Browsing by Author "Joladarashi, Sharnappa."

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Design, Synthesis and Evaluation of Twin-Tube Valve Mode Magneto-Rheological (MR) Damper for Semi-Active Automotive Suspension System
(National Institute of Technology Karnataka, Surathkal, 2021) Desai, Rangaraj Madhavrao.; Kumar, Hemantha.; Joladarashi, Sharnappa.
The change in rheological properties of smart materials like magneto-rheological (MR) fluid when brought under the influence of a magnetic field can be utilized to develop MR devices where the output has to be continuously and quickly varied using electronic control interface. A viscous damper which uses this MR fluid as the viscous medium is called as MR damper and the damping force generated by the MR damper can be varied by modulating the current given to the electromagnetic coil in the MR damper. Hence MR dampers have electronically controlled variable damping co-efficient and have a promising future for application in automotive semi-active suspensions. The main aim of the present work is to explore the design and application of twin-tube valve mode MR damper for use in automotive semi-active suspension. A viscous damper of twin tube design working in the passive mode is evaluated on a damper testing machine and its performance is characterized. Its behaviour at different velocities and frequencies of excitation is studied using sinusoidal excitations of fixed amplitude and varying frequencies. The force vs displacement plots show that the size of the loops increase with increase in frequency of excitation. Using the dissipated energy method, the equivalent damping coefficient of the damper is calculated for different frequencies of excitation. Mathematical models are developed for the force vs velocity behaviour of the damper as the damper force is a function of the damper piston velocity. These mathematical models based on the experimental results will be very much useful in designing an alternative or improved suspension system for the vehicle under consideration. A commercial MR damper, RD-8040-1 by Lord Corporation, USA, is experimentally evaluated for its application in a semi-active suspension. The experiments were carried out in damping force testing machine. Sinusoidal displacement input was given to the test damper. The set of experiments were repeated for different levels of current (0A to 1.5A in steps of 0.25A) supplied to the MR damper. Plots of force vs displacement for each frequency of excitation and plots of maximum force vs frequency of excitation show that higher values of current leads to elevated values of MR damper forces. This increase of MR damper force with current supplied is studied and analysed to develop a mathematical model of the MR damper under investigation. The non-linear softening hysteretic behaviour of the MR damper is simulated by using Genetic Algorithm (GA) provided in the optimization toolbox of MATLAB. Calculations on energy dissipation and iv equivalent damping coefficient of the MR damper show that the same damper can make the suspension system behave as an underdamped system, critically damped system or overdamped system depending on the value of current supplied to it. The performance of this MR damper in a spring-mass vibrating system is studied with the help of MATLAB simulations. A commercially available passive damper of a passenger van is tested to find the characteristic damping requirement of the vehicle. With this as reference, a twin tube MR damper working in valve mode is designed and fabricated. The magnetic flux density induced in the fluid flow gap is maximized using Taguchi analysis and Finite Element Method Magnetics (FEMM) software. The FEMM results are validated with results obtained analytically using electromagnetic circuit theory. The MR damper filled with commercially available MR fluid was experimentally tested in damper testing machine. The results demonstrate that the force developed by the MR damper is indeed increasing with the value of the current supplied. At various frequencies of input oscillation, the energy dissipated by the MR damper in a single cycle increases significantly with current supplied. The novelty of this work is that a twin tube MR damper working in valve mode was designed as a replacement for the passive damper used in a passenger van. The MR damper thus developed is capable of producing practical levels of damping force at actual operating frequencies and amplitudes of the passive damper in the passenger van. For further analysis, the behaviour of the MR damper is modelled by using the Bouc-Wen model for hysteretic systems. A Proportional-Integral-Derivative (PID) controller is used to track the desired damping force in time domain to demonstrate the application of the MR damper in a semi-active suspension system. MR fluid was synthesized to be used as a smart fluid in a twin tube MR damper operating in valve mode. The behaviour of the MR fluid is experimentally characterized in a rheometer and mathematically modelled using Herschel-Bulkley (HB) model. The parameters of the HB model are expressed as polynomial functions of strength of magnetic field in order to find the shear stress developed by MR fluid at any given strength of magnetic field applied. This fluid is filled in the MR damper which was designed for application in a passenger van and it is tested in damper testing machine. The performance of the damper at different damper velocities and current supplied is studied. The range of values for the parameters of the experimental testing are chosen to emulate the actual conditions of operation in its intended application. Non-dimensional analysis is performed, which links MR fluid rheological properties and geometrical parameters of MR damper v design with the force developed by damper. Finite Element Method Magnetics (FEMM) is used to find the strength of the magnetic field at the fluid flow gap. Analytical methods are used to calculate the damper force developed due to the field dependent yield stress and compared with experimental force values. The resulting dynamic range of the MR damper is also assessed. A mathematical model of the quarter car suspension is built for numerical simulation to compare the performance of semi-active suspension and passive suspension. Vibrations coming from the wheel due to road roughness and unevenness are given as input displacement to the suspension model. Sinusoidal excitation and random road excitation are used as input displacement. Based on experimental characterization, mathematical models are developed for the hysteresis behaviour of commercial and twin-tube MR damper using a polynomial model of hysteresis. These are used for implementing skyhook control in the semi-active suspension model. The current given to the MR damper is varied in order to achieve the best ride comfort which is demonstrated as a reduction in the sprung mass acceleration of the quarter car suspension. The dynamic behaviour of the MR damper based semi-active suspension is studied using MATLAB Simulink to show that its performance is better than passive suspension. The twin-tube MR damper working in valve mode is further developed for application in a semi-active SUV suspension system. In order to prove the superiority of semi-active suspension, a single degree of freedom quarter car test rig is built and ground excitation is given in the form of displacement input from a hydraulic actuator. Constant current control, Skyhook control and Rakheja-Sankar (RS) control are employed as three different control strategies and compared with passive suspension to study the advantages. Peak acceleration response of the sprung mass is studied for better passenger ride comfort and peak ground force is studied for preventing damage to road surface as well as to vehicle suspension elements. RS control method provides better ride comfort to passengers due to lower peak vertical acceleration when compared to constant current control or Skyhook control method. RS control method also generated much lower peak ground force values when compared to Skyhook control, especially in the high frequency region.
Investigation on Mechanical Properties of Filament Wound Composites for Pressure Vessel
(National Institute of Technology Karnataka, Surathkal, 2021) Biradar, Srikumar.; Joladarashi, Sharnappa.; Kulkarni, S M.
Metallic pressure vessels or cylinders used over many decades for processing food and beverages products, transportation of chemicals, storage of hazardous and nonhazardous chemicals for prolonged durations have been carrying limitations throughout their service period. Few limitations such as, the weight of the cylinders, corrosion and erosion effect, risk of sudden failure. The current study is connected to development of an alternative material for existing metallic cylinders to overcome few limitations. In the present study, filament wound GFRP (Glass fiber Reinforced Polymer) is proposed, which is having high strength to weight ratio compared to the existing metallic material. The FE (Finite Element) analysis of cylindrical pressure vessels used for LPG storage is carried out by alternative materials such as LCS (Low Carbon Steel), Aluminium 6061 T6, and GFRP. Based on maximum specific strength, the best alternative material obtained among others is GFRP, and this material is chosen for further studies. The GFRP pressure vessel cylinder is further studied by varying filament winding process parameters such as fiber volume fraction (0.55,0.65,0.75), winding angle (±45°, ±50°, ±55°, ±60°, ±65°, ±70°,±75°) and stacking sequence (SS1, SS2, SS3, SS4, SS5, SS6) using FE analysis tool. A total of 336 FE simulations were carried out, i.e., with PVC (Poly-Vinyl Chloride) liner (168) and without PVC liner (168). The optimization tool MCDM (Multi criteria Decision Making) VIKOR method is used for the selection of best alternative among existing 168 FE simulation compositions (with PVC liner). The liner act as leak-proof material in filament wound composite vessels and hence can be used for storage or processing of different viscous and non-viscous fluids. The optimization of the FE simulation result leads to best attribute, which is selected and fabricated as per its respective fabrication iii process parameters for experimental studies. Similarly, next to five attributes are selected as per available testing laboratory facilities (physical, mechanical and tribological, hygrothermal ageing). The filament wound GFRP cylinders are cut into test coupons for physical, mechanical, and tribological characterization studies. Further hygrothermal ageing of all 6 compositions are studied. In hygrothermal ageing effect is studied using three different fluids such as tap water, sea water, and tap water with oil. The hygrothermal ageing is carried out for a period of 45 days at a constant temperature of 80°C. The aged and unaged samples are subjected to mechanical tests such as hoop tensile strength, tensile, compression, and bending tests. The mechanical test results are compared for a possible reduction in strength of aged filament wound GFRP samples. The obtained results are further examined with fractography study using Scanning Electron Microscope (SEM). The different mechanical testing results (ultimate tensile strength, ultimate compressive strength, ultimate flexural strength, hoop tensile strength) highlights that the filament wound GFRP samples are moderately affected by ageing. In overall, in the case of FE simulations studies, the product with composition of fiber volume fraction, Vf = 0.55, winding angle = ±55° and stacking sequence of (±55°2/90°2/±55°2) is suggested as the best alternative or attribute-based on average Von Mises of 45.64 MPa and hoop stress of 44.82 MPa compared to other compositions. As far as the experimental study of filament wound GFRP test coupons is concerned, retention of important mechanical properties such as tensile, compression, flexural, and hoop tensile strength is the main factor. Hence it is observed from different hygrothermal ageing effect studies that filament wound GFRP material with 1200TEX is least or moderately iv affected by hygrothermal ageing. The product which has the least ageing effect and having the highest strength (hoop tensile, tensile, compression, and flexural strength) retention rate (nearly 90%) is product-P1(055WA55SS1) with compositions of fiber volume fraction, Vf = 0.55, winding angle of ±55º, stacking sequence of SS1 = (±φ°2/90°2/±φ°2). Hence this product P1 can be suggested as an alternative material to existing metallic material for elevated temperature applications (up to 80ºC).
Performance Evaluation of Flexible Jute-Natural Rubber Composites for Impact Behaviour
(National Institute of Technology Karnataka, Surathkal, 2020) M, Vishwas.; Joladarashi, Sharnappa.; Kulkarni, S M.
A composite material is made from two or more constituent materials with significantly different physical or chemical properties which are combined to produce a material with characteristics different from the individual components. ‗Flexible composites‘ is a term coined to identify the composites making use of elastomeric polymers as matrix. These flexible composites exhibit usable range of deformations which are much larger than conventional stiff composites. The ability of flexible composites to undergo larger deformation and still provide high load carrying ability makes them suitable for many engineering applications. Flexible composites are better energy absorbers compared to conventional stiff composites subjected to impact loading. The objectives and scope of the present study includes proposing, developing and characterizing the flexible ‗green‘ composite for impact applications. An extensive literature review was carried out to explore the potential constituent materials for impact applications and accordingly the present study is carried out to explore the possible use of jute and rubber for impact applications. Initially, the feasibility of using natural rubber (NR) as a constituent material in composite is studied using commercially available finite element (FE) package. Further different stacking sequences of the flexible green sandwich composite are optimized and the three stacking sequences are selected for experimental study. These three optimized stacking sequences of the proposed flexible green sandwich composite are prepared using compression moulding technique and are characterized for their physical and mechanical properties. Further, the proposed flexible green composites are studied for their abrasive behaviour under two body environments and erosive behaviour under slurry environment. Finally, the impact behaviour of the proposed flexible composites is studied under low velocity impact (LVI) and lower ballistic impact. The mechanical characterization of the proposed flexible composites revealed that the composite with jute/rubber/jute (JRJ) exhibits better tensile and tear strength compared to jute/rubber/rubber/jute (JRRJ) and jute/rubber/jute/rubber/jute (JRJRJ) with JRJ exhibiting 57.7% and 64.47% higher tensile strength compared to JRRJ and JRJRJ respectively. Also, the tear strength of JRJ is found to be 0.4% and 2.38%higher than JRRJ and JRJRJ respectively. The interlaminar shear strength (ILSS) studies shows that short beam strength of JRJRJ is better compared to JRRJ and JRJ with JRJRJ exhibiting nearly 2.1 times and 2.75 times better ILSS compared to JRRJ and JRJ respectively. The proposed flexible green composites are further studied for their abrasive behaviour under two body environments and erosive behaviour under slurry environment, the outcome of which reveals that JRJ provides better results compared to its counterpart JRRJ and JRJRJ. Various factors affecting the wear behaviour of the flexible composites are also studied from which it is clear that abrading distance and sand concentration affects the weight loss of the proposed flexible green composite in case of two body wear and slurry erosion respectively. Flexible ‗green‘ composites of different stacking sequences are further subjected to impact tests at low velocity and lower ballistic velocity at different impact energies. The results of low velocity impact reveals that flexible green composite with JRJ stacking sequence exhibit better energy absorption and the stacking sequences JRJRJ exhibit better resistance to damage with no appreciable variation in specific energy absorption of the composites. The lower ballistic impact study reveals that the flexible composites are better energy absorbers with JRJRJ exhibiting better lower ballistic response compared to JRJ and JRRJ. The ballistic limit of JRJRJ is enhanced by 39.7% and 6% compared to JRJ and JRRJ respectively. The energy absorption at ballistic limit of JRJRJ is more compared to JRJ and JRRJ by 97.7% and 12.7% respectively. The energy absorption of JRRJ is enhanced by 75.5% compared to JRJ. The specific energy absorption (SEA) of JRJRJ is enhanced by 52% and 2.7% compared to JRJ and JRRJ respectively. The proposed flexible green composite can be a potential material for sacrificial structures in order to protect the primary structural components.