Modelling the Influence of Air Jet Configurations on Non-Woven Steel Fibre Mixing in the Melt Overflow Process

The mixing of non-woven steel fibres in melt overflow process for use in automotive muffler systems was simulated. The aim was to identify optimum parameters for achieving a good fibre mix. Numerical models of mixing chambers of melt overflow process were developed. Multiphysics analyses involving heat transfer, fluid flow and particle tracking were carried out using COMSOL code. The influence of air jet configurations on the fibre distribution was studied. The fibres settled on the moving bed within the mixing chamber were examined for their uniformity. The effect of additional air jets to the existing chamber in a range of regions was explored. An optimum configuration was identified by analyzing the compactness of the particle clusters deposited in the simulation and validated using pixel data acquired from real time imaging. The results showed that by employing dual air jets at the front end of the chamber, the density of the fibre material has improved. We conclude that through multi-physics modelling, it was possible to identify the optimum air-jet configurations leading to fibre uniformity and its distribution. This work also paves the way for incorporating a vision system to evaluate fibre density in real time.

Influence of Water Stability on Bond Performance Between Magnesium Phosphate Cement Mortar and Steel Fibre

The fibre pullout test was conducted to investigate the influence of the water stability on the bond behaviour between the Magnesium phosphate cement(MPC)matrix and the steel fibre.The composition of the MPC-matrix and the immersion age of the specimens are experimentally investigated.The average bond strength and the pullout energy are investigated by analysing the experimental results.In addition,the microscopic characteristics of the interface transition zone are investigated using scanning electron microscopy(SEM).The experimental results showed that the bond performance between the MPC-matrix and the steel fibre decreased significantly with the increase of the duration of immersion in water.The average bond strength between the steel fibre and the MPC-matrix reduced by more than 50%when the specimens were immersed in the water for 28 days.The effect of the water on the interface between the steel fibre and the MPC-matrix was found to be more significant compared to the composition of the MPC-matrix.In addition,the MgO-KH2PO4 mole ratio of the MPC significantly influenced the water stability of the interface zone between the steel fibre and MPC-matrix.

Rheology of Steel Fibre Containing Alumina-Magnesia-Extruded Graphite Pellets Self-Flowing Castables

The influences of adding steel fibres of different lengths up to 3 volume percentages, on the rheological behaviour of an alumina-magnesia-extruded graphite pellet containing castables have been studied using a rheometer. Free-flow measurements have shown that the flow is severely affected by increasing the length of steel fibres. The calculated values of rheological constants indicate that 19 mm and 25 mm fibre up to 2 volume percentage is permitted while one volume percentage of 50 mm fibres severely degrades the rheology of the castable.

Accelerated engineering properties of high and low volume fly ash concretes reinforced with glued steel fibers

The present study focuses on the improvement of pozzolanic reaction of fly ash particles with the cement hydration products.Low and high volume fly ash concrete mixtures were studied systematically with the addition of accelerating admixtures and accelerated curing of the concrete specimens in a steam chamber for 18 h at 75℃.Also,the reinforcing effects of glued steel fibers addition on the compressive and flexural performance of fly ash concrete were investigated.The test results indicated that the addition of accelerator improved the rate of hardening and the inclusion of steel fibers provided higher flexural performance.Also,it can be noted that the high volume fly ash(50%)addition in concrete showed a reduction in strength;however,the addition of accelerator has compensated the deceleration in strength gain.The proper selection of concrete ingredients,addition of accelerator and initial steam curing for 18 h showed better improvement on the engineering properties in fly ash concrete.A maximum increase(41.7%)in compressive strength of fly ash concrete around 52.90 MPa was noticed for 25%fly ash substitution and 1.5%steel fibers addition.Dynamic elastic modulus was also calculated in loaded concrete specimen using ultrasonic pulse velocity test and showed a good agreement with the experimental value.