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Rotating machinery, such as turbo-jet engines, operate at a high rotational speed and passes through critical zones. The dynamic response of high-speed machines is critical for long-term stability and functioning. In this work, a fast and effective method for detecting coupling misalignment utilising time-frequency analysis (TFA) based on both the adaptive noise added complete ensemble empirical mode decomposition and wavelet-based denoising is presented. This novel and innovative method detect the coupling misalignment feature via the amplitude modulation aspect in the envelope analysis of the fault-containing intrinsic mode function. The Hilbert spectrum analysis provides spontaneous frequency and spectral energy in the time-frequency domain. The experiments were performed for various rotor accelerations and combined parallel and angular coupling misalignments using a laboratory test rig. The suggested approach gives excellent denoising efficiency and can improve misalignment identification accuracy. Additionally, it may be highly helpful for machinery that starts and stops often.

In this paper, the effect of increasing shear rate was studied on the viscosity of shear thickening fluid (STF). It was observed that the viscosity as well as the severity of shear thickening increased with the shear rate. The recovery rate ratio for STF at 25 °C was measured as 88.54% after 30 s, in three interval thixotropy test. Mathematical modeling was also done with the existing viscosity function of STF at 25 °C. It was observed that the viscosity obtained from mathematical model was in good match with the experimental data. For the validation of numerical simulation results, a 3D model of cone and plate was generated in ANSYS FLUENT. A user defined function (UDF) with all the chemical and physical properties of STF was used in 3D model at 25 °C. It was found that STF with UDF depicted similar results as obtained from experimental results, showing shear thinning at low shear rates and shear thickening beyond the critical shear rate. Critical viscosity obtained from experimental, mathematical model and numerical simulation was 0.653 Pa.s at critical shear rate of 10 s−1. Post shear thickening viscosity of 30.017 Pa.s was achieved for experimental and mathematical model and 30 Pa.s for numerical simulation.

The present work deals with the dynamic analysis of exponential law-based functionally graded (FG) rotor-bearing systems. The effect of thermal gradation and porosity on dynamic characteristics of FG rotor shafts has been studied first time, using exponential law with a novel two-nodded FG rotor element based on Timoshenko beam theory (TBT). Porous material properties are assorted using exponential law and thermal gradation across the cross section of the FG shaft using exponential temperature distribution (ETD). The effects of temperature and porosity on natural frequencies and whirl frequencies are studied. It has been observed that there is a significant reduction in natural frequencies and whirl frequencies with an increase in volume fraction of porosity and temperature. Attempts have been made to obtain suitable reasons for the behaviours based on the material properties. Furthermore, the steady-state and transient vibration responses have been simulated using the Houbolt time marching technique for the ceramic-based FG rotor shaft system. The result shows the maximum amplitude of the steady-state and transient vibration responses is increased, and the critical speed of the FG rotor system shifts towards the left with the increase in volume fraction of porosity and temperature.

In this paper, a numerical model of the shear thickening fluid (STF) is generated and the rheological properties are compared with the experimental data. Power Law model has been used to fit the rheological data for STF. Experimental data is taken from a performed study and a user defined function (UDF) has been written to develop the shear thickening behavior. The purpose of this study is to exactly model the behavior of shear thickening fluids by using UDF, to explain the shear-thickening mechanisms under different shear rates. Different parameters like viscosity, shear stress and velocity of the STF have also been reported.

In this paper, numerical investigation is carried out on two-dimensional Ahmed body model using Computational Fluid Dynamics in ANSYS Fluent 19.1. The 2-D model is designed in Catia v5 for 25°, 35° and 45° slant angles. The turbulent model used to analyze the flow dynamics is Realizable k-ε model. The drag coefficient variation with respect to slant angle is computed. The skin friction coefficient, wall shear stress and frictional velocity are also calculated.

Vibration analysis is widely used for the monitoring of the health of rotating machinery. There are different methods to interpret the vibration signals like time-domain analysis and frequency domain analysis, where the conventional Fast Fourier Transform (FFT) method is applied. FFT has been used successfully to extract stationary parameters from the frequency domain data. Complex machines normally consist of many parts and their vibration response contains many non-stationary signals and nonlinear signals. The objective of this research is to explore the feasibility of utilizing the wavelet transform (WT) and empirical mode decomposition (EMD) to efficiently decompose the sophisticated vibration signals of a rotor-bearing system into a finite number of intrinsic mode functions so that the fault characteristics of the rotor-bearing system can be analysed. A test rig of a rotor-bearing system was used to perform the experiments, and the vibration signals were recorded through NI-DAQ system. Vibration signals received from the test rig were analyzed using MATLAB software to present the useful information. The analysis result showed that the proposed approach is capable of diagnosing the faults of the rotor-bearing system.

The Shear Thickening Fluid (STF) is a non- Newtonian fluid which comes under dilatant material, STF undergoes phase transition from a low to high viscosity when shear stress is applied on it. In this paper modelling and simulation tools are used to study the STF fluid interaction when subjected to applied shear stress. The Eulerian description used for the fluid flow and the model considered the Lagrangian description of the rigid particles. The numerical analysis inspects important guideline such as acceleration of the flow, particle dispersion and the base of Non-Newtonian fluid. The fluid particles interrelation of STF showed that the shape, arrangement, volume concentration, and size of the particles had a vital effect on the behavior of STF. By adding sand particles in non-Newtonian fluids and applying high shear strain rates showed improvement in the shear thickening effects.

For the first time, the influence of moisture ingress and egress on the dynamic performance of commercial grades of Ultra-High-Molecular-Weight-Polyethylene (UHMWPE) composites is investigated. Two different grades of UHMWPE prepregs comprising Thermoplastic Elastomer (TPE) and Polyurethane (TPU) matrix were compression moulded and cylindrical specimens were cut-out for the high strain rate testing on a Split Hopkinson Pressure Bar (SHPB) apparatus. For identical incident energies, different strain rates were attained by the dry, wet and forced dried specimens of both the matrices. The experimental results indicate that the stress, strain and toughness significantly increase the pseudo properties with increasing rates of loading, irrespective of the type of conditioning process adopted. Moisture ingress reduced the strength of TPE and TPU matrix based composite by half and quarter of the strength of its dry composite. Moisture egress resulted in higher property enhancement of TPU based composite as compared to TPE based composite. The study thus substantiates the importance of moisture-proofing the composites meant for ballistic applications even from minor damage.