期刊
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
卷 146, 期 -, 页码 -出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmps.2020.104172
关键词
Viscoelasticity; Soft materials; Volume controlled cavity expansion; Rate dependent effects; Mullins effect
资金
- Army Research Office, United States of America [W911NF-19-1-0275]
- Office of Naval Research, United States of America [N00014-20-1-2561]
Measuring local rate dependent mechanical properties with minimally invasive experimental methods is crucial in understanding the behavior of soft and biological materials. Enhancements to the Volume Controlled Cavity Expansion technique have been proposed to characterize the viscoelastic response at low to medium stretch rates. The technique allows for accurate estimation of both quasistatic and dynamic material parameters, addressing possible overestimation of the quasistatic elastic modulus in previous studies.
Minimally invasive experimental methods that can measure local rate dependent mechanical properties are essential in understanding the behaviour of soft and biological materials in a wide range of applications. Needle based measurement techniques such as Cavitation Rheology (Zimberlin et al., 2007) and Volume Controlled Cavity Expansion (VCCE, Raayai-Ardakani et al. (2019a)), allow for minimally invasive local mechanical testing, but have been limited to measuring the elastic material properties. Here, we propose several enhancements to the VCCE technique to adapt it for characterisation of viscoelastic response at low to medium stretch rates (10(-2) - 1 s(-1)). Through a carefully designed loading protocol, the proposed technique performs several cycles of expansion-relaxation at controlled stretch rates in a cavity expansion setting and then employs a large deformation viscoelastic model to capture the measured material response. Application of the technique to soft PDMS rubber reveals significant rate dependent material response with high precision and repeatability, while isolating equilibrated states that are used to directly infer the quasistatic elastic modulus. The technique is further established by demonstrating its ability to capture changes in the rate dependent material response of a tuneable PDMS system. The measured viscoelastic properties of soft PDMS samples are used to explain earlier reports of rate insensitive material response by needle based methods: it is demonstrated that the conventional use of constant volumetric rate cavity expansion can induce high stretch rates that lead to viscoelastic stiffening and an illusion of rate insensitive material response. We thus conclude with a cautionary note on possible overestimation of the quasistatic elastic modulus in previous studies and suggest that the stretch rate controlled expansion protocol, proposed in this work, is essential for accurate estimation of both quasistatic and dynamic material parameters.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据