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Doctoral Thesis
DOI
https://doi.org/10.11606/T.3.2020.tde-13022020-093229
Document
Author
Full name
Pouria Bahrami Ataabadi
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2019
Supervisor
Committee
Alves, Marcilio (President)
Donadon, Maurício Vicente
Luersen, Marco Antônio
Marinucci, Gerson
Vaziri, Reza
Title in English
Axial impact on carbon fiber tubes: numerical and experimental study.
Keywords in English
CFRPs
Crashworthiness
Experimental tests
Finite element analysis
Tubular absorber
Abstract in English
Carbon Fiber-Reinforced Plastics, CFRPs, have been widely used in the industry due to their high specific strength and stiffness ratios as well as good crushing performance when used as energy absorbers. Here, an experimental characterization of the crushing mechanism of tubular carbon fiber/epoxy absorbers is described in details, side by side with a finite element, FE, simulation of these components under compression. In the experimental study, CFRP tubes with two different stacking sequences, cross-ply and angle-ply, underwent axial quasi-static and impact in order to investigate possible effects of loading rate, stacking sequence and cross-section shape on the energy absorption capacity of the tubes. The experimental results were used to support the development of the finite element model of the composite parts under axial impact. Using Abaqus/Explicit code, a multi-layer model of laminated tube was conceived. Concentric layers of conventional shell element (S4R), in contrast to the extensive use of continuum elements, were adopted. A simple tying technique based on Continuum Damage Mechanics (CDM) was used to tie adjacent composite layers. The implementation of this bonding technique is more straightforward when comparing with the cohesive zone modes, requiring fewer mechanical properties as input. The results obtained from the numerical model agreed well with the experimental campaign, encouraging the use of the advanced finite element model developed here.
Title in Portuguese
Impacto axial em tubos de fibra de carbono: estudo numérico e experimental.
Keywords in Portuguese
Absorvedor tubular
Método dos elementos finitos
Segurança pessoal em automóveis
Testes experimentais
Abstract in Portuguese
Componentes de fibra de carbono, CFRPs, têm sido amplamente utilizados na indústria devido às suas altas taxas de resistência e rigidez específicas, bem como ao bom desempenho de esmagamento quando usados como absorvedores de energia. Aqui, uma caracterização experimental do mecanismo de esmagamento de absorvedores tubulares de fibra de carbono / epóxi é descrita em detalhes, lado a lado com a simulação via elementos finitos desses componentes sob compressão. No estudo experimental, os tubos CFRP com duas seqüências de empilhamento diferentes, camada cruzada e camada angular, foram sujeitados a carregamentos quase estático e de impacto axiais a fim de investigar possíveis efeitos da taxa de carregamento, sequência de empilhamento e forma da seção transversal na absorção de energia dos tubos. Os resultados experimentais foram utilizados para apoiar o desenvolvimento do modelo de elementos finitos das peças compostas sob impacto axial. Utilizando o código Abaqus / Explicit, foi concebido um modelo multicamada de tubo laminado. Camadas concêntricas do elemento de casca convencional (S4R), em contraste com o uso extensivo de elementos contínuos, foram adotadas. Uma técnica simples, baseada na Mecânica do Dano do Continuum (CDM), foi usada para unir as camadas compostas adjacentes. A implementação desta técnica de ligação é mais direta quando comparada com os modos de zona coesa, exigindo menos propriedades mecânicas como entrada. Os resultados obtidos no modelo numérico concordaram bem com a campanha experimental, incentivando o uso do modelo avançado de elementos finitos aqui desenvolvido.
 
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Publishing Date
2020-02-13
 
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