Density-driven flow is numerically studied. The sinking fluid is set as a power-law non-Newtonian fluid with a higher density than the environmental fluid. During the simulation process, saturation concentration is fixed on the upper boundary, thus downward plumes are formed because of gravitational instability. The dissolution flux undergoes a series of changes, from the initially diffusion-dominated regime to the convection-dominated regime due to the appearance of finger structures, and then to the transition of finger structures merging into larger plumes. Finally, it enters the shut-down regime as the plumes start to reach the impermeable bottom boundary. In the process of plume sinking, different fluid properties have an important impact on the downward velocity, shape of plumes, and the dissolution flux of the flow field. The tip velocity of the plumes is slowed until high-concentration fluid is supplied to further push the plumes downward. For the shear-thinning fluid ambient fluid, this phenomenon is even more drastic. However, for shear-thickening fluid, this phenomenon is almost not observed. In addition, unlike the condition of a Newtonian fluid, protoplumes on the original interface appear at the early stage. Prominent protoplumes have developed between the primary plumes in non-Newtonian fluids throughout the entire process.
{"title":"Numerical Simulation of Density-Driven Non-Newtonian Fluid Flow","authors":"Yu-Shan Li, Ching-Yao Chen","doi":"10.1093/jom/ufad017","DOIUrl":"https://doi.org/10.1093/jom/ufad017","url":null,"abstract":"\u0000 Density-driven flow is numerically studied. The sinking fluid is set as a power-law non-Newtonian fluid with a higher density than the environmental fluid. During the simulation process, saturation concentration is fixed on the upper boundary, thus downward plumes are formed because of gravitational instability. The dissolution flux undergoes a series of changes, from the initially diffusion-dominated regime to the convection-dominated regime due to the appearance of finger structures, and then to the transition of finger structures merging into larger plumes. Finally, it enters the shut-down regime as the plumes start to reach the impermeable bottom boundary. In the process of plume sinking, different fluid properties have an important impact on the downward velocity, shape of plumes, and the dissolution flux of the flow field. The tip velocity of the plumes is slowed until high-concentration fluid is supplied to further push the plumes downward. For the shear-thinning fluid ambient fluid, this phenomenon is even more drastic. However, for shear-thickening fluid, this phenomenon is almost not observed. In addition, unlike the condition of a Newtonian fluid, protoplumes on the original interface appear at the early stage. Prominent protoplumes have developed between the primary plumes in non-Newtonian fluids throughout the entire process.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":"170 ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41280614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, a finite element model is developed to analyze the grinding force and warpage of silicon wafers during the backside grinding process. Due to the decreasing size of consumer electronic devices, such as smartphones, notebooks, and portable electronics, it is necessary to address the issues pertaining to grinding silicon wafers. The backside grinding process is a mature technology that is widely used for silicon wafers. However, for ultrathin silicon wafers, warpage is a critical issue. Wafer warpage is induced by the residual stress and surface damage that arises during the backside grinding process. To analyze the grinding stress on silicon wafers during the backside grinding process, a finite element model is established by setting dynamic loads, and contact conditions. An explicit dynamic model is used to simulate the relationship between the grinding wheel and the silicon wafer. A static model is incorporated with the explicit dynamic model to predict wafer warpage. The simulation results for the residual stress are in good agreement with the experimental results. The results indicate that the wheel rotational speed, wafer rotational speed, and feed rate effectively control wafer warpage. Hence, the warpage of ultrathin silicon wafers can be decreased by adjusting the manufacturing process parameters. Furthermore, the developed simulation model can also be used to analyze warpage in fan-out wafers during the backside grinding process.
{"title":"A coupled finite element scheme to study the grinding force and warpage of silicon wafers during the backside grinding process","authors":"Mei-Ling Wu, Wei-Jhih Wong, J. Lan","doi":"10.1093/jom/ufad018","DOIUrl":"https://doi.org/10.1093/jom/ufad018","url":null,"abstract":"\u0000 In this study, a finite element model is developed to analyze the grinding force and warpage of silicon wafers during the backside grinding process. Due to the decreasing size of consumer electronic devices, such as smartphones, notebooks, and portable electronics, it is necessary to address the issues pertaining to grinding silicon wafers. The backside grinding process is a mature technology that is widely used for silicon wafers. However, for ultrathin silicon wafers, warpage is a critical issue. Wafer warpage is induced by the residual stress and surface damage that arises during the backside grinding process. To analyze the grinding stress on silicon wafers during the backside grinding process, a finite element model is established by setting dynamic loads, and contact conditions. An explicit dynamic model is used to simulate the relationship between the grinding wheel and the silicon wafer. A static model is incorporated with the explicit dynamic model to predict wafer warpage. The simulation results for the residual stress are in good agreement with the experimental results. The results indicate that the wheel rotational speed, wafer rotational speed, and feed rate effectively control wafer warpage. Hence, the warpage of ultrathin silicon wafers can be decreased by adjusting the manufacturing process parameters. Furthermore, the developed simulation model can also be used to analyze warpage in fan-out wafers during the backside grinding process.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46051212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The development of new electronic packaging structures often involves a design-on-simulation (DoS) approach. However, simulation results can be subjective, and there can be variances in outcomes depending on who is conducting the simulation. To address this issue, packaging designers are now turning to machine learning to increase the accuracy and efficiency of the design process. This research study focuses on using support vector regression (SVR) techniques, such as single kernel, multiple kernels, and a new support vector regression technique, to predict the reliability of the Wafer-Level Package (WLP). By doing so, the study aims to provide designers with a reliable way to assess the reliability life cycle of their packaging designs. The study involves three steps: validating the WLP's reliability using FEA and experiment results, the validated FEA result will serve as input to obtain a predictive model through the SVR technique, and the predictive model's performance will be evaluated. The results show that the predictive models developed using the SVR technique have stable performance on different testing data, which is consistent with the FEA results.
{"title":"Wafer-level packaging solder joint reliability lifecycle prediction using SVR-based machine learning algorithm","authors":"H. Kuo, C. Y. Chang, Cadmus C A Yuan, K. Chiang","doi":"10.1093/jom/ufad016","DOIUrl":"https://doi.org/10.1093/jom/ufad016","url":null,"abstract":"\u0000 The development of new electronic packaging structures often involves a design-on-simulation (DoS) approach. However, simulation results can be subjective, and there can be variances in outcomes depending on who is conducting the simulation. To address this issue, packaging designers are now turning to machine learning to increase the accuracy and efficiency of the design process. This research study focuses on using support vector regression (SVR) techniques, such as single kernel, multiple kernels, and a new support vector regression technique, to predict the reliability of the Wafer-Level Package (WLP). By doing so, the study aims to provide designers with a reliable way to assess the reliability life cycle of their packaging designs. The study involves three steps: validating the WLP's reliability using FEA and experiment results, the validated FEA result will serve as input to obtain a predictive model through the SVR technique, and the predictive model's performance will be evaluated. The results show that the predictive models developed using the SVR technique have stable performance on different testing data, which is consistent with the FEA results.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49508019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is of utmost importance to prioritize the exploration of alternative green energy sources, reducing our dependence on coal and oil, in order to mitigate the detrimental effects of greenhouse gases. This paper introduces an innovative energy harvester that utilizes a single magnet driven by a buoy attached to a pole within a lake. We delve into the correlation between the induced electricity and various factors such as wind speed, lake length and depth, as well as the design parameters of the energy harvester. To enhance the performance of the energy harvester, we employ the Firefly Algorithm, gradually fine-tuning its control parameters to acquire the most optimal design data. Our analysis reveals that, under specific conditions including a fetch of 4 km, a lake depth of 10 m, and a wind speed of 4.5 m/s, the one-magnet energy harvester exhibits a commendable electrical power output of 0.1 Watt. This research not only emphasizes the potential of hydraulic energy generation as a promising and sustainable green energy source but also provides valuable insights into optimizing energy harvesters to achieve maximum electricity production.
{"title":"Optimization of Buoy-Type Energy Harvesting Device in Lake Using Firefly Algorithm","authors":"M. Chiu, Ho-Chih Cheng","doi":"10.1093/jom/ufad013","DOIUrl":"https://doi.org/10.1093/jom/ufad013","url":null,"abstract":"\u0000 It is of utmost importance to prioritize the exploration of alternative green energy sources, reducing our dependence on coal and oil, in order to mitigate the detrimental effects of greenhouse gases. This paper introduces an innovative energy harvester that utilizes a single magnet driven by a buoy attached to a pole within a lake. We delve into the correlation between the induced electricity and various factors such as wind speed, lake length and depth, as well as the design parameters of the energy harvester. To enhance the performance of the energy harvester, we employ the Firefly Algorithm, gradually fine-tuning its control parameters to acquire the most optimal design data. Our analysis reveals that, under specific conditions including a fetch of 4 km, a lake depth of 10 m, and a wind speed of 4.5 m/s, the one-magnet energy harvester exhibits a commendable electrical power output of 0.1 Watt. This research not only emphasizes the potential of hydraulic energy generation as a promising and sustainable green energy source but also provides valuable insights into optimizing energy harvesters to achieve maximum electricity production.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43748115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The purpose of this study was to examine the fracture toughness of epoxy-based graphene nanocomposites. The single edge notched bending (SENB) samples with precrack tips were created by either tapping or sliding methods. For the tapping method, a single tap was conducted on a razor blade such a crack with a length of 2 mm was instantly propagated. For the sliding method, a razor blade was slid forward and backward into the samples, and a crack was generated with the blade edge. The SENB samples with graphene loadings (0.15 and 0.3 wt%) were subjected to three-point bending tests to evaluate fracture toughness. Results indicated that the graphene loading did not considerably affect the fracture toughness of the samples with tapping-induced precrack tips. However, the fracture toughness of the samples with sliding-induced precrack tips decreased as the graphene loading increased. For the 0.3-wt% graphene nanocomposites, the fracture toughness levels of the samples with sliding- and tapping-induced precrack tips were equal. In order to explicate the experimental results, the plastic zone sizes around the crack tip were evaluated using finite element analysis. For the sharp precrack tips (tapping method), the plastic zone was comparatively small (brittle behavior); hence, the effect of graphene on the inception of crack extension was minimal. Nevertheless, for blunt crack tips (sliding method), the plastic zone was larger and the size decreased as graphene loading increased; thus, the fracture behavior measured from the sliding method was dramatically influenced by the graphene loading.
{"title":"Investigating fracture toughness of graphene epoxy nanocomposites using single edge notched bending specimens","authors":"Po-Chun Chuang, Chen- Yu Chao, Mi Yang, J. Tsai","doi":"10.1093/jom/ufad007","DOIUrl":"https://doi.org/10.1093/jom/ufad007","url":null,"abstract":"\u0000 The purpose of this study was to examine the fracture toughness of epoxy-based graphene nanocomposites. The single edge notched bending (SENB) samples with precrack tips were created by either tapping or sliding methods. For the tapping method, a single tap was conducted on a razor blade such a crack with a length of 2 mm was instantly propagated. For the sliding method, a razor blade was slid forward and backward into the samples, and a crack was generated with the blade edge. The SENB samples with graphene loadings (0.15 and 0.3 wt%) were subjected to three-point bending tests to evaluate fracture toughness. Results indicated that the graphene loading did not considerably affect the fracture toughness of the samples with tapping-induced precrack tips. However, the fracture toughness of the samples with sliding-induced precrack tips decreased as the graphene loading increased. For the 0.3-wt% graphene nanocomposites, the fracture toughness levels of the samples with sliding- and tapping-induced precrack tips were equal. In order to explicate the experimental results, the plastic zone sizes around the crack tip were evaluated using finite element analysis. For the sharp precrack tips (tapping method), the plastic zone was comparatively small (brittle behavior); hence, the effect of graphene on the inception of crack extension was minimal. Nevertheless, for blunt crack tips (sliding method), the plastic zone was larger and the size decreased as graphene loading increased; thus, the fracture behavior measured from the sliding method was dramatically influenced by the graphene loading.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44028451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Multiple cracks grow from pre-existing defects during the manufacturing/installation process or from small cracks initiated are primary concerns in evaluating the structural integrity. In this study, the interaction behavior for coplanar multiple embedded cracks subjected to bending load in creep regimes was studied using numerical simulation approach. Influences of crack configurations (crack shape, crack depth and crack distance) and creep properties on creep interaction factor and C* distribution along the embedded cracks were evaluated based on the three-dimensional finite element solutions. Due to the interaction among the multiple cracks, the C* distribution was asymmetric along the crack front and the C* values were pronounced as the cracks approached each other. Moreover, crack depth, crack distance and creep exponent significantly affected the creep interaction factor and crack shape had limited influence. However, the maximum creep interaction factor did not coincide with the maximum C* values occurring along the crack front. The creep interaction factor determined by the average C* values along the crack front was employed to represent the intensity effect of multiple embedded cracks on the crack growth behavior. Finally, an empirical relation was proposed for estimating crack creep interaction factors of embedded cracks.
{"title":"Interaction behavior for multiple embedded cracks subjected to bending load in creep regimes","authors":"Zhifang Gao, Lei Zhao","doi":"10.1093/jom/ufad005","DOIUrl":"https://doi.org/10.1093/jom/ufad005","url":null,"abstract":"\u0000 Multiple cracks grow from pre-existing defects during the manufacturing/installation process or from small cracks initiated are primary concerns in evaluating the structural integrity. In this study, the interaction behavior for coplanar multiple embedded cracks subjected to bending load in creep regimes was studied using numerical simulation approach. Influences of crack configurations (crack shape, crack depth and crack distance) and creep properties on creep interaction factor and C* distribution along the embedded cracks were evaluated based on the three-dimensional finite element solutions. Due to the interaction among the multiple cracks, the C* distribution was asymmetric along the crack front and the C* values were pronounced as the cracks approached each other. Moreover, crack depth, crack distance and creep exponent significantly affected the creep interaction factor and crack shape had limited influence. However, the maximum creep interaction factor did not coincide with the maximum C* values occurring along the crack front. The creep interaction factor determined by the average C* values along the crack front was employed to represent the intensity effect of multiple embedded cracks on the crack growth behavior. Finally, an empirical relation was proposed for estimating crack creep interaction factors of embedded cracks.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41954240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigated the heat and mass that are transferred when a fluid undergoes convective flow along an inclined plate through a porous medium, and also considered the corresponding chemical reaction and activation energy. The influences of the variable viscosity, mixed convection intensity, inclination angle, thermal radiation, magnetic field, internal heat source, activation energy, chemical reaction, and Soret and Dufour effects for fluid flowing through a Darcy porous medium are all discussed. Numerical techniques, namely Runge–Kutta integration and the shooting method, were applied to obtain solutions to similarity-transformed Eqs. governing continuity, momentum, energy, and concentration. The study examined the distributions of flow velocity, temperature, and concentration under the interactive effects of the fluid. The results revealed that the activation energy of the Arrhenius Eq. plays an important role in fluid transport mechanisms within a chemically reactive system involving the Soret and Dufour effects for a low-Schmidt-number fluid. When the activation energy parameter E was greater within the range 0 < E < 5, the wall shear stress was stronger, heat transfer rate increased, and mass transfer rate decreased.
{"title":"Chemical reaction and activation energy on heat and mass transfer for convective flow along an inclined surface in darcy porous medium with soret and dufour effects","authors":"J. S. Huang","doi":"10.1093/jom/ufad006","DOIUrl":"https://doi.org/10.1093/jom/ufad006","url":null,"abstract":"\u0000 This study investigated the heat and mass that are transferred when a fluid undergoes convective flow along an inclined plate through a porous medium, and also considered the corresponding chemical reaction and activation energy. The influences of the variable viscosity, mixed convection intensity, inclination angle, thermal radiation, magnetic field, internal heat source, activation energy, chemical reaction, and Soret and Dufour effects for fluid flowing through a Darcy porous medium are all discussed. Numerical techniques, namely Runge–Kutta integration and the shooting method, were applied to obtain solutions to similarity-transformed Eqs. governing continuity, momentum, energy, and concentration. The study examined the distributions of flow velocity, temperature, and concentration under the interactive effects of the fluid. The results revealed that the activation energy of the Arrhenius Eq. plays an important role in fluid transport mechanisms within a chemically reactive system involving the Soret and Dufour effects for a low-Schmidt-number fluid. When the activation energy parameter E was greater within the range 0 < E < 5, the wall shear stress was stronger, heat transfer rate increased, and mass transfer rate decreased.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42334465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Knowing that the end effects arising from the end torsional loads will disturb the stress distribution in a torque tube, this paper develops a means of blocking the stress disturbances from the end where a torsional load is applied, such that the stress distributions of the Saint Venant torsion can be maintained. The stress disturbance barrier (SDB) as an end effect shielding barrier is considered installed on an end of a circular toque tube whose material property can be with the cylindrical orthotropy. In general, the SDB is comprised of two layers: the front layer and the blocking layer. The front layer which is optional and directly contacted with the external load is for enhancing the durability, while the blocking layer situated between the front layer and the torque tube body is mainly for blocking the stress disturbances. The analysis is base on the state space formalism, whose uncoupling feature on cylindrically orthotropic materials is benefit for the further extension of the research. It is found that the parameters crucial to determine an effective SDB with a given thickness are the cylindrical orthotropy parameter and the longitudinal shear modulus. The approach of how to determine the proper material constants for having an effective SDB is clearly provided. As shown by the numerical results presented in the examples, an effective SDB of this research can fully block the stress disturbances from the external torsional loads that can be mathematically expanded by power series.
{"title":"A Stress Disturbance Barrier on a Circular Torque Tube blocking the End Effects","authors":"Chung-Hao Wang","doi":"10.1093/jom/ufad004","DOIUrl":"https://doi.org/10.1093/jom/ufad004","url":null,"abstract":"\u0000 Knowing that the end effects arising from the end torsional loads will disturb the stress distribution in a torque tube, this paper develops a means of blocking the stress disturbances from the end where a torsional load is applied, such that the stress distributions of the Saint Venant torsion can be maintained. The stress disturbance barrier (SDB) as an end effect shielding barrier is considered installed on an end of a circular toque tube whose material property can be with the cylindrical orthotropy. In general, the SDB is comprised of two layers: the front layer and the blocking layer. The front layer which is optional and directly contacted with the external load is for enhancing the durability, while the blocking layer situated between the front layer and the torque tube body is mainly for blocking the stress disturbances. The analysis is base on the state space formalism, whose uncoupling feature on cylindrically orthotropic materials is benefit for the further extension of the research. It is found that the parameters crucial to determine an effective SDB with a given thickness are the cylindrical orthotropy parameter and the longitudinal shear modulus. The approach of how to determine the proper material constants for having an effective SDB is clearly provided. As shown by the numerical results presented in the examples, an effective SDB of this research can fully block the stress disturbances from the external torsional loads that can be mathematically expanded by power series.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46582058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, we conducted a theoretical analysis of thermal stress around an arbitrarily-shaped hole in a thermoelectric material under electric current density and energy flux loading. Based on complex variable methods, conformal mapping, and analytical continuation theorem, the exact solutions of the thermal stress around a hole were obtained for the Seebeck coefficient and electric and heat conductivity. Based on the conversion efficiency equation of thermoelectric materials, higher electrical conductivity, and lower heat conductivity should be selected to achieve an optimal design. The theoretical results indicated that higher electrical conductivity could reduce the thermal stress around the hole. However, energy flux and thermal stress concentration might be generated around the adiabatic hole due to the presence of a matrix with lower heat conductivity. Hence, thermoelectric materials with lower thermal conductivity should be selected carefully to avoid premature failure around the hole caused by thermal stress concentration. Finally, we also obtained and discussed the stress intensity factors of a hypocycloid-type crack.
{"title":"Effects of Material Characteristics on Thermal Stress around an Equiangular Polygonal Hole in a Thermoelectric Material","authors":"M. Shen, Yi-Lun Liao, S. Tseng, C. Chao","doi":"10.1093/jom/ufad003","DOIUrl":"https://doi.org/10.1093/jom/ufad003","url":null,"abstract":"\u0000 In this study, we conducted a theoretical analysis of thermal stress around an arbitrarily-shaped hole in a thermoelectric material under electric current density and energy flux loading. Based on complex variable methods, conformal mapping, and analytical continuation theorem, the exact solutions of the thermal stress around a hole were obtained for the Seebeck coefficient and electric and heat conductivity. Based on the conversion efficiency equation of thermoelectric materials, higher electrical conductivity, and lower heat conductivity should be selected to achieve an optimal design. The theoretical results indicated that higher electrical conductivity could reduce the thermal stress around the hole. However, energy flux and thermal stress concentration might be generated around the adiabatic hole due to the presence of a matrix with lower heat conductivity. Hence, thermoelectric materials with lower thermal conductivity should be selected carefully to avoid premature failure around the hole caused by thermal stress concentration. Finally, we also obtained and discussed the stress intensity factors of a hypocycloid-type crack.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43595010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ming Yang, Ju-bao Liu, Y. Ding, Q. Yue, Qiang Zhang
The collision between solids in fluid is common in engineering, but the numerical simulation method is less studied. A direct numerical simulation method combining the sharp interface immersed boundary method and the finite element method based on penalty function was established for solid-solid collision and coupling with fluid. The lubrication model for cylinder structures with and without fluid flow was developed using the data regression method. The partitioned coupling algorithm was used to realize the coupling solution between the fluid and solid domains. Four numerical examples were presented to demonstrate the validity of the established method. The numerical simulation of the vortex-induced collisions between two side-by-side cylinders showed the capabilities of the proposed method.
{"title":"A direct numerical simulation method for solid-solid collision and coupling with fluid","authors":"Ming Yang, Ju-bao Liu, Y. Ding, Q. Yue, Qiang Zhang","doi":"10.1093/jom/ufad001","DOIUrl":"https://doi.org/10.1093/jom/ufad001","url":null,"abstract":"The collision between solids in fluid is common in engineering, but the numerical simulation method is less studied. A direct numerical simulation method combining the sharp interface immersed boundary method and the finite element method based on penalty function was established for solid-solid collision and coupling with fluid. The lubrication model for cylinder structures with and without fluid flow was developed using the data regression method. The partitioned coupling algorithm was used to realize the coupling solution between the fluid and solid domains. Four numerical examples were presented to demonstrate the validity of the established method. The numerical simulation of the vortex-induced collisions between two side-by-side cylinders showed the capabilities of the proposed method.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":" ","pages":""},"PeriodicalIF":1.7,"publicationDate":"2023-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48494117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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