Numerical Simulation of Fatigue in Composites

Abstract

For the past several years, composite marine structures have been designed but without having a complete characterization the composite materials. The main reason is due to the large quantity of variables that affect the behavior of said materials. One of the tasks that has not been properly characterized is the behavior of composite structures under fatigue loads that appear in marine structures that are subjected to cyclic loads. Therefore, numerical tools that characterize fatigue performance are required in order to design more reliable structures. The formulation proposed in this work is based on the Serial/Parallel Rule of Mixtures [1] and a fatigue damage model [2]. The Serial/Parallel Rule of Mixtures can be understood as a constitutive law manager that provides the response of the composite from the constitutive performance of its constituents. Therefore, the constitutive laws chosen to represent the behavior of each constituent material have to fit with their real performance. Also, the fatigue damage model is based on the use of a reduction function which takes into account the cyclic degradation of the materials, both strength and stiffness degradation, in function of the number of cycles, maximum stress and stress amplitude. Current work presents a numerical tool developed to characterize fatigue in composites. The fatigue behavior of constituent materials is defined using mechanic parameters taken from literature. Afterwards, a reproduction of the tests will be done in order to validate the fatigue formulation proposed. [1] Car, E., Oller, S., Oñate, E. "Estudio del comportamiento no lineal en materiales compuestos", Techincal Report 264,CIMNE, 1997. [2] Oller, Salomon, O., Oñate, E. “A continuum mechanics model for mechanical fatigue analysis", Composite Materials Science, Vol 32, Issue 2, pp 175-195, 2005

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This presentation was held at the ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering (OMAE) in Madrid on June 19th, 2018. OMAE2018-77889