Critical plane method is one of the most promising approaches to predict the fatigue life when the structure is subjected to the multiaxial loading.The stress-strain status and the critical plane position for smooth s...Critical plane method is one of the most promising approaches to predict the fatigue life when the structure is subjected to the multiaxial loading.The stress-strain status and the critical plane position for smooth specimens are calculated using theoretical approaches when the loading mode is a continuous function.However,because of the existence of stress concentration and the characteristic of multiaxial non-proportion,it is difficult to calculate the stress-strain status and the critical plane position of geometric discontinuity structure by theory method.In this paper,a new numerical simulation method is proposed to determine the critical plane of geometric discontinuity structure under multiaxial loading.Firstly,the strain status of dangerous point is analyzed by finite element method.Secondly,the maximum shear strain amplitude of arbitrary plane is calculated using coordinate transformation principle.Finally,the plane which has the maximum shear strain amplitude is defined as the critical plane.The critical plane positions are analyzed when loading mode and notch parameters are different.Meanwhile,the relationship between notch depth and associated parameters on critical plane as well as that between loading amplitude and associated parameters on critical plane are given quantitatively.展开更多
Although graphene aerogels(GA)have been attracted great attention,the easy-operation and large-scale production of GA are still challenges.Further,most GA have a monolith-like appearance,limiting their application-spe...Although graphene aerogels(GA)have been attracted great attention,the easy-operation and large-scale production of GA are still challenges.Further,most GA have a monolith-like appearance,limiting their application-specific needs.Herein,we highlight graphene aerogel spheres with controllable hollow structures(HGAS)that are delicately designed and manufactured via coaxial electrospinning coupled with freeze-drying and calcination.The HGAS exhibit a spherical configuration at the macroscale,while the construction elements of graphene on the microscale showing an interconnected radial microchannel structure.Further ball-in-ball graphene aerogel spheres(BGAS)are obtained by reference to the triaxial electrospinning technology.The as-prepared spheres possess the controllable integrated conductive networks,leading to the effective dielectric loss and impedance matching thus bringing on high-performance microwave absorption.The as-obtained HGAS shows a minimum reflection loss of-52.7 dB and a broad effective absorption bandwidth(f)of 7.0 GHz with thickness of 2.3 mm.Further,the fe reaches 9.3 GHz for BGAS with thickness of 3.4 mm.Aforementioned superior microwave absorption of HGAS and BGAS confirms combination of multiaxial electrospinning and freeze-drying on the multiscale is an effective strategy for scalable fabrication of advanced microwave.absorbing functional graphene aerogel spheres.展开更多
基金the National Natural Science Foundation of China(Nos.51778273 and 51605212)the Universities and Colleges Innovation Ability Improvement Project of Gansu(No.2019A-225)
文摘Critical plane method is one of the most promising approaches to predict the fatigue life when the structure is subjected to the multiaxial loading.The stress-strain status and the critical plane position for smooth specimens are calculated using theoretical approaches when the loading mode is a continuous function.However,because of the existence of stress concentration and the characteristic of multiaxial non-proportion,it is difficult to calculate the stress-strain status and the critical plane position of geometric discontinuity structure by theory method.In this paper,a new numerical simulation method is proposed to determine the critical plane of geometric discontinuity structure under multiaxial loading.Firstly,the strain status of dangerous point is analyzed by finite element method.Secondly,the maximum shear strain amplitude of arbitrary plane is calculated using coordinate transformation principle.Finally,the plane which has the maximum shear strain amplitude is defined as the critical plane.The critical plane positions are analyzed when loading mode and notch parameters are different.Meanwhile,the relationship between notch depth and associated parameters on critical plane as well as that between loading amplitude and associated parameters on critical plane are given quantitatively.
基金This work was financially supported by the National Natural Science Foundation of China(No.51903213)the Science and Technology Planning Project of Sichuan Province(Nos.2018GZ0132 and 2018GZ0427).
文摘Although graphene aerogels(GA)have been attracted great attention,the easy-operation and large-scale production of GA are still challenges.Further,most GA have a monolith-like appearance,limiting their application-specific needs.Herein,we highlight graphene aerogel spheres with controllable hollow structures(HGAS)that are delicately designed and manufactured via coaxial electrospinning coupled with freeze-drying and calcination.The HGAS exhibit a spherical configuration at the macroscale,while the construction elements of graphene on the microscale showing an interconnected radial microchannel structure.Further ball-in-ball graphene aerogel spheres(BGAS)are obtained by reference to the triaxial electrospinning technology.The as-prepared spheres possess the controllable integrated conductive networks,leading to the effective dielectric loss and impedance matching thus bringing on high-performance microwave absorption.The as-obtained HGAS shows a minimum reflection loss of-52.7 dB and a broad effective absorption bandwidth(f)of 7.0 GHz with thickness of 2.3 mm.Further,the fe reaches 9.3 GHz for BGAS with thickness of 3.4 mm.Aforementioned superior microwave absorption of HGAS and BGAS confirms combination of multiaxial electrospinning and freeze-drying on the multiscale is an effective strategy for scalable fabrication of advanced microwave.absorbing functional graphene aerogel spheres.
