Effect of Needle Type, Number of Layers on FPAFC Composite against Low-Velocity Projectile Impact

Abstract

Protective structures subjected to intensive loads that may benefit from the use of multilayer composite structures with excellent hardness and impact resistance represent an emerging research field in recent times. In this study, low-velocity projectile impact tests were performed on Functionally-graded Preplaced Aggregate Fibrous Concrete (FPAFC) mixtures to evaluate their performance. The effects of projectile needle type, fibre type and hybridization in addition to the number of layers in the composites on projectile impact were investigated. The bioinspiration of the excellent impact strength of turtle shells was used to design an FPAFC comprising a higher amount of steel and polypropylene fibres at the outer layers. In parallel, one and two-layered concretes were also cast to assess the effectiveness of three-layered FPAFC. The tests were performed on disc specimens using non-deformable compound bevel, convex edge and hollow edge projectiles. The damage severity was quantified by the top damage area, bottom damage area and depth of penetration. In addition, a simple analytical model for predicting the composite mass expulsion was developed and implemented. Findings indicated that regardless of fiber type and distribution, the compound bevel projectile needle produced the lowest impact numbers for all single, double and triple-layer specimens compared to the convex edge and hollow edge projectiles. Repeated projectile impacts increased the penetration depth and damaged area at the top and bottom surfaces of all targets. Targets were more resistant to convex edge and hollow edge projectile penetration than the compound bevel. The experimental and analytical model results for mass expelled from the top surface are reasonably acceptable. This research gives an idea of developing advanced fibrous composite with superior impact resistance for the promising protective structures.

Influence of MgO on the Hydration and Shrinkage Behavior of Low Heat Portland Cement-Based Materials via Pore Structural and Fractal Analysis

“…Generally, several strategies are utilized to control temperature and prevent cracks in practical engineering, including the adoption of pre-cooling aggregate and ice water, a pipe cooling method by circulating cold water through internal pipes during the concrete hardening stage [11], and the usage of a certain dosage of fly ash [12][13][14][15], fibers [16][17][18][19][20][21][22][23], and a magnesia expansion agent (abbreviated as MgO thereafter) [24][25][26][27][28][29][30]. However, the pre-cooling method and pipe cooling method need some additional labor as well as more construction time and cost [11].…”

Investigations on the Response of Novel Layered Geopolymer Fibrous Concrete to Drop Weight Impact

“…Results indicated that a 28% increase in absorbed impact energy may be achieved by the double-layered beam, compared to the similar single-layered beam with the same fibre quantity. Nandhu prasad et al [30] investigated the projectile impact performance of threelayered functionally graded preplaced aggregate fibrous concrete. Steel and polypropylene fibres were used in three layers with different dosages and hybrid combinations.…”

High-Performance Construction Materials: Latest Advances and Prospects

“…Prasad et al [11] evaluated the performance of functionally graded preplaced aggregate fibrous concrete (FPAFC) via the low-velocity projectile impact tests. The bioinspiration of the excellent impact strength of turtle shells was used to design an FPAFC comprising a higher amount of steel and polypropylene fibers at the outer layers.…”