FATIGUE DAMAGE ESTIMATION USING FREQUENCY DOMAIN APPROACH

Walter Jesus Paucar Casas¹; Saul Camelo¹; Cesar Gonçalves dos Reis¹

¹ Universidade Federal do Rio Grande do Sul

doi:10.20906/CPS/COB-2015-2549

Resumo

Structures and mechanical components, such as wind turbines, car chassis, or offshore structures, are often submitted to random loading. This loading makes the stress vary with time, and resulting in the failure of the structure, when the stress level is high enough. The failure caused by alternating stress is called fatigue. The fatigue is the main mode of mechanical components failure and the durability of the component must be determined during the project. The damage estimation can be calculated in the time domain through the stress cycle counting, or in the frequency domain through the estimation of the distribution of probability of a certain stress level. The spectral approach presents a lower computing effort and best understanding of the dynamic behavior. This paper presents the frequency domain approach for the calculation of damage estimation of a cantilever plate with a hole, using numeric simulations through the combination of the available tools in the Abaqus® and nCode® softwares. The spectral analysis results are compared with simulations in the time domain by the Rainflow method, with the objective of evaluating the frequency with the time approaches. The results show that the methodology used in the frequency domain leads to solutions that are equivalent to the time domain approach, but with a lower computing cost.

Palavras-chave: Frequency domain; Damage estimation; Random fatigue