We present a shape memory polymer (SMP) honeycomb with tuneable and shape morphing mechanical characteristics. Kirigami (Origami with cutting allowed) techniques have been used to design and manufacture the honeycomb. The cellular structure described in this work has styrene SMP hinges that create the shape change and the deployment actuation. To create a large volumetric deployment, the Kirigami open honeycomb configuration has been designed by setting an initial three-dimensional re-entrant auxetic (negative Poisson's ratio) configuration, while the final honeycomb shape assume a convex (positive Poisson's ratio) layout. A model was developed to predict the shape change of the structure, and compared to experimental results from a demonstrator honeycomb deployment test.

We present in this work the manufacturing, modeling, and testing of dome-shaped cellular structures with auxetic (negative Poisson's ratio) behavior. The auxetic configurations allow the creation of structures with synclastic (i.e., dome-shaped) curvatures, and this feature is used to evaluate the performance of cellular metamaterials under quasi-static indentation conditions. We consider here different cellular geometries (re-entrant, arrow-head, tri-chiral, hexagonal) and the implications of their manufacturing using 3D printing techniques with PLA material. The dome-shaped configurations are modeled using full-scale non-linear quasi-static and explicit dynamic FE models that represent both the geometry and approximate constitutive models of the PLA filament material derived from tensile tests on dogbone specimens. The cellular metamaterials samples are subjected to indentation tests, with maps of strains obtained through DIC measurements. The correlation between experimental and numerical simulations is good, and shows the peculiar indentation behavior of these cellular structures. We also perform a comparative analysis by simulation of the force/displacement, strain and fracture history during quasi-static loading, and discuss the performance of the different cellular topologies for these dome-shape metamaterial designs.

The work describes the mechanics of novel woven jute fibers reinforced polyester (JFRP) laminates under uniaxial and multi-axial static and fatigue loading cases. JFRP laminates with 25 % fibre volume fraction (FVF) have been manufactured using a hand-layup molding technique at a low pressure. Static uniaxial tests have shown that these novel bio-reinforced laminates have an ultimate tensile strength around 42 MPa under tensile loading and 7.5 N-m under torsional loading. The Multi-axial (tension/torsion) static tests yield an ultimate strength of 21.7 MPa and 5 N-m for tensile and torsion loading conditions, respectively.Fatigue tests have been carried out under displacement and angular control at three different loading levels with a frequency of 5Hz. The fatigue tests results are extensively analyzed using stiffness degradation behavior, hysteresis loops, energy dissipation and strain versus number of cycles (ɛ-N) diagrams. The fatigue endurance limit (over one million cycles) for JFRP is achieved at a stress level of 65% of ultimate displacement. The implication of this work is the use of these materials in areas such as car and aircraft interiors promises to significantly reduce weight, cost and carbon footprints without sacrificing performance.

We present here a design of a unit cell of a mechanical metamaterial based on the use of a tensegrity structural configuration with metal rubber. Tensegrity combines the use of compression and tension-only elements, and allows the creation of structures with high rigidity per unit mass. Metal rubber is a multiscale porous metal material with high energy absorption and vibration damping capabilities under compressive load. The combination of the two structural and material concepts gives rise to a mechanical metamaterial with increased energy absorption and tuneable nonlinearity under quasi-static, vibration and impact loading. We develop prototypes, models and perform tests under static and dynamic loading conditions to assess the performance of this mechanical metamaterial.