| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 1.74 MB | Adobe PDF |
Autores
Orientador(es)
Resumo(s)
Os materiais inteligentes são compósitos capazes de receber estímulos do ambiente
externo e responder de uma forma pré-determinada. Eles possuem a capacidade de se
adaptar à situações que exijam seu esforço ou relaxamento mecânico, permitindo uma
grande eficiência na sua atuação e uma ampla área de aplicação para diversos setores.
Entre essa classe de materiais inteligentes, incluem-se as ligas de memória de forma,
que possuem a capacidade de modificar suas propriedades em função da temperatura
e/ou tensão mecânica. Estes materiais de alta performance possuem grande potencial.
Ao serem dominados seu processamento e, em conjunto com os efeitos de memória de
forma, podem abrir novas perspectivas com respeito ao desenvolvimento da engenharia
estrutural com formas e outras propriedades adaptativas. Os principais objetivos deste
trabalho foram o processamento e a caracterização do compósito inteligente formado por
uma matriz polimérica epóxi, fibras de carbono e ligas de memória de forma NiTi. Foram
estabelecidos, o comportamento e as propriedades mecânicas destes materiais. A partir da
aplicação e avaliação de tratamentos superficiais dos fios embutidos nos provetes ensaiados,
foram obtidos os efeitos de cada um deles na rugosidade da interface entre matriz e
filamentos por meio de testes de tração e adesão, e determinado qual método apresenta os
melhores resultados em um compósito de liga de memória de forma de alta performance.
No que diz respeito às características mecânicas, conclui-se que, o objetivo de obter a
melhor resistência interfacial nos filamentos foi alcançado. A configuração que obteve
a melhor performance, durante ambos os ensaios, apresentou provetes com filamentos
submetidos ao tratamento químico. Estes provetes resultaram em uma tensão máxima
de ruptura mais elevada, com 255,43 MPa, provocando um deslocamento dos provetes de 2,71% (um aumento de até 10% em comparação aos demais provetes), e mantendo seu
módulo de elasticidade constante, em torno de 14,64 GPa. Com o tratamento químico,
também foi obtida uma melhor adesão da resina nos fios, com valores de até 122,31 N
para remoção dos filamentos do compósito. Desse modo, a infiltração em uma área de
contato maior entre os dois materiais, através das saliências presentes na superfície dos
fios, induz a uma força média de extração elevada.
Smart materials are composites capable of receive stimuli from the external environment and responding in a predetermined way. They can adapt to situations that require their effort or mechanical relaxation, allowing a great efficiency in their performance and a wide application area for several sectors. Among this class of intelligent materials are shape memory alloys, which can modify their properties as a function of temperature and/or mechanical stress. These high-performance materials have great potential. When mastered their processing and, in conjunction with shape memory effects, they can open new perspectives regarding the development of structural engineering with shapes and other adaptive properties. The main objectives of this work were the processing and characterization of the intelligent composite formed by an epoxy polymer matrix, carbon fibers, and NiTi shape memory alloys. During this, were established the behavior and mechanical properties of these materials. From the application and evaluation of surface treatments of the wires embedded in the tested specimens, the effects of each on the roughness of the interface between matrix and filaments were obtained by tensile and adhesion tests and determined which method presents the best results in a high-performance shape memory alloy composite. Concerning mechanical characteristics, was achieved the objective of obtaining better interfacial strength in the filaments. The configuration that gives the best performance during both tests presented specimens with filaments submitted to chemical treatment. These specimens resulted in higher maximum rupture stress, with 255.43 MPa, causing a specimen displacement of 2.71% (an increase of up to 10% compared to the other specimens), and keeping its elasticity modulus constant, around 14.64 GPa. With the chemical treatment, better adhesion of the resin to the threads was also obtained, with values of up to 122.31 N for removal of the filaments from the composite. Thus, infiltration into a larger contact area between the two materials, through the protrusions on the surface of the wires, induces a high average extraction force.
Smart materials are composites capable of receive stimuli from the external environment and responding in a predetermined way. They can adapt to situations that require their effort or mechanical relaxation, allowing a great efficiency in their performance and a wide application area for several sectors. Among this class of intelligent materials are shape memory alloys, which can modify their properties as a function of temperature and/or mechanical stress. These high-performance materials have great potential. When mastered their processing and, in conjunction with shape memory effects, they can open new perspectives regarding the development of structural engineering with shapes and other adaptive properties. The main objectives of this work were the processing and characterization of the intelligent composite formed by an epoxy polymer matrix, carbon fibers, and NiTi shape memory alloys. During this, were established the behavior and mechanical properties of these materials. From the application and evaluation of surface treatments of the wires embedded in the tested specimens, the effects of each on the roughness of the interface between matrix and filaments were obtained by tensile and adhesion tests and determined which method presents the best results in a high-performance shape memory alloy composite. Concerning mechanical characteristics, was achieved the objective of obtaining better interfacial strength in the filaments. The configuration that gives the best performance during both tests presented specimens with filaments submitted to chemical treatment. These specimens resulted in higher maximum rupture stress, with 255.43 MPa, causing a specimen displacement of 2.71% (an increase of up to 10% compared to the other specimens), and keeping its elasticity modulus constant, around 14.64 GPa. With the chemical treatment, better adhesion of the resin to the threads was also obtained, with values of up to 122.31 N for removal of the filaments from the composite. Thus, infiltration into a larger contact area between the two materials, through the protrusions on the surface of the wires, induces a high average extraction force.
Descrição
Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Palavras-chave
Materiais inteligentes Liga de memória de forma Tratamento de superfície Ligação interfacial