Experimental and numerical study of the crushing behavior of pultruded composite tube structure

Pultrusion is considered to be a cost efficient method for developing composite structures. It facilitates the fabrication of uniform cross-section products with improved fiber alignment, mechanical properties, good surface characteristics, etc. In order to ascertain the crashworthiness, the pultruded composites shall be able to resist impact loads, and in this concern, the energy absorption capacity of the pultruded composites must be explored. This article presents the experimental and numerical investigation of the crushing behavior of polyester based pultruded composite with rectangular cross section. Pultruded rectangular tubes with e-glass/polyester composites have been developed for this study. The cross-section of the tubes was developed into two triggering profiles, the uniform edge around the section and the tulip pattern. The tubes were subjected to impact loads, and the effect of these triggering profiles on the energy absorption capacity of the tubes has been investigated. The testing of all composites has been carried out at three different impact velocities (10, 20 and 45 mm/min). The results have revealed the dependence of crushing behavior of the tubes on the loading velocity and the triggered profiles. Lower peak load and high specific energy absorption (SEA) was observed in the tube with tulip pattern profile. The results obtained from the simulation have also shown consistency with the real-time experiments.

On-site evaluation of a modified pultrusion process: Fibre spreading and resin injection-based impregnation

The focus of the current research was to demonstrate a modified pultrusion technique at an industrial site using a commercial production machine. In this instance, the conventional resin bath was replaced by a custom-designed compact impregnation unit. The dimensions of the impregnator were 310 mm × 400 mm × 9 mm. The relatively short length of the impregnator, when compared to a 5 litre resin bath, meant that it had to be efficient in impregnating the reinforcing fibre bundles. This was achieved using a fibre spreading unit and a facility to inject the resin under low-pressure. The design basis for the fibre spreading unit and the impregnator are presented along with the methodology that was used to select the pultrusion speed and die temperature. The pultrusion experiments were performed using filled and unfilled vinyl ester resin and E-glass fibres. The profile of the 0.5 metre-long die was rectangular with dimensions of 32 mm × 2.2 mm. The fibre spreading unit and the impregnator were retrofitted to the pultrusion line with ease. The physical, mechanical and thermo-mechanical properties were determined for the pultruded composites using the resin bath and the modified technique. The properties of the latter were found to be equivalent or marginally superior when compared to the resin bath-based production method. However, in the modified pultrusion technique, when compared to conventional resin bath-based pultrusion, the volume of waste resin generated was 97% lower. The volume of solvent required to clean the equipment after production was reduced by 90%.

Pultruded glass fiber reinforced brominated-epoxy composites: Dynamic mechanical and flame retardant properties

With the improvements in quality of life and better awareness about the requirement for a secure environment, fire-resistant materials have gradually attracted the world’s attention and recognition. This paper investigates a proprietary process to manufacture glass fiber (GF) reinforced brominated-epoxy (BEP) flame retardant composites through pultrusion. BEP resin is manufactured with fillers as matrices, GF as reinforcements for pultrusion. The dynamic mechanical properties (DMA) and flame retardant properties of the GF reinforced BEP composites manufactured through pultrusion have been investigated. The DMA test showed higher dynamic storage modulus [Formula: see text] and lower curve of tan [Formula: see text] of pultruded composites when the filler content, postcure temperature and postcure time increased. At the same time, the glass transition temperature [Formula: see text] of the pultruded composites were shifted to a higher temperature when the filler content, postcure temperature and postcure time increased. From the flame retardant test for UL-94 and limited oxygen index (LOI), all of the pultruded GF reinforced BEP composites as well as the BEP resin showed excellent flame retardant properties.

Thermoplastic Reaction Injection Pultrusion for Continuous Glass Fiber-Reinforced Polyamide-6 Composites

In this paper, glass fiber-reinforced polyamide-6 (PA-6) composites with up to 70 wt% fiber contents were successfully manufactured using a pultrusion process, utilizing the anionic polymerization of caprolactam (a monomer of PA-6). A novel thermoplastic reaction injection pultrusion test line was developed with a specifically designed injection chamber to achieve complete impregnation of fiber bundles and high speed pultrusion. Process parameters like temperature of injection chamber, temperature of pultrusion die, and pultrusion speed were studied and optimized. The effects of die temperature on the crystallinity, melting point, and mechanical properties of the pultruded composites were also evaluated. The pultruded composites exhibited the highest flexural strength and flexural modulus, reaching 1061 MPa and 38,384 MPa, respectively. Then, effects of fiber contents on the density, heat distortion temperature, and mechanical properties of the composites were analyzed. The scanning electron microscope analysis showed the great interfacial adhesion between fibers and matrix at 180 °C, which greatly improved the mechanical properties of the composites. The thermoplastic reaction injection pultrusion in this paper provided an alternative for the preparation of thermoplastic composites with high fiber content.