Relationship Between Matrix Cracking and Delamination in CFRP Cross-Ply Laminates Subjected to Low Velocity Impact.

The effect of matrix cracking on the delamination morphology inside carbon fiber reinforced plastics (CFRP) laminates during low-velocity impact (LVI) is an open question. In this paper, the relationship between matrix cracking and delamination is studied by using cross-ply laminates. Several methods, including micrograph, C-scan, and visual inspection, were adopted to characterize the damage after LVI experiments.

Multiscale Analysis of CFRP Laminates with MMF3 Criterion under Different Off-Axis Loading Conditions.

A multiscale analysis strategy with physical modified-micromechanics of failure (MMF3) criterion was proposed to analyze the failure behaviors of carbon fiber reinforced plastic (CFRP) laminates. The quantitative relationship between the macro- and micro- stresses was determined considering two typical fiber distributions. Thermal residual stress was taken into account in the stress transformation.

Modelling viscoacoustic wave propagation with the lattice Boltzmann method.

In this paper, the lattice Boltzmann method (LBM) is employed to simulate wave propagation in viscous media. LBM is a kind of microscopic method for modelling waves through tracking the evolution states of a large number of discrete particles. By choosing different relaxation times in LBM experiments and using spectrum ratio method, we can reveal the relationship between the quality factor Q and the parameter τ in LBM.

A reverberation-ray matrix method for guided wave-based non-destructive evaluation.

The paper presents an application of the reverberation-ray matrix (RRM) method for guided wave-based non-destructive evaluation (NDE). An exact analytical model for elastic wave propagation in multilayered anisotropic composites is developed with the RRM method. Dispersion curves, namely phase and group velocities varying with frequencies, can be calculated based on the analytical model, which are critical to the guided wave-based NDE.

The Green's functions for peridynamic non-local diffusion.

In this work, we develop the Green's function method for the solution of the peridynamic non-local diffusion model in which the spatial gradient of the generalized potential in the classical theory is replaced by an integral of a generalized response function in a horizon. We first show that the general solutions of the peridynamic non-local diffusion model can be expressed as functionals of the corresponding Green's functions for point sources, along with volume constraints for non-local diffusion. Then, we obtain the Green's functions by the Fourier transform method for unsteady and steady diffusions in infinite domains.

Modeling adsorption with lattice Boltzmann equation.

The research of adsorption theory has recently gained renewed attention due to its critical relevance to a number of trending industrial applications, hydrogen storage and shale gas exploration for instance. The existing theoretical foundation, laid mostly in the early twentieth century, was largely based on simple heuristic molecular interaction models and static interaction potential which, although being insightful in illuminating the fundamental mechanisms, are insufficient for computations with realistic adsorbent structure and adsorbate hydrodynamics, both critical for real-life applications. Here we present and validate a novel lattice Boltzmann model incorporating both adsorbate-adsorbate and adsorbate-adsorbent interactions with hydrodynamics which, for the first time, allows adsorption to be computed with real-life details.

An investigation on piezoresistive behavior of carbon nanotube/polymer composites: II. Positive piezoresistive effect.

Due to the diversity of carbon nanotubes (CNTs), polymers, and the preparation processes of the composites, CNT-filled polymeric composites present various piezoresistive properties. One puzzling issue is the concurrence of a negative piezoresistive effect and a positive piezoresistive effect in composites with different polymer matrixes. In this paper, we present a microscopic view of the nature of the positive piezoresistive effect and its dependence on the polymer matrix types based on the model in our previous study, in which the piezoresistive behavior was tailored by a parameter-the average junction gap variation (AJGV)-describing the statistical property of the CNT conductive network.

Modeling nonlinearities of ultrasonic waves for fatigue damage characterization: theory, simulation, and experimental validation.

A dedicated modeling technique for comprehending nonlinear characteristics of ultrasonic waves traversing in a fatigued medium was developed, based on a retrofitted constitutive relation of the medium by considering the nonlinearities originated from material, fatigue damage, as well as the "breathing" motion of fatigue cracks. Piezoelectric wafers, for exciting and acquiring ultrasonic waves, were integrated in the model. The extracted nonlinearities were calibrated by virtue of an acoustic nonlinearity parameter.

Development/global validation of a 6-month-old pediatric head finite element model and application in investigation of drop-induced infant head injury.

Drop is a frequent cause for infant head injury. To date, finite element (FE) modeling was gradually used to investigate child head dynamic response under drop impact conditions, however, two shortages still exist on this topic: (1) due to ethical reasons, none of developed 6-month-old (6MO) head FE model was found to be quantitatively validated against child cadaver tests at similar age group; (2) drop height and impact surface stiffness effects on infant head responses were not comprehensively investigated. In this study, motivated by the recently published material properties of soft tissues (skull and suture, etc.