Voids, the most studied type of manufacturing defects, form very often in processing of fiber-reinforced composites. Due to their considerable influence on physical and thermomechanical properties ...

https://journals.sagepub.com/doi/pdf/10.1177/0021998318772152

Voids in fiber-reinforced polymer composites: A review on their formation, characteristics, and effects on mechanical performance:

3D printed continuous CF/PA6 composites: Effect of microscopic voids on mechanical performance

https://research-information.bris.ac.uk/files/160357689/02_Manuscript_COST_2017_3638_final_submission_compressed.pdf

Experimental investigation of the effect of defects in Automated Fibre Placement produced composite laminates

Fatigue behaviour of glass/epoxy laminates in the presence of voids

In this study, four plied jute, carbon, E-glass fabric-reinforced and their hybridized composites are manufactured. Nine composite laminates with different stacking sequences are manufactured by vacuum infusion technique. In order to understand the structure of the composites, fiber weight and fiber volume ratios in the laminate system are initially figured out. Furthermore, void fractions of samples are calculated by using theoretical and experimental densities of the composite samples to examine the impact of amount of fiber content on the void fraction. The effect of hybridizing jute fabric-reinforced polyester composite with E-glass fabric and carbon fabric and also the effect of stacking sequence of fabric layers on the mechanical properties (tensile strength, impact strength) of composite laminates are investigated. According to the outcomes of this investigation, it is realized that incorporating high impact resistant fibers to the outer layers of the composites leads to higher impact resistance, a...

The effect of hybridization on significant characteristics of jute/glass and jute/carbon-reinforced composites:

The manufacture of composite structures is inevitably linked to the formation of voids. Several non-destructive techniques are potentially able of detecting defects, but just the exact knowledge of the effects of defects on the mechanical properties allows the definition of thresholds for the purpose of quality management. In this paper an experimental program for characterizing the effect of voids on the composite materials behaviour is presented. Therefore glass fibre non-crimp fabric reinforced epoxy composites were produced using vacuum assistant resin transfer moulding. For obtaining various void contents specially modified process parameters were used. Nominally defect free specimens are compared with flawed specimens. Tensile testing at different loading speeds and fatigue tests in tension-compression loading are performed.

Voids and their effect on the strain rate dependent material properties and fatigue behaviour of non-crimp fabric composites materials

Defects in laminated composite structures like voids and impact damages have a major influence on the fatigue behaviour. These defects may occur in the manufacturing process and during lifetime of composite parts and lead to matrix cracks within single layers and to delaminations between adjacent layers with different fibre orientations. We investigated the relationship between voids and impact damage and fatigue lifetime. Specimens made of a glass fibre non-crimp fabric were produced by vacuum assisted resin infusion. Voids were introduced by air-bypass simulating a leakage during the vacuum assisted resin infusion-process. Impact damage was induced using a canon. Stringer-panels with the basic dimensions of 1000 mm × 1200 mm and a radius of 1980 mm were tested under multiaxial load situations in a hexapod test rig and a tension/compression-shear test rig.

N. Kosmann

Papers

Voids and their effect on the strain rate dependent material properties and fatigue behaviour of non-crimp fabric composites materials

Influence of voids and impact damage on the fatigue behaviour of large scale composites