Similar to hydraulic fracturing(HF), the coalescence and fracture of cracks are induced within a rock under the action of an ultrasonic field, known as ultrasonic fracturing(UF). Investigating UF is important in both ...Similar to hydraulic fracturing(HF), the coalescence and fracture of cracks are induced within a rock under the action of an ultrasonic field, known as ultrasonic fracturing(UF). Investigating UF is important in both hard rock drilling and oil and gas recovery. A three-dimensional internal laser-engraved crack(3D-ILC) method was introduced to prefabricate two parallel internal cracks within the samples without any damage to the surface. The samples were subjected to UF. The mechanism of UF was elucidated by analyzing the characteristics of fracture surfaces. The crack propagation path under different ultrasonic parameters was obtained by numerical simulation based on the Paris fatigue model and compared to the experimental results of UF. The results show that the 3D-ILC method is a powerful tool for UF research.Under the action of an ultrasonic field, the fracture surface shows the characteristics of beach marks and contains powder locally, indicating that the UF mechanism includes high-cycle fatigue fracture, shear and friction, and temperature load. The two internal cracks become close under UF. The numerical result obtained by the Paris fatigue model also shows the attraction of the two cracks, consistent with the test results. The 3D-ILC method provides a new tool for the experimental study of UF. Compared to the conventional numerical methods based on the analysis of stress-strain and plastic zone, numerical simulation can be a good alternative method to obtain the crack path under UF.展开更多
This paper considers the multi-field coupling in magneroelectroelastic composite materials consisting of the inclusion and the matrix are magnetoelectroelastic materials. The mechanical,electric and magnetic fields ar...This paper considers the multi-field coupling in magneroelectroelastic composite materials consisting of the inclusion and the matrix are magnetoelectroelastic materials. The mechanical,electric and magnetic fields around an elliptical cylinder inclusion are formulated by complex potentials. Inside the inclusion,the strain,electric and magnetic fields are found to be uniform and vary with the shape of the ellipse. When the inclusion is reduced to a crack,along the interface,the strain,electric field strength and magnetic field strength equal the corresponding remote ones,which can be used as the boundary condition. Special cases,such as a rigid and permeable inclusion,a soft and impermeable inclusion,a line inclusion and a crack problem are discussed in detail.展开更多
To provide insights into deforming Ce-O-S-Al inclusions in steels and improving the mechanical properties,the evolution process of such harmful inclusions in clean steels was investigated by thermodynamic calculation,...To provide insights into deforming Ce-O-S-Al inclusions in steels and improving the mechanical properties,the evolution process of such harmful inclusions in clean steels was investigated by thermodynamic calculation,metallographic examination and first-principles calculation in this paper.For the tested IF steel,the thermodynamic analysis results are consistent with the calculated formation enthalpy.After Ce addition,the inclusions are transformed from Al_(2)O_(3)and TiN-Al_(2)TiO_(5)-Al_(2)O_(3)to Ce2O_(3),Ce_(2)O_(2)S,CeAlO_(3),TiN-Al_(2)TiO_(5)-Ce_(2)O_(3)and TiN-Al_(2)TiO_(5)-Ce_(2)O_(2)S composite inclusions,which can be confirmed by metallographic examination.The elastic constants were calculated,and the bulk modulus,Young's modulus,shear modulus and Poisson's ratio were evaluated by the Voigt-Reuss-Hill(VRH)approximation.All inclusions except Ce_(2)O_(3)show apparent brittleness.TiN,Al_(2)O_(3),Al_(2)TiO_(5)and CeAlO_(3)present much higher hardness than iron matrix,while the hardness of Ce2O_(3)or Ce_(2)O_(2)S is close to that of iron matrix.The thermal expansion coefficients of Ce_(2)O_(3)and CeAlO_(3)are close to that of iron matrix,whereas,Ce_(2)O_(2)S inclusion has largely different thermal expansion coefficient from iron matrix and may deteriorate the steel performance at higher temperatures.The relatively small differences between Ce inclusions and iron matrix in terms of hardness,toughness,brittleness,and thermal expansion coefficient can explain the improvement of the mechanical properties of the tested steel.展开更多
Ultrasonic fracturing(UF)can be used to form crack networks for oil or gas in the mining industry and hard rock excavation.In this paper,the three-dimensional internal laser-engraved crack method(3DILC)is introduced t...Ultrasonic fracturing(UF)can be used to form crack networks for oil or gas in the mining industry and hard rock excavation.In this paper,the three-dimensional internal laser-engraved crack method(3DILC)is introduced to make penny-shaped internal crack within the samples without any damage to the surfaces.Physical experiments were performed on the transparent samples with internal cracks at different depths.The macro-and micro-fracture fractography characteristics were focused on and analyzed in details.Based on fractography,the mechanisms of the UF were revealed.The propagation paths of cracks of different depths were simulated based on the Paris fatigue model and compared with experimental results.The results show that the 3D-ILC method is a powerful tool for the experimental research on the internal crack propagation in the UF.Under the action of ultrasonic field,fractography shows the characteristics of beach marks,lance-like pattern,rime-like pattern and glass powder.It can be judged that the mechanisms of UF include high cycle fatigue fracture,shear fracture,and friction.The results of the numerical simulation using the Paris fatigue model are consistent with the experimental results.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 52104125, U1765204 and 51739008)
文摘Similar to hydraulic fracturing(HF), the coalescence and fracture of cracks are induced within a rock under the action of an ultrasonic field, known as ultrasonic fracturing(UF). Investigating UF is important in both hard rock drilling and oil and gas recovery. A three-dimensional internal laser-engraved crack(3D-ILC) method was introduced to prefabricate two parallel internal cracks within the samples without any damage to the surface. The samples were subjected to UF. The mechanism of UF was elucidated by analyzing the characteristics of fracture surfaces. The crack propagation path under different ultrasonic parameters was obtained by numerical simulation based on the Paris fatigue model and compared to the experimental results of UF. The results show that the 3D-ILC method is a powerful tool for UF research.Under the action of an ultrasonic field, the fracture surface shows the characteristics of beach marks and contains powder locally, indicating that the UF mechanism includes high-cycle fatigue fracture, shear and friction, and temperature load. The two internal cracks become close under UF. The numerical result obtained by the Paris fatigue model also shows the attraction of the two cracks, consistent with the test results. The 3D-ILC method provides a new tool for the experimental study of UF. Compared to the conventional numerical methods based on the analysis of stress-strain and plastic zone, numerical simulation can be a good alternative method to obtain the crack path under UF.
基金supported by the National Natural Science Foundation of China (No. 10772059)
文摘This paper considers the multi-field coupling in magneroelectroelastic composite materials consisting of the inclusion and the matrix are magnetoelectroelastic materials. The mechanical,electric and magnetic fields around an elliptical cylinder inclusion are formulated by complex potentials. Inside the inclusion,the strain,electric and magnetic fields are found to be uniform and vary with the shape of the ellipse. When the inclusion is reduced to a crack,along the interface,the strain,electric field strength and magnetic field strength equal the corresponding remote ones,which can be used as the boundary condition. Special cases,such as a rigid and permeable inclusion,a soft and impermeable inclusion,a line inclusion and a crack problem are discussed in detail.
基金Project supported by National Natural Science Foundation of China(51774190,51664044)Natural Science Foundation of Inner Mongolia,China(2018LH05005).
文摘To provide insights into deforming Ce-O-S-Al inclusions in steels and improving the mechanical properties,the evolution process of such harmful inclusions in clean steels was investigated by thermodynamic calculation,metallographic examination and first-principles calculation in this paper.For the tested IF steel,the thermodynamic analysis results are consistent with the calculated formation enthalpy.After Ce addition,the inclusions are transformed from Al_(2)O_(3)and TiN-Al_(2)TiO_(5)-Al_(2)O_(3)to Ce2O_(3),Ce_(2)O_(2)S,CeAlO_(3),TiN-Al_(2)TiO_(5)-Ce_(2)O_(3)and TiN-Al_(2)TiO_(5)-Ce_(2)O_(2)S composite inclusions,which can be confirmed by metallographic examination.The elastic constants were calculated,and the bulk modulus,Young's modulus,shear modulus and Poisson's ratio were evaluated by the Voigt-Reuss-Hill(VRH)approximation.All inclusions except Ce_(2)O_(3)show apparent brittleness.TiN,Al_(2)O_(3),Al_(2)TiO_(5)and CeAlO_(3)present much higher hardness than iron matrix,while the hardness of Ce2O_(3)or Ce_(2)O_(2)S is close to that of iron matrix.The thermal expansion coefficients of Ce_(2)O_(3)and CeAlO_(3)are close to that of iron matrix,whereas,Ce_(2)O_(2)S inclusion has largely different thermal expansion coefficient from iron matrix and may deteriorate the steel performance at higher temperatures.The relatively small differences between Ce inclusions and iron matrix in terms of hardness,toughness,brittleness,and thermal expansion coefficient can explain the improvement of the mechanical properties of the tested steel.
基金supported by the National Natural Science Foundation of China(Nos.51739008 and 41831281)the Natural Science Foundation of Jiangsu Province(No.BK20171130).
文摘Ultrasonic fracturing(UF)can be used to form crack networks for oil or gas in the mining industry and hard rock excavation.In this paper,the three-dimensional internal laser-engraved crack method(3DILC)is introduced to make penny-shaped internal crack within the samples without any damage to the surfaces.Physical experiments were performed on the transparent samples with internal cracks at different depths.The macro-and micro-fracture fractography characteristics were focused on and analyzed in details.Based on fractography,the mechanisms of the UF were revealed.The propagation paths of cracks of different depths were simulated based on the Paris fatigue model and compared with experimental results.The results show that the 3D-ILC method is a powerful tool for the experimental research on the internal crack propagation in the UF.Under the action of ultrasonic field,fractography shows the characteristics of beach marks,lance-like pattern,rime-like pattern and glass powder.It can be judged that the mechanisms of UF include high cycle fatigue fracture,shear fracture,and friction.The results of the numerical simulation using the Paris fatigue model are consistent with the experimental results.
