Faculty Publications
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Item Optimization of process parameters for ballistic impact response of hybrid sandwich composites(Springer-Verlag Italia s.r.l., 2023) Mohan Kumar, T.S.; Joladarashi, S.; Kulkarni, S.M.; Doddamani, S.The low-cost, eco-friendly ballistic impact resistance materials are gaining more importance in defense applications. The present work investigates the findings of ballistic impact behavior of a Jute-Rubber-Jute-Epoxy (Sand)-Jute-Rubber-Jute (JRJ-ES-JRJ) hybrid sandwich composite for different core thicknesses (10, 15, 20 mm) and different filler composition (0, 20, 40%) subjected to impact at 350 mps using different shaped projectiles like flat (F), conical (C), and hemispherical (H) using a numerical and parametric approach. Hybrid JRJE(%S)JRJ sandwich composites is modeled and simulated using commercially available dynamic explicit software, with the projectile as a rigid body and the target as a deformable material. Simulations are performed as per Taguchi's design of experiments approach for the L27 orthogonal array. The results show that filler composition and core thickness are the most critical factors determining ballistic behavior for the proposed hybrid sandwich composite structure. The Hybrid JRJ-ES-JRJ sandwich composites impacted with a conical-shaped projectile absorb the maximum energy, but the composite impacted with a flat-shaped projectile suffers more severe and immediate damage. © 2022, The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.Item Investigation of impact energy absorption of AA6061 and its composites: role of post-aging cooling methods(Gruppo Italiano Frattura, 2023) Krishna Reddy, G.V.; Naveen Kumar, B.K.; Hareesha, G.; Rajesh, A.M.; Doddamani, S.Al6061 and its composites are widely employed in applications requiring high strength and impact resistance. Heat treatment, particularly ageing, is a well-established method for enhancing the mechanical properties of these composites. However, the influence of post-ageing cooling methods on the impact energy absorption capacity of Al6061 and its composites is not well understood. This investigation aims to examine the impact energy absorption of Al6061 and its composites after ageing at 460°C for 2 hours, employing different cooling methods, including furnace cooling, air cooling, and water cooling. The composites were produced using the stir casting technique with varying weight fractions of graphite and SiC particles based on Taguchi's design of experiments. Charpy impact tests were conducted using a specialised testing machine. The results reveal that the impact energy absorption capacity of the composites is influenced by the cooling method used after the ageing treatment. Furnace cooling demonstrated the highest impact energy absorption capacity compared to the other cooling methods, exhibiting a 28% increase relative to the monolithic aluminium alloy. Furthermore, it was observed that the impact energy absorption capacity of the composites did not improve with an increase in the weight fraction of SiC particles, while the addition of graphite negatively impacted the absorption capacity. © 2023, Gruppo Italiano Frattura. All rights reserved.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 Effects of Addition of Graphite on the Tribological Behaviour of Al7075-SiC Hybrid Composites Using Design of Experiments(Springer Science and Business Media Deutschland GmbH, 2024) Gudipalli, K.R.V.; Chapke, Y.; Hareesha, H.; Doddamani, S.Despite the widespread use of Al7075-SiC composites in various engineering applications, their tribological performance remains a subject of interest due to challenges related to friction and wear. This study addresses the need for improved lubrication in such composites by investigating the potential of Al7075-SiC/Graphite hybrid materials. The incorporation of graphite particles, up to 9% by weight, aims to enhance the self-lubricating properties of these composites. Stir casting is employed to fabricate specimens with varying graphite content (3–9% by weight), followed by comprehensive tribological assessments under dry sliding conditions. Factors including sliding distance, load, and graphite composition are systematically evaluated using Taguchi’s optimization techniques, including design of experiments, ANOVA, and regression analyses. Results reveal that the addition of 9% graphite content notably reduces both the coefficient of friction and wear rate. According to the data, sliding distance significantly impacts wear behaviour, followed by the applied load. In contrast, the composition has a 77% impact on the coefficient of friction than load, while the sliding distance has a relatively small impact. As a result, the Al7075-SiC/Graphite composite material demonstrated its suitability as a self-lubricating substance. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.Item Optimizing dental implant design parameters through orthotropic properties of bone: a DOE-based approach(Springer-Verlag Italia s.r.l., 2025) Singh, R.K.; Verma, K.; Kumar, G.C.; Doddamani, S.Dental implant research has provided insights into the effects of thread design and occlusal loading rate on stress distribution within implants and adjacent bone structures. However, ongoing advancements in materials necessitate further investigation to optimize implant performance through a thorough understanding of design parameters. This study developed a comprehensive three-dimensional CAD model of dental implants, incorporating cortical and cancellous bone, crown, and various thread types (V type, buttress, and trapezoidal threads). Multiple thread design parameters (pitch, length, angle, and depth) were varied to analyze their impact on stress distribution. Taguchi's design of experiments, combined with finite element analysis, was employed to explore stress distribution around dental implants. The implant material used was Ti6Al7Nb alloy, comprising 90% titanium, 6% aluminium, and 7% niobium. Von Mises stresses were compared to identify the optimal design. Taguchi's analysis revealed that raising all parameters except pitch reduced implant stress. However, for trapezoidal and buttress designs, increasing pitch resulted in higher stress levels. A confirmation experiment, utilizing the developed regression equation, validated these findings. Comparative analysis between simulation and statistical results showed a close match across all cases; with an error rate of less than 10%. These findings underscore the reliability and accuracy of the research outcomes, emphasizing the significance of identified thread types and their impacts on implant stress. Further research in this area could lead to advancements in dental implant design, enhancing patient outcomes and implant longevity. © The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature 2025.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.