Shear thickening fluid (STF) is a very interesting and promising material in several application fields where a different mechanical is demanded based on loading rates, like body armor and vibration insulators. Cork is a natural cellular material by excellence, filled with well-known beneficial effects in terms of insulation and also interesting crashworthiness properties. In this work, cork grains of very small size (0.5–1.0 mm) are added to two different shear thickening suspensions, one of them a fully natural water and cornstarch, and the other based on fumed silica and polyethylene glycol. The rheology of these eco-friendly suspensions was investigated and the influences of including cork grains were discussed. In addition, microscopic analyses were carried out to observe the deformations at each component during the shear thickening phenomenon. Cork grains reduce the load-carrying capacity in the suspensions due to the deformable characteristics of cork. For this reason, shear thickening properties are suppressed in the mixtures. Despite this, it is possible to state that viscosity increase in the mixtures leads to strong particle contacts, and thereby resulting in particle deformations in the main constituent powder as well as in the cork additives due to their softer structures.

中文翻译：

---

具有剪切增稠特性的天然智能悬浮液的流变和变形行为

剪切增稠液（STF）是在一些应用领域中非常有趣且很有前途的材料，在这些应用领域中，根据加载速率要求使用不同的机械，例如防弹衣和防震材料。软木塞是一种卓越的天然多孔材料，在绝缘性和有趣的耐撞性方面都充满了众所周知的有益效果。在这项工作中，将非常小的尺寸（0.5-1.0毫米）的软木粒添加到两种不同的剪切增稠悬浮液中，其中一种是纯天然水和玉米淀粉，另一种是基于气相二氧化硅和聚乙二醇。研究了这些环保悬浮液的流变学，并讨论了包括软木粒在内的影响。此外，进行了微观分析，以观察在剪切增稠现象期间每个组件的变形。软木粒由于软木的可变形特性而降低了悬浮液的承载能力。因此，混合物中的剪切增稠性能受到抑制。尽管如此，可以指出混合物中的粘度增加导致牢固的颗粒接触，并由于其较软的结构而导致主要成分粉末以及软木添加剂中的颗粒变形。