Effect of load orientation and weave pattern on the mechanical properties of woven active textiles for the design of wearable devices and soft actuators

Active textiles featuring pneumatic actuators, such as thin McKibben muscles, enable tunable stiffness, which is desirable for soft robotics, but the characterisation of their mechanical properties, particularly with respect to load orientation and weave pattern, remains lacking. Consequently, this paper ascertains the mechanical properties of active textiles, crucial for real-world scenarios, with unevenly distributed strains often misaligned with the weave pattern. The results show that: (i) tensile properties exhibit a hysteretic behaviour, with a maxima at 0.05 MPa during pressurisation and a minima at 0.15 MPa during depressurisation and a reduction in tensile modulus for increasing rotation angle; (ii) greater tensile properties are achieved by minimising the warp’s deviation from straightness, via weave pattern or reduction in muscle density; (iii) flexural properties require both a non-zero pressure and rotation angle greater than 15° to exhibit meaningful flexural properties, reaching circa 30 MPa at 90°; and (iv) where out-of-plane curvature occurs, flexural properties are significantly affected by the concave face’s orientation. Ultimately, tensile properties are driven by the warp’s alignment with the load, while flexural properties are driven by the weft’s alignment with the load. These findings provide novel insights into the mechanical properties and design optimisation of active textiles.