Maturing process of solitary wave train in a step-down chain

In a step-down chain a solitary wave (SW) evolves into an SW train (SWT), but the formation of well-defined SWT takes time and space and little is known of the process from immature into mature SWT. We therefore perform a detailed numerical study of this process by analysing the local velocity amplitude and peak overlap of immature ordered SWs. The first SW continuously increases to maximal velocity amplitude and peak overlap until it is matured, but for following SWs there exist a minimal and maximal value of local velocity amplitude and, a minimal and maximal value of local peak overlap, clarifying the details of the energy propagation along the stepped chain. The immature and mature SWTs show the same dependence of the phase velocity on the SWs sequence. These provide guidelines for when or where the attention should be paid in the study of SWT.     

一维复合颗粒链中能量衰减的动力学分析

重颗粒区域由压缩到稀疏的结构转变导致了一维复合颗粒链中能量衰减的渡越行为,并且这种结构转变与界面附近重颗粒的运动状态的变化密切关联.分析表明这种运动状态的转变导致了界面处的反射率在两个分支存在较大差别,从而导致了轻颗粒区域能量在两个分支以不同的速率衰减. 关键词： 复合颗粒链 渡越     

Biphasic behavior of energy in a stepped chain

The impact energy decay in a step-up chain containing two sections is numerically studied.There is a marked biphasic behavior of energy decay in the first section.Two sections close to the interface are in compression state.The degree of compression of the first section first decreases and becomes weakest at "crossing" time of biphasic behavior of energy,then increases.The further calculations provide the dependence of the character time on mass ratio(m1/m2),where m1 and m2are the particle mass in the first and second section respectively.The bigger the α(α = [(? m_1-m_2)/(? m_1+ m_2)]~2 with? = 1.345),the bigger the energy ratio is.The multipulse structure restricts the transport of energy.