Aside from ultrahigh strength and elasticity, metallic glasses (MGs) possess a number of favorable properties. However, their lack of dislocation based plastic deformation mechanisms in crystalline metals and the resulting loss of ductility have restricted the engineering applications of MGs over the last 60 years. This review aims to provide an overview of deformation and failure mechanisms of MGs via formation and propagation of shear bands (SBs), with an emphasis on the control of SBs to promote strength-ductility synergy. With this goal in mind, we highlight some of the emerging strategies to improve the ductility of MGs. Topics covered include post-processing techniques such as pre-compression, heterogeneity tuning, and rejuvenation, with a primary focus on recent progresses in structural design based methods including nanoglasses, notched MGs, and MG nanolattices, as future innovations towards strength-ductility synergy beyond the current benchmark ranges.
{"title":"Shear Band Control for Improved Strength-Ductility Synergy in Metallic Glasses","authors":"Z. Sha, Y. Teng, L. H. Poh, T. Wang, Huajian Gao","doi":"10.1115/1.4056010","DOIUrl":"https://doi.org/10.1115/1.4056010","url":null,"abstract":"\u0000 Aside from ultrahigh strength and elasticity, metallic glasses (MGs) possess a number of favorable properties. However, their lack of dislocation based plastic deformation mechanisms in crystalline metals and the resulting loss of ductility have restricted the engineering applications of MGs over the last 60 years. This review aims to provide an overview of deformation and failure mechanisms of MGs via formation and propagation of shear bands (SBs), with an emphasis on the control of SBs to promote strength-ductility synergy. With this goal in mind, we highlight some of the emerging strategies to improve the ductility of MGs. Topics covered include post-processing techniques such as pre-compression, heterogeneity tuning, and rejuvenation, with a primary focus on recent progresses in structural design based methods including nanoglasses, notched MGs, and MG nanolattices, as future innovations towards strength-ductility synergy beyond the current benchmark ranges.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"29 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2022-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74438153","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}
Untethered mobile robots at the micro-scale have the ability to improve biomedical research by performing specialized tasks inside complex physiological environments. Light-controlled wireless microbots are becoming the center of interest thanks to their accuracy in navigation and potential to carry out operations in a non-invasive manner inside living environments. The pioneering light-engineered microbots are currently in the early stage of animal trials. There is a long way ahead before they can be employed in humans for therapeutic applications such as targeted drug delivery, cancer cell diagnosis, tissue engineering, etc. The design of light-actuated microbots is one of the challenging parts along with the biocompatibility and precision control for in vivo applications. Recent progress in light-activated microbots has revealed a few innovative design concepts. In this study, we presented a framework on the different aspects with a comparative analysis of potential designs for the next generation of light-controlled microbots. Utilizing numerical simulations of fluid-structure interactions, limiting design elements of the microbots are addressed. We envision that this study will eventually facilitate the integration of robotic applications into the real world owing to the described design considerations.
{"title":"Design and Fabrication of Untethered Light-Actuated Microbots in Fluid for Biomedical Applications","authors":"Md. Faiyaz Jamil, Mishal Pokharel, Kihan Park","doi":"10.3390/applmech3040071","DOIUrl":"https://doi.org/10.3390/applmech3040071","url":null,"abstract":"Untethered mobile robots at the micro-scale have the ability to improve biomedical research by performing specialized tasks inside complex physiological environments. Light-controlled wireless microbots are becoming the center of interest thanks to their accuracy in navigation and potential to carry out operations in a non-invasive manner inside living environments. The pioneering light-engineered microbots are currently in the early stage of animal trials. There is a long way ahead before they can be employed in humans for therapeutic applications such as targeted drug delivery, cancer cell diagnosis, tissue engineering, etc. The design of light-actuated microbots is one of the challenging parts along with the biocompatibility and precision control for in vivo applications. Recent progress in light-activated microbots has revealed a few innovative design concepts. In this study, we presented a framework on the different aspects with a comparative analysis of potential designs for the next generation of light-controlled microbots. Utilizing numerical simulations of fluid-structure interactions, limiting design elements of the microbots are addressed. We envision that this study will eventually facilitate the integration of robotic applications into the real world owing to the described design considerations.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"16 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2022-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83537897","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}
A Dynamic Finite Element (DFE) method for coupled axial–flexural undamped free vibration analysis of functionally graded beams is developed and subsequently used to investigate the system’s natural frequencies and mode shapes. The formulation is based on the Euler–Bernoulli beam theory and material grading is assumed to follow a power law variation through the thickness direction. Using the closed-form solutions to the uncoupled segments of the system’s governing differential equations as the basis functions of approximation space, the dynamic, frequency-dependent, trigonometric interpolation functions are developed. The interpolation functions are used with the weighted residual method to develop the DFE of the system. The resulting nonlinear eigenvalue problem is then solved to determine the coupled natural frequencies. Example elements using DFE, Finite Element Method (FEM) and the Dynamic Stiffness Method (DSM) are implemented in MATLAB for testing, verification, and validation. Good agreement was observed and the DFE formulation exhibited superior convergence performance compared to the FEM.
{"title":"Undamped Free Vibration Analysis of Functionally Graded Beams: A Dynamic Finite Element Approach","authors":"A. Gee, S. M. Hashemi","doi":"10.3390/applmech3040070","DOIUrl":"https://doi.org/10.3390/applmech3040070","url":null,"abstract":"A Dynamic Finite Element (DFE) method for coupled axial–flexural undamped free vibration analysis of functionally graded beams is developed and subsequently used to investigate the system’s natural frequencies and mode shapes. The formulation is based on the Euler–Bernoulli beam theory and material grading is assumed to follow a power law variation through the thickness direction. Using the closed-form solutions to the uncoupled segments of the system’s governing differential equations as the basis functions of approximation space, the dynamic, frequency-dependent, trigonometric interpolation functions are developed. The interpolation functions are used with the weighted residual method to develop the DFE of the system. The resulting nonlinear eigenvalue problem is then solved to determine the coupled natural frequencies. Example elements using DFE, Finite Element Method (FEM) and the Dynamic Stiffness Method (DSM) are implemented in MATLAB for testing, verification, and validation. Good agreement was observed and the DFE formulation exhibited superior convergence performance compared to the FEM.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"1 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2022-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88405038","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}
Predicting the behavior of a saturated rock with variations in pore fluid pressure during geo-energy production and storage, deep geological disposal of nuclear wastes, etc. is carried out using the isothermal theory of poroelasticity that incorporates Biot's effective stress principle. Several experimental methods for determining Biot's effective stress parameter have been documented in the literature. The original definition of Biot's effective stress is constantly being extended to account for non-linear and inelastic behavior of the rock. The objective of this study is to review the fundamentals of the original experimental approach for determining Biot's coefficient and other developments, their advantages and disadvantages, and include several case studies. Current techniques are based on different premises: jacketed and unjacketed bulk moduli or compressibility values; volume changes of the bulk and pore fluid from a drained triaxial test on a saturated sample; isotropic-isochoric compression tests on a saturated sample; matching volumetric strains or failure envelopes for dry and saturated samples; variations of rock properties, such as volumetric strain, permeability, compressional and shear wave velocities, with respect to confining stress and pore pressure; estimation of the Biot coefficient from other poroelastic parameters; and approximation of the dry bulk modulus or unjacketed bulk modulus of the rock from mineralogical compositions or ultrasonic wave velocities. This article discusses variations in Biot's effective stress coefficients produced using the different techniques and how factors such as pore geometry, test conditions, stress path, and test temperature affect the Biot's coefficient.
{"title":"A Review of Techniques for Measuring the Biot Coefficient and Other Effective Stress Parameters for Fluid-Saturated Rocks","authors":"H. Kasani, A. Selvadurai","doi":"10.1115/1.4055888","DOIUrl":"https://doi.org/10.1115/1.4055888","url":null,"abstract":"\u0000 Predicting the behavior of a saturated rock with variations in pore fluid pressure during geo-energy production and storage, deep geological disposal of nuclear wastes, etc. is carried out using the isothermal theory of poroelasticity that incorporates Biot's effective stress principle. Several experimental methods for determining Biot's effective stress parameter have been documented in the literature. The original definition of Biot's effective stress is constantly being extended to account for non-linear and inelastic behavior of the rock. The objective of this study is to review the fundamentals of the original experimental approach for determining Biot's coefficient and other developments, their advantages and disadvantages, and include several case studies. Current techniques are based on different premises: jacketed and unjacketed bulk moduli or compressibility values; volume changes of the bulk and pore fluid from a drained triaxial test on a saturated sample; isotropic-isochoric compression tests on a saturated sample; matching volumetric strains or failure envelopes for dry and saturated samples; variations of rock properties, such as volumetric strain, permeability, compressional and shear wave velocities, with respect to confining stress and pore pressure; estimation of the Biot coefficient from other poroelastic parameters; and approximation of the dry bulk modulus or unjacketed bulk modulus of the rock from mineralogical compositions or ultrasonic wave velocities. This article discusses variations in Biot's effective stress coefficients produced using the different techniques and how factors such as pore geometry, test conditions, stress path, and test temperature affect the Biot's coefficient.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"46 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2022-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87334262","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}
Damaged support bores due to wear and ovality can be critical for a machine and its operation, in addition to representing a safety problem and risk of pin breakage. It can be a costly operation to perform the required repairs in between planned service periods, especially because of the unplanned down time. A joint with a standard cylindrical pin will often experience wear and ovality in the support bore surfaces, and at some point, repairs will have to be performed. This study investigates and compares five options when a joint with a cylindrical pin has reached a severe level of wear and ovality, outside its planned service stop. The work involved testing the viability of 3D scanning of the damaged bore surface, 3D printing of a metal bushing, and inserting the bushing into the damaged joint. In addition, two pin solutions, i.e., a standard cylindrical pin and an expanding pin type, were installed into the repaired joint, loaded, and the strain on the pin ends close to the supports was measured. For the sake of comparison, the supports had both smooth circular bore and severe wear and ovality. It was concluded that it is possible to produce and install the 3D-printed bushing insert without major problems; the insert had satisfactory capability during test loading, and it most probably represents a good solution when it comes to the reduction in unwanted downtime during unplanned repairs of damaged joints.
{"title":"A Novel Technique for Temporarily Repair and Improvement of Damaged Pin Joint Support Bores","authors":"Ø. Karlsen, H. Lemu, I. Berkani","doi":"10.3390/applmech3040069","DOIUrl":"https://doi.org/10.3390/applmech3040069","url":null,"abstract":"Damaged support bores due to wear and ovality can be critical for a machine and its operation, in addition to representing a safety problem and risk of pin breakage. It can be a costly operation to perform the required repairs in between planned service periods, especially because of the unplanned down time. A joint with a standard cylindrical pin will often experience wear and ovality in the support bore surfaces, and at some point, repairs will have to be performed. This study investigates and compares five options when a joint with a cylindrical pin has reached a severe level of wear and ovality, outside its planned service stop. The work involved testing the viability of 3D scanning of the damaged bore surface, 3D printing of a metal bushing, and inserting the bushing into the damaged joint. In addition, two pin solutions, i.e., a standard cylindrical pin and an expanding pin type, were installed into the repaired joint, loaded, and the strain on the pin ends close to the supports was measured. For the sake of comparison, the supports had both smooth circular bore and severe wear and ovality. It was concluded that it is possible to produce and install the 3D-printed bushing insert without major problems; the insert had satisfactory capability during test loading, and it most probably represents a good solution when it comes to the reduction in unwanted downtime during unplanned repairs of damaged joints.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"24 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2022-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77926557","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}
L. Gerdes, S. Berger, J. Saelzer, Pascal Franck, Ramon Helwing, A. Zabel, F. Walther
In order to achieve realistic simulations of the chip formation, high quality input data regarding the flow stress and damage behavior of the materials are required. The split Hopkinson pressure bar (SHPB) test setup for the characterization of highly dynamic material properties offers a suitable method for generating high strain rates, similar to those in the chip formation zone. However, the strain measurement in SHPB is usually performed by means of strain gauges. This leads to an unreliable evaluation of strain rate and flow stress/shear flow stress in the case of an inhomogeneous material deformation, since this method presents the total strain whilst excluding local deformations. Inhomogeneous deformations are induced deliberately in special shear specimens, as they are also observed in the investigated cylindrical specimens. The present work deals with this issue by providing two additional measurement techniques, which are applied in SHPB tests for cylindrical specimens made of AISI 1045 and Ti6Al4V. To enable a local strain resolution, digital image correlation (DIC) is applied to high-speed images of the deformation process. In order to allow for the detection of shear bands in the specimens, a deep-learning-based approach is presented. The two measurement methods (strain gauges and DIC) are compared and discussed. In particular, the findings regarding the inhomogeneous deformation of Ti6Al4V allow for future improvements in the result quality of SHPB tests. The presented algorithm shows promising predictions for shear band detection and creates the basis for an automated evaluation of shear sample results, as well as an AI-based pre-selection of frames for the DIC evaluation of SHPB tests.
{"title":"Application-Oriented Digital Image Correlation for the High-Speed Deformation and Fracture Analysis of AISI 1045 and Ti6Al4V Materials","authors":"L. Gerdes, S. Berger, J. Saelzer, Pascal Franck, Ramon Helwing, A. Zabel, F. Walther","doi":"10.3390/applmech3040068","DOIUrl":"https://doi.org/10.3390/applmech3040068","url":null,"abstract":"In order to achieve realistic simulations of the chip formation, high quality input data regarding the flow stress and damage behavior of the materials are required. The split Hopkinson pressure bar (SHPB) test setup for the characterization of highly dynamic material properties offers a suitable method for generating high strain rates, similar to those in the chip formation zone. However, the strain measurement in SHPB is usually performed by means of strain gauges. This leads to an unreliable evaluation of strain rate and flow stress/shear flow stress in the case of an inhomogeneous material deformation, since this method presents the total strain whilst excluding local deformations. Inhomogeneous deformations are induced deliberately in special shear specimens, as they are also observed in the investigated cylindrical specimens. The present work deals with this issue by providing two additional measurement techniques, which are applied in SHPB tests for cylindrical specimens made of AISI 1045 and Ti6Al4V. To enable a local strain resolution, digital image correlation (DIC) is applied to high-speed images of the deformation process. In order to allow for the detection of shear bands in the specimens, a deep-learning-based approach is presented. The two measurement methods (strain gauges and DIC) are compared and discussed. In particular, the findings regarding the inhomogeneous deformation of Ti6Al4V allow for future improvements in the result quality of SHPB tests. The presented algorithm shows promising predictions for shear band detection and creates the basis for an automated evaluation of shear sample results, as well as an AI-based pre-selection of frames for the DIC evaluation of SHPB tests.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"26 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2022-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84133572","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 design and optimization of re-entry spacecraft or its subsystems is a multidisciplinary or multiobjective optimization problem by nature. Multidisciplinary design optimization (MDO) focuses on using numerical optimization in designing systems with several subsystems or disciplines that have interactions and independent actions. In the present paper, the system-level optimizer, trajectory, geometry and shape, aerodynamics, and aerothermodynamics differential equations, are converted to algebraic equations using the Radau pseudospectral method (RPM) since a spacecraft is a nonlinear, extensive, and sparse system. The solution to the problem with the help of MDO is reached by iterating all the disciplines together; one can simultaneously enhance the design, decrease the time and cost of the entire design cycle, and minimize the structural mass of a re-entry spacecraft. Considering various methods presented in earlier research works, a combined and innovative all-at-once (AAO), RPM-based MDO method, including the key subsystems in the design process of a re-entry capsule-shape spacecraft with a low lift-to-drag ratio (L/D), is presented. Considering the applicable state and control variables, various constraints, and parameters applied to several geometric shapes of a blunt capsule and using Apollo’s aerodynamic and aerothermodynamic coefficients, the optimized dimensions for a re-entry spacecraft are presented. The introduced optimization scheme led to a 17% mass reduction compared to the original mass of the Apollo vehicle. Fast computing and simplified models are used together in this method to analyze a wide range of vehicle shapes and entry types during conceptual design.
{"title":"Multidisciplinary Design Optimization of a Re-Entry Spacecraft via Radau Pseudospectral Method","authors":"Masoud Kabganian, S. M. Hashemi, J. Roshanian","doi":"10.3390/applmech3040067","DOIUrl":"https://doi.org/10.3390/applmech3040067","url":null,"abstract":"The design and optimization of re-entry spacecraft or its subsystems is a multidisciplinary or multiobjective optimization problem by nature. Multidisciplinary design optimization (MDO) focuses on using numerical optimization in designing systems with several subsystems or disciplines that have interactions and independent actions. In the present paper, the system-level optimizer, trajectory, geometry and shape, aerodynamics, and aerothermodynamics differential equations, are converted to algebraic equations using the Radau pseudospectral method (RPM) since a spacecraft is a nonlinear, extensive, and sparse system. The solution to the problem with the help of MDO is reached by iterating all the disciplines together; one can simultaneously enhance the design, decrease the time and cost of the entire design cycle, and minimize the structural mass of a re-entry spacecraft. Considering various methods presented in earlier research works, a combined and innovative all-at-once (AAO), RPM-based MDO method, including the key subsystems in the design process of a re-entry capsule-shape spacecraft with a low lift-to-drag ratio (L/D), is presented. Considering the applicable state and control variables, various constraints, and parameters applied to several geometric shapes of a blunt capsule and using Apollo’s aerodynamic and aerothermodynamic coefficients, the optimized dimensions for a re-entry spacecraft are presented. The introduced optimization scheme led to a 17% mass reduction compared to the original mass of the Apollo vehicle. Fast computing and simplified models are used together in this method to analyze a wide range of vehicle shapes and entry types during conceptual design.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"173 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2022-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77154725","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}
Multiwall polycarbonate sheets are applied as construction elements. Modelling and analysis of thermal processes that occur in this material demand the knowledge of solar transmittance. Values of this parameter determined in laboratory conditions are given in the technical specification of the product. However, the parameter is in practice a complex function depending on the number of factors. This paper presents theoretical and experimental research results for total solar transmittance (TST) for a polycarbonate sheet with twin wall rectangular structure. Theoretical TST is calculated as a product of transmissivity after accounting for light absorption in polycarbonate and of transmissivity after accounting for multiple reflections of solar rays from walls of a channel. The first kind of transmissivity is insignificant and can be neglected. The second one depends on the number of reflection layers, season, and time of day. Experimental TST is determined as the ratio of irradiance under and above the polycarbonate sheet measured by pyranometers. Experimental TST is also a function of time of day and season. Both kinds of TST have an approximately constant value in the time about noon. The theoretical values of TST (0.74) are approximately equal to experimental values of TST (0.75) for the selected summer day. The value of TST in catalogue is equal to 0.82.
{"title":"Theoretical and Experimental Comparisons of Total Solar Transmittance for Polycarbonate Sheet with Twin Wall Rectangular Structure","authors":"Z. Zapałowicz, Agnieszka Garnysz-Rachtan","doi":"10.3390/applmech3040066","DOIUrl":"https://doi.org/10.3390/applmech3040066","url":null,"abstract":"Multiwall polycarbonate sheets are applied as construction elements. Modelling and analysis of thermal processes that occur in this material demand the knowledge of solar transmittance. Values of this parameter determined in laboratory conditions are given in the technical specification of the product. However, the parameter is in practice a complex function depending on the number of factors. This paper presents theoretical and experimental research results for total solar transmittance (TST) for a polycarbonate sheet with twin wall rectangular structure. Theoretical TST is calculated as a product of transmissivity after accounting for light absorption in polycarbonate and of transmissivity after accounting for multiple reflections of solar rays from walls of a channel. The first kind of transmissivity is insignificant and can be neglected. The second one depends on the number of reflection layers, season, and time of day. Experimental TST is determined as the ratio of irradiance under and above the polycarbonate sheet measured by pyranometers. Experimental TST is also a function of time of day and season. Both kinds of TST have an approximately constant value in the time about noon. The theoretical values of TST (0.74) are approximately equal to experimental values of TST (0.75) for the selected summer day. The value of TST in catalogue is equal to 0.82.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"65 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2022-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78170019","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}
E. Ananiadis, Alexander Efstathios Karantzali, D. Exarchos, T. Matikas
New particle reinforced aluminum matrix composites with the addition of refractory High Entropy Alloy, MoTaNbVW, fabricated via powder metallurgy process were assessed for their properties. Basic mechanical properties (modulus of elasticity, hardness) for the aluminum matrix, the pure aluminum and the reinforcement phase were assessed by means of dynamic nano-indentation technique. Nano-indentation based creep response was also evaluated in these three areas of interest. Hardness shows an increase with the addition of the particulates and so does the elastic moduli and the ratio of the energy absorbed in the elastic region. The creep response was approached in terms of dislocation mobility and critical volume for their nucleation. The produced Al–HEA composites were also studied for their sliding wear behavior and showed that with the increase in percentage of RHEA particulates the wear resistance increases. Microstructural considerations, wear track morphologies, and debris characteristics were used for the assessment of the involved wear mechanisms.
{"title":"Al-RHEA Particulates MMCs by PM Route: Mechanical Properties and Sliding Wear Response","authors":"E. Ananiadis, Alexander Efstathios Karantzali, D. Exarchos, T. Matikas","doi":"10.3390/applmech3030065","DOIUrl":"https://doi.org/10.3390/applmech3030065","url":null,"abstract":"New particle reinforced aluminum matrix composites with the addition of refractory High Entropy Alloy, MoTaNbVW, fabricated via powder metallurgy process were assessed for their properties. Basic mechanical properties (modulus of elasticity, hardness) for the aluminum matrix, the pure aluminum and the reinforcement phase were assessed by means of dynamic nano-indentation technique. Nano-indentation based creep response was also evaluated in these three areas of interest. Hardness shows an increase with the addition of the particulates and so does the elastic moduli and the ratio of the energy absorbed in the elastic region. The creep response was approached in terms of dislocation mobility and critical volume for their nucleation. The produced Al–HEA composites were also studied for their sliding wear behavior and showed that with the increase in percentage of RHEA particulates the wear resistance increases. Microstructural considerations, wear track morphologies, and debris characteristics were used for the assessment of the involved wear mechanisms.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"9 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2022-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87111084","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}
A. Sudasinghe, Padmassun Rajakareyar, E. Matida, Hamza abo el Ella, M. ElSayed
The growth of the airline industry has highlighted the need for more environmentally conscious aviation, leading to the conceptualization of more fuel-efficient aircraft. One concept that has received significant attention and has been associated with improved fuel efficiency is the boundary layer ingesting (BLI) propulsion system, which refers to the ingesting of the aircraft wake by the propulsors. Although BLI has theoretically been proven to reduce fuel burn, this can potentially be offset by the reduced efficiency and stability experienced by the propulsor in the presence of distorted inflow. Therefore, engine intakes must be optimized in order to mitigate the effects of BLI on the propulsion system. In this work, the shape optimization of a BLI intake is investigated using a free-form deformation technique in combination with a multi-objective genetic algorithm, in order to minimize pressure losses and distortion at the engine inlet. The optimization is performed on an S-duct intake at a cruise altitude of approximately 37,000 feet and a free stream Mach number of 0.7. An optimization strategy was developed for the task which was able to produce a Pareto optimal set of designs with improved pressure recovery and distortion. The general trend of the optimal designs shows that to reduce distortion the optimizer accelerates the flow to reduce the size of the low total pressure region and increase the dynamic pressure at the engine inlet. In contrast, the pressure recovery was increased by reducing velocity as well as shifting the maximum velocity region to the outlet, which reduces the viscous dissipation losses within the intake. The final result is a fully autonomous optimization strategy resulting in reduced pressure losses and reduced distortion leading to higher efficiency BLI S-duct intake designs.
{"title":"Aerodynamic Shape Optimization of an Aircraft Propulsor Air Intake with Boundary Layer Ingestion","authors":"A. Sudasinghe, Padmassun Rajakareyar, E. Matida, Hamza abo el Ella, M. ElSayed","doi":"10.3390/applmech3030064","DOIUrl":"https://doi.org/10.3390/applmech3030064","url":null,"abstract":"The growth of the airline industry has highlighted the need for more environmentally conscious aviation, leading to the conceptualization of more fuel-efficient aircraft. One concept that has received significant attention and has been associated with improved fuel efficiency is the boundary layer ingesting (BLI) propulsion system, which refers to the ingesting of the aircraft wake by the propulsors. Although BLI has theoretically been proven to reduce fuel burn, this can potentially be offset by the reduced efficiency and stability experienced by the propulsor in the presence of distorted inflow. Therefore, engine intakes must be optimized in order to mitigate the effects of BLI on the propulsion system. In this work, the shape optimization of a BLI intake is investigated using a free-form deformation technique in combination with a multi-objective genetic algorithm, in order to minimize pressure losses and distortion at the engine inlet. The optimization is performed on an S-duct intake at a cruise altitude of approximately 37,000 feet and a free stream Mach number of 0.7. An optimization strategy was developed for the task which was able to produce a Pareto optimal set of designs with improved pressure recovery and distortion. The general trend of the optimal designs shows that to reduce distortion the optimizer accelerates the flow to reduce the size of the low total pressure region and increase the dynamic pressure at the engine inlet. In contrast, the pressure recovery was increased by reducing velocity as well as shifting the maximum velocity region to the outlet, which reduces the viscous dissipation losses within the intake. The final result is a fully autonomous optimization strategy resulting in reduced pressure losses and reduced distortion leading to higher efficiency BLI S-duct intake designs.","PeriodicalId":8048,"journal":{"name":"Applied Mechanics Reviews","volume":"40 1","pages":""},"PeriodicalIF":14.3,"publicationDate":"2022-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78117409","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：