Mechanical properties characterization of adhesively bonded T-joint at elevated temperature

Both experimental and analytical studies on mechanical behaviour of adhesive T-joint at elevated temperature are presented. Preliminary analyses established the main variables in adhesive bonding and allowed an experimental study to be developed. The analytical study of adhesive T -joint was developed to predict the adhesive bonding strength and to determine failure mechanism on the stress distribution along interfaces of adhesive layer. The purpose of this study was to identify mechanical properties of adhesive that have good temperature resistance while providing high bond strength to the adhesively-bonded T -joint. The effects of the adhesive thickness and environmental on the bonded strength were established from a series of experiments conducted in elevated temperature. Together with the assessment of physical properties of the adhesive structure morphology and with the supporting studies of the microstructure of epoxy adhesive, this information was also used to propose the adhesive failure factors occurs. The strength of adhesive was related to the cross-linked of particles at different levels of temperatures. The higher strength of adhesive joint also was proposed, in which near glass transition temperature of the fully cured network. Beyond the glass transition temperature of the fully curednetwork, T goo the thermal degradation iiritiate on the adhesive whereby the changes of physical properties occurs. In experiment outcomes, 2.0 mm is an effective adhesive thickness of adhesively bonded T -joint for temperature ranging from 55 °C up to 100 °C. Besides that, 1.0 mm and 1.5 mm obtained had optimum strength at room temperature and 35 °C respectively. The highest tensile stress of 1.9063 MPa was obtained at 35 °C would refer to all ranges of bond line thicknesses. This argument has been supported in physical properties, where at this condition; adhesive reached the optimum glass transition temperature of the fully cured network T goo value. The joint prediction from FEM calculation was made. It is found that the rupture occurs when the Von-misses stress obtained on the FEM of the T -joint reaches the adhesive strength and concluded to be the joint strength. Therefore, a simple relationship between the mechanical properties of the adhesive joint, adhesive strength at different level of adhesive thickness and thermal conditions was presented. Adhesive strengths shows more sensitive when Tcure < Tgoo. At 35°C, adhesive shows the highest strength for all range of adhesive thickness. Increasing cure temperature will increased the thermal degradation level due to the changes of physical properties and its composition. Thus, the degradation will reduce the adhesive strength. The evaluation of the temperature dependence of joint strength by comparing them at various temperatures with the value at room temperature has been accomplished. The development of finite element models, validation and prediction of adhesively bonded T -joint models subjected to static uniaxial loading has been accomplished. The results show the joint strength prediction performed by using elastic-plastic FEM which have significant consistence between the prediction and measured results.