Faculty Publications
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Item Polymer-based composite materials possess superior properties such as high strength-to-weight ratio, stiffness-to-weight ratio, and good corrosive resistance and therefore, are preferred for high-performance applications such as in the aerospace, defense, and sport goods industries. Drilling is one of the indispensable methods for building products with composite panels. Drilling tests have been conducted on glass fiber-reinforced plastic composite GFRP laminates using an instrumented CNC milling center. Machining parameters such as drill size, feed rate, and cutting speed have been observed for damage-free drilling of GFRP materials. A series of drilling experiments have been conducted on glass fiber-reinforced polyester laminates and the responses experienced such as thrust force and torque as functions of feed rate and drill size have been characterized to develop a semiempirical relationship which correlated well with an established model in terms of cutting parameters. Results indicated that experimental values correlated better with the model of thrust for 6mm drill size than for 10mm and torque correlated better for lower feed ranges than for the higher feed ranges. © 2005 Sage Publications.(Machining of fiber-reinforced thermoplastics: Influence of feed and drill size on thrust force and torque during drilling) Mohan, N.S.; Ramachandra, A.; Kulkarni, S.M.2005Item Tribo-mechanical and physical characterization of filament wound glass/epoxy composites(Institute of Physics Publishing helen.craven@iop.org, 2019) Biradar, S.; Joladarashi, S.; Kulkarni, S.M.The present research aims to investigate mechanical, physical and tribological properties of filament wound Glass Fibre Reinforced Polymer (GFRP) composite pressure vessel as per respective ASTM standards. Here test coupons prepared from GFRP vessel are subjected to tensile, compression, flexural and impact testing to investigate mechanical properties. The physical properties are studied from density, ignition loss and water absorption tests. The tribological study was carried out using abrasive slurry erosion tester. All tests carried out in this study are as per respective ASTM standard. The results obtained from various mechanical testings are satisfactory and also almost equal in strength with respect to metallic pressure vessels. Particularly from impact testing, the strength of sea water treated sample has considerably increased. Fractography study was conducted on failed samples to study various mode of failure in detail. The physical characterization has elaborated the behavior of filament wound GFRP material under moisture environment which has observed a maximum of 0.5% water absorption rate. As per ignition loss study which reveals about 95%-98% weight of ignition loss is recorded, which indicates perfect fibre to resin ratio and almost nil or least % of void content. The slurry erosion test results are within the expected range and maximum wear of 9.67% is recorded under extreme case. The overall study reveals that the presence of voids, non-uniform distribution of fibre and matrix have an impact on the outcomes of many mechanical properties. From the above study we can conclude that filament wound GFRP pressure vessel can be used in many applications since it is a non-hydrophobic, better wear resistant and several strength parameters have also improved or unaltered under rigorous testing conditions. © 2019 IOP Publishing Ltd.Item Evaluation of tensile strength and slurry erosive behaviour of jute reinforced natural rubber based flexible composite(International Information and Engineering Technology Association info@iieta.org, 2020) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.Polymer based natural fiber reinforced composites are finding their applications in almost all fields of engineering. Flexible composites are different class of composite materials finding their usage in secondary structural application such as sacrificial structures like claddings. Mechanical and tribological characterization of the newly developed composites becomes important prior to using them in any engineering application. The present study concentrates on evaluating the tensile and slurry erosive behaviour of flexible composite manufactured by reinforcing naturally available jute fiber in the form of woven fabric in the naturally available sun dried rubber sheets (NR) using compression moulding technique. ASTM D412 standard is used to evaluate the tensile properties of the proposed flexible composite and the NR sheets. The slurry erosive behaviour is assessed using Ducom slurry erosion testing machine. The results reveal that reinforcing jute with natural rubber enhances the tensile strength compared to natural rubber sheet and the wear of the proposed flexible composite is minimal due to inclusion of natural rubber which is elastic in nature. © 2020 Lavoisier. All rights reserved.Item Development and mechanical characterization of novel polymer-based flexible composite and optimization of stacking sequences using VIKOR and PSI techniques(SAGE Publications Ltd, 2021) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.The development of natural fiber-reinforced polymer composites is becoming prominent in numerous engineering applications over the synthetic fiber-reinforced composites mainly because of their environment-friendly characteristics. This article deals with comparative study on selection of optimal stacking sequence (jute/rubber/jute (JRJ), jute/rubber/rubber/jute, and jute/rubber/jute/rubber/jute) of the jute/natural rubber-based completely biodegradable flexible composite using multi-attribute decision making (MADM) approaches namely hybrid entropy-VIse Kriterijumska Optimizacija kompromisno Resenja (VIKOR) and preference selection index (PSI) methods. Tensile strength, tear strength, specific impact strength, and specific wear rate are used as attributes for MADM methods. The results show good agreement between hybrid entropy-VIKOR and PSI methods used for stacking sequence selection. Scanning electron microscope analysis is carried out to study the failure mechanisms of the proposed flexible composite. The findings of the present study led to the choice of JRJ as the preferred stacking sequence among all the three stacking sequences considered as it exhibited the best overall properties compared to other two configurations of the flexible composite. © The Author(s) 2019.Item Investigation of mechanical properties of luffa fibre reinforced natural rubber composites: Implications of process parameters(Elsevier Editora Ltda, 2024) Gurjar, A.K.; Kulkarni, S.M.; Joladarashi, S.; Doddamani, S.Natural fiber-reinforced composite materials are highly beneficial due to their excellent strength-to-weight ratio, and the compression molding process is frequently used to prepare natural fiber composites. The primary objective of the present work is to optimize the process parameters of the compression molding method to prepare luffa fiber-reinforced natural rubber composite and investigate the influence of process parameters on mechanical properties. Pre-processing parameters, specifically oven-dry temperature and time, processing parameters such as soaking temperature, time, and compression pressure, and post-processing parameters, such as oven-dry temperature and time, were considered to optimize. Natural rubber in its latex phase is utilized as a matrix material, and luffa fiber is used as reinforcement. The Plackett-Burman screening design technique was employed to identify the impact of different processing parameters on the mechanical properties of the luffa fiber-reinforced natural rubber (LNR) composite, and based on Taguchi's design of experiments, several process parameters were utilized to create L27 orthogonal array and the mentioned composites prepared accordingly. The ASTM standard is followed while testing the composite samples to determine their density, shore A hardness, and tensile strength. The density of the composite is unaffected by the process parameters; however, the shore A hardness of the composite is significantly affected. All the processing parameters most significantly impacted the tensile strength of LNR composites. The optimized process parameters for preparing LNR composite are the pre-oven temperature of 65 °C and time of 150min, the soaking temperature of 75 °C and time of 5min, compression pressure of 1.5 MPa, and the post-oven dry temperature of 55 °C and time of 45min. LNR composite can absorb energy due to its rubber matrix, making it useful for high-impact applications. © 2024 The AuthorsItem The influence of hygrothermal aging on the hoop tensile strength of glass fiber wound polymer composites fabricated via filament winding technique(Institute of Physics, 2024) Biradar, S.; Hiremath, S.; Vishwanatha, H.M.; Joladarashi, S.; Kulkarni, S.M.The study investigates the impact of moisture environment treatment, on the hoop tensile strength (HTS) of glass fiber-reinforced polymer (GFRP) composites, through hygrothermal aging. GFRP cylinders were fabricated with varied parameters—volume fraction, winding angle, and stacking sequences using a filament winding machine. The fabricated samples are subjected to hygrothermal aging using seawater and tap water with oil at 80 °C for 1080 h (45 days). The HTS tests were performed on unaged and aged samples. There was a reduction in HTS for aged samples which is attributed to heat, seawater contamination, and oil. The highest and lowest HTS values recorded are 402.9 MPa and 118.3 MPa for unaged and tap water with oil-aged samples respectively. HTS in aged samples is compared with unaged samples. The study opens up avenues in identifying the best-suitable combination for retaining HTS under various aging conditions. © 2024 The Author(s). Published by IOP Publishing Ltd.Item Experimental and numerical investigation on the elastic properties of luffa–cenosphere-reinforced epoxy hybrid composite(John Wiley and Sons Inc, 2024) Gurjar, A.K.; Kulkarni, S.M.; Joladarashi, S.; Doddamani, S.Estimating the elastic characteristics of natural fiber-reinforced polymer composites such as luffa fiber reinforced with epoxy is challenging. The structure of luffa cylindrica is complex, like a three-dimensional natural fibrous mat, netting-like structure. The multiscale modeling of such structures is the challenge to be addressed. The prime objective of this work is to determine the specific elastic properties of luffa–cenosphere-reinforced epoxy (LCE) composite, considering the effect of filler volume fractions. Furthermore, multiscale modeling techniques, such as representative volume elements (RVEs) of finite element techniques with chopped, unidirectional, plain, and twill weaving fiber arrangements, were employed. The longitudinal modulus, transverse modulus, shear modulus, and Poisson's ratio were predicted through these modeling approaches. However, experimental and analytical methodologies, including the rule of mixture and Halpin–Tsai, were considered to validate the finite element analysis results. The elastic characteristics of LCE composite were therefore shown to be enhanced by increasing filler volume fraction. However, the cenosphere's 20% volume fraction has the highest elastic properties as determined by analytical, experimental, and computational models. Analytical and finite element simulation results were compared with the experimental results, and based on the findings, the most suitable (unidirectional, chopped, plain, and twill weaving) RVE was identified for finite element modeling of LCE composite for the evaluation of elastic properties. Results from practical approaches and the RVE twill weaving model showed good agreement, with less than 1% error, compared to the other analytical and finite element methods. Highlights: NFCs are gaining ground in polymer composites. Overcoming challenges in modeling of luffa fiber inside epoxy matrix. The study uses multiscale modeling with diverse fiber arrangements. Experimental and analytical methods used to confirm FEA results. Increased cenosphere volume fraction boosts LCE composite properties. © 2024 Society of Plastics Engineers.Item Experimental and Numerical Investigation of the Performance of Luffa Fiber-Reinforced Natural Rubber Composites with Process Parameter Optimization using DOE(Korean Fiber Society, 2025) Gurjar, A.K.; Kulkarni, S.M.; Joladarashi, S.; Doddamani, S.Composite materials have gained significant attention due to their high strength-to-weight ratio and sustainability. In particular, natural fiber-reinforced composites are increasingly investigated as environmentally friendly alternatives to synthetic counterparts. This study focuses on fabricating lightweight and biodegradable luffa fiber-reinforced natural rubber (LNR) composites using compression molding, emphasizing optimizing key processing parameters—temperature, curing time, and compression pressure. Latex-form natural rubber was selected as the matrix owing to its biodegradability, low cost, and compatibility with natural fibers. In contrast, luffa fiber served as reinforcement due to its favorable mechanical properties. The Design of Experiments (DOE) approach, specifically Taguchi’s method, was employed to systematically analyze the influence of processing parameters on physical and mechanical performance. Experimental evaluation of mechanical properties was conducted according to ASTM standards. The rule of mixture was used to evaluate the mechanical properties analytically. The multiscale material modeling finite element (FEM) methods were used to assess the orthotropic properties using the representative volume element technique. Results showed that density was only marginally affected by processing conditions, with ROM and FEM generally overestimating values; however, FEM provided closer agreement to experimental data. Shore A hardness and longitudinal modulus highly depended on curing temperature and time, with optimal properties obtained at 100 °C for 15 min under 1.0 MPa pressure. Similarly, the maximum ultimate tensile strength (0.40 MPa) was achieved under the same conditions, attributed to enhanced fiber–matrix bonding and crosslinking. Statistical analysis (ANOVA) confirmed temperature as the most influential parameter, followed by pressure and curing time. Optimized processing conditions significantly improved fiber–matrix adhesion, resulting in superior mechanical performance. These findings provide reliable processing guidelines for developing high-performance, environmentally sustainable LNR composites, making them suitable for high-impact applications in defense and consumer sectors. © The Author(s), under exclusive licence to the Korean Fiber Society 2025.