The Nail Penetration Behaviour of Carbon Nanotube Composite Electrodes for Energy Storage

The high surface area, electrical and mechanical properties of carbon nanotube (CNT) composites has rendered them promising candidates for structural power composites. Nevertheless, it is important to understand their mechanical behaviour before they are applied in energy storage devices amid the safety concerns. This work explores the nail penetration behaviours of supercapacitor specimens consisting of CNT electrodes and pseudocapacitor specimens with carbon nanotube-polyaniline (CNT/PANI) electrodes. Specimens with and without electrolyte were tested. The dry cells without electrolyte follow a power law behaviour, while the wet cells with the electrolyte exhibit a piece-wise nonlinear relationship. The force, voltage and temperature of the supercapacitor were recorded during the nail penetration test. No temperature change or overheating was observed after short-circuit. Moreover, electrochemical testing is performed before and after the specimen penetration. The cyclic voltammetry shows the dramatic loss of capacitance, changing the cell behaviour from capacitor to resistor-like manner. Johnson-Cook model was used to predict the nail penetration behaviour. The coefficients of Johnson-Cook model are calibrated from the experimental load-displacement curves. The finite element model predictions are in a good agreement with the experimental results.

On the applicability of viscosity-based capillary bundle concepts to predict the penetration behaviour of polymer solutions into sand

The increasing use of polymer solutions as support fluids in pile drilling, diaphragm walling or tunnelling applications demands a more detailed discussion of their penetration behaviour and prediction thereof. In this context, the capillary bundle approach can be a useful tool. However, while it is widely discussed in the oil and gas application, the subject is currently addressed only scarcely with regard to support fluid penetration targeting stagnation, where small flow velocities and non-cohesive soil environments are of relevance. In these boundary conditions, the applicability of capillary bundle approaches is not yet sufficiently confirmed and substantiated. The current paper thus reviews current capillary bundle models based on Hagen–Poiseuille in combination with a power-law rheological model and discusses their applicability with respect to support fluid application in the context of experimental soil permeation tests for small gradients ($$i\le 10$$ i ≤ 10 ). Two granular materials of similar grain size, but different angularity (glass beads and sand), and four polymer solutions varying in polymer chain length and concentration are investigated, and the impact of model assumptions and bulk material input variables is systematically discussed. The experimental results show that the theoretical models are generally able to predict the filter velocity qualitatively for values above $${\bar{v}}=5\times 10^{-7}$$ v ¯ = 5 × 10 - 7 m/s and also quantitatively, when an empirical shift factor $$\alpha ^*$$ α ∗ is introduced and water permeability values are determined experimentally. With respect to the influence of soil parameters, it was found that the soil particle roughness decreases the flow velocity of the polymer solution despite similar hydraulic conductivity in water. Polymer chain length and concentration were observed to control the degree of possible dilution ($$\alpha ^*<1$$ α ∗ < 1 ) in the porous system compared to bulk rheological characteristics. It can therefore be concluded that capillary bundle models can indeed be applied in the targeted fields even though they are unable to predict a complete stagnation for $$i>0$$ i > 0 . However, rather than specific model assumptions for tortuosity, taking into account the specific soil-polymer interaction has shown to be of primary importance to ensure no under- or over-prediction of penetration velocities solely based on bulk rheology.

Influence of stacking towards the aqueous proton penetration behaviour across two-dimensional graphtetrayne

Two-dimensional (2D) graphtetrayne (G4) with intrinsic patterned triangular nanopores has been predicted to be an excellent candidate for next-generation proton exchange membrane for its superior proton conductivity and selectivity. However,...

Ballistic Performance Study of Kevlar29 Fibre Reinforced Polyester Composite

Ballistic qualities of the material are important for the military defence barrier application for protection of military persons, their vehicles and equipment. In the present investigation ballistic performance of Kevlar29 fibre reinforced polyester composite (KPC) is analysed. A definite parametric study, taking into account various shape of projectiles (Flat-F, Spherical-S and Conical-C) impact on the composite target of different thicknesses (12, 16 and 20 mm). Impact velocity of the projectile considered for analysis 100-400 m / s. Ballistic parameters such as residual velocity, deformation and penetration behaviour are predicted. Conical projectile has more effect on the composite target compared to other projectiles. Composite thickness influenced the energy absorption. The thickness increase from 12 mm to 20 mm which leads to increase in energy absorption by almost 20%.

Vertical Penetration of Offshore Pipelines: A Comparative Study Between Finite Element and Finite Volume Methods

Deepwater surface laid pipelines generally penetrate a fraction of their diameter into the seabed. The near surface penetration behaviour of steel catenary risers (SCRs) is equally important in offshore oil and gas developments. Theoretical, physical and numerical investigations have been performed to understand pipeline–soil interaction during vertical penetration. The large deformation finite element (LDFE) modeling is a recent and advanced tool among different numerical modeling techniques. The authors of this study simulated the penetration of pipeline using Abaqus CEL Finite Element (FE) software [1]. They also developed a numerical modeling technique based on finite volume approach using ANSYS CFX [2] and showed some of its advantages. However, in that study an ideal soil (i.e. no softening or strain rate effects on undrained shear strength) was used. Strain rate and softening have significant effects on penetration behaviour and therefore in this study a numerical technique has been developed to incorporate these effects in ANSYS CFX. Comparison of the results shows that ANSYS CFX can also model the penetration behaviour. Moreover, ANSYS CFX has some advantages including low computational time, modeling of suction and pipeline–soil–water interaction. A parametric study is also presented to provide more insights into the pipeline–soil–water interaction.