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Simulação e validação experimental de termografia ativa para compósitos de matriz polimérica reforçados com fibras contínuas produzidos por manufatura aditiva
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Resumo(s)
Os materiais compósitos de matriz polimérica (CMP) são cruciais na engenharia e
quando obtidos por Manufatura Aditiva (MA) tornam a sua inspeção um desafio. A
inspeção rápida, não invasiva, automatizável e a produção de uma imagem sobreponível
com a peça potencia a Termografia (Ta) nos Ensaios Não Destrutivos (END) dos CMP.
Os principais objetivos desta dissertação foram: com base em simulações numéricas
preliminares, fabricar provetes em CMP por Fused Deposition Modelling (FDM®); ensaiar
experimentalmente por Termografia Transiente Ativa (TTA) e Duplamente Ativa (TTDA)
os provetes produzidos; e identificar os novos modelos numéricos para a simulação numérica
da TTA e da TTDA.
Os provetes reforçados com fibras contínuas de carbono, de vidro, de Kevlar®, e os
provetes sem reforço foram fabricados com sucesso numa impressora 3D convencional
adaptada para a impressão com fibras embebidas, sendo que duas delaminações foram
incutidas artificialmente a diferentes profundidades. Foram realizados 260 ensaios experimentais
e, em conjunto com a simulação dos modelos numéricos, fez-se uma análise
das respostas transientes térmicas, tendo sido quantificada a influência das propriedades
térmicas das fibras contínuas nos parâmetros da Ta.
A validação dos novos modelos numéricos foi realizada tendo como referência os ensaios
experimentais, tendo-se apresentado uma correlação muito boa dos resultados da
simulação numérica com os resultados experimentais. A simulação numérica torna-se
assim indispensável à plena compreensão dos fenómenos envolvidos, sendo o desenvolvimento
e a validação dos modelos numéricos um elemento-chave no avanço da Ta como
END dos CMP obtidos por FDM®.
Polymer matrix composites (PMC) materials are crucial in engineering and when they are obtained through Additive Manufacturing (AM), inspection of the composite becomes a challenge. Rapid, non-invasive, automatable inspection and production of a superimposable image with the part enhances Thermography in Non-Destructive Testing (NDT) of PMC. The main objectives of this dissertation were to: execute the manufacture of specimens through Fused Deposition Modelling (FDM®) based on preliminary numerical simulations; experimentally test the specimens through Active Transient Thermography (ATT) and Doubly Active (DATT); and identify the new numerical models for the numerical simulation of ATT and DATT. Carbon, glass, Kevlar®, and unreinforced specimens have been successfully manufactured in a conventional 3D printer adapted for printing with impregnated fibres, with two delaminations being artificially instilled at different depths. A total of 260 experimental tests were carried out and, together with the simulation of the numerical models, an analysis of the transient thermal responses was conducted. The influence of the thermal properties of continuous fibres on the parameters of thermography was also quantified. The validation of the new numerical models was performed using the experimental tests as a reference, and a very good correlation of the results of the numerical simulations with the experimental results was achieved. Numerical simulation becomes thus indispensable to a full understanding of the phenomena, with development and validation of numerical models being a key element to advance thermography as NDT of the PMC obtained by FDM®.
Polymer matrix composites (PMC) materials are crucial in engineering and when they are obtained through Additive Manufacturing (AM), inspection of the composite becomes a challenge. Rapid, non-invasive, automatable inspection and production of a superimposable image with the part enhances Thermography in Non-Destructive Testing (NDT) of PMC. The main objectives of this dissertation were to: execute the manufacture of specimens through Fused Deposition Modelling (FDM®) based on preliminary numerical simulations; experimentally test the specimens through Active Transient Thermography (ATT) and Doubly Active (DATT); and identify the new numerical models for the numerical simulation of ATT and DATT. Carbon, glass, Kevlar®, and unreinforced specimens have been successfully manufactured in a conventional 3D printer adapted for printing with impregnated fibres, with two delaminations being artificially instilled at different depths. A total of 260 experimental tests were carried out and, together with the simulation of the numerical models, an analysis of the transient thermal responses was conducted. The influence of the thermal properties of continuous fibres on the parameters of thermography was also quantified. The validation of the new numerical models was performed using the experimental tests as a reference, and a very good correlation of the results of the numerical simulations with the experimental results was achieved. Numerical simulation becomes thus indispensable to a full understanding of the phenomena, with development and validation of numerical models being a key element to advance thermography as NDT of the PMC obtained by FDM®.
Descrição
Palavras-chave
Ensaios Não Destrutivos (END) Manufatura Aditiva (MA) Materiais Compósitos Simulação Numérica Termografia Transiente Ativa (TTA) Termografia Transiente Duplamente Ativa (TTDA)