1,721,038 research outputs found
Mixed mode fracture assessment of U-notched graphite Brazilian disk specimens by means of the local energy
No full textA fracture criterion based on the strain energy density (SED) over a control volume, which embraces the notch edge, is employed in the present paper to assess the fracture loads of some U-notched Brazilian disk (UNBD) specimens. The specimens are made of commercial graphite and have been tested under pure mode I, pure mode II and mixed mode I/II loading. The results show that the SED criterion allows to successfully assess the fracture loads of graphite specimens for different notch tip radii and various mode mixity conditions with discrepancies that fall inside the scatter band of +/- 20%
Large-Scale Yielding Failure Prediction of Notched Ductile Plates by Means of the Linear Elastic Notch Fracture Mechanics
No full textElastic-plastic fracture analysis of notched Al 7075-T6 plates by means of the local energy combined with the equivalent material concept
No full textThe main goal of the present research is to analyze tensile fracture in Al 7075-T6 thin plates weakened by blunt V-notches. For this purpose, first, 27 fracture tests are carried out on rectangular plates containing a central rhombic hole with two blunt V-shaped corners horizontally located. The experimental observations indicated that a plastic region initiates from the notch tip and grows as the tensile load monotonically increases, and finally, fracture happens suddenly with a significant opening of the notch tip. By showing significant plastic deformations around the notch tip and also inclined fracture planes, the specimens after fracture confirm well the ductile rupture in V-notched Al 7075-T6 plates. As the main experimental result, the load-carrying capacity of the notched plates corresponding to the onset of crack initiation from the notch tip is recorded. To theoretically predict the experimental results, the equivalent material concept is utilized together with the well-known brittle fracture criterion, namely the averaged strain energy density criterion. Without requiring elastic-plastic finite element analysis, it is shown that the combination of the averaged strain energy density and equivalent material concept is successful in predicting the load-carrying capacity of the V-notched Al 7075-T6 plates that fail by moderate-scale yielding regime
Experimental and theoretical investigation of brittle fracture in key-hole notches under mixed mode I/II loading
No full textThe Brazilian disk specimen weakened by a central dumbbell-shaped slit with two key-shaped ends and made of PMMA is employed to perform mixed mode I/II brittle fracture experiments on key-hole notches for various notch lengths and radii and, also, different mode mixity ratios. The load-carrying capacity of the specimen resulting from the test machine at the onset of sudden fracture is theoretically predicted by means of a well-known brittle fracture criterion, namely the local strain energy density criterion. A good agreement is found to exist between the theoretical and the experimental results
Local strain energy density to predict mode II brittle fracture in Brazilian disk specimens weakened by V-notches with end holes
No full textThe present paper reports some experimental, theoretical and numerical results on brittle fracture of notched components made of Polymethylmethacrylate (PMMA). First, fracture experiments were carried out at room temperature on V-notches with end holes (VO-notches) under mode II loading by means of a recently proposed disk-type specimen, called the Brazilian disk containing central VO-notches (VO-BD specimen) made of PMMA for different notch angles and various notch radii.Then, the well-established averaged strain energy density (SED) criterion over the specified control volume which embraces the notch border was formulated and employed to predict theoretically the experimental fracture loads. The center of the control volume is located on the notch edge, where the principal stress reaches its maximum value. The correct orientation is obtained by a rigid rotation of the crescent-shaped volume while the size depends on the fracture toughness and the ultimate strength of the material. This methodology has been already used in the literature to analyze U- and V-shaped notches subject to different loading modes with very good results and advantages with respect to classic approaches.In this contribution it was demonstrated that SED works well also on VO-notches under pure mode II loading. © 2014 Elsevier Ltd
Strain energy density to assess mode II fracture in U-notched disk-type graphite plates
No full textThe brittle fracture criterion, namely the strain energy density (SED) over a control volume, which embraces the notch edge, is utilized in the present research to assess the experimentally obtained fracture loads of several U-notched Brazilian disk (UNBD) specimens made of a type of commercial graphite under pure mode II loading. The results show that the SED criterion could successfully predict the fracture loads of graphite specimens for different notch tip radii with an average discrepancy of about ±10%. It is proved in this investigation that not only the SED criterion works well on brittle fracture of notched graphite components under pure mode I, mixed mode I/II and pure mode III loading conditions, but also under pure mode II loading
A successful combination of the equivalent material concept and the averaged strain energy density criterion for predicting crack initiation from blunt V-notches in ductile aluminum plates under mixed mode loading
No full textTensile fracture analysis of V-notches with end holes by means of the local energy
No full textThis paper deals with investigating brittle fracture in V-notches with end holes under mode I loading. Thirty-six fracture test results, reported most recently in the literature on a new notched disk-type specimen, namely the Brazilian disk containing central VO-shaped notch made of polymethyl-metacrylate, were theoretically predicted by means of the well-known brittle fracture criterion, namely the strain energy density over a critical control volume which embraces the notch edge. A very good agreement was shown to exist between the experimental and theoretical results
Mode II Brittle Fracture Assessment of Key-Hole Notches by Means of the Local Energy
No full textBrittle fracture of key-hole notches under pure mode II loading is investigated both experimentally and theoretically. In the experimental part, a new version of the well-known Brazilian disk specimen containing a central dumbbell-shaped slit with two key-ends, called the Key-BD specimen, made of polymethyl-methacrylate (PMMA), is utilized to perform fracture experiments at room temperature for different notch lengths and various notch radii. In the theoretical part, the experimentally recorded fracture loads are predicted by means of the strain energy density (SED) averaged over a specified control volume, which embraces the notch edge. It is found that the SED criterion can successfully predict the test result
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