Implementation of fatigue model for unidirectional laminate based on finite element analysis: theory and practice

Abstract

The aim of this study is to deal with the simulation of intralaminar fatigue damage in unidirectional composite under multi-axial and variable amplitude loadings. The variable amplitude and multi-axial loading is accounted for by using the damage hysteresis operator based on Brokate method [6]. The proposed damage model for fatigue is based on stiffness degradation laws from Van Paepegem combined with the 'damage' cycle jump approach extended to deal with unidirectional carbon fibres. The parameter identification method is here presented and parameter sensitivities are discussed. The initial static damage of the material is accounted for by using the Ladevèze damage model and the permanent shear strain accumulation based on Van Paepegem's formulation. This approach is implemented into commercial software (Siemens PLM). The validation case is run on a bending test coupon (with arbitrary stacking sequence and load level) in order to minimise the risk of inter-laminar damages. This intra-laminar fatigue damage model combined efficient methods with a low number of tests to identify the parameters of the stiffness degradation law, this overall procedure for fatigue life prediction is demonstrated to be cost efficient at industrial level. This work concludes on the next challenges to be addressed (validation tests, multiple-loadings validation, failure criteria, inter-laminar damages…).

Fatigue life analysis of a composite materials structure using allowable strain criteria

“…The main analysis equation in the original work of the author of the method [13] was successfully used in calculating the durability of a woven prepreg with [0]n and [±45]n lay-up. For the case of an orthotropic layer of a unidirectional material, the main calculation equation was adopted in [20] 𝑌 𝑇 , 𝑌 𝐶transverse tensile and compressive strength of the material, respectively;…”

“…This directly follows from the fact that the growth of damage in the model is reflected in the progressive change in the mechanical characteristics at each point, and therefore the values of the stresses acting at the point cannot be constant due to the need to satisfy the equilibrium equations in the mechanical system [19]. If the system is rather complicated, as is the case of real multicomponent structures, then it is efficient to perform stress redistribution using the finite element method [20,21]. Thus, to clarify the stress-strain state at certain stages of cyclic loading, a recalculation of the reference static case is required.…”

A numerical investigation of the interaction between interlaminar and intralaminar damages in a fatigued composite panel

“…Similarly, intralaminar damages and mechanical property degradation due to fatigue have been extensively assessed in the literature. One of the most famous and widespread methods to simulate the residual strength, residual stiffness, and fatigue life of laminates under fatigue is the “generalized residual material property degradation model.” 22,23 The study of Carrella‐Payan 24 deals with the intralaminar damages simulation in unidirectional composites under fatigue loading conditions. The considered damage model is based on the Van Paepagem 25 stiffness degradation model.…”

Description of Fatigue Sensitivity Curves and Transition to Critical States of Polymer Composites by Cumulative Distribution Functions

“…Damage accumulation in the composites frequently leads to mechanical properties (Young's modulus, ultimate strength, etc.) reduction [14][15][16][17][18].…”