Dulal Hemanta, Alaie Seyedhamidreza
New Mexico State University, Las Cruces, USA.
HardwareX. 2024 Nov 22;21:e00608. doi: 10.1016/j.ohx.2024.e00608. eCollection 2025 Mar.
Hyperelastic materials are extensively incorporated in medical implants and microelectromechanical systems due to their large, elastic, recoverable strains. However, their mechanical properties are sensitive to processing parameters that may lead to inconsistent characterization. Various test setups have been employed for characterizing hyperelastic materials; however, they are often costly. Recent advancements in additive manufacturing and open-source software/hardware suggest the possibility of simpler solutions in research settings for characterizing them; raising the question of whether one can characterize these materials with low-cost tools and tests that take advantage of soft and small form-factor samples. Here, the authors investigate the potential of an open-source, 3D-printed test system designed for characterizing such materials. This system is tailored for small form-factor samples (sub-mm thickness) and large elastic deformations, common in polymeric parts of minimally invasive implants. The authors developed parts using additive manufacturing for uniaxial and planar tension testing, with a low-cost image correlation method adapted for measuring large strains. Polydimethylsiloxane was chosen for demonstration of a two-parameter Mooney-Rivlin model, due to its documentation and use in biocompatible devices. The estimated Young's and shear moduli were repeatable and consistent with the literature. Curve-fitting was challenging and dependent on the optimization choices, when data points were limited, consistent with prior reports. However, with a large number of data points and ideal optimization error choice, and were found to be close to those reported previously. This work demonstrates a low-cost, 3D-printed, open-source test setup for characterizing hyperelastic materials using a two-parameter Mooney-Rivlin model with reasonable accuracy.
由于超弹性材料具有大的、弹性的、可恢复的应变，它们被广泛应用于医疗植入物和微机电系统中。然而，它们的机械性能对加工参数敏感，这可能导致表征不一致。已经采用了各种测试装置来表征超弹性材料；然而，它们通常成本高昂。增材制造以及开源软件/硬件的最新进展表明，在研究环境中可能存在更简单的解决方案来表征这些材料；这就提出了一个问题，即是否可以使用低成本工具和利用柔软且外形尺寸小的样品的测试来表征这些材料。在此，作者研究了一种专为表征此类材料而设计的开源3D打印测试系统的潜力。该系统专为外形尺寸小的样品（亚毫米厚度）和大弹性变形量身定制，这在微创植入物的聚合物部件中很常见。作者使用增材制造开发了用于单轴和平面拉伸测试的部件，并采用了一种低成本的图像相关方法来测量大应变。由于聚二甲基硅氧烷在生物相容性装置中的文献记载和应用，作者选择它来演示双参数穆尼-里夫林模型。估计的杨氏模量和剪切模量具有可重复性，并且与文献一致。当数据点有限时，曲线拟合具有挑战性，并且依赖于优化选择，这与先前的报告一致。然而，在有大量数据点和理想的优化误差选择的情况下，发现 和 与先前报道的结果接近。这项工作展示了一种低成本、3D打印的开源测试装置，用于使用双参数穆尼-里夫林模型以合理的精度表征超弹性材料。
