摘要
聚合物基底-薄膜结构被广泛应用于光电医疗、食品生物等领域。但是,在镀膜的过程中往往会因薄膜和基底之间的热膨胀性能差异、晶格失配等因素,在构件中产生残余应力,从而影响使用寿命和耐用性。为此,本文建立了考虑残余应力的单层膜基结构二维弹性应力分析模型,应用强度准则和能量准则两个判据分析裂纹的萌生及填充过程,并提出了一种在被施加预应力的基底上进行磁控溅射镀膜的预加载来模拟残余应力的实验方法。在125μm聚酰亚胺基底上沉积100nm铬膜制成膜基结构试件,对存在压缩应力的膜基结构进行单轴拉伸损伤实验,探究了残余应力对裂纹萌生和填充演化的影响。研究表明,残余压应力的大小与起裂时基底的应变值近似成线性关系,残余压应力越大对应的临界拉伸载荷越大;当拉伸应变较小时,残余压应力越大的薄膜中的裂纹间距越大;在描述裂纹填充演化过程中裂纹间距的变化时,强度准则比能量准则更接近实验测量的结果。
The polymer substrate-film assembly is widely used in the fields of optoelectronics and food biology.However,in the process of depositing films,due to factors such as the difference in thermal expansion coefficient and lattice mismatch between the film and the substrate,residual stresses are generated in the devices,which affects the service life and durability.In this paper,a two-dimensional elastic theoretical model of a single-layer film/substrate assembly considering residual stress is established.The initiation and filling process of cracks is analyzed using strength criterion and energy criterion.A preloading method for simulating residual stress is proposed by depositing a thin film on the prestressed substrate.After the preload is released,uniaxial tensile tests of 100 nm Cr films deposited on 125μm polyimide substrates are carried out to explore the influence of residual stress on crack initiation and filling propagation.Results indicate that the magnitude of the compressive residual stress is approximately linearly related to the applied strain when the cracks occur.The larger the residual stress,the greater the critical tensile load.What's more,when the applied strain is small,the greater the compressive residual stress,the greater the crack length in the film.When describing the variation of crack length during crack filling and propagation,the strength criterion is closer to the experimental measurement result than the energy criterion.
作者
王琦
李林安
李军
李传崴
王志勇
王世斌
曾炎涛
WANG Qi;LI Linan;LI Jun;LI Chuanwei;WANG Zhiyong;WANG Shibin;ZENG Yantao(Department of Mechanics,School of Mechanical Engineering,Tianjin University,Tianjin 300350,China)
出处
《实验力学》
CSCD
北大核心
2021年第4期440-450,共11页
Journal of Experimental Mechanics
基金
国家自然科学基金(11572218)资助。
关键词
膜基结构
残余应力
预加载
裂纹萌生
裂纹填充
film/substrate assembly
residual stress
preload
crack initiation
crack filling
