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The use of composite materials in several sectors, such as aeronautics and automotive, has been gaining distinction in recent years. However, due to their high costs, as well as unique characteristics, consequences of their heterogeneity, they present challenging gaps to be studied. As a result, the finite element method has been used as a way to analyze composite materials subjected to the most distinctive situations. Therefore, this work aims to approach the modeling of composite materials, focusing on material properties, failure criteria, types of elements and main application sectors. From the modeling point of view, different levels of modeling—micro, meso and macro, are presented. Regarding properties, different mechanical characteristics, theories and constitutive relationships involved to model these materials are presented. The text also discusses the types of elements most commonly used to simulate composites, which are solids, peel, plate and cohesive, as well as the various failure criteria developed and used for the simulation of these materials. In addition, the present article lists the main industrial sectors in which composite material simulation is used, and their gains from it, including aeronautics, aerospace, automotive, naval, energy, civil, sports, manufacturing and even electronics.

Masked Stereolithography (mSLA) is an additive manufacturing technique that has been recently explored. Currently, studies in the literature addressing the investigation of stress concentrators in photosensitive resin parts printed on mSLA devices using the Whitney–Nuismer analytical method combined with Finite Element Analysis (FEA) and Digital Image Correlation (DIC) are rare. This work utilizes the combination of these techniques to analyze stress concentrators in specimens subjected to axial and eccentric loads, considering the effects imposed by the clamp restraint and a complementary study considering the free loading condition. For axial loading, the results are consistent, with variations in the stress concentration factor ranging from 0.42% to 5.25%. For the eccentric loading studies, the results indicate that the most suitable method for the test was the analysis considering the restraint imposed by the clamp, as the deformation results show a maximum error of 6.9% compared to 24.7% when the restraints were disregarded. The consistency of the results reinforces the quality of the employed technique, demonstrating that this study not only achieved its objectives but also provided a foundation for future investigations in the field.

Metalworking is an essential process for the manufacture of machinery and equipment components. The design of the die geometry is an essential aspect of metalworking, and directly affects the resultant product’s quality and cost. As a matter of fact, a comprehensive understanding of the die bearing geometry plays a vital role in the die design process. For the specific case of wire drawing, however, few efforts have been dedicated to the study of the geometry of the bearing zone. In this regard, the present paper involves an attempt to investigate the effects of different geometries of the die bearing. For different forms of reduction as well as bearing zones, measurements are carried out for the wire-drawing process. Subsequently, by extracting the friction coefficients from the electrolytic tough pitch copper wire in cold-drawn essays, the numerical simulations are also implemented. We present the results on both the superficial and center radial tensions obtained by finite element methods. It is observed that the reduction of the friction coefficient leads to an increase in radial stress, while for a given friction coefficient, the substitution of the C-type die by the R-type one results in a decrease in the superficial radial stress of up to 93.27%, but an increase at the center of the material. Moreover, the die angle is found to play a less significant role in the resultant center radial stress, but it significantly affects the superficial radial stress. Lastly, R-type dies result in smaller superficial radial stress, with a change of up to 34.48%, but a slightly larger center radial stress up to 6.55% for different die angles. The implications of the present findings are discussed.

This study presents an experimental and numerical investigation into the stress field in cylinders manufactured from photosensitive resin using the Masked Stereolithography (MSLA) technique. For material characterization, tensile and bending test data from resin specimens were utilized. The stress field in resin disks was experimentally analyzed using photoelasticity and Digital Image Correlation (DIC) methods, subjected to compressive loads, according to the cylinder–plane contact model. Images were captured during the experiments using polarizing film and a low-cost CPL lens, coupled to a smartphone. The experimental results were compared with numerical and analytical simulations, where the formation of fringes and regions indicating the direction and magnitude of normal and shear stresses were observed, with variations ranging from 0.6% to 8.2%. The convergence of the results demonstrates the feasibility of using parts produced with commercially available photosensitive resin on non-professional printers for studying contact theory and stress fields. In the future, this methodology is intended to be applied to studies on stress in gears.

The future of the automotive industry appears to hinge on the integration of dissimilar materials, such as aluminum alloys and carbon steel. However, this combination can lead to galvanic corrosion, compromising the structural integrity. In this study, laser-welded joints of 6013-T4 aluminum alloy and DP980 steel were evaluated for their morphology, microhardness, and corrosion resistance. Corrosion resistance was assessed using the electrochemical noise technique over time in 0.1 M Na2SO4 and 3.5% NaCl solutions. The wavelet function was applied to remove the DC trend, and energy diagrams were generated to identify the type of corrosive process occurring on the electrodes. Corrosion on the electrodes was also monitored using photomicrographic images. Analysis revealed an aluminum–steel mixture in the melting zone, along with the presence of AlFe, AlFe3, and AlI3Fe4 intermetallic compounds. The highest Vickers microhardness was observed in the heat-affected zone, adjacent to the melt zone, where a martensitic microstructure was identified. The 6013-T4 aluminum alloy demonstrated the highest corrosion resistance in both media. Conversely, the electrochemical noise resistance was similar for the DP980 steel and the weld bead, indicating that the laser welding process does not significantly impact this property. The energy diagrams showed that localized pitting corrosion was the predominant form of corrosion. However, generalized and mixed corrosion were also observed, which corroborated the macroscopic analysis of the electrodes.

Controlling oil well pressure during drilling is one of the most complex and hazardous processes in the exploration stage. The drilling system undergoes constant variations, influenced by factors such as drilling depth, which in turn affects other process parameters. Consequently, applying a time-invariant control strategy becomes impractical. This study aimed to identify the PID parameters necessary to regulate bottom-hole pressure during drilling across different operating depths, with the goal of maintaining system stability and robustness. To achieve this, the parameters were tested using a Gain Scheduling (GS) controller, which adjusted the control gains according to various operating points. In the first section, the development of a mathematical model of the process, based on fluid mechanics, is presented. Linearizing this model introduced an integrating element, which complicated the process dynamics. In the second section, we present the design of the controller using the Internal Model Control (IMC) tuning methodology to address the integration challenges. Finally, PID parameters for different drilling depths were obtained and integrated into the GS controller via Matlab Simulink. The controller’s performance was then evaluated through simulations of typical drilling issues, such as simulated disturbances, confirming its viability. The GS-controlled system was compared to a system using an adaptive controller, demonstrating superior performance in the former.

Differential diagnosis of elevated high sensitive Troponin T (hsTnT) in acute ischemic stroke includes myocardial infarction (MI) and neurogenic stunned myocardium (NSM). The aim of this study was to identify factors associated with baseline hsTnT levels and MI or NSM in acute ischemic stroke. We studied 204 consecutive patients of the prospective acquired Bern Stroke Database with acute ischemic stroke diagnosed by brain MR. All patient histories and cardiac examinations were reviewed retrospectively. Volumetry of lesions on diffusion and perfusion weighted brain imaging (circular singular value decomposition, Tmax >6sec) was performed. Voxel based analysis was performed to identify brain areas associated with hsTnT elevation. Linear regression analysis was used to identify predictors of baseline hsTnT levels and myocardial infarction. Elevated hsTnT was observed in 58 of the 204 patients (28.4%). The mean age was 68.3 years in the normal hsTnT group and 69.7 years in the elevated hsTnT group. Creatinine (p<0.001, OR 6.735, 95% CI 58.734-107.423), baseline NIHSS score (p = 0.029, OR 2.207, 95% CI 0.675-12.096), ST segment depression (p = 0.025, OR 2.259, 95% CI 2.419-35.838), and negative T waves in baseline ECG (p = 0.002, OR 3.209, 95% CI 13.007-54.564) were associated with hsTnT elevation, while infarct location and size were not. Coronary angiography was performed in 30 of the 204 patients (14.7%) and myocardial infarction was diagnosed in 7 of them (23.3%). Predictive factors for myocardial infarction could not be identified. Elevated baseline baseline hsTnT was associated with NIHSS, creatinine, ST segment depression and inverted T waves, but not with stroke location or size. None of the factors was helpful to differentiate MI and NSM. Therefore, ancillary investigations such as coronary angiography, cardiac MRI or both may be needed to solve the differential diagnosis.

This study investigates the mechanical behavior of water-washable photosensitive resins used in masked stereolithography (mSLA) 3D printing, evaluating the effect of post-curing time (0, 5, 10, 30, and 60 min) and printing orientation (Flat [XY], Vertical [Z], and On-edge [XZ]) on the material characteristics. Specimens were manufactured according to ISO 527-2 type 1B and ISO 178 standards for tensile and bending tests, respectively. A Matlab algorithm was developed to automate the processing of experimental data. This tool enabled the extraction of parameters to fit distinct mathematical models for the elastic (linear) and nonlinear (polynomial) regimes, allowing the material response to be characterized at different curing times and print orientations. These models were implemented in Ansys Workbench for comparison with experimental results. The results show that increasing the post-curing time from 0 to 60 min raises the elastic modulus from 964.5 to 1892.4 MPa in the Flat [XY] orientation and from 774 to 1661.2 MPa in the Vertical [Z] orientation for tensile testing. In bending testing, the Flat [XY] orientation presented the best mechanical properties, while the Vertical [Z] and On-edge [XZ] orientations showed similar behavior. The numerical simulations adequately reproduced the experimental results, validating the developed constitutive models. Finally, a stress–strain correlation model is presented that enables estimation for any post-curing time between 0 and 60 min. This study provides essential data for optimizing 3D printing processes and developing structural applications with photopolymer resins.

Objective: To evaluate soft tissue characteristics in individuals with cleft lip and palate and the degree of satisfaction of these individuals after rehabilitation. Setting: Hospital for Rehabilitation of Craniofacial Anomalies, Brazil. Patients: Forty-five individuals with repaired complete unilateral cleft lip and palate, aged 15 to 30 years. Interventions: One hundred thirty-five frontal facial photographs were obtained at rest and in natural and forced smile. Specialists in periodontics evaluated the soft tissue characteristics. Both patients and specialists evaluated the smiles and scored them as esthetically unpleasant, acceptable, or pleasant. Main Outcome Measures: Comparison of the cleft area with the contralateral region was performed for evaluation of soft tissue. The results of the degree of satisfaction with smile were expressed as percentages and means. The findings between patients and periodontists experienced or inexperienced with cleft care were compared. Results: Statistically significant differences were observed for alveolar process deficiency and absence of papilla in the esthetic area between groups (p < .05). Results show 84.4% of individuals considered their smile as esthetically pleasant. Specialists in periodontics of both groups scored the natural smile and forced smile as esthetically acceptable. There was a statistically significant difference in the mean of patients compared with both groups of specialists in periodontics (p < .05). Conclusions: Evaluation and knowledge of the soft tissue characteristics is extremely important for successful rehabilitation. The esthetic values and degree of patient satisfaction are essential for treatment success, since smile reconstruction should be esthetically pleasant to the patient.

Several inventories of insect galls have been performed in the Atlantic Forest of Rio de Janeiro, mostly in restingas, whereas the other phytophysiognomies remain poorly sampled. The present study inventoried the insect galls of Reserva Biológica União (RJ), a protected area comprising mainly Ombrophilous Forest. Field work was performed every two months from January to October, 2013. Insect galls were collected, photographed, characterized and transported to the laboratory. Adults were obtained by rearing and immature stages by gall dissection. The insects were deposited in the Cecidomyiidae Collection of the Museu Nacional. A total of 153 gall morphotypes were found on plants representing 37 plant families, 69 genera, 55 species and 53 morphospecies. Among them, two plant genera and five species were reported for the first time as host plants in Ombrophilous Forest. REBIO União showed little similarlity of host plant species and insect gall morphotypes when compared with other investigated Ombrophilous Forest areas. The leaf was the most attacked plant organ as expected. Asteraceae, Bignoniaceae, Fabaceae and Myrtaceae, and Mikania (Asteraceae) and Myrcia (Myrtaceae) were the richest host families and genera, respectivey, in number of gall morphotypes, all previously indicated as superhosts by other Brazilian Ombrophilous Forest inventories, except Bignoniaceae. Their great species richness may be related to their great gall richness, adding evidence in support of the taxon size hypothesis. Fusiform and globose galls were the most frequent, green was the predominant color, and most morphotypes did not present an indumentum. The highest gall richness was recorded in June and August. The gallers were distributed among Diptera (Cecidomyiidae), Lepidoptera, Hymenoptera, Hemiptera and Thysanoptera, with the first being predominant, following a global pattern. Eight gall-inducing species are recorded for the first time in REBIO União and four in Ombrophilous Forest. About 25% of the gall morphotypes were occupied by dwellers other than those that created the gall. They comprised parasitoids (Hymenoptera), inquilines (Diptera: Sciaridae and Muscomorpha, Hemiptera, and Lepidoptera) and successors (Psocoptera, mites, and Hymenoptera: Formicidae). Although these taxa were previously reported by Brazilian inventories of insect galls, 12 new association with plants are recorded. The amount of new records reinforces the importance of inventories. Resumo: Vários inventários de galhas de insetos vem sendo desenvolvidos no estado do Rio de Janeiro, principalmente em restingas, enquanto as outras fitofisionomias permanecem pouco estudadas. O presente estudo inventariou as galhas de insetos da Reserva Biológica União (RJ), uma área protegida ocupada principalmente por Floresta Ombrófila. Trabalhos de campo foram realizados a cada dois meses de janeiro a outubro de 2013. Galhas de insetos foram coletadas, fotografadas, caracterizadas e transportadas para o laboratório. Adultos foram obtidos por criação e os imaturos pela dissecção das galhas. Os insetos foram depositados na Coleção de Cecidomyiidae do Museu Nacional (MMRJ). Um total de 153 morfotipos de galhas foram encontrados em plantas de 37 famílias, 69 gêneros, 55 espécies e 53 morfoespécies. Dentre estas, dois gêneros botânicos e cinco espécies foram registradas pela primeira vez como plantas hospedeiras em Floresta Ombrófila. A REBIO União mostrou uma pequena similaridade de plantas hospedeiras e morfotipos de galhas quando comparada com outras áreas de Floresta Ombrófila. As folhas foram o órgão vegetal mais atacado, como o esperado. Asteraceae, Bignoniaceae, Fabaceae e Myrtaceae, e Mikania (Asteraceae) e Myrcia (Myrtaceae) foram as famílias hospedeiras e gêneros botânicos mais ricos em número de morfotipos de galhas, todos previamente indicados como superhospedeiros em outros inventários na Floresta Ombrófila brasileira, exceto Bignoniaceae. A grande riqueza de espécies destes táxons pode estar relacionada a sua grande riqueza de galhas, adicionando evidências para a hipótese do tamanho do táxon. Galhas fusiformes e globoides foram as mais frequentes, a cor verde predominou e a maioria dos morfotipos não apresentou indumento. A maior riqueza de galhas ocorreu em junho e agosto. Diptera (Cecidomyiidae), Lepidoptera, Hymenoptera, Hemiptera e Thysanoptera foram as ordens indutoras encontradas, com predomínio dos Cecidomyiidae, seguindo o padrão mundial. Oito espécies galhadoras são registradas pela primeira vez na REBIO União e quatro em Floresta Ombrófila. Cerca de 25% dos morfotipos de galhas foram ocupados por outros artrópodes, que atuaram como parasitoides (Hymenoptera), inquilinos (Diptera: Sciaridae and Muscomorpha, Hemiptera, and Lepidoptera) e successores (Psocoptera, ácaros e Hymenoptera: Formicidae). Embora estes táxons já tivessem sido reportados em inventários de galhas de insetos do Brasil, 12 novas associações com plantas são registradas. A quantidade de novos registros reforça a importância dos inventários.