The aim of this work is to analyze the effect of water absorption on the mechanical properties and damage mechanisms of polyester/glass fiber/jute fiber hybrid composites obtained using the compression molding and vacuum-assisted resin transfer molding (VARTM) techniques with different stacking sequences. For this purpose, the mechanical behavior under tensile stress of the samples was evaluated before and after hygrothermal aging at different temperatures: TA, 50 °C, and 70 °C for a period of 696 h. The damage mechanism after the mechanical tests was evaluated using SEM analysis. The results showed a tendency for the mechanical properties of the composites to decrease with exposure to an aqueous ambient, regardless of the molding technique used to conform the composites. It was also observed that the stacking sequence had no significant influence on the dry composites. However, exposure to the aqueous ambient led to a reduction in mechanical properties, both for the molding technique and the stacking sequence. Damage such as delamination, fiber pull-out, fiber/matrix detachment, voids, and matrix removal were observed in the composites in the SEM analyses.

In this study, the ballistic effectiveness of Kevlar 29 composites was analyzed by combining 400 and 460 GSM grammages with a polyurethane matrix. Plates measuring 300 mm × 250 mm were fabricated using hand lamination and compression techniques, with reinforcement designs consisting of 10, 14, and 18 layers of Kevlar 29 fabric oriented at a 90° angle. Ballistic tests were conducted following the parameters of the NIJ 0108.01 standard, applying five impacts with 9 mm FMJ and 22 (5.5 mm) caliber bullets. Both the composites and pure Kevlar were evaluated. Post-damage visual analysis was conducted on the front and back faces, as well as the interior of the composite, to identify delamination and fractures. The results show that .22 caliber bullets were captured at various stacking levels depending on the configuration, whereas 9 mm bullets penetrated all the plates. Localized fractures and delamination associated with the impacts were observed, highlighting the importance of stacking design and grammage in the material’s energy dissipation capacity.

Seaweed polysaccharide films are potential alternatives to petroleum-derived flexible packaging, but literature data are sparse and heterogeneous. This study evaluates whether composition-only machine-learning models can prioritize reported seaweed formulations for experimental follow-up near a nominal low-density polyethylene (LDPE) mechanical target of 15 MPa tensile strength and 300% elongation at break. A published dataset of 115 formulations with 41 compositional predictors was analyzed using a regularized linear baseline (ridge regression), random forest, and a deliberately shallow, regularized XGBoost model. Model performance was estimated using repeated five-fold cross-validation (10 repeats; 50 test-fold evaluations). For tensile strength, mean R² was 0.617 ± 0.174 for random forest and 0.628 ± 0.150 for XGBoost, with corresponding RMSE values of 12.35 ± 3.52 and 12.27 ± 3.84 MPa. For elongation, random forest and XGBoost reached mean R² values of 0.498 ± 0.194 and 0.470 ± 0.188, respectively. The linear baseline was materially less stable, indicating that the available composition-property relations are not adequately represented by a global linear model. The maximum observed elongation was 172.5%, which is 42.5% below the 300% screening target; equivalently, the target lies 73.9% above the dataset maximum. Consequently, the model cannot establish LDPE equivalence or credible extrapolation to the target. Residual diagnostics, learning curves, and SHAP analyses were added to bound interpretation. The defensible outcome is experimental prioritization within the observed domain, not inverse design or material substitution.

Este trabalho apresenta o projeto, fabricação e teste de um protótipo de motocicleta de motovelocidade, desenvolvido no âmbito da Universidade Federal de Campina Grande (UFCG), com o objetivo de fomentar a pesquisa acadêmica aplicada à engenharia de motocicletas no Brasil. A motivação central foi suprir a escassez de veículos nacionais voltados exclusivamente à prática esportiva de motovelocidade. A metodologia adotada compreendeu revisão bibliográfica especializada, pesquisa de mercado de motocicletas esportivas de baixa cilindrada, análise de parâmetros geométricos (caster, trail e entre-eixos), simulações com auxílio dos softwares SolidWorks e Excel, além da coleta de dados técnicos em eventos nacionais e internacionais, como o MotoStudent (Espanha) e o Superbike Brasil (PE). O desenvolvimento foi conduzido no Laboratório de Engenharia da Motocicleta (LABEM), integrando teoria, modelagem e prática construtiva. O resultado foi a construção de um protótipo funcional, com geometria otimizada e desempenho compatível com padrões internacionais da categoria Moto3. Conclui-se que é tecnicamente viável desenvolver motocicletas de competição utilizando tecnologia nacional, reforçando o potencial das universidades brasileiras em liderar projetos inovadores no setor de duas rodas.

Fire-risk mitigation in vulnerable wildland–urban interface (WUI) settlements is a portfolio problem: warning, evacuation, fuel management, dwelling hardening, and spatial interventions are complementary yet compete for limited implementation resources. This study develops an auditable portfolio decision framework and applies it to public-document evidence for El Olivar, Viña del Mar, Chile. Six actions are represented by evidence-bounded ordinal envelopes for risk-reduction relevance, feasibility, time to initial benefit, and resilience to delayed external access; implementation-resource demand is imposed as a hard constraint rather than a compensatory criterion. A binary portfolio model is evaluated under equal, rank-order-centroid, unrestricted-simplex, and ordered-simplex preference structures using 200,000 uncertainty realizations without assuming equal spacing between ordinal categories. Under the baseline normalized implementation requirements (1–3 additive planning units, not monetary costs), routes/maps plus decentralized warning has a portfolio-acceptability fraction of 89.2–95.3% at $B=2$. At $B=4$, vegetation-fuel management joins that core, with a portfolio-acceptability fraction of 66.7–91.5%. These fractions quantify robustness of optimal selection across the defined admissible evidence and preference inputs; they are not empirical probabilities of intervention effectiveness, fire-loss reduction, or implementation success. Structural actions enter mainly as resources expand, while cluster-scale compartmentation remains limited by transferability to attached-housing morphology. The framework identifies staged bundles conditional on stated evidence, preference, and resource assumptions rather than a universal action ranking.

The aim of this work is to analyze resin flow during RTM manufacturing of GFRP composites containing embedded impermeable inserts. High-density polyethylene inserts were embedded in the composites during processing via vacuum assisted resin transfer molding (RTM). The processing station plate was assembled so that digital image analysis of flow during and after processing could be taken. Three-point bending test specimens were cutout from the plates and their fractured surfaces were analyzed by optical fractography. Results indicate the inserts to block transverse resin flow making it difficult to wet the fibers thoroughly, which led to non-uniform plate thickness. Resin rich regions near the sides of the inserts were observed. Three-point bending failure mode analysis showed the occurrence of fiber delamination by type II shear stress, detachment between the fiber/matrix interface and the insert, and fracture of the composite to proceed by crack propagation through the resin rich region.