Faculty Publications
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Item Statistical analysis of flexural modulus of cenospheres-reinforced, recycled poly(ethylene terephthalate) using Taguchi method(SAGE Publications Ltd, 2014) Prabhu, B.K.; Dudse, S.; Kulkarni, S.M.Statistical methods are playing an important role in the design and analysis of engineering experiments. One such method called Taguchi method is found to provide sufficient information to optimize a process with the use of minimum number of experiments. This article presents systematic application of Taguchi method for optimizing the process parameters of compression moulding process. The response under consideration is flexural modulus. The study includes the use of recycled polyethylene terephthalate reinforced with fly ash cenospheres. The use of these recycled materials is promising to reduce the cost of the engineering parts and help nature by increasing waste utilization. A model for flexural modulus is designed and verified through experiments. The outcome from analysis of variance brings out the facts that moulding pressure, moulding temperature and weight fraction of cenospheres are the three most significant parameters of flexural modulus, contributing 59.44, 21.45 and 7.75%, respectively. The optimum set values for these parameters are found to be 5 MPa, 50°C and 15%. The proposed quadratic model for flexural modulus proves to be well in agreement with the experimental results. © The Author(s) 2013.Item Effect of ketjenblack and barium titanate on the piezoresistive behaviour of silicone rubber particulate composites(IOP Publishing Ltd, 2021) Manohar Shankar, B.S.; Hiremath, H.; Kulkarni, S.M.In the present study, silicone rubber reinforced with ketjenblack and barium titanate were fabricated using high temperature compression molding method. These particulate composites are characterized for piezoresistive sensitivity. Ketjenblack and barium titanate are the conducting and dielectric fillers in the high temperature vulcanized silicone rubber matrix. The effects of ketjenblack and barium titanate fillers, filler loading, amount of curing agent, curing temperature and mixing time on the piezoresistive properties of these composites were investigated. The piezoresistive sensitivity recorded maximum values of 3.7(10-3) (kPa)-1 for dielectric and dielectric-conductive composites. The linear variation of normalized resistance change was observed for change in pressure up to 20 kPa. The dielectric composite sensitivity increases with reduction in dielectric filler and curing agent loadings, increasing with mixing time and curing temperature. The piezoresistive sensitivity for dielectricconductive composites depends on ketjenblack and barium titanate filler loading. These composites demonstrate interaction effects among the factors. © 2021 The Author(s). Published by IOP Publishing Ltd.Item An experimental study on adhesion, flexibility, interlaminar shear strength, and damage mechanism of jute/rubber-based flexible “green” composite(SAGE Publications Ltd, 2022) Mahesh, V.; Joladarashi, S.; Kulkarni, S.M.Determining the interlaminar shear strength (ILSS) of the composite laminates is vital for deciding their usage in any engineering applications. The matrix used and its curing characteristics are vital in deciding the ILSS of the composite. Present work deals with an experimental study on adhesive behavior, degree of flexibility, ILSS, and damage mechanism of the novel jute/rubber-based flexible “green” composite. The proposed flexible composites were prepared in three different stacking sequences, namely jute/rubber/jute (JRJ), jute/rubber/rubber/jute (JRRJ), and jute/rubber/jute/rubber/jute (JRJRJ), using compression molding technique. After determining the optimal curing characteristics of the proposed rubber-based matrix, the constituents are tested for their adhesive strength with the matrix which showed that rubber matrix system is compatible with jute fabric and natural rubber sheet. Composites are prepared and degree of flexibility for each stacking sequence is found out. Results pertaining to ILSS show that JRJRJ has better ILSS compared to JRJ and JRRJ. Fractographic analysis using scanning electron microscope reveals the mode of failure of the composites and the mechanism governing their failure. Fourier transform infrared spectroscopic study reveals the bonding between the constituents is good enough to be used in composites with flexibility. © The Author(s) 2019.Item Effect of fillers on the piezocapacitive behaviour of silicone rubber particulate composites(Institute of Physics, 2024) Manohar Shankar, B.S.M.; Kulkarni, S.M.Robotics and fluid dynamics applications have created demand for development of electronic skins with embedded pressure sensors. These applications require simple and low-cost fabrication processes with large area deployment. Both structured and unstructured material approaches to sensor development have been followed. Among the various sensing mechanisms, piezo capacitive transduction is superior. This paper reports the influence of fillers on the piezo capacitive characteristics of unstructured solid silicone rubber composites. Dielectric, conductive and conductive-dielectric fillers were incorporated into solid silicone rubber and fabricated using high temperature compression moulding to form dielectric-dielectric, conductive-dielectric and conductive-dielectric dielectric composites. The results reveal that piezo capacitive sensitivity varies with filler type, filler loading, curing agent loading, mixing time and curing temperature. The experiments reveal improved normalized capacitance with pressure characteristics of linearity and sensitivity of 3.9 × 10−3 (kPa)−1 in the 0-20 kPa range of pressure. These composites are thus candidate materials for flexible pressure sensing applications. © 2024 IOP Publishing LtdItem 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 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.