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This issue of the RECENT journal was edited with the support of: ContentsEffect of Carbon Nanotube Modified Epoxy Matrix on the Tensile Performance and Damage Behaviour of Flax and Jute Fabric Reinforced Composites
RECENT J. (2026), 79:004-011 https://doi.org/10.31926/RECENT.2026.79.004 Abstract This study investigates the effect of carbon nanotube (CNT) modification of an epoxy matrix on the tensile performance and damage behaviour of flax and jute fabric reinforced composites manufactured using the resin infusion process. Multi-walled carbon nanotubes were incorporated into the epoxy matrix at different weight fractions, and composite laminates were produced with identical stacking sequences and processing conditions to enable direct comparison. Tensile properties, damage initiation behaviour and damage evolution were evaluated through tensile testing, strain mapping and acoustic emission analyses. The results show that CNT incorporation leads to significant improvements in the mechanical performance of both flax and jute reinforced composites. At an optimum CNT content of 1.0 wt.%, tensile strength increased by approximately 33% for flax composites and 32% for jute composites compared to CNT-free reference laminates. Over the same CNT range, elastic modulus values increased by 27% and 30% for flax and jute composites, respectively. Damage initiation strain values increased by 56% for flax composites and 61% for jute composites, accompanied by a reduction of 30–35% in acoustic emission event counts, indicating improved damage tolerance. Increasing the CNT content to 1.5 wt.% resulted in a reduction of tensile performance relative to the optimum CNT level, suggesting the onset of CNT agglomeration effects. Although flax reinforced composites consistently exhibited higher absolute tensile strength and stiffness than jute reinforced systems, both fibre types showed comparable relative improvements with CNT modification. When compared with conventional glass and carbon fibre reinforced epoxy composites, CNT-enhanced natural fibre composites remain lower in absolute mechanical performance; however, CNT modification significantly narrows the performance gap relative to unmodified natural fibre composites while maintaining advantages related to low density and sustainability. Overall, the findings demonstrate that CNT-modified epoxy matrices provide an effective strategy to enhance the tensile performance and damage resistance of natural fibre reinforced composites, supporting their potential use in semi-structural and sustainability-driven engineering applications. Keywords natural fibre composites; flax composites; jute composites; carbon nanotubes; tensile properties; damage behaviour Effect of Carbon Nanotube Modified Epoxy Matrix on the Charpy Impact Behaviour of Flax and Jute Fabric Reinforced Composites
RECENT J. (2026), 79:012-021 https://doi.org/10.31926/RECENT.2026.79.012 Abstract This study investigates the Charpy impact behaviour of flax and jute fabric reinforced epoxy composites modified with different contents of carbon nanotubes (CNTs) through an integrated experimental and numerical approach. Composite laminates were manufactured using a resin infusion technique with identical stacking sequence and fibre architecture to ensure consistent fibre volume fraction. CNTs were incorporated into the epoxy matrix at contents of 0.0, 0.5, 1.0 and 1.5 wt.% to evaluate their influence on impact energy absorption. The experimental results reveal a significant enhancement in Charpy impact performance with CNT incorporation up to an optimum content of 1.0 wt.%. Compared to CNT-free composites, the absorbed impact energy increased by approximately 31% for both flax and jute reinforced laminates at this optimum CNT level. Beyond this concentration, a reduction in impact energy was observed, attributed to CNT agglomeration and increased matrix brittleness. Flax reinforced composites consistently exhibited higher impact energy absorption than jute composites, with improvements ranging between 11% and 13% across all CNT contents. Normalised impact strength values confirmed that CNT-modified natural fibre composites reached the upper range of impact performance typically reported for epoxy-based natural fibre systems. When benchmarked against conventional glass fibre reinforced epoxy composites, the CNT-modified flax and jute composites achieved approximately 35–45% of the impact strength of glass/epoxy laminates, significantly narrowing the performance gap between natural and synthetic fibre composites. A numerical model based on normalised energy absorption successfully captured the experimentally observed trends, predicting a maximum increase of approximately 30–31% at 1.0 wt.% CNT for both fibre systems. Although not intended to reproduce absolute impact energy values, the numerical results provide mechanistic insight into the role of CNT-modified matrices in enhancing impact resistance. The combined experimental and numerical findings demonstrate that CNT modification is an effective strategy for improving the impact energy absorption capability of flax and jute fabric reinforced epoxy composites, supporting their potential use in sustainable and impact-sensitive engineering applications. Keywords natural fibre composites; flax composites; jute composites; carbon nanotubes; Charpy impact; energy absorption; numerical modelling How to Certify a Defence Contractor According DIN 2303 Requirements
RECENT J. (2026), 79:022-029 https://doi.org/10.31926/RECENT.2026.79.022 Abstract The article is reviewing the necessary developments regarding certification and quality assurance activities within armour steel welded products. The commitment to the standards and especially to DIN 2303 is underlined. As stipulated in welding standards for every armour welded product, quality requirements must be compass before manufacturing defence products on a regular basis. The quality system validation and the manufacturing system compliance to the standards, third party, customer and/or authorities must be certified. The quality system must be assessed starting with ISO 9001 and following ISO 3834 standard series requirements and followed by the specific requirements underlined within DIN 2303. The results of these analyses emphasize the importance of the quality management system certification by a third party. A certified system is supporting the success of defence product development and manufacturing. These are highlighting the company professionalism and will increases the company's competitiveness and profitability. These conclusions could be a starting point for companies in strengthening their management to drive product innovation and business growth. The general pattern from the idea to the certification itself is based on knowing and implementing the standard requirements according to ISO 9000, ISO 9001, ISO 19011, ISO 3834 series, EN 1090 series and DIN 2303. The purpose of this article does not consist in building an exhaustive list of standards but a pattern of milestones to be followed and passed to reach the quality management system certification. Many other standards and specific documents are involved in the certification process endeavour in accordance with the company portfolio. Keywords defence; welding; armour; EN 3834; DIN 2303
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