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19 results on '"Kini M, Vijaya"'

1. Experimental study on the tension-tension fatigue behaviour of glass/epoxy quasi-isotropic composites

Author

N.H. Padmaraj, Kini M. Vijaya, and Pai Dayananda

Subjects
Fatigue damage, Quasi-isotropic, Stiffness, Stress ratio, Frequency, Engineering (General). Civil engineering (General), TA1-2040
Abstract

This study investigates the tension-tension fatigue behaviour of glass/epoxy quasi-isotropic laminates. Constant amplitude tension-tension fatigue tests were performed at different stress level at a stress ratio, R = 0.1 and at a frequency of 3 Hz. The damage growth in the material was characterized by evaluating the degradation in stiffness. A phenomenological cumulative stiffness degradation based damage model was used to predict the damage development in the material. It was observed that, in the initial fatigue loading cycle, the material exhibited rapid reduction in stiffness and maintained a constant rate of degradation until failure.

Published
2020
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2. Influence of seawater absorption on vibrational and tensile characteristics of quasi-isotropic glass/epoxy composites

Author

Acharya Pavan, Pai Dayananda, Kini M. Vijaya, Sriharsha Hegde, and Padmaraj Narampady Hosagade

Subjects
Mining engineering. Metallurgy, TN1-997
Abstract

Glass fibre reinforced composites are common structural materials in civil engineering and marine applications. Exposure to moisture is the key challenge for using fibre-reinforced composites in marine structures. This study focuses on preparation of quasi-isotropic E-glass/epoxy laminates with stacking sequence [0°/90°/+45°/−45°]s fabricated using vacuum bagging technique. Ageing studies in artificial seawater was conducted in sub-zero and ambient temperatures for a duration of 3600 h. Moisture absorption behaviour, variation of damping, stiffness properties, and microstructural failure analysis studies were carried out as per ASTM standards. Results indicate that the rate of moisture absorption depends on ageing temperature. In the current study, it is observed that composites aged in ambient temperature absorbed higher amount of moisture than sub-zero temperature aged specimen. Moisture absorption reduced stiffness and natural frequency of quasi-isotropic laminates. Keywords: Damping, Quasi-isotropic, Stiffness, Seawater, Ageing, Moisture absorption

Published
2019
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6. Influence of seawater absorption on vibrational and tensile characteristics of quasi-isotropic glass/epoxy composites

Author

Pai Dayananda, Acharya Pavan, Padmaraj Narampady Hosagade, Sriharsha Hegde, and Kini M. Vijaya

Subjects
lcsh:TN1-997, 010302 applied physics, Materials science, Structural material, Moisture, Glass fiber, Metals and Alloys, Artificial seawater, 02 engineering and technology, Epoxy, Composite laminates, 021001 nanoscience & nanotechnology, 01 natural sciences, Surfaces, Coatings and Films, Biomaterials, visual_art, 0103 physical sciences, Ultimate tensile strength, Ceramics and Composites, visual_art.visual_art_medium, Composite material, 0210 nano-technology, Absorption (electromagnetic radiation), lcsh:Mining engineering. Metallurgy
Abstract

Glass fibre reinforced composites are common structural materials in civil engineering and marine applications. Exposure to moisture is the key challenge for using fibre-reinforced composites in marine structures. This study focuses on preparation of quasi-isotropic E-glass/epoxy laminates with stacking sequence [0°/90°/+45°/−45°]s fabricated using vacuum bagging technique. Ageing studies in artificial seawater was conducted in sub-zero and ambient temperatures for a duration of 3600 h. Moisture absorption behaviour, variation of damping, stiffness properties, and microstructural failure analysis studies were carried out as per ASTM standards. Results indicate that the rate of moisture absorption depends on ageing temperature. In the current study, it is observed that composites aged in ambient temperature absorbed higher amount of moisture than sub-zero temperature aged specimen. Moisture absorption reduced stiffness and natural frequency of quasi-isotropic laminates. Keywords: Damping, Quasi-isotropic, Stiffness, Seawater, Ageing, Moisture absorption

Published
2019

9. Slurry erosion behaviour of carbon/epoxy quasi-isotropic laminates based on Taguchi’s optimization method

Author

Pai Dayananda, Kini M. Vijaya, U. Amritha, N.H. Padmaraj, and Shreepannaga

Subjects
Angle of rotation, Materials science, Scanning electron microscope, General Engineering, Rotational speed, Epoxy, Composite laminates, Taguchi methods, visual_art, Slurry, Erosion, visual_art.visual_art_medium, General Materials Science, Composite material
Abstract

Erosion of composite structure due to interaction with slurry and water debris is one of the major challenges faced by the marine industries. The present work focuses on studying the influence of specimen angle of rotation, slurry concentration and rotational speed on erosion behaviour of carbon/epoxy quasi-isotropic laminates. Specimens were fabricated using prepreg and autoclave curing process. Experiments were conducted in a slurry pot erosion test rig using sea sand par�ticles as erodent material. Taguchi L27 array is used to analyse the effect of selected factors on the erosion. Morphology of the eroded surfaces was examined using a scanning electron microscope to study the erosion behaviour. It is observed that rotational speed and angle of rotation have a significant influence on the erosion behaviour and maximum erosion observed at a rotational angle of 15◦ and the nature of erosion process can be categorized into semi ductile erosion behaviour. Experiments conducted at a testing condition of 1500 RPM, 70% slurry concentration and 15◦ of rotational angle showed maximum mass loss.

Published
2021

10. Fatigue behaviour and damage characterization of quasi-isotropic carbon/epoxy laminates.

Author

Padmaraj, N. H., Pai, K. Dayananda, Shreepannaga, Shreepannaga, and Kini, M. Vijaya

Subjects
FATIGUE cracks, LAMINATED materials, EPOXY resins, SCANNING electron microscopes, STRESS-strain curves
Abstract

The present research work focuses on understanding the tension-tension fatigue durability of autoclave cured carbon/epoxy quasi-isotropic laminates. Based on the experimental results, S-N curve and stiffness degradation behaviour were developed. Damage growth mechanisms were studied based on the energy dissipated in each loading cycle at different stress levels. C-Scan and Scanning Electron Microscope were used to characterize the micro-crack growth and nature of fatigue failure. A bilinear trend was observed in the stress–strain curve with the failure of 90° oriented fibres in the initial phase followed by 0° oriented fibres. The energy dissipated and damage growth of the laminates at different stress levels followed a characteristic damage state curve. The C-Scan images showed the initiation of cracks on the specimen edges and propagating towards the center in the transverse direction. [ABSTRACT FROM AUTHOR]

Published
2022
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11. Experimental investigation on fatigue behaviour of glass/epoxy quasi-isotropic laminate composites under different ageing conditions

Author

Pai Dayananda, N.H. Padmaraj, and Kini M. Vijaya

Subjects
Materials science, Mechanical Engineering, Glass epoxy, Artificial seawater, Fatigue damage, 02 engineering and technology, Epoxy, Composite laminates, 021001 nanoscience & nanotechnology, Industrial and Manufacturing Engineering, 020303 mechanical engineering & transports, Stiffness degradation, 0203 mechanical engineering, Mechanics of Materials, Ageing, Modeling and Simulation, visual_art, Ultimate tensile strength, visual_art.visual_art_medium, General Materials Science, Composite material, 0210 nano-technology
Abstract

The present work investigates the effect of ageing on fatigue performance of glass/epoxy quasi-isotropic laminates. Specimens were aged in artificial seawater at ambient, sub-zero and humid conditions for a period of 180 days. Static tensile and dynamic tension-tension fatigue tests were performed on pristine and aged specimens and based on the experimental results S-N curve, rate of stiffness degradation and damage accumulation were established. The results revealed that fatigue damage growth depends upon the ageing conditions and percentage of moisture content. Multiple cracks, interfiber debonding and matrix decomposition from the fibre surface are responsible for the deterioration of fatigue properties.

Published
2021

13. Experimental investigation on solid particle erosion behaviour of glass/epoxy Quasi-isotropic laminates

Author

Kini M. Vijaya, N. H. Padmaraj, and Pai Dayananda

Subjects
Materials science, Polymers and Plastics, Impact angle, Metals and Alloys, Glass epoxy, Epoxy, Composite laminates, Erosion rate, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Biomaterials, chemistry.chemical_compound, chemistry, visual_art, Solid particle erosion, visual_art.visual_art_medium, Erosion, Aluminium oxide, Composite material
Abstract

He erosion behaviour of glass/epoxy quasi-isotropic laminates were investigated using Aluminium Oxide as erodent. Mass loss of the target material was used to estimate the erosion rate. An erosion rate prediction model was developed using Response

Published
2019

18. Physio-chemico-thermo-mechanical properties of selected biodegradable polymers

Author

Priyodip, P., Balaji, S., and Kini, M. Vijaya

Abstract

Polymers from renewable resources recently attracted research community mainly because of environmental concerns, low cost, availability and their biodegradability after usage. However, the intrinsic deficiencies of natural biopolymers, including poor mechanical properties, poor water resistance and difficult processability limit their use. The analysis presented here, is on renewable, bio-based resins for their mechanical, morphological, thermal and hydrolytic properties. The resins were prepared from starch, cellulose, lignin, chitosan, gelatin and their derivatives. All these matrices had good thermoplastic and mechanical properties. Among these blends, a representative starch-based specimen had maximum load bearing capacity 118·17 N on tensile stress of 1·97 MPa and modulus 221·36 MPa. In case of lignin, maximum load bearing capacity was 19·96 N on tensile stress of 0·44 MPa and modulus 287·11 MPa. In chitosan, maximum load bearing capacity was 74·03 N on tensile stress of 1·68 MPa and modulus 372·35 MPa. In case of gelatin, maximum load bearing capacity was 46·43 N on tensile stress of 1·22 MPa and modulus 829·75 MPa. Mechanical strength based on modulus showed: gelatin > chitosan > lignin > starch > cellulose. Thermal withstanding trend (dry heat) showed: gelatin > lignin > chitosan > cellulose > starch, whereas moist heat showed: gelatin > lignin > starch > chitosan > cellulose. Microscopic observations and biodegradability is also discussed.

Published
2016
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