental Validation","authors":"N. Jamia, M. Friswell, S. El-Borgi, P. Rajendran","doi":"10.1115/IMECE2018-87414","DOIUrl":"https://doi.org/10.1115/IMECE2018-87414","url":null,"abstract":"In gas turbines, the blade vibration caused by aerodynamic excitation or by self-excited vibration and flutter leads to high cycle fatigue that represents the main cause of damage in turbomachinery. Turbine operators have resorted to assess the blade vibrations using non-contact systems. One of the well-known non-contact methods is Blade Tip Timing (BTT). BTT is based on monitoring the time history of the passing of each blade tip by stationary sensors mounted in a casing around the blades. The BTT method evaluates the blade time of arrival (ToA) in order to estimate the vibration. To perform the BTT technique, optical sensors were widely used by industry due to their high accuracy and performance under high temperatures, but the main drawback of these systems is their low tolerance to the presence of contaminants. To mitigate this downside, Eddy Current Sensors (ECS) are a good alternative for health monitoring application in gas turbines due to their immunity to contaminants and debris. This type of sensor was used by many researches, predominantly on the experimental side. The focus was to extract response frequencies and therefore the accuracy of the timing measurement was ignored due to the lack of modeling. This paper fills the gap between experiments and modeling by simulating a BTT application where detailed finite element modeling of active and passive ECS outputs was performed. A test rig composed of a bladed disk with 12 blades clamped to a rotating shaft was designed and manufactured in order to validate the proposed models with experimental measurements. Finally, a comparison between these different types of sensor output is presented to show the effect of the blade tip clearance and rotational speed on the accuracy of the BTT measurement.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"184 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114326964","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}
Robust design and analysis of carbon fiber reinforced polymers (CFRP) mandates a thorough understanding of the onset and propagation of damaging mechanisms. Damage can manifest from fiber tension, fiber compression, matrix tension, and matrix compression. Of these damage forms, matrix compression has seen the least attention. Previous work has developed experimental specimens that enabled characterization of the onset and propagation of matrix compression damage. However, if high performance composite materials are used complications can arise when the matrix compression strength (σMC) exceeds the matrix tension strength (σMT). When the σMC/σMT ratio is greater than 2, compact compression (CC) specimens can exhibit matrix tension damage before the onset of matrix compression damage. The onset of matrix tension damage prevents proper characterization of matrix compression damage mechanisms. This paper presents the development of a novel stepped compact compression specimen. The reduced thickness of the stepped region allows significant matrix-compression damage to occur prior to tensile failure. Specimens comprised of 90° plies were fabricated using either a machined taper or a layering process. Both methods were successful however variability in machining generated substantial inconsistency and layering was found to be superior.
{"title":"Development of Novel Compact Compression Specimen for Matrix Compression Damage Initiation and Propagation Behavior in Fiber Reinforced Composites","authors":"T. McKinley, K. Carpenter, J. Parmigiani","doi":"10.1115/IMECE2018-87106","DOIUrl":"https://doi.org/10.1115/IMECE2018-87106","url":null,"abstract":"Robust design and analysis of carbon fiber reinforced polymers (CFRP) mandates a thorough understanding of the onset and propagation of damaging mechanisms. Damage can manifest from fiber tension, fiber compression, matrix tension, and matrix compression. Of these damage forms, matrix compression has seen the least attention. Previous work has developed experimental specimens that enabled characterization of the onset and propagation of matrix compression damage. However, if high performance composite materials are used complications can arise when the matrix compression strength (σMC) exceeds the matrix tension strength (σMT). When the σMC/σMT ratio is greater than 2, compact compression (CC) specimens can exhibit matrix tension damage before the onset of matrix compression damage. The onset of matrix tension damage prevents proper characterization of matrix compression damage mechanisms. This paper presents the development of a novel stepped compact compression specimen. The reduced thickness of the stepped region allows significant matrix-compression damage to occur prior to tensile failure. Specimens comprised of 90° plies were fabricated using either a machined taper or a layering process. Both methods were successful however variability in machining generated substantial inconsistency and layering was found to be superior.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125037215","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}
Characterizing the permeation performance of nano-porous material is an initial step towards predicting micro-flows and achieving acceptable designs in sealing and filtration applications. The present study deals with analytical, numerical, and experimental studies of gaseous leaks through soft packing materials. The paper presents a new analytical model to accurately predict and correlate gaseous leak rates through nano-porous materials. The analytical prediction is done with a model of fluid flow through capillaries of an exponentially varying section. Based on Navier-Stokes equations with different flow regimes, the analytical model is used to predict gaseous flow rates through soft packing materials. In addition, for comparison, computational fluid dynamic modelling using CFX software is used to estimate the flow rate of compression packing ring materials assuming the fluid flow to follow Darcy’s law. Helium gas is used as a reference gas to characterize the porosity parameters. The analytical and CFX numerical leak predictions are compared to leak rates measured experimentally using different gas types (Helium, Nitrogen, Air, and Argon) at different pressures and gland stresses. The packing material is subjected to different compression stress levels in order to change its porosity.
{"title":"Prediction of Leak Rates Through Porous Materials Using Analytical and Numerical Approaches","authors":"Ali Salah Omar Aweimer, A. Bouzid, Zijian Zhao","doi":"10.1115/IMECE2018-88683","DOIUrl":"https://doi.org/10.1115/IMECE2018-88683","url":null,"abstract":"Characterizing the permeation performance of nano-porous material is an initial step towards predicting micro-flows and achieving acceptable designs in sealing and filtration applications. The present study deals with analytical, numerical, and experimental studies of gaseous leaks through soft packing materials.\u0000 The paper presents a new analytical model to accurately predict and correlate gaseous leak rates through nano-porous materials. The analytical prediction is done with a model of fluid flow through capillaries of an exponentially varying section. Based on Navier-Stokes equations with different flow regimes, the analytical model is used to predict gaseous flow rates through soft packing materials. In addition, for comparison, computational fluid dynamic modelling using CFX software is used to estimate the flow rate of compression packing ring materials assuming the fluid flow to follow Darcy’s law. Helium gas is used as a reference gas to characterize the porosity parameters. The analytical and CFX numerical leak predictions are compared to leak rates measured experimentally using different gas types (Helium, Nitrogen, Air, and Argon) at different pressures and gland stresses. The packing material is subjected to different compression stress levels in order to change its porosity.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121764781","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}
We introduce a sensor concept for an integrated measurement of the curvature angle of soft bending actuators using inertial measurement units (IMUs). In particular, IMUs are placed at both ends of the soft bending actuator, and the integrated magnetic sensors are used for small and the integrated acceleration sensors for medium and large inclination angles of the soft actuator’s bending plane. The experimental results show absolute measurement errors of up to 20° for small and less than 5° for medium and large inclination angles. Furthermore, we investigate experimentally whether the assumption of a constant curvature in our sensor concept is still fulfilled when the soft bending actuator is loaded by an external force at its free end. The results indicate that this is the case for loading masses of up to 30 g at large inclination angles.
{"title":"Integrated Curvature Sensing of Soft Bending Actuators Using Inertial Measurement Units","authors":"A. Seibel, Lars Schiller","doi":"10.1115/IMECE2018-87104","DOIUrl":"https://doi.org/10.1115/IMECE2018-87104","url":null,"abstract":"We introduce a sensor concept for an integrated measurement of the curvature angle of soft bending actuators using inertial measurement units (IMUs). In particular, IMUs are placed at both ends of the soft bending actuator, and the integrated magnetic sensors are used for small and the integrated acceleration sensors for medium and large inclination angles of the soft actuator’s bending plane. The experimental results show absolute measurement errors of up to 20° for small and less than 5° for medium and large inclination angles. Furthermore, we investigate experimentally whether the assumption of a constant curvature in our sensor concept is still fulfilled when the soft bending actuator is loaded by an external force at its free end. The results indicate that this is the case for loading masses of up to 30 g at large inclination angles.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122044365","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}
M. Ardebili, K. T. Ikikardaslar, Erik Chauca, F. Delale
Auxetic structures exhibiting non-linear deformation are a prevalent research topic in the material sciences due to their negative Poisson’s ratio. The auxetic behavior is most efficiently accomplished through buckling or hinging of 3d printed structures created with soft or flexible materials. These structures have been hypothesized to have some unique characteristics and may provide advantages over conventional engineering materials in certain applications. The objective of present study is to gain a better understanding of behavior of auxetic structures subjected to tensile, compressive and impact loads and assess geometric parameters affecting these structures in applications such as impact shielding or biomedicine. Analytical and experimental methods were employed to investigate two different types of auxetic structures which were 3d-printed with TPU (thermoplastic polyurethane). The first was based on symmetric re-entrant angles cells patterned to form sheet-like structure. Rotation of members in opposite directions in a cell induces negative Poisson’s ratio when the structure is subjected to tensile loading. The second structure was based on rectangular lattice of circular holes. This structure exhibited auxeticity due to formation of pattern of alternating mutually orthogonal ellipses when subjected to compressive and impact loads. Parameters of interest in this study included hardness of the plastic used in printing the structures, the fill pattern of 3d-printed solid parts, porosity of cylinders in the lattice structure, angles and thickness of members in the re-entrant structure. Preliminary results indicated that per unit weight of material, the re-entrant structure requires less tensile load to strain than a solid structure. This is advantageous in applications where expansion in lateral direction is required. The lattice of circular holes structure exhibited similar trend in impact and compressive loading. The results indicate that geometric parameters influence auxeticity of the structure a great deal. When the porosity of the lattice is too small, positive Poisson’s ratio is observed. The length to height ratio of the re-entrant cell has similar effect on the structure’s Poisson’s ratio. The main advantage gained by employing such structures is their overall ability to resist buckling and withstand impact load without cracking. This study will help to develop 3D-printing techniques in manufacturing better performing structures under similar conditions.
{"title":"Behavior of Soft 3D-Printed Auxetic Structures Under Various Loading Conditions","authors":"M. Ardebili, K. T. Ikikardaslar, Erik Chauca, F. Delale","doi":"10.1115/IMECE2018-87859","DOIUrl":"https://doi.org/10.1115/IMECE2018-87859","url":null,"abstract":"Auxetic structures exhibiting non-linear deformation are a prevalent research topic in the material sciences due to their negative Poisson’s ratio. The auxetic behavior is most efficiently accomplished through buckling or hinging of 3d printed structures created with soft or flexible materials. These structures have been hypothesized to have some unique characteristics and may provide advantages over conventional engineering materials in certain applications. The objective of present study is to gain a better understanding of behavior of auxetic structures subjected to tensile, compressive and impact loads and assess geometric parameters affecting these structures in applications such as impact shielding or biomedicine. Analytical and experimental methods were employed to investigate two different types of auxetic structures which were 3d-printed with TPU (thermoplastic polyurethane). The first was based on symmetric re-entrant angles cells patterned to form sheet-like structure. Rotation of members in opposite directions in a cell induces negative Poisson’s ratio when the structure is subjected to tensile loading. The second structure was based on rectangular lattice of circular holes. This structure exhibited auxeticity due to formation of pattern of alternating mutually orthogonal ellipses when subjected to compressive and impact loads.\u0000 Parameters of interest in this study included hardness of the plastic used in printing the structures, the fill pattern of 3d-printed solid parts, porosity of cylinders in the lattice structure, angles and thickness of members in the re-entrant structure. Preliminary results indicated that per unit weight of material, the re-entrant structure requires less tensile load to strain than a solid structure. This is advantageous in applications where expansion in lateral direction is required. The lattice of circular holes structure exhibited similar trend in impact and compressive loading. The results indicate that geometric parameters influence auxeticity of the structure a great deal. When the porosity of the lattice is too small, positive Poisson’s ratio is observed. The length to height ratio of the re-entrant cell has similar effect on the structure’s Poisson’s ratio. The main advantage gained by employing such structures is their overall ability to resist buckling and withstand impact load without cracking. This study will help to develop 3D-printing techniques in manufacturing better performing structures under similar conditions.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125094930","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}
In this work, we perform a numerical study on the flow induced by the motion of a rigid cantilever beam undergoing finite amplitude oscillations, in a viscous fluid, under a free surface. To this aim, we use a lattice Boltzmann volume of fluid (LB-VOF) integrated method, which includes the tracking of the fluid surface. The adopted approach couples the simplicity of the LB method with the possibility to track the free surface by means of a VOF strategy. Through a parametric analysis, we study the effects related to the depth of submergence, for several values of the oscillation frequency and amplitude. Results are provided in terms of a complex hydrodynamic function, whose real and imaginary parts are the added mass and the viscous damping, respectively, acting on the lamina. Validation of the results is carried out by comparing the solution, for the limit case of lamina submerged in an infinite fluid, with those from available literature studies. We find that the presence of the free surface strongly influences the flow physics around the lamina, especially at low values of the depth of submergence. In facts, when the lamina approaches to the free surface, the fluid waves, generated by the motion of the lamina, interact with the oscillating body itself, giving rise to additional effects, which we quantify in terms of added mass and viscous damping.
{"title":"Analysis of the Fluid Motion Induced by a Vibrating Lamina Through Free Surface-Lattice Boltzmann Coupled Method","authors":"D. Chiappini, G. D. Ilio, G. Bella","doi":"10.1115/IMECE2018-87715","DOIUrl":"https://doi.org/10.1115/IMECE2018-87715","url":null,"abstract":"In this work, we perform a numerical study on the flow induced by the motion of a rigid cantilever beam undergoing finite amplitude oscillations, in a viscous fluid, under a free surface. To this aim, we use a lattice Boltzmann volume of fluid (LB-VOF) integrated method, which includes the tracking of the fluid surface. The adopted approach couples the simplicity of the LB method with the possibility to track the free surface by means of a VOF strategy. Through a parametric analysis, we study the effects related to the depth of submergence, for several values of the oscillation frequency and amplitude. Results are provided in terms of a complex hydrodynamic function, whose real and imaginary parts are the added mass and the viscous damping, respectively, acting on the lamina. Validation of the results is carried out by comparing the solution, for the limit case of lamina submerged in an infinite fluid, with those from available literature studies. We find that the presence of the free surface strongly influences the flow physics around the lamina, especially at low values of the depth of submergence. In facts, when the lamina approaches to the free surface, the fluid waves, generated by the motion of the lamina, interact with the oscillating body itself, giving rise to additional effects, which we quantify in terms of added mass and viscous damping.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125625529","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}
Stretching properties of single-walled carbon nanotubes (CNTs) of large diameters are studied in atomistic simulations. The simulations are performed based on the AIREBO empirical interatomic potential for three types of CNTs: Nanotubes with circular cross section, permanently collapsed nanotubes with “dog-bone”-shaped cross sections, and collapsed nanotubes with intra-tube covalent cross-links. In the last case, the cross-links between parallel quasi-planar parts of the nanotube wall are assumed to be formed by interstitial carbon atoms. The calculated equilibrium shape of collapsed nanotubes and the threshold diameter for permanently collapsed CNTs are found to agree with existing literature data. Elastic modulus, maximum stress, and strain at failure are calculated for zigzag CNTs with the equivalent diameter up to 6.27 nm in the temperature range from 5 K to 500 K. The simulations show that these mechanical properties only moderately depend on the diameter of circular CNTs. For collapsed CNTs with and without cross-links, the mechanical properties are practically independent of the CNT diameter for nanotubes with diameters larger than 4.7 nm. The elastic modulus and maximum stress of collapsed nanotubes are found to be smaller than those for the equivalent circular CNTs. The intra-tube cross-linking increases the elastic modulus and strength of collapsed CNTs in up to 50% compared to corresponding collapsed CNTs without cross-links, but reduces the breaking strain. Thermal softening of CNTs with increasing temperature in the range from 100 K to 500 K induces a decrease in the elastic modulus and maximum stress in about 12–33%.
{"title":"Atomistic Simulations of Mechanical Properties of Circular and Collapsed Carbon Nanotubes With Covalent Cross-Links","authors":"Arun Thapa, A. Volkov","doi":"10.1115/IMECE2018-88172","DOIUrl":"https://doi.org/10.1115/IMECE2018-88172","url":null,"abstract":"Stretching properties of single-walled carbon nanotubes (CNTs) of large diameters are studied in atomistic simulations. The simulations are performed based on the AIREBO empirical interatomic potential for three types of CNTs: Nanotubes with circular cross section, permanently collapsed nanotubes with “dog-bone”-shaped cross sections, and collapsed nanotubes with intra-tube covalent cross-links. In the last case, the cross-links between parallel quasi-planar parts of the nanotube wall are assumed to be formed by interstitial carbon atoms. The calculated equilibrium shape of collapsed nanotubes and the threshold diameter for permanently collapsed CNTs are found to agree with existing literature data. Elastic modulus, maximum stress, and strain at failure are calculated for zigzag CNTs with the equivalent diameter up to 6.27 nm in the temperature range from 5 K to 500 K. The simulations show that these mechanical properties only moderately depend on the diameter of circular CNTs. For collapsed CNTs with and without cross-links, the mechanical properties are practically independent of the CNT diameter for nanotubes with diameters larger than 4.7 nm. The elastic modulus and maximum stress of collapsed nanotubes are found to be smaller than those for the equivalent circular CNTs. The intra-tube cross-linking increases the elastic modulus and strength of collapsed CNTs in up to 50% compared to corresponding collapsed CNTs without cross-links, but reduces the breaking strain. Thermal softening of CNTs with increasing temperature in the range from 100 K to 500 K induces a decrease in the elastic modulus and maximum stress in about 12–33%.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122697621","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}
Square tubes are primarily used in automotive structures to absorb energy in the event of an accident. The energy absorption capacity of these structural members depends on several parameters such as tube material, wall thickness, axial length, deformation modes, locking strain, crushing stress, etc. In this paper, the work presented is a continuation of research conducted on exploring the effects of the introduction of cellular core in tubular structures under axial compressive loading. Here, the crushing response of composite cellular core tube was numerically studied using ABAQUS/Explicit module. The energy absorbing characteristics such as deformation or collapsing modes, crushing/ reactive force, crushing stroke, and energy curves were discussed. The composite cellular core tube shows promise for improving the crashworthiness of automobiles.
{"title":"Study of Energy Absorption Characteristics of Square Tube With Composite Cellular Core","authors":"Muhammad Ali, E. Ohioma, K. Alam","doi":"10.1115/IMECE2018-86916","DOIUrl":"https://doi.org/10.1115/IMECE2018-86916","url":null,"abstract":"Square tubes are primarily used in automotive structures to absorb energy in the event of an accident. The energy absorption capacity of these structural members depends on several parameters such as tube material, wall thickness, axial length, deformation modes, locking strain, crushing stress, etc. In this paper, the work presented is a continuation of research conducted on exploring the effects of the introduction of cellular core in tubular structures under axial compressive loading. Here, the crushing response of composite cellular core tube was numerically studied using ABAQUS/Explicit module. The energy absorbing characteristics such as deformation or collapsing modes, crushing/ reactive force, crushing stroke, and energy curves were discussed. The composite cellular core tube shows promise for improving the crashworthiness of automobiles.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"2014 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127526915","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}
So far, mathematical modelling of Lamb wave propagation under fluid-structure interaction (FSI) was limited to the case of rigid structure. We extend this concept to account for structural dynamics. Thereby, we provide a model that is suitable for the structural health monitoring (SHM) during the operation of the structure. The model we develop is referred to as the “eXtended Fluid-Structure Interaction” (eXFSI) problem, which is a one-directional coupling of typical FSI problem with an ultrasonic wave propagation in fluid-solid and their interface (WpFSI). Here, the strongly coupled problem of acoustic & elastic wave equations is denoted by WpFSI. Next, we explore the approach to the efficient numerical solution of the problem. We use a combination of Finite Element and Finite Difference methods and employ a dual-loop algorithm to balance the computational cost and quality of the numerical solution. To facilitate our solution algorithm, we rely upon the software library package DOpElib.
{"title":"Numerical Modeling and Approximation of the Coupling Lamb Wave Propagation With Fluid-Structure Interaction Problem","authors":"B. Hai, M. Bause","doi":"10.1115/IMECE2018-87448","DOIUrl":"https://doi.org/10.1115/IMECE2018-87448","url":null,"abstract":"So far, mathematical modelling of Lamb wave propagation under fluid-structure interaction (FSI) was limited to the case of rigid structure. We extend this concept to account for structural dynamics. Thereby, we provide a model that is suitable for the structural health monitoring (SHM) during the operation of the structure. The model we develop is referred to as the “eXtended Fluid-Structure Interaction” (eXFSI) problem, which is a one-directional coupling of typical FSI problem with an ultrasonic wave propagation in fluid-solid and their interface (WpFSI). Here, the strongly coupled problem of acoustic & elastic wave equations is denoted by WpFSI. Next, we explore the approach to the efficient numerical solution of the problem. We use a combination of Finite Element and Finite Difference methods and employ a dual-loop algorithm to balance the computational cost and quality of the numerical solution. To facilitate our solution algorithm, we rely upon the software library package DOpElib.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132217948","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}
Non-pneumatic tires (NPTs) have drawn attention mainly due to low contact pressure and low rolling resistance due to use of hyper-elastic materials in their construction. In this paper, an attempt to innovate the conventional design of NPT with hexagonal honeycomb cellular structure is made by creating the boundary planar geometries of the tire, skew to each other at a certain angle. Adding to the functionality as a tire, this modified structure increases the performance of automobile components by rejection of heat through convection (forced) at the expense of engine power. The primary investigation includes study of the effects of variation in degree of skewness with the strength and flow of air through the tire. The flow parameters are computed for rotational case and the heat transfer is computed for flow over a brake disk. The secondary investigation consists of finding an optimum range of the degree of skewness. The validation for strength is computed through Finite Element Analysis. The fluid flow is computed through Computational Fluid Dynamics approach in ANSYS Fluent. This modified structure improves the aerodynamic condition near the brake rotor that increases the rate of heat rejection by forced convection from the brake rotor surface.
{"title":"Investigation of Non-Pneumatic Tires Based on Helical Hexagonal Cellular Structure","authors":"M. Pewekar, Pranit Pravin Sandye, K. Chaudhari","doi":"10.1115/IMECE2018-87631","DOIUrl":"https://doi.org/10.1115/IMECE2018-87631","url":null,"abstract":"Non-pneumatic tires (NPTs) have drawn attention mainly due to low contact pressure and low rolling resistance due to use of hyper-elastic materials in their construction. In this paper, an attempt to innovate the conventional design of NPT with hexagonal honeycomb cellular structure is made by creating the boundary planar geometries of the tire, skew to each other at a certain angle. Adding to the functionality as a tire, this modified structure increases the performance of automobile components by rejection of heat through convection (forced) at the expense of engine power. The primary investigation includes study of the effects of variation in degree of skewness with the strength and flow of air through the tire. The flow parameters are computed for rotational case and the heat transfer is computed for flow over a brake disk. The secondary investigation consists of finding an optimum range of the degree of skewness. The validation for strength is computed through Finite Element Analysis. The fluid flow is computed through Computational Fluid Dynamics approach in ANSYS Fluent. This modified structure improves the aerodynamic condition near the brake rotor that increases the rate of heat rejection by forced convection from the brake rotor surface.","PeriodicalId":375383,"journal":{"name":"Volume 9: Mechanics of Solids, Structures, and Fluids","volume":"258 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127388739","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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