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Fracture of hollow clay units simulated by sequentially linear analysis
The sequential linear continuum model described has been implemented in the free open source finite element code OOFEM. Examples of applications in three dimensional simulations were given. From the analysis of a notched beam, it appears that mesh-objectivity can be achieved. With hexaeder elements, the behaviour of a nonlinear reference analysis could be reproduced. With tetraeder elements, peak-load and fracture energy are overestimated, probably due to non-existent localization of deformation into a single element-layer. Further research is needed to clarify this matter. The model is also applicable to more complex structures, as illustrated by the analysis of fracture of a hollow-clay unit. Sharp snap-back behaviour of load-displacement curves is reproduced, which would have been almost impossible employing nonlinear analysis. A realistic strain localization pattern is obtained. CPU-times for sequential linear continuum analysis can be large. The coarse hollow-clay unit mesh with 20 saw-teeth softening required about 25.000 linear analyses to complete failure, the fine mesh twice as many. But the calculations always "converge". Complex solution techniques like arc-length or indirect displacement control, to pass drops and snaps are not required and a lot of man-hours are saved, which would normally have to be spent controlling the corresponding nonlinear analysis.
Fracture of hollow clay units simulated by sequentially linear analysis
The sequential linear continuum model described has been implemented in the free open source finite element code OOFEM. Examples of applications in three dimensional simulations were given. From the analysis of a notched beam, it appears that mesh-objectivity can be achieved. With hexaeder elements, the behaviour of a nonlinear reference analysis could be reproduced. With tetraeder elements, peak-load and fracture energy are overestimated, probably due to non-existent localization of deformation into a single element-layer. Further research is needed to clarify this matter. The model is also applicable to more complex structures, as illustrated by the analysis of fracture of a hollow-clay unit. Sharp snap-back behaviour of load-displacement curves is reproduced, which would have been almost impossible employing nonlinear analysis. A realistic strain localization pattern is obtained. CPU-times for sequential linear continuum analysis can be large. The coarse hollow-clay unit mesh with 20 saw-teeth softening required about 25.000 linear analyses to complete failure, the fine mesh twice as many. But the calculations always "converge". Complex solution techniques like arc-length or indirect displacement control, to pass drops and snaps are not required and a lot of man-hours are saved, which would normally have to be spent controlling the corresponding nonlinear analysis.
Fracture of hollow clay units simulated by sequentially linear analysis
Simulation des Bruches von hohlen Toneinheiten durch sequentielle lineare Analysis
Hannawald, J. (author)
2010
10 Seiten, 9 Bilder, 5 Quellen
Conference paper
English
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