Purpose-As a key structure in the railway power supply system,the overhead catenary pillar carries the entire weight and dynamic load of the contact suspension device and supporting equipment.Its stability and reliabi...Purpose-As a key structure in the railway power supply system,the overhead catenary pillar carries the entire weight and dynamic load of the contact suspension device and supporting equipment.Its stability and reliability are directly related to the operational safety and efficiency of electrified railways.Design/methodology/approach-Regarding the phenomenon of abnormal shedding of coating above the support under the cantilever of the catenary pillar in the track running line,a three-dimensional model is established to analyse the rigid cantilever type catenary and the force analysis of the cantilever part is carried out by using ABAQUS to calculate the contact force of the bow network under different running speeds of the highspeed train.The load is applied at the locator end of the simplified model of the cantilever to get the support reaction force at the connection between the cantilever and the support.Findings-The support reaction force is applied as a load to the three-dimensional model of the pillar support;the stress cloud and the stress extreme value of 86.14 MPa are obtained for the pillar and the support part and the fatigue life of the pillar’s key parts is calculated to be 12.02 years,respectively.Originality/value-The upper part of the lower support of the high-speed rail catenary pillar is subjected to the alternating load transmitted by the bow net,which causes the fretting damage at this position,resulting in the abnormal peeling of the coating on the upper part of the lower support.Through combining the ABAQUS analysis with the structural characteristics and operating conditions of the catenary system,the main causes of component failure are determined.展开更多
Micromotion and fretting damages at the dental implant/bone interface are neglected for the limitation of check methods, but it is particularly important for the initial success of osseointegration and the life time o...Micromotion and fretting damages at the dental implant/bone interface are neglected for the limitation of check methods, but it is particularly important for the initial success of osseointegration and the life time of dental implant. This review article describes the scientific documentation of micromotion and fretting damages on the dental implant/bone interface. The fretting amplitude is less than 30 l^m in vitroand the damage in the interface is acceptable. While in vivo, the micromotion＇s effect is the combination of damage in tissue level and the real biological reaction.展开更多
This paper introduces the definition,classification,and running modes of fretting damage,as well as industrial phenomena of fretting damage cases.It is detail reviewed the progress of two-types fretting map theory(run...This paper introduces the definition,classification,and running modes of fretting damage,as well as industrial phenomena of fretting damage cases.It is detail reviewed the progress of two-types fretting map theory(running condition fretting map-RCFM and material response fretting map-MRFM),and outlines the protection strategy of fretting wear according to the fretting map theory,i.e.eliminating the mixed fretting regime and slip regime,increasing the strength of the contact surface,reducing the coefficient of friction,and selecting and matching of materials.Several surface engineering techniques(such as PVD,laser surface modification technology,bonded solid lubricant coating,thermal spraying coating,and micro-arc oxidation coating)against fretting wear are reviewed,several mechanisms to alleviating fretting wear are proposed as well as a collection of practical examples of surface engineering designs to anti-fretting wear.Base on the review of previous studies,mechanisms of surface engineering technologies for alleviating fretting wear have been proposed.In addition,the content and process of surface engineering design are introduced in this paper.A quantitative evaluation method using polar coordinate diagram is applied to choose appropriate surface engineering technology.Finally,taking the locking pin of variable gauge train as an example,the process of surface engineering design is further expounded.展开更多
基金Supported by the State Railway Administration of China(J2022G008).
文摘Purpose-As a key structure in the railway power supply system,the overhead catenary pillar carries the entire weight and dynamic load of the contact suspension device and supporting equipment.Its stability and reliability are directly related to the operational safety and efficiency of electrified railways.Design/methodology/approach-Regarding the phenomenon of abnormal shedding of coating above the support under the cantilever of the catenary pillar in the track running line,a three-dimensional model is established to analyse the rigid cantilever type catenary and the force analysis of the cantilever part is carried out by using ABAQUS to calculate the contact force of the bow network under different running speeds of the highspeed train.The load is applied at the locator end of the simplified model of the cantilever to get the support reaction force at the connection between the cantilever and the support.Findings-The support reaction force is applied as a load to the three-dimensional model of the pillar support;the stress cloud and the stress extreme value of 86.14 MPa are obtained for the pillar and the support part and the fatigue life of the pillar’s key parts is calculated to be 12.02 years,respectively.Originality/value-The upper part of the lower support of the high-speed rail catenary pillar is subjected to the alternating load transmitted by the bow net,which causes the fretting damage at this position,resulting in the abnormal peeling of the coating on the upper part of the lower support.Through combining the ABAQUS analysis with the structural characteristics and operating conditions of the catenary system,the main causes of component failure are determined.
基金the support of the National Natural Science Foundation of China (Nos. 81170996, 81070867, and 81100777)Sichuan Province Science and Technology Innovation Team Program (2011JTD0006)
文摘Micromotion and fretting damages at the dental implant/bone interface are neglected for the limitation of check methods, but it is particularly important for the initial success of osseointegration and the life time of dental implant. This review article describes the scientific documentation of micromotion and fretting damages on the dental implant/bone interface. The fretting amplitude is less than 30 l^m in vitroand the damage in the interface is acceptable. While in vivo, the micromotion＇s effect is the combination of damage in tissue level and the real biological reaction.
基金National Natural Science Foundation of China(Nos.U2141212,52075460 and 52005117)Sichuan Science and Technology Program(Nos.2023NSFSC0411 and 2022023)the Fundamental Research Funds for the Central Universities(2682023ZTPY006,2682022CX043,2682022ZTPY014).
文摘This paper introduces the definition,classification,and running modes of fretting damage,as well as industrial phenomena of fretting damage cases.It is detail reviewed the progress of two-types fretting map theory(running condition fretting map-RCFM and material response fretting map-MRFM),and outlines the protection strategy of fretting wear according to the fretting map theory,i.e.eliminating the mixed fretting regime and slip regime,increasing the strength of the contact surface,reducing the coefficient of friction,and selecting and matching of materials.Several surface engineering techniques(such as PVD,laser surface modification technology,bonded solid lubricant coating,thermal spraying coating,and micro-arc oxidation coating)against fretting wear are reviewed,several mechanisms to alleviating fretting wear are proposed as well as a collection of practical examples of surface engineering designs to anti-fretting wear.Base on the review of previous studies,mechanisms of surface engineering technologies for alleviating fretting wear have been proposed.In addition,the content and process of surface engineering design are introduced in this paper.A quantitative evaluation method using polar coordinate diagram is applied to choose appropriate surface engineering technology.Finally,taking the locking pin of variable gauge train as an example,the process of surface engineering design is further expounded.
