Active mechanics of fire-ant networks

Active networks are omnipresent in nature, from the molecular to the macroscale. Here, we will discuss the mechanics of fire-ant aggregations, whose swarming behavior has shown impressive dynamics that culminates with the aggregation’s capacity to self-heal and adapt to the environment. Although empirical models have enabled us to characterize these the combined elasticity and rheology of these networks, it is still not clear how the behavior of individual building blocks (ants) affect their emerging response. In this presentation, we will discuss an alternative way to think about these materials by seeing them as a collection of individual building blocks connected by elastic chains that can associate and dissociate over time. From the knowledge of these connections (elasticity, activity), we will construct a statistical description of the chain stretch and derive an evolution equation of the corresponding distribution. This time-evolving distribution is then used to determine important macroscopic measures such as stress, energy storage, and dissipation in the network. In this context, we will show how the physical characteristics and activity of single ants can explain the elasticity, rheological properties, and behavior of the aggregation.