The flexure response of novel thermoplastic (Elium^®) 3D fibre-reinforced composites (FRC) was evaluated and compared with a conventional thermoset (Epolam^®)-based 3D-FRC. Ten different types of sample 3D-FRC were prepared by varying fibre orientations, i.e., 0°, 30°, 45°, 60° and 90°, and resin system, i.e., thermoplastic and thermoset. The bending characteristics and failure mechanisms were determined by conducting a three-point bend test. Results elucidate that the on-axis specimens show linear response and brittle failure; in contrast, the off-axis specimens depicted highly nonlinear response and ductile failure. The thermoplastic on-axis specimen exhibited almost similar flexure strength; in comparison, the off-axis specimens show ~17% lower flexure strength compared to thermoset 3D-FRC. Thermoplastic 3D-FRC shows ~40% higher energy absorption, ~23% lower flexure modulus and ~27% higher flexure strains as compared to its thermoset counterpart.

In recent years, there has been an increasing interest in open-hole and filled-hole laminate failure analysis. The open and filled-hole laminate failure analysis is used in several important areas, especially in designing mechanically fastened composite joints. Various analytical, empirical, and numerical methods are available for the design of mechanically fastened composite joints. The large number of material and geometrical design variables at the preliminary design stage makes the empirical and numerical methods effortful, expensive, and time-consuming. Therefore, analytical methods are recommended over numerical and empirical methods at the preliminary design stage merely because of their simplification in calculations, making them computationally efficient. Taking this into consideration, current research presents an improvement to the analysis capabilities of the previously introduced analytical method, i.e., the coupled approach of Classical laminate theory (CLT) and Lekhnitskii solutions. These improvements include the development of failure envelops for the open-hole and filled-hole laminates, estimation of optimized filling material for attaining maximum load-bearing capacity of filled-hole laminates, and optimization of stacking sequence for maximum load-bearing capacity of open-hole and filled-hole laminates. From the failure envelop results, it was found that failure envelopes of filled-hole laminates are bigger than open-hole laminates. Furthermore, it was found that the stiffness of the filling material should be equal to the stiffness of the laminate to achieve maximum bearing strength of the filled-hole laminate. It was also demonstrated that the coupled approach of CLT and Lekhnitskii solutions may provide carpet plots that can be utilized to optimize the stacking sequence for open-hole and filled-hole laminates.

Microbiologically influenced corrosion (MIC) is a serious threat to the integrity of crude oil pipelines. Sulphate-reducing bacteria (SRB) are the primary microorganisms responsible for MIC, and their aggressiveness is dependent on the energy source available to them. Acetate, a common energy source, has been shown to accelerate the corrosion of carbon steel in the presence of SRB. This study investigated the effect of acetate on the growth of SRB and the corrosion of carbon steel plates in simulated anaerobic conditions. The corrosion kinetics were studied using linear polarization resistance (LPR) and weight loss immersion tests for 42 days. The samples were characterized using Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDX). The results show that the addition of acetate to cultured media significantly increased the corrosion rate of carbon steel plates in both formation water and Postgate Medium B (PMB). This was due to increased growth of SRB in the presence of acetate, which led to the production of more corrosive hydrogen sulphide (H₂S). The findings based on experimental data obtained from this study confirm that acetate can accelerate the corrosion of carbon steel in the presence of SRB.

The aim of this study is to improve the flexural performance and damage mechanism of nano-filled three-dimensional orthogonal woven E-glass/epoxy composites (3DOWC). The inherent brittleness of epoxy-based 3DOWC leads to the early onset of damage mechanisms such as matrix cracking, fibre-matrix debonding, and fibre failure. To overcome these limitations, epoxy resin has been modified with nano-fillers such as graphene nanoplatelets (GNP) and the novel nanostrength® (NS). The epoxy resin was infused in 3DOWC using VARI with different weight percentages of GNP (0.5, 1.0, and 1.5 wt.%) and NS (2.5, 5.0, and 7.5 wt.%). Three samples in each warp and weft direction of 3DOWC were tested in a three-point bend test. The results showed an increase of 48.4%, 56.2%, and 27.4% in flexural strength, final failure, and energy absorption under warp-loading with 0.5 wt.% GNP, respectively, whereas weft-loaded samples with 1.5 wt.% GNP exhibited 12.0% and 10.5% increases in flexural strength and final failure, respectively. However, 7.5 wt.% NS showed an increase in flexural strength in the warp and weft directions by 36.9% and 39.3%, respectively, and an increase in final failure and energy absorption in the warp direction by 39.4% and 12.3%, respectively. For weft-loaded samples, the final failure increased by 39.3% for the same weight percentage, but there was no significant increase in energy absorption in this direction. Scanning electron microscopy (SEM) of damaged samples revealed that crack reconnection by GNP and fibrils formation and plasticization by NS particles improved the overall flexural performance of 3DOWC.