Effect of voids on the crack formation in a [45/−45/0]s laminate under cyclic axial tension. (December 2016)

• Record Type: Journal Article
• Authors: Maragoni, L.; Carraro, P.A.; Quaresimin, M.
• Is Part Of: Composites. Volume 91:Part 2(2016)
• Page Start: 493
• Page End: 500
• Publication Date: 2016-12
• Subjects: B: Defects -- B: Fatigue -- C: Damage mechanics -- Micro-cracks; Composite materials -- Periodicals; Manufacturing processes -- Periodicals; Composite materials; Manufacturing processes; Periodicals; 620.11805
• DOI: 10.1016/j.compositesa.2016.02.018
• Languages: English
• ISSNs: 1359-835X

Abstract

Abstract: In the present work, the influence of manufacturing induced voids on damage mechanisms at the microscopic scale was analysed on [45/−45/0]s laminates subjected to tension fatigue loading. Microscopic observations of the top surface of the 45° ply revealed that the first event of damage at the microscopic scale was the initiation of multiple micro-cracks in the matrix between the fibres, located preferentially in correspondence of the voids in that layer. The subsequent coalescence of these micro-cracks gave rise to the formation of a crack propagating in the 45° fibres direction. This is qualitatively the same scenario observed in void-free specimens in a recent work by the authors, thus confirming that the same crack initiation criterion can be applied in the absence and presence of voids. In addition, the micro-scale damage is shown to evolve faster and therefore off-axis cracks to initiate earlier and in a larger quantity in the presence of voids.