Sensitivity Analysis of GFRP Composite Drilling Parameters and Genetic Algorithm-Based Optimisation

In this article, a genetic algorithm (GA) is used for optimizing a metamodel of surface roughness (R_a ) in drilling glass-fibre reinforced plastic (GFRP) composites. A response surface methodology (RSM) based three levels (-1, 0, 1) design of experiments is used for developing the metamodel. Analysis of variance (ANOVA) is undertaken to determine the importance of each process parameter in the developed metamodel. Subsequently, after detailed metamodel adequacy checks, the insignificant terms are dropped to make the established metamodel more rigorous and make accurate predictions. A sensitivity analysis of the independent variables on the output response helps in determining the most influential parameters. It is observed that f is the most crucial parameter, followed by the t and D. The optimization results depict that the R_a increases as the f increases and a minor value of drill diameter is the most appropriate to attain minimum surface roughness. Finally, a robustness test of the predicted GA solution is carried out.

Investigation of Jute and Glass Fibre Reinforced Hybrid Composites Manufactured through Compression Molding Process

Expensive and non-biodegradable synthetic fibres are commonly utilized as reinforcement in composites for better mechanical properties. The eco-friendly and low-cost properties of natural fibres are promising alternative reinforcement for composites. In this study epoxy-based glass and jute fibres reinforced hybrid composites are fabricated varying fibre stacking sequences, 1jute-1glass alternatively (j-g-j-) and 4glass-9jute-4glass (4g-9j-4g). Hybridization of jute and glass fibre results better tensile, flexural and water absorption properties than only jute fibre reinforced composites but inferior to only glass fibre reinforced composites. The 4g-9j-4g stacking sequence resulted in better mechanical and water absorption properties than j-g-j-- stacking sequence. The effect of chemical treatment and glass microfiber infusion are also investigated. Chemically treated jute fibre and 2 wt.% microfiber infused hybrid composite shows about 42% improvements in flexural strength as compared to untreated and without microfiber infused composites. However, fibre chemical treatment and microfiber do not have a positive impact on tensile strength.

Effects of drilling parameters on delamination of kenaf-glass fibre reinforced unsaturated polyester composites

Drilling is a secondary material removal and usually carried out to facilitate fastening of parts together. Drilling of composite materials is not usually a problem-free process. Issues related to delamination composite laminates need to be addressed because it introduces the stress concentration point on the composite. This study focussed on the influence of process parameters such as spindle speed, feed rate, type of drill bits and geometry on the extend of delamination experienced by the composite during the drilling process of kenaf-glass fibre-reinforced unsaturated polyester composite, and the delamination measurements were taken under a microscope. Taguchi methods and analysis of variance were employed to find the optimal parameters. From the results, the most significant parameter was the feed rate. The minimum delamination was achieved when the feed rate was 0.05 mm/rev and spindle speed was 700r/min using both types of drill bits. The quality of the drill hole using the twist drill bit has been proven to be better than the brad drill bit.

Fatigue strength evaluation of PPGF35 by energy approach during mechanical tests

Thanks to the progress of research on thermoplastic materials, the properties of composite materials have improved considerably. The aim of this study is the evaluation of fatigue strength of glass-fibre-reinforced polypropylene composite (PPGF35) by applying both the Risitano Thermographic Method (RTM) and the new Static Thermographic Method (STM).

OPTIMIZATION OF PROCESS PARAMETERS FOR SURFACE ROUGHNESS OF GFRP WITH AWJ MACHINING USING TAGUCHI AND GRA METHODS

For machining of composites like glass fibre reinforced polymers, abrasive water jet machining is generally used. In the present paper, an experimental investigation is described which is focused on studying the influence of AWJM process parameters on surface roughness of machined samples. Four process parameters namely water pressure, traverse speed, stand-off distance and abrasive mass flow rate are considered in the present study. Taguchi technique is used for the design of experiments and analysis of variance (ANOVA) is performed to determine the significance of parameters. It is found that water pressure and traverse speed are the major significant parameters for influencing surface roughness. Surface roughness decreases with increase in water pressure and decrease in traverse speed. For surface roughness minimization Grey Relational Analysis (GRA) technique is used for multi optimization of process parameters and experimental results are analyzed using Grey Relational Grades (GRG).

Effect of μPlasma Modification on the Wettability and the Ageing Behaviour of Glass Fibre Reinforced Polyamide 6 (GFPA6)

Glass fibre reinforced polyamide 6 (GFPA6) thermoplastic composites (TPCs) are promising materials with excellent properties, but due to their low surface free energy they are usually difficult to wet, and therefore, possesses poor adhesion properties. μPlasma modification offers potential solutions to this problem through functionalisation of the GFPA6 surface. In this study, the effect of μPlasma on the wetting behaviour of GFPA6 surfaces was investigated. Following single μPlasma treatment scans of GFPA6 samples, a substantial enhancement in wettability was observed. However, the effect of the μPlasma modification was subject to an ageing (hydrophobic recovery) phenomenon, although the enhancement was still partially maintained after 4 weeks. The ageing process was slower when the GFPA6 material was pre-dried and stored in low humidity conditions, thereby demonstrating the importance of the storage environment to the rate of ageing. Orientation of the fibres to the observed contact angle was found to be crucial for obtaining reproducible measurements with lower deviation. The influence of testing liquid, droplet volume and surface texture on the repeatability of the measured contact angle were also investigated.