Long fiber thermoplastic composites under high-velocity impact: Study of fiber length

Abstract

This study experimentally investigates the high-velocity impact response of long glass fiber-reinforced polypropylenes with different fiber lengths. The study considers three long fiber thermoplastic composites, i.e. 5, 10, and 20 mm prepared via a combination of extrusion and pultrusion processes and a crosshead die. An internal mixer was used to obtain an isotropic compound. The dispersion quality of each compound was confirmed using burn off test. A gas gun with a spherical projectile was employed to conduct high-velocity impact tests at three velocities of 144, 205, and 240 m/s. Internal mixer operation resulted in extensive fiber length reduction for all three long fiber thermoplastic lengths. Results from mechanical tests (Tensile and Izod impact) revealed an increasing value with increase in long fiber thermoplastic length, i.e. fiber length. High-velocity impact results showed higher impact performance for 20 mm long fiber thermoplastic compound compared to 5 and 10 mm long fiber thermoplastic containing specimens. Rate of increase in energy absorption from neat polypropylene to 5 and 10 mm long fiber thermoplastic compounds is much higher than from 10 to 20 mm long fiber thermoplastics. High-velocity impact tests indicated that there may be a threshold value for fiber length beyond which the fiber length plays a lesser role. Scanning electron microscopic analysis showed more fiber breakage at the impact point at a higher impact velocity than the lower end of high-velocity impact.

Research Progress on Interlaminar Failure Behavior of Fiber Metal Laminates

“…Selecting a matrix material with excellent property, safety, and environmental protection is more conducive to achieving energy conservation and environmental protection. ermoplastic FMLs have higher toughness and good impact resistance and are recyclable [23,24,137]. From the current research, there are few studies on the tensile property and fatigue property of the surface-treated thermoplastic FMLs.…”

“…Under the influence of cyclic temperature changes in the test samples, the observed reduction in the strength of the layer subjected to thermal shocks is mainly caused by significantly different values of thermal expansion of the composite materials [46]. Due to the complicated loading conditions of impact and fatigue failure, the current research in this area mainly focuses on the dynamic response research under low-velocity impact [12,110,128,129], but there are few detailed simulation models for analysis, and there are few studies on the impact of high-velocity impact on material properties [24,85]. is requires scholars to thoroughly study the mechanical behavior of materials under two-dimensional and three-dimensional stress conditions and further improve the establishment of three-dimensional damage models of composite materials.…”

“…However, due to the poor interlaminar shear strength of the ARALL, it can only be applied to the flat structure or the single curved surface with small curvature of the aircraft [18]. In the 1990s, glass reinforced aluminum laminates (GLARE) started to be used in some big aircrafts because of the excellent properties [20][21][22][23][24][25]. For the first time, the bulkhead on the rear of the A340 passenger aircraft was made of GLARE laminates and three radial crack locking devices were also made of GLARE laminates [26].…”

Thermoplastic Pultrusion: A Review

“…Kahl et al [ 184 ] used different types of reinforcement (cellulose and glass fibers) and matrix material (polypropylene and polyamide) to evaluate the influence of raw materials on the mechanical performance of manufactured specimens. Shayan Asenjan et al [ 185 ] conducted the experimental study to understand a correlation between the length of fibers and high-velocity impact performance. Chen et al [ 154 ] investigated the influence of volume fraction of reinforcement on the density, heat distortion temperature, void occurrence, and mechanical characteristics of the glass fiber–polyamide-6 (PA-6) composites produced by RIM pultrusion.…”

High velocity impact response of corrugated core composite sandwich structures

“…This may be not adequate enough for academic studies of corrugated core composite sandwich structures under hard or soft impact loading and certainly insufficient for the investigation of the impact performance of structural parts in aircraft during flight. 7…”