||The aim of this thesis is to manufacture Ti/APC-2 hybrid composite laminates and obtain its mechanical properties and fatigue characteristics at elevated temperatures. Ti/APC-2 laminates were composed of two layers of APC-2 and three layers of titanium sheets. For superior bonding ability between titanium and APC-2, chromic anodic method was adopted to treat titanium sheets in manufacturing process and APC-2 was stacked according to cross-ply [0/90]s and quasi-isotropic [0/45/90/-45] sequences. Then, the modified curing process was adopted to fabricate Ti/APC-2 hybrid composite laminates. Tension and fatigue tests carried out with MTS 810 and MTS 651 environmental control chamber to lift and maintain experimental temperatures, such as 25°C, 75°C, 100°C, 125°C and 150°C.|
From static tensile tests, the mechanical properties of cross-ply and quasi-isotropic composite laminates, such as ultimate strength, longitudinal stiffness were gained and the stress-strain diagrams of laminates were also plotted from testing data at elevated temperature. From fatigue tests we obtained laminate’s fatigue resistance properties and the experimental data of applied stress vs. cycles were plotted as S-N diagrams at elevated temperature.
From the tensile and fatigue tests, the important remarks were summarized as follows. First, no matter what the APC-2 stacking sequence was, the ultimate strength and longitudinal stiffness decreased while temperature rising, especially at 150°C; second, a turning point appeared at each stress-strain diagram that kink angle caused the decrease of stiffness while temperature rising; third, combining fatigue data and stress-strain diagrams we analogized a presumption that the region before turning point was in elastic behavior and after turning point in plastic deformation; fourth, quasi-isotropic laminates had better fatigue resistance than that of cross-ply laminates; sixth, the longitudinal stiffness before turning point was in good agreement with the prediction by using the modified ROM, however, after turning point the errors became large.