Browsing by Author "Joladarashi, Sharnappa"

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Design and Real-Time Experimental Evaluation of A Semiactive Suspension System of A Four-Wheeler With Costeffective Magneto-Rheological Damper
(National Institute Of Technology Karnataka Surathkal, 2023) Jamadar, Mohibb E Hussain; Kumar, Hemantha; Joladarashi, Sharnappa
The purpose of a damper in a vehicle suspension system is to isolate the vehicle body from disturbances arising from road undulations, generally referred to as ride comfort, while maintaining contact with the road at all times, generally referred to as road handling. Achieving good ride comfort and good road handling are the two conflicting criteria to be satisfied by an ideal vehicle suspension system. The viscous passive dampers, currently used in vehicle suspension systems, compromise a part of ride comfort to achieve partly good road handling in an attempt to satisfy these two criteria. A semi-active suspension system with Magneto Rheological (MR) dampers is one of the cost-effective methods to overcome the need for this compromise. The semiactive suspension system provides better control over energy dissipation by introducing a damper capable of achieving variable damping force during its operation. Although semi-active MR dampers are the cheapest option among the types of suspension systems (Passive, Active and Semiactive suspension systems), they are not the most affordable ones available in the automobile market. Hence, they can be found factory fitted only in some premium luxury cars. The work presented in this thesis attempts to develop and experimentally evaluate a cost-effective MR damper for application in a passenger vehicle while collaborating with a shock absorber manufacturer, Rambal Ltd., Chennai, India. In the research work presented in this thesis a commercial MR damper is first characterized in the damper testing machine and fitted with two mathematical models, Equivalent Damping Model (EDM) and Magic Formula Model (MFM). The two mathematical models are compared for their accuracy and computational efficiency based on the simulation response of a Quarter Car Model (QCM) with a semiactive seat suspension system. The MFM was as accurate as the EDM while being computationally efficient. Meanwhile, an MR damper was designed for application in the test vehicle, a passenger van, using a commercial MR fluid. The designed MR damper was fabricated at Rambal Ltd., Chennai. The fabricated MR damper was tested on the damper testing machine and also on the test vehicle. The results from the experiments on the damper iv testing machine revealed that the fabricated damper delivered the desired MR effect. The experiments on the test vehicle revealed improved ride comfort and road handling with the developed MR damper. The cost evaluation of the developed MR damper revealed its cost-effectiveness compared to the commercially available MR dampers. An attempt was made to further reduce the cost of the developed MR damper by designing a cost-effective MR fluid. The designing of MR fluid generally involves optimizing the composition of magnetic particles in the carrier fluid. The same was carried out in this study based on the simulation response of the full car model of the test vehicle subjected to the random road and the cost of synthesizing the MR fluid. The performance of the developed MR fluid was compared with the commercial MR fluid, MRF-132DG, on the rheometer, the damper testing machine and the test vehicle. The developed MR fluid yielded higher shear stress than the commercial MR fluid on the rheometer. Consequently, a higher damping force was achieved by the fabricated MR damper using the optimized MR fluid than the commercial MR fluid. The experiments conducted on the test vehicle with the developed MR fluid revealed its superior performance over the commercial MR fluid, indicated by higher ride comfort and road handling of the test vehicle compared to the ones achieved in previous experiments on the test vehicle. The optimized MR fluid was found to be more affordable than commercial MRF-132DG. An acceleration-based control strategy is also proposed in this work to reduce the computational load and improve the overall reaction time of the semiactive suspension system. The performance and computational efficiency of the proposed control strategy were compared with an existing control strategy based on the experimental response and simulation time, respectively, of a Single Degree of Freedom (SDOF) system with an MR damper. The proposed control strategy was both effective and computationally efficient than the existing control strategy.
Dynamic Analysis of Composite Sandwich Beam Under The Passive, Semi-Active and Active Vibration Control Techniques
(National Institute Of Technology Karnataka Surathkal, 2023) Suryarao, Nagiredla; Joladarashi, Sharnappa; Kumar, Hemantha
The present study is aimed at understanding the behavior of sandwich beams and the influence of vibration control methods on the dynamic response. The passive, semiactive, and active vibration control techniques are implemented on the sandwich beams. The present study developed a finite element (FE) formulation for the composite sandwich beam and utilized the Euler-Bernoulli's method for sandwich beam element and Lagrange's approach is considered to obtain the equation of motion (EOM). The FE formulation solution is validated using different case studies available in the literature. The validation process ensures that the developed model is accurate and reliable for predicting the dynamic response of sandwich beams. The study provides insights into the effectiveness of different vibration control methods and the impact of various parameters and boundary conditions on the dynamic response of sandwich beams. Viscoelastic materials can dissipate the vibrational energy in the form of heat when the structure undergoes cycles of deformation. For the passive vibration control of sandwich beam, two different viscoelastic materials and four different axial gradation configurations of viscoelastic materials are considered. The influence of viscoelastic material and boundary conditions on natural frequency, loss factor, and frequency response are investigated as a part of the initial study. Further, the influence of axial gradation configurations of the viscoelastic materials on the dynamic response is reported. Then, a comparison study of all configurations at different boundary conditions is discussed. The field-dependent magneto-rheological (MR) fluid is used for the semi-active vibration control of the sandwich beam. MR fluid comes under the category of smart materials, and it can transform its rheological properties when it is exposed to an externally applied magnetic field. This nature of the MR fluid provides additional stiffness and damping for the sandwich beam applications. The effect of combined damping due to composite facings and MR fluid on the dynamic response of composite sandwich beams is discussed. The static, free, and forced vibration analyses of the composite sandwich beam are extracted to understand the influence of various iv parameters on the static and dynamic response of the sandwich beam applications. A detailed study is conducted to evaluate the effect of composite laminate angle, magnetic field, and thickness ratio on the static deflection, natural frequency, loss factor, and frequency response. The influence of the magnetic field on the percentage of deviation in natural frequency, loss factor, and static deflection is also discussed. Further, the influence of MR fluid pocket configuration type on the dynamic response of the sandwich beam is presented. The configuration types include 1/4th, 1/2th, 3/4th, and the full length of the MR fluid pockets at different locations. In addition, a detailed study of the influence of each MR fluid pocket configuration type on the natural frequency, loss factor, and frequency response are presented for the clamped-free (CF), clamped-clamped (CC), simply-supported (SS), clamped-simple (CS) and simple-free (SF) boundary conditions. In addition, two different compositions of in-house MR fluid samples with 24 and 30 percentage of volume fractions of carbonyl iron (CI) particles are prepared. The influence of oscillating driving frequency, strain amplitude, magnetic field, and the percentage of CI particles on the rheological properties of the MR fluid samples are discussed. The properties of MR fluid samples are used in the numerical formulations to explore the influence of the iron particles volume percentage on the dynamic response of the MR sandwich beam. Further, the active vibration control technique is implemented in combination with passive and semi-active control techniques. The Proportional, Integral, and Derivative (PID) controller is developed to compare the transient response of the sandwich beam with the controller and without the controller.
Elevated Temperature Sliding Wear Behavior Of Cocrnitimox And Cocrnitiwx High Entropy Alloys Processed Using Mechanical Alloying and High-Velocity Oxy-Fuel Spray
(National Institute Of Technology Karnataka, Surathkal., 2024) Addepalli, Syam Narayana; Joladarashi, Sharnappa; M.R., Ramesh
Maraging steels, widely used in the aircraft landing gear components were subjected to wear due to the harsh working conditions. Surface modification of these components by the deposition of advanced coating materials prolong their life. High entropy alloys (HEA) are a contemporary class of materials with multiple primary elements having applications in different fields, owing to their exceptional mechanical and physical properties. Therefore the curent research is aimed at enhancing the wear performance of maraging steels, by the deposition of HEA coatings. CoCrNiTiMox and CoCrNiTiWx (x: molar ratio; x= 0.5, 1, 1.5) HEAs were processed by mechanical alloying of pure metal powders for further application as feedstock in the High velocity oxy-fuel (HVOF) technique. The phase and microstructural transformation of the ball milled powders is investigated in detail by optimizing the milling time and speeds. The milling process is extended for 50 h and milled powder samples were collected at regular intervals of 10, 20, 30, 40 and 50 h to characterize the samples for their suitability to deposit using thermal spray techniques. The milled powders were characterized with respect to the phases, particle morphology, chemical homogeneity, particle size and crystallite sizes. Based on the characterization studies, the powders milled at a speed of 200 rpm for 10 h were selected as feedstock for HVOF deposition. After the deposition of coatings, the microstructural and mechanical characterization of coatings were performed. The phases and microstructure of the deposited HEA coatings were determined by X-ray diffraction (XRD) and scanning electron microscope (SEM). The microhardness of the coating was determined by using a vickers indenter on the coatings cross-section, with a load of 300 g and a dwell time of 15 s. The deposited coatings fracture toughness was determined by using the Evans and Wilshaw’s approach. The tribological behaviour of CoCrNiTiMox and CoCrNiTiWx HEA coatings at elevated temperatures was studied extensively using a Pin-on-Disc tribometer. The deposited coatings exhibited a lamellar structure and good mechanical bonding with the substrate. The porosities of CoCrNiTiMox and CoCrNiTiWx HEA coatings, as calculated using ImageJ software, were found to be in the range of 1-2%. i The mechanical performance of the CoCrNiTiMox and CoCrNiTiWx HEA coatings revealed superior values, when compared to other HEA coatings. The microhardness of CoCrNiTiMo0.5, CoCrNiTiMo, and CoCrNiTiMo1.5 HEA coatings were found to be 841±62 HV0.3, 927 ± 45 HV0.3 and 952±23 HV0.3, respectively. On the other hand, the microhardness of CoCrNiTiW0.5, CoCrNiTiW, and CoCrNiTiW1.5 HEA coatings were found to be 863±52 HV0.3, 951 ± 38 HV0.3 and 1025±39 HV0.3, respectively. The fracture toughness of CoCrNiTiMo0.5, CoCrNiTiMo, and CoCrNiTiMo1.5 HEA coatings were found to be 2.89 ± 0.31 (Mpa m1/2), 3.26 ± 0.25 (Mpa m1/2) and 3.79 ± 0.35 (Mpa m1/2) respectively. Likewise, the fracture toughness of CoCrNiTiW0.5, CoCrNiTiW, and CoCrNiTiW1.5 HEA coatings, were found to be 3.22 ± 0.26 (Mpa m1/2), 3.54 ± 0.32 (Mpa m1/2) and 3.87 ± 0.3 (Mpa m1/2) respectively. Further, it can be witnessed that the as-sprayed HEA coatings exhibited a steady increment in the mechanical properties with an increment in the molar fraction of Molybdenum and Tungsten. The specific wear rate of CoCrNiTiMo HEA coating dropped by 70.5%, declining from 17.34 ± 2.8 x10-6 mm3/N-m to 5.1 ± 1.6 x10-6 mm3/N-m, while CoCrNiTiW dropped by 76.3%, decreasing from 15.8 ± 3.7 x10-6 mm3/N-m to 3.73 ± 2.1 x10-6 mm3/N-m, with an increase in the temperature from RT to 600 °C. The wear rates of coatings exhibited a significant reduction at elevated temperatures, owing to the formation of TiO2, CoMoO4, NiO tribofilms for CoCrNiTiMo, and TiO2, CoWO4, WO3 oxides for CoCrNiTiW. Further, the CoCrNiTiMo1.5 HEA coatings offered better wear resistance, as compared to CoCrNiTiMo0.5 HEA coatings, at any temperature and loading condition, due to the increment in the molar fraction of Molybdenum. Additionally, the CoCrNiTiW1.5 HEA coatings exhibited superior wear performance, when compared to all the six compositions in the current research. The investigation of worn surfaces showed a transformation in wear mechanisms from adhesive and abrasive wear at room temperature to oxidative wear at elevated temperatures.
Investigation on Elevated Temperature Adhesive Wear Behavior of Microwave Fused Thermal Spray Tribaloy Composite Coatings
(National Institute of Technology Karnataka, Surathkal, 2019) C, Durga Prasad; Joladarashi, Sharnappa; Ramesh, M. R.
Metallic materials that operate under high speed, high temperature and harsh chemical environments are prone to wear and corrosion degradation. This leads to the failure of metallic components and results in huge economic loss to industries. The amorphous alloy or metallic glasses exhibit superior properties like high hardness, good wear, and corrosion resistance. Metallic glasses eliminate an ordered crystalline structure, hinders plastic deformation. The Co-based amorphous alloy is the best example of bulk metallic glassy structure alloy and presence of primary intermetallic laves phase’s exhibits good mechanical as well as chemical properties. This is mostly employed as coatings because they are too brittle to be used in bulk form. Co-based metallic glass coating depositing on metallic materials could positively eliminate the failure of the working component caused by serious wear and erosion issues. In the present study, CoMoCrSi superalloy powder (Tribaloy-T400) comprising of a primary intermetallic laves phase of Co-rich solid solution has shown better mechanical and tribological properties. Processing of CoMoCrSi feedstock powder is carried out through a high-energy ball milling (HEBM) technique to obtain a higher volume fraction of intermetallic laves phases. The hard phases of 30% Cr3C2, WC-CrC-Ni and WC-12Co are reinforced into milled CoMoCrSi feedstock. The four different feedstock powders CoMoCrSi, CoMoCrSi+30%Cr3C2, CoMoCrSi+30%WC-CrC-Ni and CoMoCrSi+30%WC- 12Co are sprayed on pure titanium grade-15 substrate using High-Velocity-Oxy-Fuel (HVOF) and flame spray methods. The as-sprayed coatings are subjected to post heat treatment to refine their metallurgical and mechanical properties using microwave hybrid heating technique. Characterization of feedstock, as-sprayed and microwave fused coatings is done by using Scanning Electron Microscopy (SEM), Energy dispersive spectroscopy (EDS) and X-ray Diffraction (XRD). Porosity, surface roughness, microhardness, and adhesion strength of as-sprayed and fused coatings are evaluated. The substrate, as-sprayed and microwave fused coatings are subjected to elevated temperature sliding wear test against alumina disc under dry conditions. The test is carried out at 200°C, 400°C, and 600°C temperatures for 10 N and 20 N normal loads. Microwave fused coatings exhibit higher wear resistance than the as-sprayed coatings and substrate. The hard intermetalliclaves phases which are amorphous (bulk metallic glass) in nature strengthen the coatings at high temperatures. Co3Mo2Si, Co7Mo6, Mo3Si, Co3Mo, and Co2Mo3 are the intermetallic laves phases generated in CoMoCrSi feedstock during HEBM process. The coatings produced from HVOF and flame spray process exhibits heterogeneous structure by showing cracks and pores, also cohesive strength between splats is low. The microhardness and adhesion strength of as-sprayed coatings is lower than fused coatings. Microwave fused coatings exhibit homogeneous structure with less porosity, and surface roughness. The posttreated coatings reveals the inter-diffusion of atoms near substrate-coating interface region, these results in formation of metallurgical bonding leads to increase in microhardness and adhesion strength. The as-sprayed coatings exhibits higher wear rate and coefficient of friction due to lower microhardness. The worn surface of as-sprayed coatings reveals detachment of splats with severe deformation results in adhesive wear mechanism. Microwave fused coatings exhibits lower wear rate and coefficient of friction due to higher microhardness obtained from intermetallic laves phases and also formation of homogeneous structure. The fused coatings exhibits tribo-oxide layers during sliding action which is the main phenomenon for improving the wear resistance of the fused composite coatings. CoMoCrSi+WC-12Co composite coating showed better mechanical and tribological properties compared to other types of coatings.
Performance Evaluation of Sandwich Composites with Functionally Graded Core for Ballistic Impact
(National Institute of Technology Karnataka, Surathkal., 2024) T.S., Mohan Kumar; Joladarashi, Sharnappa; S.M., Kulkarni
Sandwich composites with flexible skin and stiff core are appropriate for a wide range of engineering applications because of their capacity to withstand greater deformation while maintaining a high load-carrying capacity. The main objective of the current research includes material selection, fabricating, and analyzing functionally graded sandwich composite for ballistic impact applications. Statistical Six Sigma DMAIC methodology was used for material selection, incorporating qualitative and quantitative approaches, ensuring a comprehensive and accurate material selection process. Considering a careful literature review, the choice of jute and rubber for skin material paired with epoxy and sea sand for core material in the sandwich composite. Finite element (FE) studies, based on the rule of mixtures, estimated composite material properties, showing increased energy absorption and a decrease in residual velocity with higher filler composition (0% to 30%) at velocities of 10, 50, 100, and 350 m/s, and with core thickness from 10mm to 30mm at 350 m/s. Following the initial FE studies, experimental testing was conducted on composite coupons to evaluate their physical and mechanical properties. The gradation test was performed to check the functional gradience for the core material. These tests provided insights into sea sand's spatial distribution and gradation within the core samples, emphasizing the impact of sea sand composition on the stepwise layering gradation. The void % (3.44%) in the composite coupons increases as the filler composition increases. Specific tensile strength decreases (2.41 times) with an increase in the filler composition. Hardness (12.47%), Flexural strength (27.93%), and impact strength (2.35 times) increase as the filler composition increases compared to neat epoxy. High strain rate compression strength is improved with higher strain rates. The FE analysis for low and ballistic impact testing was conducted based on the properties obtained experimentally from the composite coupons. For low-velocity and impact testing, it is observed that a sandwich with 30% sea sand composition has superior damage resistance capabilities compared to its counterparts. Both experimental and FE analyses show that higher filler percentages lead to increased energy absorption. The sandwich composite with 30% sea sand exhibited the lowest depth of damage and minimized overall damage across all impact energies, demonstrating superior damage resistance compared to other compositions. For ballistic impact, the similar trend that increasing the volume percentage of sea sand and core thickness improved energy absorption, with a 30 vol% sand content and 30mm core thickness performing the highest energy absorption capability compared to its counterparts. The results indicate that while thinner cores (10 mm) are inadequate for arresting projectiles, thicker cores (20 mm and 30 mm) show progressively better performance, with the 30 mm core providing the most effective ballistic impact protection. Incorporating sea sand into epoxy reduced costs by 8.9% to 32.47%, making it an economical core material for ballistic impact applications. Experimental and FE simulations for the entry area at 200 m/s showed a damage area percentage error of about 12.61%. Fractography analysis indicated face sheet damage from compression and bending, fiber breakage, rubber tearing, and core failure from sand particle crushing and matrix cracking, with a river like pattern suggesting brittle failure.
Static and Dynamic Studies on Fg Porous Sandwich Structures With Viscoelastic Boundary Conditions In Thermal Environment
(National Institute Of Technology Karnataka Surathkal, 2023) Patil, Rakesh; Joladarashi, Sharnappa
The present study investigates the static bending, buckling, and vibration behavior of functionally graded (FG) sandwich beams and plates with a viscoelastic interlayer. Finite element (FE) and analytical methods are used for the formulations. The metal- ceramic gradation of FG stiff layers along the thickness is governed by the rule of mixture and power law index. The kinematics of the sandwich beam stiff layers are based on the Euler-Bernoulli beam theory. The viscoelastic interlayer is assumed to undergo only shear. Lagrange density functions for sandwich beams have been deduced, taking into account the effect of strain energies of the stiff and core layers along with the corresponding translational energies and work done by external forces. Static and dynamic equilibrium equations of sandwich beams are derived using Euler- Lagrange equations. FE solutions are developed to solve equilibrium equations. The developed FE sandwich beam model is validated with an analytical model. Navier’s solution method is used to solve simply supported sandwich beams. Further porosity models and viscoelastic boundary conditions (VBCs) are incorporated into the study; bending, buckling, and vibration studies are carried out. A complex stiffness model is adopted for VBCs. Various types of porosity patterns, such as H, O, V, and X, across the thickness directions are assumed. The effect of porosities and VBCs on transverse deflection, natural frequency (NF), and loss factor (LF) of the FG sandwich beam is investigated. The results convey that VBCs contribution to vibration damping is more predominant when the supports are less stiff (more viscous). In addition, the effect of temperature on buckling and free vibration of FG porous sandwich beams with VBCs is discussed. The study also addresses the geometric nonlinearity of sandwich beams due to thermal stresses. Accordingly, temperature-dependent material properties are considered for FG stiff layers and viscoelastic interlayers. The study investigates the sandwich beam’s critical buckling temperature (CBT), natural frequency, and loss factors in thermal environment. Further, the proposed sandwich beam model is used to study the vibration and damping behavior of the disc brake pad. In the first case, only the back plate with brake insulator is considered as a sandwich beam. iiiA comparison study is presented in terms of the free and forced vibration characteristics of different back plate-brake insulator sandwich beams such as Steel-Acrylic-Steel, FGM-Acrylic-Steel, FGM-Acrylic-Aluminium, and Steel-Acrylic-Aluminium. The study reveals that the natural frequency, loss factor, and with regard to dynamic loading, the imaginary part of transverse deflection, axial displacement, stress, and strain of FGM-Acrylic-Steel are higher. As a result, FGM-Acrylic-Steel is a suitable combination for back plate and brake insulator assembly that enhances the overall disc brake system’s damping capacity and helps to reduce brake squeal problems associated with the operation of the disc brake system. In the second case, a complete brake pad (including friction material) is considered as a sandwich plate. Free and forced vibration studies are carried out on the brake pad for simply supported case (SSSS) using an analytical sandwich plate model. A comparative examination is provided among the brake pads with conventional steel and Al-Al2O3 FG back plates. The influence of several parameters on fundamental frequency and loss factors is also discussed. In addition, transient and steady-state analysis is carried out for the brake pad subjected to uniformly distributive transverse load (UDL) using the Newmark method. The results and analysis reveal that the brake pad with an Al-Al2O3 FG back plate having 0 to 100% Al2O3 variation is as stiff as a pad with a steel back plate and withstands the transverse load (brake load) effectively. The replacement of the steel back plate with an Al-Al2O3 FG enhances energy dissipation in the brake pad and is more efficient in vibration reduction.