Adhesively joints are increasingly being used in aerospace, automotive and maritime industries.The use of this type of joining provides some advantages such as reduction in weight and cost.However, adhesive joints in transportation industry may be exposed to aggressive environments such as high humidity during their service life. A particular issue with the reliability of adhesive joints is the presence of cracks and flaws. Fracture mechanics tests for adhesive joints provide relevant mechanical properties to determine the adhesive toughness and play an important role in design process.This research aims to determine the fracture toughness of aluminum/adhesive/aluminum joints under pure mode I, pure mode II and mixed mode loadings. The fracture characterization of adhesively joints was performed when these specimens were submitted to mixed mode loadings and pure modes (shear and opening). The experimental tests Double Cantilever Beam (DCB) and End-Notched Flexure (ENF) were also done in order to assess the fracture toughness in pure modes I and II, respectively. A mixed mode apparatus was used to perform the mixed mode tests from pure mode I to near mode II. Test for dry and wet condition were performed with the main purpose to predict the influence of humidity in the toughness properties. The adhesive characterized was a ductile epoxy adhesive, Nagase Chemtex ® XNR 6852E-2.The diffusion coefficient was measured and the water uptake behavior was studied for a temperature of 50 ºC. Finite element analysis (FEA) was carried out to predict the moisture content in the adhesive layer, using ABAQUS ® .The influence of water in the behavior of the adhesive joint (DCB) was verified by changes in the values of the fracture mechanics properties. The load necessary to initiate a crack propagation is lower for aged adhesive joints when compared with dry adhesive joints for pure modes and different mixed mode ratios. vi vii ResumoAs ligações adesivas são cada vez mais utilizadas na indústria aeroespacial, automóvel e naval.A utilização deste tipo de ligação fornece algumas vantagens, tais como redução do peso e do custo. Contudo, na indústria dos transportes, estas ligações podem ser expostas a ambientes agressivos, tais como ambientes com elevada humidade durante a sua vida útil. Uma questão particular é a fiabilidade das juntas adesivas na presença de fendas e falhas. Os ensaios de mecânica da fratura para juntas adesivas proporcionam propriedades mecânicas relevantes, de forma a determinar a resistência adesiva e desempenham um papel importante no processo de design de juntas.Esta pesquisa tem como objetivo determinar a tenacidade à fratura de juntas de alumínio / adesivo / alumínio em modo puro I, II e modo misto. A caracterização à fratura de juntas adesivas foi realizada quando estas estavam submetidas a cargas de modo misto e modos puros (corte e abertura). Os ensaios Double Cantilever Beam (DCB) e End-Notched Flexure (ENF)foram realizados para avaliar a resistência à fratura em modos puros I e II, respetiv...