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Abstract(s)
As ligações adesivas apareceram pela necessidade de se encontrar formas de unir componentes, por vezes dissimilares, através de técnicas mais vantajosas. Nos tempos atuais, qualquer estrutura deve ter como característica a resistência, a robustez e a leveza, o que amplificou o interesse industrial e investigação nas ligações adesivas, principalmente na melhoria das propriedades de resistência e fratura dos materiais.
Assim sendo, nos últimos anos, o emprego de juntas adesivas em aplicações industriais tem crescido gradualmente, substituindo alguns métodos de ligação tradicionais, por presentarem vantagens tais como redução de concentração de tensões, reduzido peso e preço, e facilidade de processamento/fabrico.
Nesta dissertação, as leis coesivas de três adesivos, Araldite® AV138, Araldite® 2015 e Sikaforce® 7752, foram obtidas pela aplicação de um método inverso de ajuste entre curvas força-deslocamento (P-δ) numéricas e experimentais, de ensaios Double-Cantilever Beam (DCB) para caracterização à tração e ensaios End-Notched Flexure (ENF) para caraterização ao corte. Posteriormente estas leis são validadas com dados xperimentais de juntas de sobreposição simples (JSS) e sobreposição dupla (JSD) através do software ABAQUS®.
Para os adesivos Araldite®AV138 e Araldite®2015, à tração e ao corte, a lei triangular previu o comportamento do adesivo de forma bastante adequada, verificando-se uma elevada concordância entre os resultados experimentais e numéricos. Para a previsão da resistência do adesivo Sikaforce® 7752, a lei triangular não se ajustou convenientemente nem à tração nem ao corte. Considera-se que, devido à ductilidade do mesmo, para o adesivo Sikaforce, uma lei trapezoidal é a que melhor se adequa.
Adhesive bonds appeared by the necessity to find ways of joining components, sometimes dissimilar, through more advantageous techniques. Nowadays, any structure must have strength, robustness and lightness, which has amplified the industrial interest nd investigation in adhesive joints, mainly in the improvement of the strength and fracture properties of the materials. Thus, in recent years, the use of adhesive joints in industrial applications has gradually grown, replacing some traditional bonding methods, since they have advantages such as reduced stress concentrations, reduced weight and cost, and ease of processing/manufacturing. In this dissertation, the cohesive laws of three adhesives, Araldite® AV138, Araldite® 2015 and Sikaforce® 7752, were obtained by the application of an inverse method of adjustment between the numerical and experimental force-displacement curves (P-δ) of Double-Cantilever Beam (DCB) tests for tensile characterization and End-Notched Flexure (ENF) tests for shear characterization. Next, these laws are validated with experimental data of single-lap joints (SLJ) and double-lap joints (DLJ) through the ABAQUS® software. For the adhesives Araldite®AV138 and Araldite®2015, in tension and shear, the triangular law predicted the behavior of the adhesive very accurately, with a high agreement between the experimental and numerical results. To predict the strength of the adhesive Sikaforce® 7752, the triangular law did not suitably fit either the tension or shear behaviours. It is considered that, due to its ductility, for the adhesive Sikaforce, a trapezoidal law is the one that suits best.
Adhesive bonds appeared by the necessity to find ways of joining components, sometimes dissimilar, through more advantageous techniques. Nowadays, any structure must have strength, robustness and lightness, which has amplified the industrial interest nd investigation in adhesive joints, mainly in the improvement of the strength and fracture properties of the materials. Thus, in recent years, the use of adhesive joints in industrial applications has gradually grown, replacing some traditional bonding methods, since they have advantages such as reduced stress concentrations, reduced weight and cost, and ease of processing/manufacturing. In this dissertation, the cohesive laws of three adhesives, Araldite® AV138, Araldite® 2015 and Sikaforce® 7752, were obtained by the application of an inverse method of adjustment between the numerical and experimental force-displacement curves (P-δ) of Double-Cantilever Beam (DCB) tests for tensile characterization and End-Notched Flexure (ENF) tests for shear characterization. Next, these laws are validated with experimental data of single-lap joints (SLJ) and double-lap joints (DLJ) through the ABAQUS® software. For the adhesives Araldite®AV138 and Araldite®2015, in tension and shear, the triangular law predicted the behavior of the adhesive very accurately, with a high agreement between the experimental and numerical results. To predict the strength of the adhesive Sikaforce® 7752, the triangular law did not suitably fit either the tension or shear behaviours. It is considered that, due to its ductility, for the adhesive Sikaforce, a trapezoidal law is the one that suits best.
Description
Keywords
Juntas adesivas Adesivo Lei coesiva Modelos de Dano Coesivo Método de Elementos Finitos Parâmetros coesivos Método inverso Adhesive joints Adhesive Cohesive Law Cohesive Zone Models Finite Element Method Cohesive Parameters Inverse Method