In the finite element method,the numerical simulation of three-dimensional crack propagation is relatively rare,and it is often realized by commercial programs.In addition to the geometric complexity,the determination...In the finite element method,the numerical simulation of three-dimensional crack propagation is relatively rare,and it is often realized by commercial programs.In addition to the geometric complexity,the determination of the cracking direction constitutes a great challenge.In most cases,the local stress state provides the fundamental criterion to judge the presence of cracks and the direction of crack propagation.However,in the case of three-dimensional analysis,the coordination relationship between grid elements due to occurrence of cracks becomes a difficult problem for this method.In this paper,based on the extended finite element method,the stress-related function field is introduced into the calculation domain,and then the boundary value problem of the function is solved.Subsequently,the envelope surface of all propagation directions can be obtained at one time.At last,the possible surface can be selected as the direction of crack development.Based on the aforementioned procedure,such method greatly reduces the programming complexity of tracking the crack propagation.As a suitable method for simulating tension-induced failure,it can simulate multiple cracks simultaneously.展开更多
Polyacrylonitrile（PAN）-based activated carbon fiber（PACF） supporting nano-ZnO（PACF/nano-ZnO） was prepared by spin, pretreatment, carbonization, and KOH chemical activation at an activation temperature of 950℃ f...Polyacrylonitrile（PAN）-based activated carbon fiber（PACF） supporting nano-ZnO（PACF/nano-ZnO） was prepared by spin, pretreatment, carbonization, and KOH chemical activation at an activation temperature of 950℃ for 40 min. Nano-ZnO content, distribution and antibacterial properties of the PACF/nano-ZnO were studied. The pore structure and surface properties of the PACF/nano-ZnO were studied by Brunauer-Emmett-Teller（BET）, N2/77 K isothermal adsorption. The specific surface area increased markedly after the activation process and it was several hundred times greater than that before the process. The PACF/nano-ZnO shows a strong adsorption for Staphylococ- cus aureus（S, aureus） and Escherichia coli（E, coli） and antibacterial activity against them. As an experimental result, antibacterial properties of PACF/nano-ZnO increased with increasing the concentration of nano-ZnO panicles, which suggests it is a promising antibacterial material.展开更多
基金Project(2017YFC0404802)supported by the National Key R&D Program of ChinaProjects(U1965206,51979143)supported by the National Natural Science Foundation of China。
文摘In the finite element method,the numerical simulation of three-dimensional crack propagation is relatively rare,and it is often realized by commercial programs.In addition to the geometric complexity,the determination of the cracking direction constitutes a great challenge.In most cases,the local stress state provides the fundamental criterion to judge the presence of cracks and the direction of crack propagation.However,in the case of three-dimensional analysis,the coordination relationship between grid elements due to occurrence of cracks becomes a difficult problem for this method.In this paper,based on the extended finite element method,the stress-related function field is introduced into the calculation domain,and then the boundary value problem of the function is solved.Subsequently,the envelope surface of all propagation directions can be obtained at one time.At last,the possible surface can be selected as the direction of crack development.Based on the aforementioned procedure,such method greatly reduces the programming complexity of tracking the crack propagation.As a suitable method for simulating tension-induced failure,it can simulate multiple cracks simultaneously.
文摘Polyacrylonitrile（PAN）-based activated carbon fiber（PACF） supporting nano-ZnO（PACF/nano-ZnO） was prepared by spin, pretreatment, carbonization, and KOH chemical activation at an activation temperature of 950℃ for 40 min. Nano-ZnO content, distribution and antibacterial properties of the PACF/nano-ZnO were studied. The pore structure and surface properties of the PACF/nano-ZnO were studied by Brunauer-Emmett-Teller（BET）, N2/77 K isothermal adsorption. The specific surface area increased markedly after the activation process and it was several hundred times greater than that before the process. The PACF/nano-ZnO shows a strong adsorption for Staphylococ- cus aureus（S, aureus） and Escherichia coli（E, coli） and antibacterial activity against them. As an experimental result, antibacterial properties of PACF/nano-ZnO increased with increasing the concentration of nano-ZnO panicles, which suggests it is a promising antibacterial material.
