Faculty Publications
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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 Development of rubber-sand composite for enhanced impact resistance: Implications of vulcanization(Elsevier B.V., 2024) Doddamani, S.; Kulkarni, S.M.; Joladarashi, S.; Gurjar, A.K.; Mohan Kumar, T.S.Developing rubber-sand composites for enhanced impact resistance faced challenges in material selection, optimisation of vulcanisation, interfacial bonding, and understanding underlying mechanisms. This study provides insights into the effect of vulcanisation on the energy absorption of rubber-sand composites and the potential benefits of adding sand particles as reinforcement, sulfur as a vulcanising agent and carbon black as reinforcement filler. Rubber-sand composites are made from the vulcanisation of natural rubber latex and reinforced with sand particles. Taguchi's design of experiments was used to vary the contents of sulfur (2, 3 and 4) and carbon black (30, 40 and 50) parts per hundred rubber (phr) and sand particles (0, 5 and 10 vol%). After vulcanisation, the composite blocks were prepared using the hot compression moulding technique for experimentation. The shore A hardness and low-velocity drop weight tests have been carried out to investigate the Rubber-sand composite's hardness and energy absorption properties, respectively. The results showed that the increment in the sulfur content increases the hardness of the rubber-sand composite. Additionally, sand particles and carbon black improved the composite's shore A hardness and energy absorption. Multiscale modelling techniques effectively simulated the experimental behaviour of the rubber-sand (Ru-San) composite, with a 3 – 11% error, demonstrating its capability to capture the structural response and damage characteristics under projectile impact conditions. The optimised composite has potential applications in industries that require impact resistance, such as the military, automotive and sports industries. © 2024 Karabuk UniversityItem Experimental and numerical investigation on low-velocity impact response of sandwich structure with functionally graded core(John Wiley and Sons Inc, 2024) Mohan Kumar, T.S.; Joladarashi, S.; Kulkarni, S.M.; Doddamani, S.The present research investigates optimizing the impact resistance of functionally graded sandwich structures using experimental and numerical approaches. The low-velocity impact (LVI) responses of functionally graded sandwich composite (FGSC) with different configurations with skin material jute/rubber/jute (JRJ) and core material having epoxy and sea sand by volume fraction of sea sand at 0%, 10%, 20%, and 30%. Sandwich structures were impacted with LVI (5.89, 10.92, and 15.18 m/s), with the impactor dropped from heights of 0.5, 1, and 1.5 m with precompressed spring loads. FGSC samples are considered a deformable body, and the impactor is modeled as a rigid body using commercially accessible dynamic explicit software. The burn-out test and weight method were used to test the core's gradience; both methods' results substantially matched, and the variance in gradation could be observed. The proposed sandwich structure characteristics are examined by energy absorption, peak force, energy loss percentage, and coefficient of restitution. Results showed that SC30S provides greater energy absorption and superior damage resistance when tested on LVI. To evaluate the accuracy of experimental findings in predicting the indentation behavior of the sandwich structure, the finite element analysis was used to compare with the experimental results. According to the examination of these proposed FGSC overall performance, they could potentially be employed as sacrificial materials for LVI applications like claddings to shield major structural components. The systematic approach used in this work serves as a standard for choosing and using FGSC effectively for LVI applications. Highlights: Low-velocity impact behavior of sandwich structures was investigated. Combining flexible skin and epoxy core enhances energy absorption. Based on impact energy levels, impact damage areas were determined. Examined sandwich structure advantages in structural and aerospace uses. In terms of time and cost, the numerical analysis method would be useful. © 2023 Society of Plastics Engineers.Item Enhancing energy absorption in rubber–sand (Ru–San) composite blocks against ballistic impact: a multi-objective optimisation approach(Springer Science and Business Media B.V., 2024) Doddamani, S.; Kulkarni, S.M.; Joladarashi, S.; Mohan Kumar, T.S.; Gurjar, A.K.This study focuses on optimizing process parameters to minimize the thickness of Ru–San composite blocks against high-velocity impact, aiming to enhance projectile energy absorption, particularly in military trench systems. The critical challenge in developing composite blocks as potential sandbag replacements for trench-bunker systems is optimizing their thickness for improved energy absorption during high-velocity impacts. By employing an optimization technique, this study seeks to determine the minimum thickness of the rubber–sand composite block capable of withstanding the full kinetic energy of a projectile without piercing, thereby advancing protective measures in military and security applications. The material used is a rubber–sand composite, consisting of 00 to 20 wt% of sand particles with various sizes ranging from 250 to 750 μm. The optimisation approach employed in this study includes screening design, Vikor and analytic hierarchy process of optimisation techniques. Finite element simulation is used to model the projectile's impact on the rubber–sand composite block and to analyse the energy absorption behaviour of the material under high-velocity impact. The results of this study show that process parameters such as the thickness of the target, wt% of sand, and size of sand particles significantly impact the energy absorption of the rubber–sand composite block. The optimised parameters are determined to be a thickness of 40 mm, 20 wt% of sand, and sand sizes of 750 μm. The findings of this study have important implications for the design and development of materials that can effectively withstand high-velocity impact, particularly in the field of military defence. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.