标题： 将粒状电阻力理论扩展到粘性粉末尺度介质 显示英文标题

标题： Extending Granular Resistive Force Theory to Cohesive Powder-scale Media

摘要： 颗粒介质中的侵入在自然和工程环境中很常见（例如，在动物运动和行星着陆期间）。虽然复杂形状在干燥非粘性颗粒材料中的侵入已被广泛研究，但对粘性粉末中侵入的了解较少。颗粒阻力理论（RFT）——一种简化阶摩擦流体模型——通过假设作用在任意形状侵入物上的角度依赖的基本应力的线性叠加，定量预测干燥非粘性颗粒介质中的侵入力。在这里，我们将RFT的应用扩展到粘性干燥粉末，从而实现对复杂形状在侵入过程中受力的定量建模。为此，我们首先进行干燥玉米淀粉粉末中的侵入实验以创建应力函数。这些应力与非粘性介质相似；然而，我们观察到与非粘性介质相比，粘性粉末对水平侵入的阻力相对较高。我们使用该模型来识别增强此类材料中侵入阻力的几何形状，旨在最小化下沉。我们的计算得到了实验验证的支持，表明平坦表面在各种侵入角度下产生最大的应力，而弯曲表面在垂直侵入时表现出最大的阻力。因此，该模型可以有助于优化在这些环境中运行的机器人平台（例如，外星着陆器）的设计和运动策略。 显示英文摘要

摘要： Intrusions into granular media are common in natural and engineered settings (e.g. during animal locomotion and planetary landings). While intrusion of complex shapes in dry non-cohesive granular materials is well studied, less is known about intrusion in cohesive powders. Granular resistive force theory (RFT) -- a reduced-order frictional fluid model -- quantitatively predicts intrusion forces in dry, non-cohesive granular media by assuming a linear superposition of angularly dependent elemental stresses acting on arbitrarily shaped intruders. Here we extend RFT's applicability to cohesive dry powders, enabling quantitative modeling of forces on complex shapes during intrusion. To do so, we first conduct intrusion experiments into dry cornstarch powder to create stress functions. These stresses are similar to non-cohesive media; however, we observe relatively higher resistance to horizontal intrusions in cohesive powder compared to non-cohesive media. We use the model to identify geometries that enhance resistance to intrusion in such materials, aiming to minimize sinkage. Our calculations, supported by experimental verification, suggest that a flat surface generates the largest stress across various intrusion angles while a curved surface exhibits the largest resistance for vertical intrusion. Our model can thus facilitate optimizing design and movement strategies for robotic platforms (e.g. extraterrestrial landers) operating in such environments.