With the rapid development of novel technologies in the area of robotics, smart textiles (including wearable sensors), wireless sensors networks and Internet of Things, autonomous systems, medical sensors and devices, additive manufacturing and assistive technologies, an unprecedented need has been experienced for flexible and versatile materials, capable of combining various chemical, electrical and mechanical properties.

Soft Active Polymers (SAPs) represent such a group of materials that is distinctly characterised by their ability to respond to external stimuli such as mechanical, electrical or magnetic fields, temperature or humidity, biological or chemical processes and so on. Moreover, SAPs possess a number of remarkable properties like flexibility and softness, large deformability and conformability, biocompatibility, sensitivity and responsiveness, low weight and scalability (from macro to micro/nano scale), which make these materials superior and cost-effective in certain applications compared to other materials. In particular, these features make them highly suitable as building materials for actuators, sensors, energy harvesters or all-in-one sophisticated soft robots, and consequently appropriate for a variety of existing and emerging applications. However, their mechanical properties like viscoelasticity and hyperelasticity (with strain that can attain 300 to 700%), as well hysteresis, creep and relaxation strongly effect other coupled material properties, among which the dielectric permittivity, energy losses and reaction time.

Due to large variety of SAPs it is hard to experimentally test them all, not only because the experiments are costly and time consuming, but also because a relatively insignificant chemical changes (doping with nano-particles for instance) may substantially change other properties, including mechanical. In this case, a proper mathematical model of SAP behaviour would be highly useful, but there are certain issues related to the mechanical and other coupled models of such materials. Commercial FE software packages, with adapted the hyperelastic models, are highly constrained in implementing the viscoelastic effects, electromechanical coupling, or more complex interactions, like impacts.

Furthermore, these materials have a number of failure modes including, electromechanical instability, dielectric breakdown, fracture and fatigue, mostly observed experimentally and poorly described by the existing empirical models, adapted from other materials, like rubber. All these factors constrain the dynamic modelling of Soft Active Polymers, which is required for predicting the performance of the sensors, actuators, energy harvesters or robots in their natural environment. Additionally, the need of flexible structures also requires re-thinking the way the polymers are developed, manufactured (e.g., 3D printing) and implemented, all of which influence the mechanical properties of SAPs.

The general challenge and purpose of the symposium is to gather people with different backgrounds and interests within the general field of soft materials. The symposium also encourages the participation of Early Stage Researchers and will serve as an excellent opportunity for them to present their work, engage with world leading experts in the area and get new collaborations. Experiment, theory, and practice/applications are the main constituents and purposes of the symposium.

This EUROMECH “Mechanics of soft active polymers” Colloquium therefore welcomes the scientists at any career stage and industry researchers to contribute to the three sessions:

S1: Theory

This topic invites paper addressing theoretical challenges in the analysis of SAPs. It comprises developments of multiphysics theories including chemo-, thermo-, bio-, electro-, visco- elastic couplings. Such theories should be aiming at minimalistic formulations (Occam’s razor) yet allowing for a description of complex physical phenomena. This scientific arena strongly invites new developments.

S2: Experimental and numerical approaches

The papers invited for this section will address experimental treatment of soft materials. The latter is difficult task because it requires subtle laboratory equipment for a soft touch. In addition, interpretation of the experimental results is hard because it requires nontrivial analytical/computational support, e.g. cavitation, bulge test etc. Development of new and ingenious experimental protocols is the main experimental challenge.

S3: Applications, including sensors, actuators, robotics and energy harvesters

This section invites authors who develop existing and emerging applications. New applications of soft materials are in the very heart of any theoretical and experimental developments. Finding and engineering new applications are the most challenging motivation and final purpose of the whole area of soft materials. It is, arguably, more difficult than creating new theory or performing original experiment.