Plásticos reforçados a base de tecidos híbridos: efeitos da anisotropia e geometria normativa na caracterização mecânica e da fratura

As most current studies, reinforced plastics have been, in recent years, a viable alternative in building structural elements of medium and large, since the lightness accompanied by high performance possible. The design of hybrid polymer composites (combination of different types of reinforcements) may enable structural applications thereof, facing the most severe service conditions. Within this class of composite materials, reinforced the underlying tissues hybrid high performance are taking space when your application requires high load bearing and high rigidity. The objective of this research work is to study the challenges in designing these fabrics bring these materials as to its mechanical characterization and fracture mechanisms involved. Some parameters associated with the process and / or form of hybridization stand out as influential factors in the final performance of the material such as the presence of anisotropy, so the fabric weave, the process of making the same, normative geometry of the specimens, among others. This sense, four laminates were developed based hybrid reinforcement fabrics involving AS4 carbon fiber, kevlar and glass 49-E as the matrix epoxy vinyl ester resin (DERAKANE 411-350). All laminates were formed each with four layers of reinforcements. Depending on the hybrid fabric, all the influencing factors mentioned above have been studied for laminates. All laminates were manufactured industrially used being the lamination process manual (hand-lay-up). All mechanical characterization and study of the mechanism of fracture (fracture mechanics) was developed for laminates subjected to uniaxial tensile test, bending in three and uniaxial compression. The analysis of fracture mechanisms were held involving the macroscopic, optical microscopy and scanning electron microscopy

Plásticos reforçados a base de tecidos híbridos: efeitos da anisotropia e geometria normativa na caracterização mecânica e da fratura

As most current studies, reinforced plastics have been, in recent years, a viable alternative in building structural elements of medium and large, since the lightness accompanied by high performance possible. The design of hybrid polymer composites (combination of different types of reinforcements) may enable structural applications thereof, facing the most severe service conditions. Within this class of composite materials, reinforced the underlying tissues hybrid high performance are taking space when your application requires high load bearing and high rigidity. The objective of this research work is to study the challenges in designing these fabrics bring these materials as to its mechanical characterization and fracture mechanisms involved. Some parameters associated with the process and / or form of hybridization stand out as influential factors in the final performance of the material such as the presence of anisotropy, so the fabric weave, the process of making the same, normative geometry of the specimens, among others. This sense, four laminates were developed based hybrid reinforcement fabrics involving AS4 carbon fiber, kevlar and glass 49-E as the matrix epoxy vinyl ester resin (DERAKANE 411-350). All laminates were formed each with four layers of reinforcements. Depending on the hybrid fabric, all the influencing factors mentioned above have been studied for laminates. All laminates were manufactured industrially used being the lamination process manual (hand-lay-up). All mechanical characterization and study of the mechanism of fracture (fracture mechanics) was developed for laminates subjected to uniaxial tensile test, bending in three and uniaxial compression. The analysis of fracture mechanisms were held involving the macroscopic, optical microscopy and scanning electron microscopy

Estudo sobre as potencialidades de compósitos à base de gesso e fibras de coco seco para aplicação na construção civil

The use of gypsum, one of the oldest building materials for the construction industry in the country has been experiencing a significant and steady growth, due to its low cost and some of its properties that confer comparative advantage over other binder materials. Its use comprises various applications including the coating of walls and the production of internal seals and linings. Moreover, the fibers are being increasingly incorporated into arrays fragile in an attempt to improve the properties of the composite by reducing the number of cracks, the opening of the same and its propagation velocity. Other properties, depending on the function of the component material or construction, among these thermal and acoustic performances, are of great importance in the context of buildings and could be improved, that is, having better performance with this embodiment. Conduct a comparative study of physico-mechanical, thermal and acoustic composite gypsum incorporating dry coconut fiber, in the form of blanket, constituted the main objective of this work. Improving the thermal and acoustic performances of precast gypsum, used for lining and internal vertical fences of buildings, was the purpose of development of these composites. To evaluate the effect of fiber content on the properties of the composites were used to manufacture the composite layer with different thicknesses. The composites were fabricated in the form of plates with dimensions of 500x500x24mm. To facilitate the comparative study of the properties were also made with material gypsum boards only. We then determined the physico-mechanical, thermal and acoustical plaster and composites. The results indicated that the composites were significant gains in relation to thermal performance and also acoustic, in certain frequency range, increasing the thickness of the blanket. Concerning other physical-mechanical properties, the results showed that although the compressive strength was lower than for the composite did not occur after a fracture catastrophic failure. The same trend was observed with regard to resistance to bending, since the composites have not suffered sudden rupture and still continued after the load supporting point of maximum load

HIV/AIDS e estilo de vida: parâmetros imunológicos, virológicos, síndrome lipodistrófica e sua relação com a prática de exercícios

This descriptive study aimed to investigate the relationship between expression of immunological (TCD4 +) and virological (viral load) parameters, lipodystrophy syndrome and lifestyle variables of people living with HIV who underwent a program of physicalexercise. Initially, the sample was composed by 17 persons, recorded at the Department of Giselda Trigueiro Hospital Care (GTH), Natal-RN . With the passing of the stages of intervention (physical training program- PTP) the number of participants has changed (17, 9, 8 and 7) as the training phases (I, II, III and IV). Data collected were on total cholesterol, High Density Lipoprotein (HDL) and triglycerides. The % fat (% F), body mass index (BMI), waist-hip ratio (WHR), lean mass (LM), central fat (BF), total (TF) and peripheral (PF), weight and height were used to measure the morphological parameters. For control of variables (TCD4 +, viral load, Triglycerides, Cholesterol, HDL), the information contained in the blood tests every four months were investigated. After Phase I and II, it was used a structured interview. Then sampling was carried out considering the pre-and post-tests 1, 2, 3 and 4 (after 16, 32, 48 and 64 weeks of training, respectively). Daily, the intensity of the work was checked by the scale of perceived exertion for exercises adapted to resistance34. Procedures used were descriptive statistics (dispersion, absolute and relative frequencies, means, standard deviations and minimum and maximum values) as well as Spearman linear correlation adopting a significance level of p ≤ 0.05. Positive changes were observed for TCD4 + and viral load in all phases of the PTP. For the morphological components, the loss of central subcutaneous fat (CSF) and total subcutaneous fat (TSF) for both sexes and the decrease in % BF among women were the most dramatic results after the training phase I. For men, results were more significant to % F and LM in Phases I and II and peripheral subcutaneous fat (PSF) declined in all phases of the exercise. As for women, results were more expressive for % F and TM in the phases I and II and the PSF decreased in all phases of the exercise. Whereas for women, the waist/hip ratio (WCQ) and 0% F decreased and showed a positive association with triglycerides (WHR r * 0.82, p 0.042, r 0.88 TSF *, p 0.019 and r 1.00 ** CSF, p <0.001) and among men with limb subcutaneous fat (LSF)* r 0.65, p 0.029). The PTP provided improvement in the health, self-esteem and quality of life, proving to be a possible strategy to positively influence the expression of immunological parameters (TCD4 +) and virological (viral load) and morphological components of people living with HIV causing no deleterious effects in these parameters