Abstract

The use of granular jamming is proposed for designing structures with tunable rigidity of their tools (with the ability of being flexible devices for shaping and deformation but rigid for shape-locking and force transmission). The granular jamming consists in modifying the apparent rigidity of a structure by controlling the vacuum in a membrane filled with granular material. When the difference of pressure is low, the grains are free to move with respect to each other and the structure is flexible. When the vacuum in the membrane is increased, the grains are blocked and the structure is more rigid. Different mechanical characterizations of the granular jamming have been performed (triaxial compression and tension and cantilever beam bending tests) for different glass bead sizes ranging between 100 \({\upmu }{\hbox {m}}\) and 1 \(\hbox {mm}\) (used as granular material) at different vacuum levels (between 0 \(\hbox {kPa}\) and 90 \(\hbox {kPa}\)). The grain size slightly influences the stiffness while the pressure difference is the main parameter to tune the stiffness of the structure. Based on these experiments, analytical models have been developed and validated. The tension characteristics can be directly deduced from the compression behavior and the bending modulus can be obtained by a combination of the tension and compression moduli. The proposed analytical models present the advantage of a simple formulation and are suitable for estimating the performance of other structures based on the granular jamming. The models can estimate and predict satisfactorily the results of granular jamming and can be used for designing mechanical structures based on this mechanism.

Graphical Abstract

中文翻译：

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颗粒状堵塞的表征和建模：机械设计模型

摘要

提出使用粒状卡纸来设计其工具的可调刚度的结构（具有作为成形和变形的柔性装置的能力，但对于形状锁定和力传递具有刚性的能力）。粒状堵塞在于通过控制填充有粒状材料的膜中的真空来改变结构的表观刚性。当压差低时，晶粒彼此相对自由移动并且结构是柔性的。当膜中的真空度增加时，颗粒被阻塞并且结构更加刚性。对于尺寸范围在100 \（{\ upmu} {\ hbox {m}} \）之间的不同玻璃珠，已经执行了颗粒状堵塞的不同机械特性（三轴压缩和拉伸以及悬臂梁弯曲测试）。 和1  \（\ hbox {mm} \）（用作粒状材料）在不同的真空度下（0  \（\ hbox {kPa} \）到90  \（\ hbox {kPa} \））。晶粒尺寸对刚度有轻微影响，而压差是调节结构刚度的主要参数。基于这些实验，已经开发并验证了分析模型。拉伸特性可以直接从压缩行为中推导出来，弯曲模量可以通过拉伸和压缩模量的组合获得。所提出的分析模型具有简单配方的优点，并且适合于基于粒状堵塞估算其他结构的性能。该模型可以令人满意地估计和预测颗粒堵塞的结果，并且可以用于基于该机制设计机械结构。

图形概要