Three-dimensional(3D)printing technology is increasingly used in experimental research of geotechnical engineering.Compared to other materials,3D layer-by-layer printing specimens are extremely similar to the inherent...Three-dimensional(3D)printing technology is increasingly used in experimental research of geotechnical engineering.Compared to other materials,3D layer-by-layer printing specimens are extremely similar to the inherent properties of natural layered rock masses.In this paper,soft-hard interbedded rock masses with different dip angles were prepared based on 3D printing(3DP)sand core technology.Uniaxial compression creep tests were conducted to investigate its anisotropic creep behavior based on digital imaging correlation(DIC)technology.The results show that the anisotropic creep behavior of the 3DP soft-hard interbedded rock mass is mainly affected by the dip angles of the weak interlayer when the stress is at low levels.As the stress level increases,the effect of creep stress on its creep anisotropy increases significantly,and the dip angle is no longer the main factor.The minimum value of the long-term strength and creep failure strength always appears in the weak interlayer within 30°–60°,which explains why the failure of the layered rock mass is controlled by the weak interlayer and generally emerges at 45°.The tests results are verified by comparing with theoretical and other published studies.The feasibility of the 3DP soft-hard interbedded rock mass provides broad prospects and application values for 3DP technology in future experimental research.展开更多
Inspired by the cartilage-bone structure in natural joints,soft-hard integrated materials have received extensive attention,which are the most promising candidates for artificial joints due to their combination of exc...Inspired by the cartilage-bone structure in natural joints,soft-hard integrated materials have received extensive attention,which are the most promising candidates for artificial joints due to their combination of excellent load-bearing properties and lubricating properties.The latest progress showed that the combination of hydrogel and titanium alloy can realize a bionic natural joint lubrication system on the surface of titanium alloy.However,obtaining a tough interface between the hydrogel(soft and wet)and the titanium substrate(hard and dry)is still a great challenge.Here,we designed a"soft(hydrogel)-hard(Ti6Al4V)"integrated material with outstanding combination,which simulates the structure and function of cartilage-bone in the natural joint.The load-bearing properties,binding performance,and tribological behaviors for different forms of the soft-hard integrated materials were investigated.The results showed that the hydrogel layer and Ti6Al4V substrate possess ultra-high interfacial toughness(3,900 J/m^(2)).In addition,the combination of the hydrogel layer and Ti6Al4V substrate provided a good lubrication system to endow the"soft(hydrogel)-hard(Ti6Al4V)"integrated material with high load-bearing and excellent tribological properties.Therefore,this study provided an effective strategy for prolonging the service life of Ti6Al4V in the biomedical field.展开更多
The disc cutters of shield machines exhibit unsatisfactory adaptability and performance during the soft–hard varied strata tunneling process.To analyze the rotation state,cutting performance,and adaptability of disc ...The disc cutters of shield machines exhibit unsatisfactory adaptability and performance during the soft–hard varied strata tunneling process.To analyze the rotation state,cutting performance,and adaptability of disc cutters during shield tunneling in soft–hard varied strata,the Holmquist Johnson Cook and Federal Highway Administration constitutive models are introduced to numerically simulate the failure process of materials on the excavation face and to calculate the load of disc cutters.Additionally,the parameters of the models are modified based on laboratory disc cutter excavation test results.The results of numerical calculation can reflect the load level and the behavior of the disc cutters during operation.The tangential loads of the disc cutters during the cutting of four typical soft-strata excavation face models are numerically calculated,thus providing reference values for the starting torque of the disc cutters.A greater penetration is suggested for soft-strata tunneling to allow the disc cutters to rotate smoothly and continuously as well as to guarantee a better cutting effect.The disc cutters in the center of the cutterhead should be specified with a lower starting torque to prevent uneven wear,rotation stagnation,cutterhead clogging,and other adverse phenomena.展开更多
基金the support of the National Natural Science Foundation of China(Grant Nos.42207199,52179113,42272333)Zhejiang Postdoctoral Scientific Research Project(Grant Nos.ZJ2022155,ZJ2022156)。
文摘Three-dimensional(3D)printing technology is increasingly used in experimental research of geotechnical engineering.Compared to other materials,3D layer-by-layer printing specimens are extremely similar to the inherent properties of natural layered rock masses.In this paper,soft-hard interbedded rock masses with different dip angles were prepared based on 3D printing(3DP)sand core technology.Uniaxial compression creep tests were conducted to investigate its anisotropic creep behavior based on digital imaging correlation(DIC)technology.The results show that the anisotropic creep behavior of the 3DP soft-hard interbedded rock mass is mainly affected by the dip angles of the weak interlayer when the stress is at low levels.As the stress level increases,the effect of creep stress on its creep anisotropy increases significantly,and the dip angle is no longer the main factor.The minimum value of the long-term strength and creep failure strength always appears in the weak interlayer within 30°–60°,which explains why the failure of the layered rock mass is controlled by the weak interlayer and generally emerges at 45°.The tests results are verified by comparing with theoretical and other published studies.The feasibility of the 3DP soft-hard interbedded rock mass provides broad prospects and application values for 3DP technology in future experimental research.
基金financially supported by Natural Science Foundation of Jiangsu Province(Grant No.BK20211243)National Natural Science Foundation of China(Grant Nos.51705517,51875563,51875564)+1 种基金the Tribology Science Fund of State Key Laboratory of Tribology(Grant No.SKLTKF21B15)the Open Fund of State Key Laboratory of Solid Lubrication,Lanzhou Institute of Chemical Physics(Grant No.LSL-2107).
文摘Inspired by the cartilage-bone structure in natural joints,soft-hard integrated materials have received extensive attention,which are the most promising candidates for artificial joints due to their combination of excellent load-bearing properties and lubricating properties.The latest progress showed that the combination of hydrogel and titanium alloy can realize a bionic natural joint lubrication system on the surface of titanium alloy.However,obtaining a tough interface between the hydrogel(soft and wet)and the titanium substrate(hard and dry)is still a great challenge.Here,we designed a"soft(hydrogel)-hard(Ti6Al4V)"integrated material with outstanding combination,which simulates the structure and function of cartilage-bone in the natural joint.The load-bearing properties,binding performance,and tribological behaviors for different forms of the soft-hard integrated materials were investigated.The results showed that the hydrogel layer and Ti6Al4V substrate possess ultra-high interfacial toughness(3,900 J/m^(2)).In addition,the combination of the hydrogel layer and Ti6Al4V substrate provided a good lubrication system to endow the"soft(hydrogel)-hard(Ti6Al4V)"integrated material with high load-bearing and excellent tribological properties.Therefore,this study provided an effective strategy for prolonging the service life of Ti6Al4V in the biomedical field.
基金The authors gratefully acknowledge the financial support provided by the National Key R&D Program of China(No.2020YFF0426370)the National Natural Science Foundation of China(Grant No.51978040).
文摘The disc cutters of shield machines exhibit unsatisfactory adaptability and performance during the soft–hard varied strata tunneling process.To analyze the rotation state,cutting performance,and adaptability of disc cutters during shield tunneling in soft–hard varied strata,the Holmquist Johnson Cook and Federal Highway Administration constitutive models are introduced to numerically simulate the failure process of materials on the excavation face and to calculate the load of disc cutters.Additionally,the parameters of the models are modified based on laboratory disc cutter excavation test results.The results of numerical calculation can reflect the load level and the behavior of the disc cutters during operation.The tangential loads of the disc cutters during the cutting of four typical soft-strata excavation face models are numerically calculated,thus providing reference values for the starting torque of the disc cutters.A greater penetration is suggested for soft-strata tunneling to allow the disc cutters to rotate smoothly and continuously as well as to guarantee a better cutting effect.The disc cutters in the center of the cutterhead should be specified with a lower starting torque to prevent uneven wear,rotation stagnation,cutterhead clogging,and other adverse phenomena.
