1,721,261 research outputs found
A coupled FEM-BEM approach for crack growth simulation under fatigue load spectrum
Full text linkThis paper describes an original implementation of a two-parameters crack growth model for 2D crack propagation simulations under general load spectrum. In such model, in order to unify the damage process, the following basic parameters are introduced for describing the overall fatigue process: K, Kmax and the internal stress contribution to Kmax.
The coupled usage of Finite Element Method (FEM) and Dual Boundary Element Method (DBEM) is proposed in order to take advantage of the main capabilities of the two methods. The procedure is validated by comparison with in house obtained experimental results and its capability to predict the retardation phenomena following an overload is assessed. The numerical procedure is tested with reference to an MT aluminium specimen (2024HP-T3), whose fatigue calibration parameters had been previously determined using a CT specimen undergoing a constant amplitude load. As a matter of fact the main advantage of the aforementioned procedure is based on the simplicity of the crack growth law calibration, in fact, there is no need to calibrate on various overload levels but few constant amplitude test are sufficient.
One of the main capabilities of the implemented procedure is the possibility to simulate load spectrum effects under linear elastic fracture mechanics, being the plastic effects simulated by ad hoc body loads, imposed in the BEM analysis (by means of “load lines”), without the need for any non physical calibration parameters, as in many phenomenological models aimed at load spectra allowance (Willenborg model, Wheeler model, etc.). A curvilinear crack path is simulated and reproduced experimentally: the differences between the calculated and experimental delay cycles after an overload are comparable with the typical scatter of such kind of test
Snap-back analysis of fracture evolution in multi-cracked solids using boundary element method
No full textAccording to the Linear Elastic Fracture Mechanics criteria, a numerical model is developed to simulate the failure evolution of multi-cracked finite plates by means of an incremental loading procedure. A modified crack length control scheme is used in order to analyse such problems depending on one or more independent parameters. The aim is to provide information about a discontinuous response, such as the snap-back instability, which can be highlighted only by a deformation controlled process. The load vs. displacement curve, included possible snap-back branches, is numerically traced by means of a procedure based on the Displacement Discontinuity Boundary Element Method. With reference to finite plates with ordered crack distributions in plane strain loading conditions, the model is applied in order to analyse the effects of the crack interaction on the fracture evolution
Fracture evolution and snap-back instability in multi-cracked finite plates
No full textThe effects of the crack interaction on the fracture evolution of multi-cracked finite plates in plane strain loading conditions are considered. A modified crack length control scheme is presented in order to analyse such problems depending on one or more independent parameters. The aim is to provide information about a discontinuous response, such as snap-back instability, which can be only highlighted by a deformation controlled process. With reference to finite plates with one or more rows of evenly spaced collinear cracks, the snap-back branches of the load vs. displacement curve are numerically captured by means of a procedure based on the Boundary Element Method
Scaling laws for fragmentation energy density and other mechanical properties of materials
No full textSystem for the assessment of safety conditions in reinforced concrete and masonry structures
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