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Lifetime-Oriented Structural Design Concepts- P17

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Lifetime-Oriented Structural Design Concepts- P17: At the beginning of 1996, the Cooperative Research Center SFB 398 financially supported by the German Science Foundation (DFG) was started at Ruhr-University Bochum (RUB). A scientists group representing the fields of structural engineering, structural mechanics, soil mechanics, material science, and numerical mathematics introduced a research program on “lifetimeoriented design concepts on the basis of damage and deterioration aspects”. | 438 4 Methodological Implementation Beam 1 nGP 16 crit2 w mm Beam 1 nGP 16 crit2 Q1SPs o w mm Fig. 4.34. Beam 1 Load-displacement curve and number of elements for different tolerances and crit2 Q1SPs o nGP0 16 Fig. 4.35. Beam 2 Load-displacement curve and number of elements for different tolerances and crit2 Q1SPs o nGP 16 increase the number of elements up to 67 Figure 4.35b . The curve of QISPs computed with a very small tolerance see the curve s tolerr 0.00001 in Figure 4.35a hardly differs from the result achieved with a rather large tolerance Figure 4.35a s tolerr 0.05 . Different states of mesh refinement for a computation with Q1SPs o are plotted in Figure 4.36. As expected refinement starts in the loading area and in the parts of the structure where the plastic strain begins to accumulate X 4500 mm . In conclusion it should be emphasized that also the error criterion crit2 provides a physically reasonable mesh refinement. Additionally in contrast to critl it measures the quality of the solution accurately enough i.e. in such a way that computations based on a too stiff element formulation e.g. QlSPs o require a much higher mesh density for the same quality of solution. Therefore 4.2 Numerical Methods 439 Fig. 4.36. Beam 2 Different states of mesh refinement Q1SPs o 16 El. contours accumulated plastic strain the mesh refinement in Figure 4.36 is here shown for Q1SPs o. QISPs shows the same mesh refinement when the error tolerance is set equal to an extremely small value. 4.2.8.1.10.3 Biaxial Bending Thick Plate of Uniform Thickness Geometry and boundary conditions are depicted in Figure 4.37. At the boundary X 12000 mm the displacement in X-direction is constrained. Analogously at the boundary Y 12000 mm we apply constraints in Y-direction. The material parameters and the reference load are the same as in the previous example. The maximum load level is vmax 60 applied in 24 equidistant steps . For this example also Q1SPs requires a refinement of the mesh in