【摘要】：當(dāng)上層超彈性硬質(zhì)薄膜和下層可膨脹基底構(gòu)成的雙層結(jié)構(gòu)受壓時(shí),薄膜的自由表面可通過(guò)形成褶皺降低系統(tǒng)能量.研究表明,上下兩層的模量比不同時(shí),上層彈性硬質(zhì)薄膜將表現(xiàn)出不同的表面失穩(wěn)模式.本文提出了一種新穎的方法可有效抑制雙層軟材料的表面失穩(wěn),即改變基底材料的泊松比,這種方法同時(shí)適用于不具有應(yīng)變硬化的軟材料.首先基于Neo-Hookean模型發(fā)展了小變形條件下雙層結(jié)構(gòu)表面失穩(wěn)的理論模型,通過(guò)半解析的方法得到了表面失穩(wěn)的臨界應(yīng)變;然后通過(guò)有限元計(jì)算與模擬,進(jìn)一步驗(yàn)證了負(fù)泊松比基底可延緩表面失穩(wěn).結(jié)果表明:(1)當(dāng)雙層結(jié)構(gòu)基底泊松比為正且趨于0.5(不可壓縮)時(shí),雙層結(jié)構(gòu)在較小的壓縮應(yīng)變下出現(xiàn)表面失穩(wěn);(2)當(dāng)基底的泊松比為負(fù)且趨于-1時(shí),可被壓縮至46%而不出現(xiàn)表面失穩(wěn),即可膨脹基底能有效抑制薄膜的表面失穩(wěn).本文發(fā)展的方法及主要結(jié)果可為延展性電子器件的設(shè)計(jì)提供指導(dǎo).
[Abstract]:When the superelastic hard film in the upper layer and the double-layer structure composed of the expandable substrate in the lower layer are subjected to compression, the free surface of the film can reduce the energy of the system through the formation of folds. The results show that when the modulus ratio of the upper and lower layers is different, the elastic hard films in the upper layer will exhibit different surface instability modes. In this paper, a novel method is proposed to effectively suppress the surface instability of double layer soft materials, that is, to change the Poisson's ratio of substrate materials. This method is also suitable for soft materials without strain hardening. Firstly, the theoretical model of surface instability of double-layer structures under small deformation is developed based on Neo-Hookean model, and the critical strain of surface instability is obtained by semi-analytical method. Then through the finite element calculation and simulation, it is further verified that the negative Poisson ratio substrate can delay the surface instability. The results show that: (1) when the Poisson ratio of the double-layer structure is positive and tends to 0.5 (incompressible), the surface instability of the double-layer structure appears under small compression strain; (2) when the Poisson ratio of the substrate is negative and tends to-1, it can be compressed to 46% without surface instability, so the expansive substrate can effectively restrain the surface instability of the thin film. The development method and main results of this paper can provide guidance for the design of extendable electronic devices.
【作者單位】： 重慶大學(xué)航空航天學(xué)院;
【基金】：國(guó)家自然科學(xué)基金資助項(xiàng)目(11472065)
【分類(lèi)號(hào)】：O343.9
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本文編號(hào)：2440695