Anand Parey

Dynamic analysis of multi-mesh geared rotor system using modal analysis

Multi-mesh geared systems are common in many applications including rotorcraft and automotive transmissions. Coupling mechanism occurred due to gear meshing often influences dynamic characteristics of geared rotor system. This paper primarily studies the dynamic behavior of the multi-mesh rigid geared systems supported on roller bearing to include effect of gear mesh coupling in multi-mesh transmissions. This formulation combines constant mesh stiffness value in a multi-body dynamics model. Modal analysis technique is used to determine dynamic characteristics like natural frequency and forced harmonic responses of the system. The resulting modal solutions obtained for geared system are compared to study the effect of change in bearing compliance on system dynamics.

Evaluating the Performance of Signal Processing Techniques to Diagnose Fault in a Reciprocating Compressor Under Varying Speed Conditions

An inefficient detection of a fault in a reciprocating compressor (RC) by a signal processing technique could lead to high energy losses. To achieve a high-pressure ratio, RCs are used in such pressure-based applications. This paper evaluates the performance of nonstationary signal processing techniques employed for monitoring the health of an RC, based on its vibration signal. Acquired vibration signals have been decomposed using empirical mode decomposition (EMD) and variational mode decomposition (VMD) and compared respectively. Afterward, few condition indicators (CIs) have been evaluated from decomposed modes of vibration signals. Perspectives of this work are therefore detailed at the end of this paper.

Gearbox fault diagnosis using RMS based probability density function and entropy measures for fluctuating speed conditions

Fault diagnosis of gearbox which operates on low rotating speed with high fluctuations is highly important because its ignorance can led to a catastrophe. The uncertainty within the vibration signal of the gearbox can be identified by the entropy measures, on the basis of probability density function of a signal. But, under fluctuating speeds, entropies may show insignificant results, hence making them non-reliable. The aim of this article is to develop a reliable and stable technique for gear fault detection under such fluctuating speeds. Therefore, a root mean square–based probability density function is proposed to improve the efficiency of entropy measures. The fault detection capabilities of proposed technique were demonstrated experimentally. Various entropy measures, namely, Shannon entropy, Rényi entropy, approximate entropy, and sample entropy, were compared as well as evaluated for both Gaussian and proposed probability density function. The proposed technique was further validated using two condition indicators based on amplitude of probability density function. Results suggest the effective fault diagnosis using proposed method.

Use of Cyclostationarity Based Condition Indicators for Gear Fault Diagnosis Under Fluctuating Speed Condition

The vibration based gear health monitoring is one of the condition monitoring techniques, widely used in industry. Under fluctuating speed conditions, vibration based conventional gear fault diagnosis methods like FFT and condition indicators (CI) like rms and kurtosis, fails to differentiate a faulty gear from a healthy one. Under such conditions, cyclic changes are observed in mean and variance of a vibration signal. CI using such statistical parameters for non-stationary gear vibration signal may mislead the entire fault diagnosis approach. In this chapter, CI based on cyclostationarity has been explained and used for gear fault diagnosis for fluctuating speed conditions. This chapter shows an advantage of using cyclostationarity based CI over conventional CI, for example rms and kurtosis, to diagnose fault. Result shows the effectiveness of the cyclostationarity based CI in differentiating gear health.

Vibration reduction of juicer: A case study

Juicers are one of the most common kitchen appliances. A renowned company in this field experienced high vibration level in one of the model which was under development. High vibrations are unacceptable as they lead to early failure of the component. The product was about to launch and vibration levels needed to be below the acceptable limits without any changes in design of the model. This paper presents a case study on reduction of vibration level of juicer using two methods, firstly, by using tuned mass damper and secondly by modifying the shape of isolators. The vibration level came down below the acceptable limits by using modified isolator.