Nowadays, is expected that for most materials to be environmentally friendly. Besides, waste from end-of-life products may be considered a secondary source of materials with an energetic advantage due to its high energy content. This paper deals with the study of friction and wear characteristics of Glass fibre-reinforced polymer (GFRP) composites with polyester/glass fiber (P/GF) waste as filler, replacing the widely used calcium carbonate (CaCO 3 ). Polyester composites based on two or three components, using a combination of polyester, CaCO 3 , GF, and GF waste, were produced. Pin-ondisc sliding wear test was performed using a polished stainless steel counterface. Roughness, surface energy, and hardness of the composites were characterized before the tests. The GF content (15, 25, 35, and 50 wt.%), the sliding velocity (0.021 and 0.042 m/s), and the normal load (1, 5, and 10 N) were varied. Based on the experimental results, it was observed that the friction coefficient and wear rate were influenced by material composition, surface roughness and energy, adhesive, and abrasive contact mechanisms. P/GF composites having P/GF waste presented enhanced performance considering friction and wear in relation to those with CaCO 3 in their composition.
Wire ropes are widely used in applications where the axial stress is high and flexural and torsional stresses are relatively low. Study of their mechanical behavior encompasses many factors, bringing considerable complexity to the construction of numerical or analytical models that suitably represent their behavior, including contact stresses between rods, helical geometry, rotation of wires when extended and also, in the case of carbon fiber-reinforced polymer (composite) cables, their anisotropic behavior. In view of the lack of suitable analytical solutions, this work focuses on the updating of a finite element model by incorporating factors commonly neglected by simplified analytical approaches. The carbon fiberreinforced polymer cable was modeled under tensile stress and under four-point bending. After that a sensitivity analysis of the main parameters governing the problem was conducted. The updating process minimized the deviation between numerical and experimental data, and the model was able to reproduce the tensile and bending behavior with deviations smaller than 1%. The adopted methodology can be extended to similar cases.
A modelagem matemática do câncer tem sido instrumento de estudo em diversas pesquisas realizadas no intuito de conhecer quantitativamente o efeito dessa patologia nos pacientes, assim como os da quimioterapia. O estado nutricional do paciente oncológico sofre alterações decorrentes da presença do tumor e terapias antineoplásicas. Tais alterações associadas aos efeitos colaterais do tratamento influenciam significativamente a qualidade de vida do paciente [2]. Neste contexto, ressalta-se a importância da análise da mudança de massa e suas consequências nesses indivíduos através da modelagem matemática.O modelo de equações diferenciais representativo do câncer com ação da quimioterapia, baseado em duas populações de células tumorais e normais, denotadas por N 1 e N 2 , respectivamente, e um agente quimioterápico Q,é dado por:onde r 1 e r 2 representam as taxas de crescimento, k 1 e k 2 representam as capacidades suporte das células, α 1 e α 2 representam a influência entre as populações, ou competição por recursos escassos, λé a taxa de decaimento do agente quimioterápico, µ e ν são as taxas de tratamento, a e b são as velocidades de resposta a droga, e q(t)é a função da administração do agente quimioterápico. Considerando a administração em ciclos do agente quimioterápico q(t),é estabelecido a esse parâme-tro um valor ideal de 7200mg/dia para um paciente de 70Kg através da fórmula de Mosteller [3] e do limite de dose estabelecido pelo Ministério da Saúde [1]. Os resultados obtidos através do valor adotado são eficazes com relaçãoà regressão do tumor, porém a variação mássica do paciente oncológicoé multifatorial e frequente, sendo considerado fator prognóstico e limitante do tratamento [2], podendo gerar resultados significativos e passíveis de análise com relação ao desenvolvimento da doença.Diversos fatores são responsáveis pela mudança de massa. Dentre eles estão o decréscimo de atividade física influenciada pela própria doença, a alteração da taxa metabólica e a baixa ingesta alimentar decorrente da sintomatologia e da presença do tumor [2].A partir do sistema (1) foram originados gráficos das células tumorais (N 1 ) e normais (N 2 ) em função do tempo. O modelo foi implementado em código C e os gráficos foram obtidos através do software Origin. Para a implementação foram necessárias considerações importantes no que diz respeito aos dois tipos de células, suas respectivas massas e porcentagens no organismo do paciente. Após estudo detalhado da referência bibliográfica, observou-se que os resultados que melhor representam a realidade do tumor e das demais células, foram a adoção de que cada célula tumoral corresponde a 1 × 10 −9 g e representa aproximadamente 0, 0343% do organismo do paciente, e que cada célula normal corresponde a 6, 9976 × 10 −8 g e representa aproximadamente 99, 9657% do organismo do paciente. Os gráficos 1 e 2 representam o comportamento das células com o aumento e redução de 10Kg e 5Kg, que foram acrescidos ou decrescidos ao número de células a cada interação de acordo com o sua massa e p...
The tensile behavior of cables and wire ropes has been widely explored in the literature, with many analytical, numerical and experimental results available. However, their bending behavior is still not yet fully comprehended, especially when dealing with cables made of non-isotropic materials. When these materials are bended over small diameter sheaves or drums, they may experience large strains, causing nonlinearities that are not captured by any known analytical model. The aim of the present work is to numerically verify through finite-element method the tensile and bending behavior of composite CFRP cables. The numerical results were compared with experimental data. Good correlation between them was found in a four-point bending test configuration, even at large displacements and with a nonlinear response. Hybrid cable constructions (using aramid and glass rods) were also numerically analyzed relative to their tensile and bending behavior, achieving satisfactory results.
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