Fibre Distribution Characterization of Ultra-High Performance Fibre-Reinforced Concrete (UHPFRC) Plates Using Magnetic Probes

Ultra-high performance fibre reinforced concrete (UHPFRC) is an innovative cement-based engineering material. The mechanical properties of UHPFRC not only depend on the properties of the concrete matrix and fibres, but also depend on the interaction between these two components. The fibre distribution is affected by many factors and previous researchers had developed different approaches to test the fibre distribution. This research adopted the non-destructive C-shape ferromagnetic probe inductive test and investigated the straight steel fibre distribution of the UHPFRC plate. A simplified characterization equation is introduced with an attenuation factor to consider the different plate thicknesses. The effective testing depth of this probe was tested to be 24 mm. By applying this method, fibre volume content and the fibre orientation angle can be calibrated for the entire plate. The fibre volume content generally fulfilled the design requirement. The fibre orientation angle followed a normal distribution, with a mean value of 45.60°. By testing small flexural specimens cut from the plates, it was found out that the mechanical performance (peak flexural strength) correlates with the product of fibre volume content and cosine fibre orientation angle.

Multi-response optimization for machining GFRP composites using GRA and DFA

Purpose The purpose of this paper is to optimise the process parameters, namely, fibre orientation angle, helix angle, spindle speed, and feed rate in milling of glass fibre-reinforced plastic (GFRP) composites using grey relational analysis (GRA) and desirability function analysis (DFA). Design/methodology/approach In this work, experiments were carried out as per the Taguchi experimental design and an L27 orthogonal array was used to study the influence of various combinations of process parameters on surface roughness and delamination factor. As a dynamic approach, the multiple response optimisation was carried out using GRA and DFA for simultaneous evaluation. These two methods are best suited for multiple criteria evaluation and are also not much complicated. Findings The process parameters were found optimum at a fibre orientation angle of 15°, helix angle of 25°, spindle speed of 6,000 rpm, and a feed rate of 0.04 mm/rev. Analysis of variance was employed to classify the significant parameters affecting the responses. The results indicate that the fibre orientation angle is the most significant parameter preceded by helix angle, feed rate, and spindle speed for GFRP composites. Originality/value An attempt to optimise surface roughness and delamination factor together by combined approach of GRA and DFA has not been previously done.

Optimization of process parameters on machining force and MRR during end milling of GFRP composites using GRA

Purpose This paper aims to investigate the effect and parametric optimization of process parameters during milling of glass fibre-reinforced plastics (GFRP) composites using grey relational analysis (GRA). Design/methodology/approach Experiments are conducted using helix angle, spindle speed, feed rate, depth of cut and fibre orientation angle as typical process parameters. GRA is adopted to obtain grey relational grade for the milling process with multiple characteristics, namely, machining force and material removal rate (MRR). Analysis of variance is performed to get the contribution of each parameter on the performance characteristics. Findings It is observed that helix angle and fibre orientation angle are the most significant process parameters that affect the milling of GFRP composites. The experimental results reveal that the helix angle of 45°, spindle speed of 3000 rpm, feed rate of 1000 mm/min, depth of cut of 2 mm and fibre orientation angle of 15° is the optimum combination of lower machining force and higher MRR. The experimental results for the optimal setting show that there is considerable improvement in the process. Originality/value Optimization of process parameters on machining force and MRR during endmilling of GFRP composites using GRA has not been attempted previously.

Multi-objective optimisation of CNC milling process using Grey-Taguchi method in machining of GFRP composites

Purpose – In milling process the surface roughness and delamination are the most important performance characteristics, which are influenced by many factors like fibre orientation angle, helix angle, feed rate and spindle speed. The selection of these parameters at optimum level plays a vital role in getting minimum surface roughness and delamination factor. The purpose of this paper is to present multi-objective optimisation of Computer Numerical Control milling parameters using Grey-Taguchi method to get minimum surface roughness and delamination factor in machining of glass fibre reinforced plastics (GFRP) composites used in automotive, aircraft and manufacture of space ships. Design/methodology/approach – The experiments are designed and conducted based on Taguchi's L27 orthogonal array by taking fibre orientation angle, helix angle, feed rate and spindle speed at three levels and responses are surface roughness and delamination factor. Taguchi's signal-to-noise (S/N) ratio are determined based on their performance characteristics. A Grey relation grade is obtained by using S/N ratio. Based on Grey relational grade value, optimum levels of parameters have been identified by using response table and response graph. Findings – Optimum levels of parameters for GFRP composites have been identified by using response table and response graph and the significant contributions of controlling parameters are estimated using analysis of variance. Originality/value – The combined effect of fibre orientation angle and helix angle during milling of GFRP composites using Grey relational analysis has not been previously attempted for analysis.