Experimental and numerical multi-scale approach for Sheet-Molding-Compound composites fatigue prediction based on fiber-matrix interface cyclic damage

Abstract

In this paper, a multi-scale approach is proposed to predict the stiffness reduction of a Sheet-Molding-Compound (SMC) composite submitted to low cycle fatigue (until 2.10 5 cycles). Strain-controlled tensile fatigue tests (R = 0.1) are carried out at various strain ranges. Damage is investigated at both macroscopic and microscopic scales through the evolutions of Young's modulus and SEM observations, after interrupted fatigue tests at different lifetime periods. The results show that the fatigue degradation of the composite is mainly controlled by fiber-matrix interface debonding. A quantitative analysis allows determining the threshold and kinetics of the fiber-matrix interface damage during cyclic loading as a function of the orientation of fibers. Moreover, a fibermatrix interface damage criterion, taking into account the local cyclic normal and shear stresses at the interface, is introduced in the Mori and Tanaka approach in order to predict the loss of stiffness. The parameters of this local criterion are identified by reverse engineering on the basis of the experimental results described above. Finally, the predicted loss of stiffness is very consistent with the experimental results.

Micromechanical Modelling of Dynamic Behavior of Advanced Sheet Molding Compound (A-SMC) Composite

“…As a consequence, we can consider that the local stresses of the interface-interphase (σ and τ) undergone with a time increment Δt by the interface zone can modify the limiting stresses (σ 0 , τ 0 ) (Eqs. 11 and 12) due to two local phenomena: & The decohesion of the interface mainly sensitive to the strain rate [48][49][50][51] & The redistribution of local stresses due to diffuse damage on other interfacial sites…”

Sheet Molding Compound Automotive Component Reliability Using a Micromechanical Damage Approach

“…Fig. 7 Fiber-matrix interface decohesion as a main local damage mechanism in SMCs [29] where σ imp is the applied stress in fatigue, a i and σ S i are the parameter defining the loss of stiffness under tensile loading and B i represents the loss of stiffness kinetic under fatigue. The index, i, indicates the considered microstructure.…”

Fatigue behavior and modeling of chopped carbon fiber reinforced sheet molding compound composites

“…Based on the Mori and Tanaka [16] schema, a number of previous studies have developed different micromechanical models by introducing descriptors to characterize the damage status inside material. [17][18][19][20] The loss of stiffness under cyclic loading was widely adopted as the damage indicator and the corresponding fatigue life was obtained from the reference experimental data. The micromechanical models were able to predict the fatigue life of SMC materials, but the effect of microstructure heterogeneity and interaction between multiple fiber bundles were overlooked which could lead to inaccuracy in damage analysis.…”