Evaluation of laminated composite plates behavior under shear-after-impatc loading conditions: a methodology proposal

• Ano de defesa: 2021
• Autor(a) principal: Souza, Gabriel Sales Candido
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Análise de elementos finitos; Carregamento de impacto; Cisalhamento pós-impacto; Comportamento pós-impacto; Compósitos laminados; Finite element analysis; Impact loading; Laminated composites; Post-impact behavior; Shear-after-impact
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/18/18161/tde-05082021-081042/

Fiber-reinforced polymer (FRP) laminated composite materials represents the greatest revolution since the development of the jet turbine in aeronautical industry. Possessing high stiffness and strength to weight ratio, they encounter increasingly space in high-performance applications, particularly in aircrafts. However, nowadays there are limitations in their usage attached to the complexity of prediction of behavior that these materials presents under impact loadings, which can result in a significant reduction in their mechanical properties. Moreover, due to its heterogeneity and anisotropy, the description of initiation and propagation of damage and failure mechanisms are not fully understood yet. Thus, the application of composite materials in aeronautical structures still follow conservative design philosophies. In this context, it is strategic the study of the mechanical behavior and the failure development and evolution presented by these materials. Following this, the post-failure behavior comprehension, in the sense of prediction of its residual strength, it is of major relevance to use damage tolerant design philosophies when designing one structure. So, this work presents a experimental approach, computationally aided, to evaluate the shear-after (low-velocity) impact behavior of FRP composites with unidirectional (UD) reinforcement since this is a poorly explored theme by the existent literature. Based on Continuum Damage Mechanics (CDM), a material model present in the literature is employed to investigate computationally the failure and post-failure of these materials under impact an shear-after-impact loadings. Thus, experimental tests in [0º]16 specimens are conducted in a 3-rail and drop-weight tests apparatus to obtain the stress-strain curves results for laminates with and without damage. Based in these, a phenomenological damage metric for shear-after-impact is proposed to aid the obtaining of the residual strength of these materials. Computational simulations are realized aiming to obtain, using the finite element method, the tendencies experimentally observed and to evaluate the potentialities and limitations of the material model employed. It is concluded at the end of this work that the proposed methodology is promising to obtain a complementary to the already consolidated approaches of compression- and flexure-after-impact.