Hemantha Kumar

National Institute of Technology Karnataka | NITK Surathkal · Department of Mechanical Engineering

The study presented in this article attempts to determine the optimal composition of iron particles in the MR fluid for vehicular application based on the size of the particles, the simulation response of a test vehicle model, and the cost of the fluid. The MRF samples with two different-sized particles in varying compositions are prepared and char...

The current study investigates the effect of viscosity of base oil and weight fraction of carbonyl iron particles on maximum yield stress and effective damping range of a short-stroke magnetorheological damper (stroke length of 2 mm) designed for tool vibration mitigation. It is difficult to find the exact composition of magnetorheological fluid (M...

div>Most of the control strategies presented to date are based on either the velocities or displacement of the vehicle body and the wheel which are derived by filtering and converting the data from the accelerometer. This increases the computational load and therefore directly affects the performance of the semiactive suspension system. This study...

The present study is aimed to evaluate the torque generation capacity of a two plate rotor magnetorheological (MR) brake using in-house prepared MR fluid. The prepared MR fluids were studied for sedimentation rate at different temperatures and flow characterization at different currents and at specific temperatures. The yield stress of the fluid is...

Magnetorheological (MR) fluid can transform its rheological properties when it is exposed to a magnetic field. This nature of the MR fluid provides an additional stiffness and damping for the sandwich beam applications. The Lagrange’s method is used to derive the equations of motion for the current finite element formulation. The influence of an ap...

Recent studies show that the Magento-Rheological (MR) dampers can serve as a suitable replacement for passive dampers on ground vehicles. MR dampers are factory fitted in premium luxury vehicles. However, the high price of these MR dampers has restricted their use to premium vehicles only. The study presented in this article attempts to develop a M...

In this research work, two different compositions of MR fluid samples with 24 and 30 percentage (%) volume fraction of carbonyl iron (CI) particles are prepared. Prepared MR fluid (MRF) samples contain carbonyl iron particles as a dispersive medium, silicone oil as a carrier fluid, and white lithium grease as an anti-settling agent. Influence of os...

The present study investigated the influence of magnetorheological (MR) fluid pocket configuration and magnetic field intensity on the dynamic response of the composite sandwich beam under various boundary conditions. The classical beam theory is used to develop the finite element (FE) formulations for the composite sandwich beam element and it is...

PurposeIn the present study, the influence of combined damping due to composite facings and magnetorheological (MR) fluid on the static and dynamic response of the graphite/epoxy composite sandwich beam is investigated because the combined damping effect plays a crucial role in suppressing the high amplitudes of vibration for the structural applica...

Magnetorheological (MR) fluid properties are essential in analyzing the performance of any MR fluid system. The fluid properties are dependent on shape, size, and magnetic saturation of the magnetic particles. Preliminary characteristics with SEM, particle size analysis (PSA), and vibration sample magnetometer (VSM) on carbonyl iron particles were...

The magnetorheological (MR) system's performance depends on the MR fluid's temperature in operation. This study aims to evaluate the temperature effect of MR fluid on performance while the damper is working. Before synthesizing MR fluid, scanning electron microscopy, X-ray diffraction, and particle size analysis verifies for the synthesis of MR flu...

dimentation stability and high yield stress of a magnetorheological fluid (MRFs) are essential parameters for better damping performance for any practical application. Preliminary investigations have been carried out on carbonyl iron particles to determine the morphology, particle size, crystal structure, and saturation magnetization for their feas...

The research on Automotive systems is always an ongoing process with varied advancements in different sectors. One such sector is suspension system and the recent trends in vehicular suspension has taken a turn towards semiactive suspension considering its salient features like cost effectiveness and low power consumption with variable damping forc...

Magnetorheological (MR) dampers have received the ever-increasing attention of many researchers considering their wide range of applications ranging from large seismic control of structures to prosthetics in the medical field. One such application is in semi-active vehicle suspension with MR damper. Modeling the dynamic behavior of MR damper is an...

PurposeSemi-active devices are showing a greater prominence in several engineering applications in recent times. This work makes an attempt to evaluate the performance of semi-active damper when used with a class of smart material called magneto-rheological (MR) fluid.Method Initially an MR damper is developed and characterized using an in-house pr...

Ball bearing failure are most common failure in rotating machinery, which can be catastrophic. Hence obtaining early failure warning along with precise fault detection technique is at most important. Early detection and timely intervention are the key in condition monitoring for long term endurance of machine components. The early research has used...

Fault diagnosis methods based on signal analysis techniques are widely used to diagnose faults in gear and bearing. This paper introduces a fault diagnosis model that includes a multi-scale deep residual learning with a stacked long short-term memory (MDRL-SLSTM) to address sequence data in a gearbox health prediction task in an internal combustion...

Vibration-based fault diagnosis is one of the widely used techniques for condition monitoring of the machines equipped with a gearbox. Severe operating conditions of gearbox result in gear tooth failure. To develop an effective fault diagnosis technique for the mechanical system, a machine learning approach is highly necessary and plays a vital rol...

Magnetorheological dampers have been the interest of many researchers for a few decades for the reason of being an effective and rapidly progressing technology in the field of semi-active controlled suspension. The dynamic behaviour of these devices with nonlinear hysteresis is quite a complicated phenomenon. Hence, this paper aims at the design, m...

The present work reports the influence of different types of surface area, hydrophobic, and hydrophilic fumed silica mixed in silicone oil as a thixotropic additive on carbonyl particles based magnetorheological fluids (MRFs) were prepared. Scanning electron microscopy analysis confirms the fumed silica particles attached to the surfaces of CIPs. T...

Background Magneto-rheological (MR) dampers have a promising future for application in automotive semi-active suspensions. The damping force produced by MR dampers can be modulated by controlling the electric current supplied to it.PurposeThe present work explores a twin-tube MR damper working in valve mode for application in a semi-active SUV susp...

Mathematical modelling of Magneto-Rheological (MR) damper has been an intriguing field of research ever since the invention of the device itself. An accurate model of MR damper results in development of an efficient controller for a semi-active system with MR damper. Hence, a number of models have been put forward to accurately predict the MR dampe...

Magnetorheological fluid (MRF) sandwich beams belong to a class of adaptive beams that consists of MRF sandwiched between two or more face layers and have a great prospective for use in semi-active control of beam vibrations due to their superior vibration suppression capabilities. The composition of MRF has a strong influence on the MRF properties...

Advancement in vehicle technology has explored many possibilities for improvement, keeping customer satisfaction in mind. One major criterion which a passenger always wishes to possess is ride comfort. But the suspension parameters suitable for a good ride comfort may not support another salient feature called road holding. Hence, in this work an a...

Semi-active technology offers good advantages in terms of controllability and adaptability. Magneto-rheological (MR) fluid is a class of smart fluids which display significant changes in its rheological properties under the influence of a magnetic field. Previous studies carried out using MR brake for the transfemoral prosthetic device were of mult...

This paper presents an investigation on the ride comfort and road-holding performance of a vehicle equipped with the semi-active suspension system. The full car semi-active suspension model with 7 degrees of freedom (7 DOF) system is adopted for the study and a fuzzy-logic control strategy is considered for minimising the effect of road disturbance...

This paper presents an investigation on the ride comfort and road-holding performance of a vehicle equipped with the semi-active suspension system. The full car semi-active suspension model with 7 degrees of freedom (7 DOF) system is adopted for the study and a fuzzy-logic control strategy is considered for minimising the effect of road disturbance...

The design of Magnetorheological (MR) brake and the composition of MR fluid (MRF) used in it have a significant effect on its performance and hence an effort has been made in this study to determine the optimal dimensions of MR brake and composition of MRF suitable for the brake application. Initially, optimum parameters of MR brake were computed c...

Magnetorheological damper is vibration reducing system in which the magnetorheological fluid is the operating liquid which changes its behaviour with external stimulus by increasing the yield stress of fluid with the application of external magnetic field. Most of the vibration reducing equipment’s is operated with single coil, and in this paper, s...

Ball bearings are used in the different critical fields of engineering applications such as IC engine, centrifugal pump and fans. In IC engine, the ball bearing is one of the critical components and it takes various types of dynamic loads and stresses. Condition monitoring of such ball bearing is very significant to avoid the catastrophic failure o...

Semi-active systems using magnetorheological fluids have been realized in many novel devices such as linear dampers, rotary dampers, brakes, and so on. Rotary vane-type magnetorheological damper is one such device that uses magnetorheological fluid as a hydraulic medium and a controllable magnetorheological valve to generate variable resistance. Th...

The main purpose of shock absorber assembled in a vehicle is for ride comfort of passengers and better control of moving vehicle by driver. The shock absorber is assembled in between vehicle body known as sprung mass and a combine mass of wheel and suspension known as unsprung mass. In the present work, the effect of inclination angle of shock abso...

This paper is about monitoring of ball bearing used in the IC engine gearbox using condition monitoring techniques. Experiments are conducted on two stroke IC engine which is driven by the 3HP DC motor. Vibration signals are acquired from the gearbox with triaxial accelerometer. Ball bearing with good and induced faulty (outer race fault, inner rac...

The surface modification of soft carbonyl particle (CIPs) based magnetorheological (MR) fluids is the most popular method to solve sedimentation problem. In this present work,the two MR fluidswere prepared using pure CIPs (MRF#1) and Tragacanth gum coated CIPs (Tg/ CIPs) (MRF#2) are dispersed in hydraulic oil as a carrier fluid. The morphology, ele...

In dynamic systems mechanical vibration amplitudes may range from a few nanometres to meters. When the vibration amplitudes are high the system may lead to failure or lost it function. Structures often tend to failure because of the high vibration amplitudes. These vibrations can be reduced by changing the stiffness or damping of the structure. One...

Dampers are energy dissipating devices used along with energy absorbing devices like coil springs to form the major parts of an automobile suspension system. They provide the passengers of the vehicle the desired comfort and the vehicle the necessary stability and road holding. In the present work, a viscous damper of twin tube design working in th...

The performance of the magnetorheological (MR) damper is determined based on the damping force of the damper which is used to reduce the unwanted vibrations in the automobile suspension system. In this study, an axisymmetric magnetorheological damper model is analyzed using ANSYS finite element (FE) analysis to simulate a distribution of magnetic f...

In the present work, an inverted rotary drum magneto rheological (MR) brake with waveform arc boundary suitable for prosthetic knee application is optimally designed. Often, the magnetostatic analysis is performed assuming linear magnetic systems and solving a lumped parametric equivalent magnetic model (EMM). Although, this reduces the computation...

Purpose The purpose of this paper is to study the fault diagnosis of internal combustion (IC) engine gearbox using vibration signals with signal processing and machine learning (ML) techniques. Design/methodology/approach Vibration signals from the gearbox are acquired for healthy and induced faulty conditions of the gear. In this study, 50% tooth...

Mathematical modeling of magneto-rheological damper has been an intriguing field of research ever since the invention of the device itself. An accurate magneto-rheological damper model results in development of an efficient current controller in a semi-active seat suspension system featuring magneto-rheological damper. Hence, a number of models hav...

Improving the gait of transfemoral amputees and making it biomimetic and stable has always been a major effort. A dynamic model of the prosthetic device can predict the kinetic and kinematic performances, when incorporated with a musculoskeletal model. In this regard, a dynamic model of a recent trend of variable damping technology will help a grea...

MR fluids face a major problem of sedimentation rate due to the high- density difference between the magnetic particles and the carrier medium that affects the performance of the magnetorheological devices. In this work, two MRF samples are prepared, where MRF-1 and MRF-2 are pure and coated carbonyl iron particles (CIPs) based MR fluids. The surfa...

The change in rheological properties of smart materials like magnetorheological fluid when brought under the influence of a magnetic field can be utilized to develop magnetorheological devices where the output has to be continuously and quickly varied using electronic control interface. In the present study, magnetorheological fluid is synthesized...

In the present study, the magnetorheological fluid (MRF) samples are prepared using pure carbonyl iron particles (CIPs), CIPs/Claytone APA/Molyvan 855 additive, and friction reducer dispersed in poly-alpha-olefin oil. The scanning electron microscopy reveals that the Claytone additive morphology looks like a surface abundant in small folds, which c...

Magnetorheological (MR) brakes produce braking torque due to variation in the magnetorheological properties of the MR fluid when external magnetic field is applied. In this study, MR fluids having 70% and 80% weight fractions of iron powder were prepared and MR brake characteristics were tested for prepared MR fluids and a commercial Lord MRF 132 D...

This paper describes the optimal selection of chopped strand mat glass-fiber-reinforced unsaturated polyester resin (CGRP) polymer matrix composite (PMC) by considering the strength and stiffness of various composite samples. The two-, four-, six-, eight- and ten-layered CGRP-PMC samples were prepared by using a hand-layup method. Then, the natural...

The semi-active vibration control of sandwich beams made of chopped strand mat glass fiber reinforced polyester resin polymer matrix composite (PMC) and magnetorheological fluid (MRF) core were experimentally investigated in this study. Two-, four- and six-layered glass fiber reinforced polyester resin polymer matrix composites were prepared using...

Ride comfort of a vehicle is the measure of complacency that a passenger can experience during the travel. The present work focuses on optimizing the quarter car suspension parameters to provide better ride comfort and road holding. Initially a commercially available damper of a light motor vehicle has been characterized to understand its force- di...

Tool fault diagnosis is essential in modern machining process to commemorate automation and precise manufacturing with limited human intervention. Automation increases productivity and efficient job handling ability. Online tool condition monitoring enables the fault diagnosis of cutting tool. A sensor is employed to acquire the information of the...

Tool Chatter is a catastrophic phenomenon, which has a direct impact on tool life, productivity and accuracy of the machined component in any machining process. Tool chatter can be in a transverse or longitudinal direction. In this study, a mono tube magnetorheological (MR) damper is developed to suppress the tool vibration in the transverse direct...

Semi-active technology offers good advantages in terms of controllability and adaptability. Magneto-rheological (MR) fluid is a class of smart fluids that display significant changes in its rheological properties under the influence of a magnetic field. Previous studies carried out using MR brake for the transfemoral prosthetic device were of multi...

Dynamic characterization of silicon carbide particles reinforced Al6082 alloy metal matrix composite sandwich beam with magnetorheological fluid core is experimentally investigated. The study is focused on determining the effect of magnetorheological fluid core on the dynamic behavior of the sandwich structure. The magnetorheological fluid core is...

Magnetorheological (MR) fluids belong to a class of controllable fluids, and the composition and concentration of its components govern its magnetorheological properties. In this study, an optimum particle loading (or mass fraction) and size of iron particles in MR fluid for use in a shear mode monotube MR damper were determined based on the dampin...

As the rheology of a magneto-rheological (MR) fluid can be controlled by an externally applied magnetic field, the damping force generated by a MR damper can be controlled by varying the current supplied to an electromagnet inside the damper. This paper presents the experimental evaluation of such a MR damper RD-8040-1 by Lord Corporation, USA, and...

Magnetorheological (MR) brakes are a type of electromagnetic brakes that make use of controllable viscoelastic properties of magnetorheological fluid for braking. The torque capacity of the MR brake depends on the magnitude of magnetic flux density generated in the MR fluid. In this study, the effect of combination of magnetic and non-magnetic mate...

In various machining operations, the tool condition monitoring (TCM) is highly necessary to avoid uncertain downtime in production. TCM provides continuously the condition of cutting tool by noticing various parameters such as temperature, acoustic emission and vibration. One of the best ways to monitor the condition of cutting tools for unmanned m...

In the present study, a twin-rod magneto rheological (MR) damper working in flow mode is designed. The piston core, annular fluid gap, outer sleeve, and the outer cylinder forms the magnetic flow path. A nonlinear constrained optimization problem is formulated to obtain the geometric dimensions of the piston assembly. The flow mode equations of the...

The smart behavior of magneto-rheological (MR) fluid is used in the present work in designing, experimentally characterizing and analyzing a MR damper for automotive application using the twin-tube damper concept. A commercially available passive damper of a passenger van was tested to find the characteristic damping requirement of the vehicle. Wit...

Composites play a vital role in engineering applications. The main aim of this study was to analyse how addition of SiC will improve the damping properties of metal matrix composites (MMCs). The strengthening of composites depends on physical, mechanical and dynamic factors. In the present study, Al6082 and Al7075 aluminum alloy reinforced with (0,...

Effects of varying volume fractions of SiC nanoparticle (SiCNP) reinforcement on microstructure and mechanical properties of dissimilar AA2024-T351 and AA7075-T651 joints by friction stir welding (FSW) have been investigated experimentally. A rectangular section edge groove was prepared at the adjoining surfaces of the two plates with the butt conf...

Ball bearing faults are foremost cause to the breakdown of rotating machine components. In general, ball bearing in the IC engine is one of the vital machine elements and plays a major role in the rotating machine as it takes different kinds of stresses and dynamic loads under various working conditions. Monitoring of such ball bearing continuously...

Polymer Matrix Composites (PMC) plays a conspicuous role in engineering application. Cenosphere reinforced polymer matrix composite has higher strength, stiffness, lesser density and also saving in cost. These particulate composites are manufactured to meet several structural requirements. Thus there is a need to study their static and dynamic prop...

Purpose Bearings and gears are major components in any rotatory machines and thus gained interest for condition monitoring. Failure of such critical components may cause increase in down time and maintenance cost. Condition monitoring using machine learning approach is conceivable solution for the problem raised during operation of the machinery s...

This paper presents the use of multilayer perceptron (MLP) for fault diagnosis through a histogram feature extracted from vibration signals of healthy and faulty conditions of single point cutting tools. The features were extracted from the vibration signals, which were acquired while machining with healthy and different worn-out tool conditions. P...

This paper presents the dynamic analysis of a half-car model with a magnetorheological (MR) damper subjected to random excitation. Experimental studies have been conducted to predict the behavior of the prototype twin-tube MR damper. The mathematical model of the prototype MR damper has been proposed by using the Bouc-Wen model. The half-car model...

Friction stir welding (FSW) dissimilar joints of aluminium alloys of 2024-T351 and 7075-T651 were produced by reinforcing silicon carbide nano particle (SiCNP) in the rectangular cut groove made on the adjoining surface of the two dissimilar alloy plates joined in the butt configuration. A FSW tool of taper threaded cylindrical shape is used for pr...

In this work, an approach for formulation of a non-parametric-based polynomial representative model of magnetorheological damper through coupled computational fluid dynamics and finite element analysis is presented. Using this, the performance of a quarter car suspension subjected to random road excitation is estimated. Initially, prepared MR fluid...

The surface is the primary element for two bodies coming in contact to transfer motion and load. Gear tooth surfaces must be tolerant to wear, scratch, scoring in order to have a better service life. Thus it is very important for contacting mechanical bodies to have better rigidity, hardness, and smoothness to combat all the damage and failure mech...

The most promising technology in the field of semi-active suspension systems is the use of magnetorheological property of MR fluid, whose material behavior can be controlled through external magnetic field. Devices developed based on this principle are adaptive and controllable as desired for a specific application. It is important to understand th...

Magnetorheological fluids are smart materials, which are responsive to the external stimulus and changes their rheological properties. The damper performance (damping force) is dependent on the magnetic flux density induced at the annular gap. Magnetic flux density developed at fluid flow gap of MR damper due to external applied current is also dep...

Magnetorheological fluids are smart materials, which are responsive to the external stimulus and changes their rheological properties. The damper performance (damping force) is dependent on the magnetic flux density induced at the annular gap. Magnetic flux density developed at fluid flow gap of MR damper due to external applied current is also dep...

This paper presents the fault diagnosis of face milling tool based on machine learning approach. While machining, spindle vibration signals in feed direction under healthy and faulty conditions of the milling tool are acquired. A set of discrete wavelet features is extracted from the vibration signals using discrete wavelet transform (DWT) techniqu...

The controllable rheological properties of MR fluid exhibit viscoelastic properties within pre-yield, which are essential for the characterization of MR dampers for the isolation of vibration. In the present work, using particle swarm optimisation (PSO), it is identified that the proportion of MR fluid constituents, fluid gap and current are the pa...

This paper presents engine gearbox fault diagnosis based on empirical mode decomposition (EMD) and Naïve Bayes algorithm. In this study, vibration signals from a gear box are acquired with healthy and different simulated faulty conditions of gear and bearing. The vibration signals are decomposed into a finite number of intrinsic mode functions usin...