Dynamic Impact Surface Damage Analysis of 3D Woven Para-Aramid Armour Panels Using NDI Technique

The effects of the yarn composition system inside 3D woven high-performance textiles are not well investigated and understood against their final ballistic impact behaviour. The current study aims to examine the ballistic impact performances of armour panels made of different 3D woven fabric variants through postmortem observations. Four high-performance five-layer 3D woven fabric variants were engineered based on their different warp yarn compositions but similar area density. A 50 × 50 cm2 armour system of each variant, which comprises eight nonbonded but aligned panels, namely, 3D-40-8/0 (or 8/0), 3D-40-8/4 (or 8/4), 3D-40-8/8 (or 8/8) and 3D-40-4/8 (or 4/8), were prepared and moulded to resemble female frontal morphology. The armour systems were then tested with nonperforation ballistic impacts according to the National Institute of Justice (NIJ) 0101.06 standard Level-IIIA. Two high-speed cameras were used to capture the event throughout the test. Nondestructive investigation (NDI) using optical microscopic and stereoscopic 3D digital images were employed for the analysis. The armour panels made of the 8/0 and 4/8 fabric variants were perforated, whereas the armour made of the 8/8 and 8/4 fabric variants showed no perforation. Besides, the armour made of the 8/4 fabric variant revealed higher local and global surface displacements than the other armours. The current research findings are useful for further engineering of 3D woven fabric for seamless women’s impact protective clothing.

Applications of sum-frequency generation vibrational spectroscopy in friction interface

Sum-frequency generation (SFG) vibrational spectroscopy is a second-order nonlinear optical spectroscopy technique. Owing to its interfacial selectivity, SFG vibrational spectroscopy can provide interfacial molecular information, such as molecular orientations and order, which can be obtained directly, or molecular density, which can be acquired indirectly. Interfacial molecular behaviors are considered the basic factors for determining the tribological properties of surfaces. Therefore, owing to its ability to detect the molecular behavior in buried interfaces in situ and in real time, SFG vibrational spectroscopy has become one of the most appealing technologies for characterizing mechanisms at friction interfaces. This paper briefly introduces the development of SFG vibrational spectroscopy and the essential theoretical background, focusing on its application in friction and lubrication interfaces, including film-based, complex oil-based, and water-based lubricating systems. Real-time detection using SFG promotes the nondestructive investigation of molecular structures of friction interfaces in situ with submonolayer interface sensitivity, enabling the investigation of friction mechanisms. This review provides guidance on using SFG to conduct friction analysis, thereby widening the applicability of SFG vibrational spectroscopy.

Visualization of Rare Metal-Enriched Zones in Waste Landfills Using Induced Polarization Method

We consider the studied landfill site an urban mine and developed a series of projects on metal endowment forms, nondestructive investigation methods for metal-enriched zones, metal extraction methods from enriched zones, and useful metal selection methods. This paper examines the exploration method. Induced polarization (IP) exploration was carried out at a T disposal site filled in the studied valley. In addition, three drillings were conducted in the studied exploration area. Using the core samples, IP parameters and metal contents were measured. Then, by comparing these data, we examined the effectiveness of the IP method for the visualization of metal-enriched zones in unsaturated landfills. The results of this experiment revealed that the iron-sulfide-enriched zone in the valley filling landfill can be identified by IP exploration. In addition, we clarified the types and contents of rare metals that coexist in iron sulfide. This process allows for further evaluation of landfills as a deposit.

A new mechanism for void-cascade interaction from nondestructive depth-resolved atomic-scale measurements of ion irradiation–induced defects in Fe

The nondestructive investigation of single vacancies and vacancy clusters in ion-irradiated samples requires a depth-resolved probe with atomic sensitivity to defects. The recent development of short-pulsed positron beams provides such a probe. Here, we combine depth-resolved Doppler broadening and positron annihilation lifetime spectroscopies to identify vacancy clusters in ion-irradiated Fe and measure their density as a function of depth. Despite large concentrations of dislocations and voids in the pristine samples, positron annihilation measurements uncovered the structure of vacancy clusters and the change in their size and density with irradiation dose. When combined with transmission electron microscopy measurements, the study demonstrates an association between the increase in the density of small vacancy clusters with irradiation and a remarkable reduction in the size of large voids. This, previously unknown, mechanism for the interaction of cascade damage with voids in ion-irradiated materials is a consequence of the high porosity of the initial microstructure.

Micro-Raman Spectroscopy Reveals the Presence of Octacalcium Phosphate and Whitlockite in Association with Bacteria-Free Zones Within the Mineralized Dental Biofilm

Through a correlative analytical approach encompassing backscattered electron scanning electron microscopy (BSE-SEM), energy dispersive X-ray spectroscopy (EDX), and micro-Raman spectroscopy, the composition of the mineralized biofilm around a dental implant, retrieved due to peri-implantitis, was investigated. The mineralized biofilm contains two morphologically distinct regions: (i) bacteria-containing zones (Bact+), characterized by aggregations of unmineralized and mineralized bacteria, and intermicrobial mineralization, and (ii) bacteria-free zones (Bact−), comprised mainly of randomly oriented mineral platelets. Intramicrobial mineralization, within Bact+, appears as smooth, solid mineral deposits resembling the morphologies of dental plaque bacteria. Bact− is associated with micrometer-sized Mg-rich mineral nodules. The Ca/P ratio of Bact+ is higher than Bact−. The inorganic phase of Bact+ is carbonated apatite (CHAp), while that of Bact− is predominantly octacalcium phosphate (OCP) and whitlockite (WL) inclusions. Compared with native bone, the inorganic phase of Bact+ (i.e., CHAp) exhibits higher mineral crystallinity, lower carbonate content, and lower Ca/P, C/Ca, Mg/Ca, and Mg/P ratios. The various CaPs found within the mineralized dental biofilm (CHAp, OCP, and WL) are related to the local presence/absence of bacteria. In combination with BSE-SEM and EDX, micro-Raman spectroscopy is a valuable analytical tool for nondestructive investigation of mineralized dental biofilm composition and development.

Advanced NDT Methods and Data Processing on Industrial CFRP Components

In this work, enhanced thermal data processing is developed with experimental procedures, improving visualization algorithm for sub-surface defect detection on industrial composites. These materials are prone to successful infrared nondestructive investigation analyses, since defects are easily characterized by temperature response under thermal pulses with reliable results. Better defect characterization is achieved analyzing data with refined processing and experimental procedures, providing detailed contrasts maps where defects are better distinguished. Thermal data are analyzed for different CFRP specimens with artificial defects and experimental procedures are verified on real structural aeronautical component with internal anomalies due to impact simulation. A better computation method is found to be useful for simultaneous defect detection by means of automatic mapping of absolute contrast, optimized to identify defect boundaries.