The major objective of this work is to develop an efficient Finite Element Analysis (FEA) procedure to simulate wave propagation in air-filled pipes accurately. The development of such a simulation technique is essential in the study of wave propagation in pipe networks such as oil and gas pipelines and urban water distribution networks. While numerical analysis using FEA seems superficially straight forward, this paper demonstrates that the element type and refinement used for acoustic FEA have a significant effect on the accuracy of the result achieved and the efficiency of the computation. In particular, it is shown that the well-known, better overall performance achieved with 3D solid hexahedral elements in comparison with 2D-type elements in most stress and thermal applications does not occur with acoustic analysis. In this paper, FEA models were developed taking into account the influence of element type and sizes using 2D-like and 3D element formulations, as well as linear and quadratic nodal interpolations. Different mesh sizes, ranging from large to very small acoustic wavelengths, were considered. The simulation scheme was verified using the Time of Flight approach to derive the predicted acoustic wave velocity which was compared with the true acoustic wave velocity, based on the input bulk modulus and density of air. For finite element sizes of the same order as acoustic wavelengths which correspond to acoustic frequencies between 1 kHz and 1 MHz, the errors associated with the predictions based on the 3D solid hexahedral acoustic elements were mostly greater than 15%. However, for the same element sizes, the errors associated with the predictions based on the 2D-like axisymmetric solid acoustic elements were mostly less than 2%. This indicates that the 2D-like axisymmetric solid acoustic elements are much more efficient than the 3D hexahedral acoustic elements in predicting acoustic wave propagation in air-filled pipes, as they give higher accuracies and are less computationally intensive. In most stress and thermal FEA, the 3D solid hexahedral elements are much more efficient than 2D-type elements. However, for acoustic FEA, the results show that 2D-like axisymmetric elements are much more efficient than 3D solid hexahedral elements.

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Summary Pipeline blockage can result in the reduction of system carrying capacity, energy and resource wastage, and potential increase in the probability of occurrence of environmental and health problems. The primary purpose of this paper is to demonstrate a methodology to simulate acoustic wave propagation (AWP) in partially blocked fluid‐filled pipes with flow under different flow velocities. This was achieved by using computational fluid dynamics (CFD) software in conjunction with an external user‐defined function (UDF) file, which introduces compressibility effect into the CFD solution. The use of finite element analysis (FEA) to simulate AWP in fluid‐filled pipelines with blockage has been previously reported without flow. In this paper, both CFD and FEA techniques were used to simulate the AWP in air‐filled pipelines without mean flow. However, it is shown that only the CFD technique could be used to simulate the AWP in air‐filled pipelines with mean flow. The secondary purpose of the paper is to use the simulated acoustic waveforms to illustrate a blockage identification procedure for detection, localisation, and sizing of blockages in fluid‐filled pipes using time of flight (ToF) methodology. It is shown that the ToF accurately detects and locates blockages in blocked pipelines. The errors in the localisation of blockages were less than 4%. Furthermore, the effects of blockage size and the mean flow velocity on the AWP characteristics are established. It is shown that both the size of the blockage in a pipe and the mean flow velocity affect the pressure amplitude of the transmitted and reflected waveforms.

A sugar cane bagasse powder (SCBP) reinforced epoxy resin composite was developed at low cost using the hand lay-up method. The viscoelastic parameters and activation energies of the composites were evaluated using dynamic mechanical analyzer (DMA) in a temperature range from 30°C to 120°C at 10Hz oscillating frequency. It was observed that 30wt% and 40wt% SCBP/Epoxy composites are the stiffest composite materials because of their higher values of storage modulus of 950MPa and 997MPa in comparison to about 800MPa of the neat epoxy matrix. Our findings also revealed that loss modulus decreases with increase in temperature and incorporation of SCPB fiber content caused broadening of the curves which depicts an increase in thermal stability of composite materials in comparison with neat epoxy matrix. There was a gradual decrease in damping coefficients as the SCBP content increases which could be attributed to the reinforcing effect of the fiber. The decrease in activation energies of 293.013, 286.836 and 201.103KJ/mol for 20wt%, 40wt%, and 50wt%SCBP/Epoxy resin composites proved that the activation energy values are in agreement with the storage modulus which suggests an improved stiffness of the composites.

The dynamic mechanical analysis was performed on five different formulations of a reinforced epoxy resin matrix with sugarcane bagasse (SCB) using hand lay-up technique. The viscoelastic behaviours of the composites were studied by analyzing the thermal parameters such as storage modulus (MPa), loss modulus (MPa), and as the temperature increases at periodic stress frequencies of 2.5, 5, and 10 Hz using Dynamic Mechanical Analyzer (DMA). The results revealed that and (MPa) decreased with increasing temperature for all composites, while the increased with increasing temperatures. As the frequency of oscillation is increased, the viscoelastic parameters was seen to increase as well. However, the (damping coefficient) was found to decrease with increase in SCB fibre loading due to the good load-bearing capacity of the composites. The peak temperature of the composites was found to be higher than the onset temperature of (MPa) and peak temperature of (MPa) which depict higher accuracy. Futhermore, it was seen that the increase in SCB fibre content in the epoxy resin increased the glass transition temperature (T g).