【摘要】：利用能以極慢變形率直接剪切顆粒固體的實驗裝置,測量了(玻璃珠)樣品對大幅度循環(huán)剪切的力-位移曲線,以及一個循環(huán)周期后的塑性位移殘留.發(fā)現(xiàn)隨著循環(huán)頻率的降低,樣品會從有限塑性殘留的彈塑行為轉(zhuǎn)變到幾乎沒有塑性的純彈性行為,同時伴隨有率相關(guān)性.該轉(zhuǎn)變在剪切力幅度高達樣品破壞值的90%時依然存在,但需要極小的變形率(10~(-5)Hz)或慣性數(shù)(10~(-8)).這意味著無論是高頻小幅度的聲波擾動,還是極低頻大幅度的直接剪切,靜態(tài)顆粒固體都可做出純彈性的力學響應.在足夠慢的狀態(tài)變化范圍里,它仍是屬于經(jīng)典彈性理論范疇的一類材料.這個彈性區(qū)域一直未被報道和關(guān)注,可能是觀測它時需要樣品的變形率遠比通常此類研究中所采用的慢變形還要小許多(大約兩個數(shù)量級)的緣故.理論上本文測量結(jié)果支持描述顆粒固體宏觀動力學的基本方程組,不能只有彈塑和率無關(guān)行為,它們必須在極慢變形極限下退化為經(jīng)典彈性理論,并且在這個轉(zhuǎn)變過程中表現(xiàn)出率相關(guān)特性.
[Abstract]:The force-displacement curves of (glass bead) samples for large cyclic shearing and the residual plastic displacement after one cycle were measured by using an experimental device capable of directly shearing granular solids at an extremely slow deformation rate. It is found that with the decrease of cycle frequency, the elastic-plastic behavior of the sample changes from a finite plastic residue to a pure elastic behavior with almost no plasticity, which is accompanied by a rate correlation. This transition still exists when the shear force amplitude is up to 90% of the sample failure value, but requires a minimal deformation rate (10 ~ (-5) Hz) or inertia number (10 ~ (-8). This means that both high frequency and small amplitude acoustic disturbance or very low frequency large amplitude direct shear, static granular solids can make pure elastic mechanical response. In a sufficiently slow range of state variations, it is still a class of materials in the category of classical elastic theory. This elastic region has not been reported and paid attention to, possibly because the deformation rate of the sample required to observe it is much smaller (about two orders of magnitude) than the slow deformation usually used in such studies. Theoretically, the measurement results in this paper support the basic equations describing the macroscopic dynamics of granular solids. The elastoplastic behavior and rate-independent behavior should not be the only ones, but they must degenerate into classical elastic theory at the limit of extremely slow deformation. And in the process of this transition shows a rate-dependent characteristics.
【作者單位】： 中南大學物理與電子學院;
【基金】：國家自然科學基金(批準號:10904175,11274390)資助的課題~~
【分類號】：O347.7

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本文編號：2266392