Structured fabrics with tunable mechanical properties

Structured fabrics, such as woven sheets or chain mail armours, derive their properties both from the constitutive materials and their geometry(1,2). Their design can target desirable characteristics, such as high impact resistance, thermal regulation, or electrical conductivity(3-5). Once realized, however, the fabrics' properties are usually fixed. Here we demonstrate structured fabrics with tunable bending modulus, consisting of three-dimensional particles arranged into layered chain mails. The chain mails conform to complex shapes(2), but when pressure is exerted at their boundaries, the particles interlock and the chain mails jam. We show that, with small external pressure (about 93 kilopascals), the sheets become more than 25 times stiffer than in their relaxed configuration. This dramatic increase in bending resistance arises because the interlocking particles have high tensile resistance, unlike what is found for loose granular media. We use discrete-element simulations to relate the chain mail's micro-structure to macroscale properties and to interpret experimental measurements. We find that chain mails, consisting of different non-convex granular particles, undergo a jamming phase transition that is described by a characteristic power-law function akin to the behaviour of conventional convex media. Our work provides routes towards lightweight, tunable and adaptive fabrics, with potential applications in wearable exoskeletons, haptic architectures and reconfigurable medical supports. A structured fabric constructed of linked hollow polyhedral particles (resembling chain mail) can be simply and reversibly tuned between flexible and rigid states; when it is compressed, its linked particles become jammed.

Automated summary

The study presents a structured fabric with tunable bending modulus made up of three-dimensional particles arranged into layered chain mails. When pressure is applied at their boundaries, the particles interlock and jam the chain mails, resulting in a dramatic increase in bending resistance. This property is due to the high tensile resistance of the interlocking particles, providing potential for lightweight, tunable and adaptive fabrics for various applications.