High volumetric power density （VPD） is the basis for the commercial success of micro-tubular solid oxide fuel cells （mtSOFCs）. To find maximal VPD （MVPD） for anode-supported mtSOFC （as-mtSOFC）, the effects of ...High volumetric power density （VPD） is the basis for the commercial success of micro-tubular solid oxide fuel cells （mtSOFCs）. To find maximal VPD （MVPD） for anode-supported mtSOFC （as-mtSOFC）, the effects of geometric parameters on VPD are analyzed and the anode thickness, tan, and the cathode length, lea, are identified as the key design parameters. Thermo-fluid electrochemical models were built to examine the dependence of the electrical output on the cell parameters. The multiphysics model is validated by reproducing the experimental I-V curves with no adjustable parameters. The optimal lea and the corresponding MVPDs are then determined by the multiphysics model for 20 combinations of rin, the inner tube radius, and tan. And all these optimization are made at 1073.15 K. The results show that： （i） significant performance improvement may be achieved by geometry optimization, （ii） the seemingly high MVPD of 11 and 14 W/cm^3 can be easily realized for as-mtSOFC with single- and double-terminal anode current collection, respectively. Moreover, the variation of the area specific power density with/cac（2 mm, 40 mm） is determined for three representative （tin, tan） combinations. Besides, it is demonstrated that the current output of mtSOFC with proper geometric parameters is comparable to that of planar SOFC.展开更多
To determine the toughness of materials, Charpy V notch test has been widely used over the world. Originally, the Charpy-V or U tests were used mainly as a quality control tests. In this paper, effects of temperature ...To determine the toughness of materials, Charpy V notch test has been widely used over the world. Originally, the Charpy-V or U tests were used mainly as a quality control tests. In this paper, effects of temperature and notch geometry on variation of toughness/yield stress ratio were investigated. The experimental work has been performed on austenitic stainless steel 316L using Charpy tests and carried out at temperature range from 20 ℃ to 250 ℃ on different dimension of V- and U-notch specimens. Energy of fracture was determined directly from machine tests. Furthermore, Barsoum correlation has been applied to determine toughness/yield stress ratio as function of temperature. In addition, several parameters were investigated namely specimen thickness and notch cut angles. U-notch specimen offers a high resistance comparatively to the V-notch and that toughness depends on temper situation and orientation of notch relative to the rolling direction.展开更多
When pointed V-notches weaken structural components, local stresses are singular and their intensities are expressed in terms of the notch stress intensity factors （NSIFs）. These parameters have been widely used for...When pointed V-notches weaken structural components, local stresses are singular and their intensities are expressed in terms of the notch stress intensity factors （NSIFs）. These parameters have been widely used for fatigue assessments of welded struc- tures under high cycle fatigue and sharp notches in plates made of brittle materials subjected to static loading. Fine meshes are required to capture the asymptotic stress distributions ahead of the notch tip and evaluate the relevant NSIFs. On the other hand, when the aim is to determine the local Strain Energy Density （SED） averaged in a control volume embracing the point of stress singularity, refined meshes are, not at all, necessary. The SED can be evaluated from nodal displacements and regular coarse meshes provide accurate values for the averaged local SED. In the present contribution, the link between the SED and the NSIFs is discussed by considering some typical welded joints and sharp V-notches. The procedure based on the SED has been also proofed to be useful for determining theoretical stress concentration factors of blunt notches and holes. In the second part of this work an application of the strain energy density to the fatigue assessment of A17075 notched plates is presented. The experimental data are taken from the recent literature and refer to notched specimens subjected to different shot peening treatments aimed to increase the notch fatigue strength with respect to the parent material.展开更多
基金This work was supported by the National Natural Science Foundation of China （No.11374272 and No.11574284） and the Collaborative Innovation Center of Suzhou Nano Science and Technology.
文摘High volumetric power density （VPD） is the basis for the commercial success of micro-tubular solid oxide fuel cells （mtSOFCs）. To find maximal VPD （MVPD） for anode-supported mtSOFC （as-mtSOFC）, the effects of geometric parameters on VPD are analyzed and the anode thickness, tan, and the cathode length, lea, are identified as the key design parameters. Thermo-fluid electrochemical models were built to examine the dependence of the electrical output on the cell parameters. The multiphysics model is validated by reproducing the experimental I-V curves with no adjustable parameters. The optimal lea and the corresponding MVPDs are then determined by the multiphysics model for 20 combinations of rin, the inner tube radius, and tan. And all these optimization are made at 1073.15 K. The results show that： （i） significant performance improvement may be achieved by geometry optimization, （ii） the seemingly high MVPD of 11 and 14 W/cm^3 can be easily realized for as-mtSOFC with single- and double-terminal anode current collection, respectively. Moreover, the variation of the area specific power density with/cac（2 mm, 40 mm） is determined for three representative （tin, tan） combinations. Besides, it is demonstrated that the current output of mtSOFC with proper geometric parameters is comparable to that of planar SOFC.
文摘To determine the toughness of materials, Charpy V notch test has been widely used over the world. Originally, the Charpy-V or U tests were used mainly as a quality control tests. In this paper, effects of temperature and notch geometry on variation of toughness/yield stress ratio were investigated. The experimental work has been performed on austenitic stainless steel 316L using Charpy tests and carried out at temperature range from 20 ℃ to 250 ℃ on different dimension of V- and U-notch specimens. Energy of fracture was determined directly from machine tests. Furthermore, Barsoum correlation has been applied to determine toughness/yield stress ratio as function of temperature. In addition, several parameters were investigated namely specimen thickness and notch cut angles. U-notch specimen offers a high resistance comparatively to the V-notch and that toughness depends on temper situation and orientation of notch relative to the rolling direction.
基金supported by the Italian Research Program(Grant No.CPDA100715)entitled"Static and fatigue behaviour of structural notched components subjected to tension and torsion under small or large scale yielding"the Italian PRIN project(Grant No.2009Z55NWC_001)
文摘When pointed V-notches weaken structural components, local stresses are singular and their intensities are expressed in terms of the notch stress intensity factors （NSIFs）. These parameters have been widely used for fatigue assessments of welded struc- tures under high cycle fatigue and sharp notches in plates made of brittle materials subjected to static loading. Fine meshes are required to capture the asymptotic stress distributions ahead of the notch tip and evaluate the relevant NSIFs. On the other hand, when the aim is to determine the local Strain Energy Density （SED） averaged in a control volume embracing the point of stress singularity, refined meshes are, not at all, necessary. The SED can be evaluated from nodal displacements and regular coarse meshes provide accurate values for the averaged local SED. In the present contribution, the link between the SED and the NSIFs is discussed by considering some typical welded joints and sharp V-notches. The procedure based on the SED has been also proofed to be useful for determining theoretical stress concentration factors of blunt notches and holes. In the second part of this work an application of the strain energy density to the fatigue assessment of A17075 notched plates is presented. The experimental data are taken from the recent literature and refer to notched specimens subjected to different shot peening treatments aimed to increase the notch fatigue strength with respect to the parent material.
