Calculating Fatigue and Fatigue Failure of Structures

摘要

The durability performance of a structure is virtually predicted, enabling the optimization of the durability performance. In a first act, the structure is modeled by a series of calculation points. Then, for each point, the stresses and strains brought by load cycles and defining hysteresis branches are determined. Then, an accumulated damage due to the load cycles is predicted and stored. For the prediction, first, using a hysteresis operator, a change in the stress along a portion of a hysteresis branch is calculated as a function of a change in the load in time, and, second, using the change in the stress and the stored accumulated damage, a change in the damage is calculated. Hence, also a change in the properties, including the stiffness, of the structure is calculated. Then, a further change in the stresses and strains is calculated on the basis of the change in these properties to determine a new adapted hysteresis branch. Then, a further change in the stress along a further portion of the adapted hysteresis branch is calculated as a function of a further change in the load in time. At the end of the process, the structure is manufactured accordingly.

主权项

1. A process for virtually predicting the durability performance of a structure, wherein the structure is modeled by a series of calculation points, the process comprising:
for each calculation point, determining the stresses and strains brought by load cycles and defining hysteresis branches; predicting, by a processor, an accumulated damage due to the load cycles; storing, in a memory, the accumulated damage; using a hysteresis operator, calculating, by the processor, a change in the stress along a portion of a hysteresis branch as a function of a change in the load in time; using the change in the stress and the stored accumulated damage, calculating, by the processor, a change in the damage, and, hence, a change in the properties, including the stiffness, of the structure at the calculation point; calculating, by the processor, a further change in the stresses and strains on the basis of the change in the properties, providing a new adapted hysteresis branch; and calculating, by the processor, a further change in the stress along a further portion of the adapted hysteresis branch as a function of a further change in the load in time, wherein the structure is made of material that accumulates damage before the structure fails due to fatigue failure when submitted to the load cycles.