![]() This is a warning sign that our FEA model is not physically meaningful. 4: Stress distributions for the right angle model. Essentially, we will get an infinite stress as the number of elements increases to infinity.įig. There is no sign of any convergence, as shown in the log-linear scales of the plot. It is only the very local peak stress (and hence stress gradient) that is increasing. The average stress distribution in the bulk of the cross-section remains the same. At 60 elements on edge, the peak stress is 220,213 psi and the Kt value is 6.61. The value of peak stress is totally dependent on the level of mesh density around this region. The element edge axis is plotted on a log scale. 3 shows the peak stresses in the corner for a range of mesh sizes, from one element on edge to 60 elements on edge. In this case the nominal stress is calculated as 33,335 psi, giving a Kt of 3.01.įig. It is an effective baseline stress, which ignores the influence of any local stress-raising feature. It is important to realize that the nominal stress is not a “real” stress. The nominal stress is defined as the applied load divided by the narrow cross-sectional area. Kt is defined as the ratio of peak stress to nominal stress. The peak stress can be quoted as a stress concentration factor, Kt. The average stress across the bulk of the section is around 31,000 psi. Notice how localized this stress peak stress region is. 2 shows the stress variation for a model with eight elements along each local edge adjacent to the right angle. What stress will be calculated in the FEA, and is it realistic?įig. A typical mesh, using quarter symmetry, is shown in the inset in Fig. It is assumed that the FEA model ignores the fillet radius and represents this as a right angle. This represents a transition between widths of a component. ![]() We will use a typical shoulder feature as shown in Fig. In this article, I’m focusing on the last example. abrupt transition between materials and.creating abrupt transitions in local constraints.creating abrupt local transitions in local loading.The stress distribution and high levels of stress locally can be described as an FEA “artifact.” The most common examples of where this can happen are the following: In some circumstances, the stress levels that we predict from FEA are not physically meaningful. 2: Stress variation across shoulder with eight elements on edge. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |