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Stretchability is critical to wearable devices to afford a large amplitude strain. Herein, a uniformly nanoscale copper layer was successfully deposited onto the surface of a knitted fabric by a facile electroless deposition (ELD) approach for the construction of stretchable electrodes that had low and stable resistivity. A polymerized dopamine layer was pre-decorated onto the fiber surface for capturing a Pd2+ catalyst that was also partially reduced to nanoparticles by polydopamine. This process improved the electrical conductivity and stability. As a result, an initial surface resistivity R 0 as low as ∼0.32 Ω sq–1 (σ ≈ 2.83 × 105 S m–1) and a stretched R of ∼2.0 Ω sq–1 (R/R 0 ≈ 6) under 500% tensile strain were obtained. Prolonging the ELD process led to better mechanical performance and electrical conductivity of the as-made fabrics. The deformation mechanism of such e-fabrics was particularly emphasized on the “contact junction shift” principle, providing a reconstruction of the conductive networks under a large amplitude strain. Finally, two electronic prototypes with such e-fabric elements demonstrated great mechanical and chemical stability as well as washing fastness. This was the first report about the e-fabric with such high stretchability, which enabled it to be integrated efficiently with garments as a stretchable electrode or as an element of a physiotherapy device to afford perspiration evaporation and large-area stretchability and to minimize discomfort.

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This paper presents a discrete-element method simulation of mini-triaxial tests on a sand with realistically shaped grains. It compares the results with physical experiments at multiple length scales, including the macroscopic sample length scale and the particle scale. A series of image-processing techniques were utilised to binarise, segment and label the raw data in images obtained from the mini-triaxial test. The images were obtained using an X-ray synchrotron radiation scanner. A spherical harmonic analysis was used to filter the image data and to reconstruct the natural particle morphology. Two parameters, these being the radius ratio of the smallest to largest sphere [Formula: see text] and a characteristic distance [Formula: see text] within the multisphere clump method, were chosen to represent the realistic particle morphology, balancing accuracy against computational cost. A one-to-one discrete-element model, where every particle in the physical experiment has its own numerical twin, was constructed. The discrete-element model was contained by a numerically generated flexible membrane allowing free deformation of the specimen under a prescribed confining stress, as in a physical triaxial test. Finally, attention was given to particle scale properties and their influences on the mechanical response of the discrete-element model. For a given strain rate it was found that shear modulus and friction coefficient affect the initial stiffness, the peak load and the dilation significantly. This study, and the simulation results within it, demonstrate that the proposed modelling approach is capable of reproducing macroscopic (e.g. stiffness, deviatoric stress response and volumetric response) and particle-level (e.g. displacement, rotation and branch vector orientation) behaviours that are very similar to what occurs within physical experiments, validating the effectiveness of the proposed one-to-one mapping technique.

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