The cyclic behaviours of two prestrained materials with different slip modes have been com- pared.From the analysis of hysterisis loops,it is suggested that the decrease in back stress dominates the cyclic process of ...The cyclic behaviours of two prestrained materials with different slip modes have been com- pared.From the analysis of hysterisis loops,it is suggested that the decrease in back stress dominates the cyclic process of Cu-Zn alloy with planar slip mode,while the decrease in frictional stress is the main factor affecting the behaviour of Cu with wavy slip mode.The re- lation between the dislocation configuration and internal stress has been also discussed.By means of the relation just mentioned,the variations of dislocation configuration before and after fatigue of the two materials,the differences in their softening mechanism and mechani- cal behaviour could be interpreted.展开更多
In this paper we present the Brillouin Scattering measurements of the longitudinal and transverse sound velocities for the hexahalome-atllate K2SnCl6 at room temperature . The elastic constants , refractive index , vo...In this paper we present the Brillouin Scattering measurements of the longitudinal and transverse sound velocities for the hexahalome-atllate K2SnCl6 at room temperature . The elastic constants , refractive index , volume compressibility are determined from the Brillouin line shifts. Furthermore, the sound velocity in the [111] direction is investigated as a function of temperature 252K<T<270K . An acoustic adrupt change of the c11+2c12 mode is observed as the temperature approaches 256K from above, which has been analysed by means of the Pippard relations. The conclusion is that K2SnCl6 undergoes first order phase transition near T=256K. This acoustic anomaly can be interpreted by the nonlinear coupling of the elastic strain field to the fluctuation of the soft-mode coordinate.展开更多
In this paper an experimental study on damage tolerance behaviour of composite panels with softening strips is carried out. A prediction method of residual strength of panels with softening strips is proposed. The com...In this paper an experimental study on damage tolerance behaviour of composite panels with softening strips is carried out. A prediction method of residual strength of panels with softening strips is proposed. The comparison between estimated and experimental results shows that the prediction method can be applied to design. In this paper the failure mechanisms are described.展开更多
川东红层地区在强降雨条件下极易产生群发性平缓岩层滑坡,其成因一直存疑。采用现场降雨入渗观察、室内试验等手段重点探讨川东红层岩质斜坡降雨入渗规律和滑坡成因机制。研究发现:以裂缝为主的通道为降雨入渗提供途径,雨水进入潜在滑...川东红层地区在强降雨条件下极易产生群发性平缓岩层滑坡,其成因一直存疑。采用现场降雨入渗观察、室内试验等手段重点探讨川东红层岩质斜坡降雨入渗规律和滑坡成因机制。研究发现:以裂缝为主的通道为降雨入渗提供途径,雨水进入潜在滑面后会对滑带土形成软化作用。室内软化试验结果表明:原状滑带土饱水软化10 d后,黏聚力和内摩擦分别由天然时的20.76 k Pa和21.2°衰减至11.39 k Pa和4°,当泥化夹层重塑样含水率配至50%时,其抗剪强度仅为1.28 k Pa和1.24°。以此为基础归纳2类滑坡失稳模式:蠕滑–拉裂型是由于滑带土软化后强度降低引起的,平推–滑移型则主要是在后缘静水压力、底滑面扬压力和滑带土软化综合作用下发生失稳的。推导的极限平衡公式可为红层滑坡稳定性评价和防治工程提供有益参考。展开更多
文摘The cyclic behaviours of two prestrained materials with different slip modes have been com- pared.From the analysis of hysterisis loops,it is suggested that the decrease in back stress dominates the cyclic process of Cu-Zn alloy with planar slip mode,while the decrease in frictional stress is the main factor affecting the behaviour of Cu with wavy slip mode.The re- lation between the dislocation configuration and internal stress has been also discussed.By means of the relation just mentioned,the variations of dislocation configuration before and after fatigue of the two materials,the differences in their softening mechanism and mechani- cal behaviour could be interpreted.
文摘In this paper we present the Brillouin Scattering measurements of the longitudinal and transverse sound velocities for the hexahalome-atllate K2SnCl6 at room temperature . The elastic constants , refractive index , volume compressibility are determined from the Brillouin line shifts. Furthermore, the sound velocity in the [111] direction is investigated as a function of temperature 252K<T<270K . An acoustic adrupt change of the c11+2c12 mode is observed as the temperature approaches 256K from above, which has been analysed by means of the Pippard relations. The conclusion is that K2SnCl6 undergoes first order phase transition near T=256K. This acoustic anomaly can be interpreted by the nonlinear coupling of the elastic strain field to the fluctuation of the soft-mode coordinate.
文摘In this paper an experimental study on damage tolerance behaviour of composite panels with softening strips is carried out. A prediction method of residual strength of panels with softening strips is proposed. The comparison between estimated and experimental results shows that the prediction method can be applied to design. In this paper the failure mechanisms are described.
文摘川东红层地区在强降雨条件下极易产生群发性平缓岩层滑坡,其成因一直存疑。采用现场降雨入渗观察、室内试验等手段重点探讨川东红层岩质斜坡降雨入渗规律和滑坡成因机制。研究发现:以裂缝为主的通道为降雨入渗提供途径,雨水进入潜在滑面后会对滑带土形成软化作用。室内软化试验结果表明:原状滑带土饱水软化10 d后,黏聚力和内摩擦分别由天然时的20.76 k Pa和21.2°衰减至11.39 k Pa和4°,当泥化夹层重塑样含水率配至50%时,其抗剪强度仅为1.28 k Pa和1.24°。以此为基础归纳2类滑坡失稳模式:蠕滑–拉裂型是由于滑带土软化后强度降低引起的,平推–滑移型则主要是在后缘静水压力、底滑面扬压力和滑带土软化综合作用下发生失稳的。推导的极限平衡公式可为红层滑坡稳定性评价和防治工程提供有益参考。
