ABSTRACT
The article presents the results of the author's tests involving the determination of the maximal experimental value of the stress intensity factor KQ. This value was determined for a layered material obtained as the result of explosive welding of three alloys: AA2519, Ti6Al4V and AA1050, and separately for each material. In both cases tests were conducted for two temperatures-the ambient temperature (293 K), and cryogenic temperature (77 K). A model for initial assessment of the KQ value of AA2519-AA1050-Ti6Al4V (Al-Ti) layered material has also been presented. The proposed model has been developed so as to enable the determination of the curve course of load-COD for Al-Ti layered material using nominal stresses defined on the basis of a real load-COD course, obtained for the base materials, for both temperature conditions.
ABSTRACT
This study presents the testing results of methacrylic adhesive single-lap joints made from elements with different stiffness and of the adhesive itself, using cast specimens. Methods for the preparation and testing of material specimens of the adhesive joints have been presented. Moreover, an attempt was undertaken to determine the strength criterion and find out which of the presented calculation methods enables the most precise assessment of strength in the tested group of single-lap joints, that differ in terms of the adhered stiffness and thickness. For this purpose, C45 steel and 5754 aluminium flat bars were bonded. Stress distributions were determined for failure forces obtained in the experiment by means of three basic analytic and numerical methods. Stress and strain states were compared, indicating the highest consistency for the value of normal peel stresses acting in the direction perpendicular to the direction of the joint tension. Reduced stresses provided by the analyses reached values higher than those which were achieved during the specimen tension testing.
ABSTRACT
The study presents an analysis of the cracking process of explosive welded layered material AA2519-AA1050-Ti6Al4V (Al-Ti laminate) at ambient (293 K) and reduced (223 and 77 K) temperatures. Fracture toughness tests were conducted for specimens made of base materials and Al-Ti laminate. As a result of loading, delamination cracking occurred in the bonding layer of specimens made from Al-Ti laminate. To define the crack mechanisms that occur at the tested temperatures, a fracture analysis was made using a scanning electron microscope. Moreover, acoustic emission (AE) signals were recorded while loading. AE signals were segregated to link their groups with respective cracking process mechanisms. Numerical models of the tested specimens were developed, taking into account the complexity of the laminate structure and the ambiguity of the cracking process. A load simulation using the finite element method FEM allowed calculating stress distributions in the local area in the crack tip of the Al-Ti laminate specimens, which enabled the explanation of significant material cracking process development aspects. Results analysis showed an influence of interlayer delamination crack growth on the process of the Al-Ti laminate specimen cracking and the level of KQ characteristics at different temperatures.
