In-Plane Cyclic Mechanical Properties of CF/PEEK/TPU Flexible Composite with Zero Poisson Ratio.

This paper presents the in-plane deformation and cyclic mechanical properties of CF/PEEK (Carbon Fiber-Reinforced Polyetheretherketone)-reinforced TPU (thermoplastic polyurethanes) flexible composites with a zero Poisson ratio. A novel CF/PEEK honeycomb reinforcement with a zero Poisson ratio was fabricated by using 3D-printing technology. Then, TPU was bonded in the two sides of the CF/PEEK honeycomb reinforcement.

Visualization and quantification of low-velocity impact damage of three-dimensional braided CFRP composites by micro-computed tomography.

In this paper, the low-velocity impact response and damage of three-dimensional five-directional (3D5d) braided carbon/epoxy composites under different energies (30 J, 65 J, 100 J) are studied. Importantly, the damage is segmented from the axial and radial directions of the yarn to visualize and quantify the damage distributions in different regions based on micro-CT. The results show that as compared with the samples under 30 J and 100 J, the samples under 65 J energy perform higher impact properties.

Micromechanisms and Characterization of Low-Velocity Impact Damage in 3D Woven Composites.

Low-velocity impact (LVI) damage of 3D woven composites were experimentally and numerically investigated, considering different off-axis angles and impact energies. The impact responses were examined by LVI tests, and the damage morphology inside the composites was observed by X-ray micro-computed tomography (-CT). Yarn-level damage evolution was revealed by developing a hybrid finite element analysis model.

Controllable Crimpness of Animal Hairs via Water-Stimulated Shape Fixation for Regulation of Thermal Insulation.

Animals living in extremely cold plateau areas have shown amazing ability to maintain their bodies warmth, a benefit of their hair's unique structures and crimps. Investigation of hair crimps using a water-stimulated shape fixation effect would control the hair's crimpness with a specific wetting-drying process thereafter, in order to achieve the regulation of hair thermal insulation. The mechanism of hair's temporary shape fixation was revealed through FTIR and XRD characterizations for switching on and off the hydrogen bonds between macromolecules via penetration into and removal of aqueous molecules.

The Study on Semi-Blunt Puncture Behavior of Nanofiber Membrane/ Non-Woven Composite Material.

Background: Nanofiber membrane/non-woven composite material is composed of electrospinning nanofiber membrane and non-woven fabric, which combines the supporting role of nonwoven material and the special nano-size effect of nanomaterials.

Objective: These composite material can be widely used in biomedical, filtration and other related fields. In the actual use process, nanofiber membrane/non-woven composite material is often subjected to external forces such as puncture or bursting.

Origin of tensile strength of a woven sample cut in bias directions.

Textile fabrics are highly anisotropic, so that their mechanical properties including strengths are a function of direction. An extreme case is when a woven fabric sample is cut in such a way where the bias angle and hence the tension loading direction is around 45° relative to the principal directions. Then, once loaded, no yarn in the sample is held at both ends, so the yarns have to build up their internal tension entirely via yarn-yarn friction at the interlacing points.