In this article, thermo-elastic and creep evolution behaviour of ferritic steel rotating disks with variable thickness are investigated. Four thickness profiles of uniform, convex, concave and linear are considered for the disk geometry. The material creep constitutive model is defined by the Θ projection concept, based on the experimental results existing in the literature. Loading applied is due to the inertial body force caused by the rotation and a constant temperature field throughout the disk. To achieve history of stresses and displacements, a numerical procedure using finite difference and Prandtl-Reuss relations is used. Stress and deformation histories are calculated using successive elastic solution method. In order to verify the solution approach, both composite and aluminum rotating disks were taken into account and the thermo-elastic and time-dependent creep behaviours for composite as well as the former for aluminum were obtained. Results from the current study were found to be in very good agreement with those available from literature in the area. It was shown that convex thickness profile disks display the least creep displacement, creep effective and circumferential stresses. Additionally, constant and concave thickness profiles were positively correlated with time while for linear and convex ones, it was found to have an inverse trend. Manuscript profile

Changes in moisture content and temperature can perturb both stiffness and strength and as such the impact resistance of composite structures. In this paper, the pre-notched basalt fibre reinforced epoxy (BFRE) composite specimens are studied under Charpy impact loads in order to investigate the changes in impact energy absorption (fracture toughness) with different kinds of aging conditions. To create three types of aggressive environmental conditions, the specimens were frozen in dried air at T= -18 °C, frozen in tap water at T= -18 °C and kept in tap water at T= 30 °C and the results were compared with the specimen without aging influence (T= 25 °C). Water used for this examination has a high percentage of precipitation (70-80%) which causes high corrosion and consequent decrease in mechanical properties. The outcomes illustrated that the long-term exposure to tap water (T= 30 °C), dried air (T= -18 °C) and frozen in tap water (T= -18 °C) were all affected on energy absorption of BFRE composites, however, freezing effect in water was more intense. To study the nature of the failure mechanisms, all failed specimens were inspected by Scanning Electron Microscopy (SEM) photographs. Manuscript profile