Studying the effect of geometrically irregular bodies on the mechanical behavior of fault activity is of significance in understanding the seismic activity along a fault zone. By using rock mechanics ex- periment with...Studying the effect of geometrically irregular bodies on the mechanical behavior of fault activity is of significance in understanding the seismic activity along a fault zone. By using rock mechanics ex- periment with medium-scale samples, we have studied the effect of fault jogs, the most common irregularity along fault zones, on frictional behavior. The research indicates that extensional fault jog can be easily fractured because of its low strength and the fractured jog has no obvious resistance to fault sliding, and the micro-fractures occurring in the jog are indicative of stick-slip along the faults. The fault zone containing extensional jogs is characterized by velocity weakening and can be described by rate and state friction law. Compressional fault jog makes fault sliding more difficult because of its high fracturing strength, but the micro-fractures occurring in the tensile areas around fault ends at higher stress level can provide necessary condition for occurrence of stick-slip along the faults before the jog is fractured and thus act as precursors of fault instability. Compression jog can be taken as a stable indicator of fault segmentation until the jog is completely fractured and two faults are linked.展开更多
Fast walking and jogging are two common exercises for people to maintain health in daily life.But the differences in loading patterns of fast walking and jogging are still unclear.The purpose of this study was to comp...Fast walking and jogging are two common exercises for people to maintain health in daily life.But the differences in loading patterns of fast walking and jogging are still unclear.The purpose of this study was to compare loading patterns in fast walking and jogging at the same speed,and to identify how differences in foot mechanics influence plantar pressure distribution between the two modes of gait.Totally,49 healthy males participated in this study.Data of pressure parameters,including maximum force(MF),peak pressure(PP),contact area(CA),force-time integral(FTI),were recorded by Pedar-X insole plantar pressure measurement system in participants’fast walking and jogging process at 7 km/h.A Load transfer analysis method was used to quantify the plantar load transference from fast walking to jogging.The results showed that MF,PP and CA increased in metatarsal regions and midfoot regions while decreased in toes regions and heel during jogging when compared with fast walking.FTI decreased in all foot regions during jogging compared to fast walking.Under the effects of spring mechanics and the varus of rearfoot during jogging,fast walking and jogging reveal different loading patterns.Compared jogging to fast walking,load transferred as follow:1)in transverse direction,load transferred from lateral foot to medial foot in metatarsal regions and midfoot regions,2)in longitudinal direction,load transferred from toes to the metatarsal,and from heel to the metatarsal and midfoot.These results also provide suggestions for footwear designs.展开更多
髌股关节痛是一种很常见的膝关节运动损伤,鞋底前后落差、着地方式、运动环境等均会对髌股关节应力造成一定影响。对此,本文在简单分析髌股关节损伤的基础上,设计了0、5、10和15 mm 4种鞋底前后落差对髌股关节的影响试验。选取18名男性...髌股关节痛是一种很常见的膝关节运动损伤,鞋底前后落差、着地方式、运动环境等均会对髌股关节应力造成一定影响。对此,本文在简单分析髌股关节损伤的基础上,设计了0、5、10和15 mm 4种鞋底前后落差对髌股关节的影响试验。选取18名男性受试者,分别穿着不同鞋底前后落差的运动鞋以4 m/s的速度慢跑,通过三维测力台、运动捕捉系统采集受试者的生物力学数据,得出测试结果:在受试者足部着地瞬间,鞋底前后落差对足地角大小有显著影响;相比高落差运动鞋,穿着无落差运动鞋慢跑时下肢髌股关节应力峰值较低,同时应力峰值时刻髌股关节压力、伸膝力矩、股四头肌活动等也得以减弱,从而降低髌股关节运动损伤风险。展开更多
应用footscan足底压力测量系统,对32例健康女大学生被试在步行和慢跑时足底压力中心(centre of pressure,COP)轨迹的变化规律进行不同运动模式下的对照研究,分别分析左足、右足在5次步行或慢跑时整个支撑期的COP轨迹及其相似度。结果...应用footscan足底压力测量系统,对32例健康女大学生被试在步行和慢跑时足底压力中心(centre of pressure,COP)轨迹的变化规律进行不同运动模式下的对照研究,分别分析左足、右足在5次步行或慢跑时整个支撑期的COP轨迹及其相似度。结果表明:1)不同运动模式(步行与慢跑)的COP轨迹相似度低于0.25;2)同一运动模式(步行或慢跑)下,左侧、右侧的COP轨迹均具有很高的相似度(大于0.91)。其中被试内(同一被试)COP轨迹相似度高于被试间(不同被试),且前者方差低于后者,差值具有显著意义;被试内(同一被试)同侧足之间的COP轨迹相似度高于异侧足间,差值具有统计学意义。通过分析得到:步行和慢跑两个运动模式的COP轨迹相似度很低,COP轨迹可以识别不同的运动模式;运动模式相同时,不同被试间的COP轨迹相似度较高,且同一被试内同一侧的COP轨迹相似度更高。研究结果可以为临床诊断、康复评定、矫形处方和运动训练等提供参考依据。展开更多
基金the National Basic Research Program of China (Grant No. 2004CB418405)National Key Technologies R&D Program (Grant No. 2006BAC01B03)
文摘Studying the effect of geometrically irregular bodies on the mechanical behavior of fault activity is of significance in understanding the seismic activity along a fault zone. By using rock mechanics ex- periment with medium-scale samples, we have studied the effect of fault jogs, the most common irregularity along fault zones, on frictional behavior. The research indicates that extensional fault jog can be easily fractured because of its low strength and the fractured jog has no obvious resistance to fault sliding, and the micro-fractures occurring in the jog are indicative of stick-slip along the faults. The fault zone containing extensional jogs is characterized by velocity weakening and can be described by rate and state friction law. Compressional fault jog makes fault sliding more difficult because of its high fracturing strength, but the micro-fractures occurring in the tensile areas around fault ends at higher stress level can provide necessary condition for occurrence of stick-slip along the faults before the jog is fractured and thus act as precursors of fault instability. Compression jog can be taken as a stable indicator of fault segmentation until the jog is completely fractured and two faults are linked.
基金supported by National Natural Science Foundation of China,grant number:11502154.
文摘Fast walking and jogging are two common exercises for people to maintain health in daily life.But the differences in loading patterns of fast walking and jogging are still unclear.The purpose of this study was to compare loading patterns in fast walking and jogging at the same speed,and to identify how differences in foot mechanics influence plantar pressure distribution between the two modes of gait.Totally,49 healthy males participated in this study.Data of pressure parameters,including maximum force(MF),peak pressure(PP),contact area(CA),force-time integral(FTI),were recorded by Pedar-X insole plantar pressure measurement system in participants’fast walking and jogging process at 7 km/h.A Load transfer analysis method was used to quantify the plantar load transference from fast walking to jogging.The results showed that MF,PP and CA increased in metatarsal regions and midfoot regions while decreased in toes regions and heel during jogging when compared with fast walking.FTI decreased in all foot regions during jogging compared to fast walking.Under the effects of spring mechanics and the varus of rearfoot during jogging,fast walking and jogging reveal different loading patterns.Compared jogging to fast walking,load transferred as follow:1)in transverse direction,load transferred from lateral foot to medial foot in metatarsal regions and midfoot regions,2)in longitudinal direction,load transferred from toes to the metatarsal,and from heel to the metatarsal and midfoot.These results also provide suggestions for footwear designs.
文摘髌股关节痛是一种很常见的膝关节运动损伤,鞋底前后落差、着地方式、运动环境等均会对髌股关节应力造成一定影响。对此,本文在简单分析髌股关节损伤的基础上,设计了0、5、10和15 mm 4种鞋底前后落差对髌股关节的影响试验。选取18名男性受试者,分别穿着不同鞋底前后落差的运动鞋以4 m/s的速度慢跑,通过三维测力台、运动捕捉系统采集受试者的生物力学数据,得出测试结果:在受试者足部着地瞬间,鞋底前后落差对足地角大小有显著影响;相比高落差运动鞋,穿着无落差运动鞋慢跑时下肢髌股关节应力峰值较低,同时应力峰值时刻髌股关节压力、伸膝力矩、股四头肌活动等也得以减弱,从而降低髌股关节运动损伤风险。
文摘应用footscan足底压力测量系统,对32例健康女大学生被试在步行和慢跑时足底压力中心(centre of pressure,COP)轨迹的变化规律进行不同运动模式下的对照研究,分别分析左足、右足在5次步行或慢跑时整个支撑期的COP轨迹及其相似度。结果表明:1)不同运动模式(步行与慢跑)的COP轨迹相似度低于0.25;2)同一运动模式(步行或慢跑)下,左侧、右侧的COP轨迹均具有很高的相似度(大于0.91)。其中被试内(同一被试)COP轨迹相似度高于被试间(不同被试),且前者方差低于后者,差值具有显著意义;被试内(同一被试)同侧足之间的COP轨迹相似度高于异侧足间,差值具有统计学意义。通过分析得到:步行和慢跑两个运动模式的COP轨迹相似度很低,COP轨迹可以识别不同的运动模式;运动模式相同时,不同被试间的COP轨迹相似度较高,且同一被试内同一侧的COP轨迹相似度更高。研究结果可以为临床诊断、康复评定、矫形处方和运动训练等提供参考依据。
