This work presents a theoretical study for thermo-mechanical buckling of size-dependent magneto-electro-thermo-elastic func-tionally graded(METE-FG)nanoplates in thermal environments based on a refined trigonometric p...This work presents a theoretical study for thermo-mechanical buckling of size-dependent magneto-electro-thermo-elastic func-tionally graded(METE-FG)nanoplates in thermal environments based on a refined trigonometric plate theory.Temperature field has uniform,linear,and nonlinear distributions across the thick-ness.Nonlinear thermal loadings are considered as heat conduc-tion(HC)and sinusoidal temperature rise(STR).A power law function is applied to govern the gradation of material properties through the nanoplate thickness.Considering coupling impacts between magneto,electro,thermo-mechanical loadings,the equa-tions of motion,and distribution of magneto-electrical field across the thickness direction of the METE-FG nanoplate are derived.The exact solutions for critical buckling temperatures of METE-FG nanoplates are introduced implementing Navier’s method.Moreover,the accuracy of the present formulation is examined by comparing the obtained results with published ones.Furthermore,the effects played by the magneto-electrical field,various temperature rises,nonlocality,power law index,side-to-thickness ratio,and aspect ratio on the critical buckling tempera-ture response are all investigated and reported.展开更多
This paper presents an analytical solution for the free vibration behavior of functionally graded carbon nanotube-reinforced composite(FG-CNTRC) doubly curved shallow shells with integrated piezoelectric layers. Here,...This paper presents an analytical solution for the free vibration behavior of functionally graded carbon nanotube-reinforced composite(FG-CNTRC) doubly curved shallow shells with integrated piezoelectric layers. Here, the linear distribution of electric potential across the thickness of the piezoelectric layer and five different types of carbon nanotube(CNT) distributions through the thickness direction are considered. Based on the four-variable shear deformation refined shell theory, governing equations are obtained by applying Hamilton's principle. Navier's solution for the shell panels with the simply supported boundary condition at all four edges is derived. Several numerical examples validate the accuracy of the presented solution. New parametric studies regarding the effects of different material properties, shell geometric parameters, and electrical boundary conditions on the free vibration responses of the hybrid panels are investigated and discussed in detail.展开更多
The existing reservoir stimulating technologies are only applicable to hard coal but helpless for soft coal,which is one of the main factors hindering the CBM industrialization in China.Therefore,it is urgent to devel...The existing reservoir stimulating technologies are only applicable to hard coal but helpless for soft coal,which is one of the main factors hindering the CBM industrialization in China.Therefore,it is urgent to develop a universal stimulating technology which can increase the permeability in various coal reservoirs.Theoretical analysis and field tests were used to systematically analyze the mechanical mechanisms causing the formation of various levels and types of fractures,such as radial tensile fractures,peripheral tensile fractures,and shear fractures in hydraulic fracturing,and reveal the mechanism of permeability enhancement by fracture network stimulating in surrounding beds and coal reservoirs.The results show that multi-staged perforation fracturing of horizontal wells,hydraulic-jet staged fracturing,four-variation hydraulic fracturing and some auxiliary measures are effective technical approaches to fracture network stimulation,especially the four-variation hydraulic fracturing can stimulate the fracture network in vertical and cluster wells.It is concluded that the fracture network stimulating technology for surrounding beds has significant advantages,such as safe drilling operation,strong stimulation effect,strong adaptability to stress-sensitive and velocity-sensitive beds,and is suitable for coal reservoirs of any structure.Except for the limitation in extremely water-sensitive and high water-yield surrounding beds,the technology can be universally used in all other beds.The successful industrial tests in surface coal bed methane and underground coal mines gas extraction prove that the theory and technical system of fracture network stimulating in surrounding beds and coal reservoirs,as a universally applicable measure,will play a role in the CBM development in China.展开更多
文摘This work presents a theoretical study for thermo-mechanical buckling of size-dependent magneto-electro-thermo-elastic func-tionally graded(METE-FG)nanoplates in thermal environments based on a refined trigonometric plate theory.Temperature field has uniform,linear,and nonlinear distributions across the thick-ness.Nonlinear thermal loadings are considered as heat conduc-tion(HC)and sinusoidal temperature rise(STR).A power law function is applied to govern the gradation of material properties through the nanoplate thickness.Considering coupling impacts between magneto,electro,thermo-mechanical loadings,the equa-tions of motion,and distribution of magneto-electrical field across the thickness direction of the METE-FG nanoplate are derived.The exact solutions for critical buckling temperatures of METE-FG nanoplates are introduced implementing Navier’s method.Moreover,the accuracy of the present formulation is examined by comparing the obtained results with published ones.Furthermore,the effects played by the magneto-electrical field,various temperature rises,nonlocality,power law index,side-to-thickness ratio,and aspect ratio on the critical buckling tempera-ture response are all investigated and reported.
基金Project supported by the Foundation for Science and Technology Development of National University of Civil Engineering-Ha Noi-Vietnam (No. 27-2020/KHXD-TD)。
文摘This paper presents an analytical solution for the free vibration behavior of functionally graded carbon nanotube-reinforced composite(FG-CNTRC) doubly curved shallow shells with integrated piezoelectric layers. Here, the linear distribution of electric potential across the thickness of the piezoelectric layer and five different types of carbon nanotube(CNT) distributions through the thickness direction are considered. Based on the four-variable shear deformation refined shell theory, governing equations are obtained by applying Hamilton's principle. Navier's solution for the shell panels with the simply supported boundary condition at all four edges is derived. Several numerical examples validate the accuracy of the presented solution. New parametric studies regarding the effects of different material properties, shell geometric parameters, and electrical boundary conditions on the free vibration responses of the hybrid panels are investigated and discussed in detail.
基金“Research on the formation mechanism of coal seam methane”(No.41002047 and No.40972109)supported by State Natural Sciences Foundation.
文摘The existing reservoir stimulating technologies are only applicable to hard coal but helpless for soft coal,which is one of the main factors hindering the CBM industrialization in China.Therefore,it is urgent to develop a universal stimulating technology which can increase the permeability in various coal reservoirs.Theoretical analysis and field tests were used to systematically analyze the mechanical mechanisms causing the formation of various levels and types of fractures,such as radial tensile fractures,peripheral tensile fractures,and shear fractures in hydraulic fracturing,and reveal the mechanism of permeability enhancement by fracture network stimulating in surrounding beds and coal reservoirs.The results show that multi-staged perforation fracturing of horizontal wells,hydraulic-jet staged fracturing,four-variation hydraulic fracturing and some auxiliary measures are effective technical approaches to fracture network stimulation,especially the four-variation hydraulic fracturing can stimulate the fracture network in vertical and cluster wells.It is concluded that the fracture network stimulating technology for surrounding beds has significant advantages,such as safe drilling operation,strong stimulation effect,strong adaptability to stress-sensitive and velocity-sensitive beds,and is suitable for coal reservoirs of any structure.Except for the limitation in extremely water-sensitive and high water-yield surrounding beds,the technology can be universally used in all other beds.The successful industrial tests in surface coal bed methane and underground coal mines gas extraction prove that the theory and technical system of fracture network stimulating in surrounding beds and coal reservoirs,as a universally applicable measure,will play a role in the CBM development in China.
