Browsing by Author "Doddamani, S."

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Analysis of light weight natural fiber composites against ballistic impact: A review
(KeAi Publishing Communications Ltd., 2023) Doddamani, S.; Kulkarni, S.M.; Joladarashi, S.; Mohan Kumar, M.K.; Gurjar, A.K.
The main factors in the ballistic impact mechanism, an incredibly complicated mechanical process, are the target material's thickness, toughness, strength, ductility, density, and projectile parameters. Creating resilient, high-strength, and high-modulus fibers has made it possible to use natural fibers and their composite laminates for various impact-related applications today. Kinetic energy absorption, penetration depth, and residual velocity were the parameters affecting the performance of natural fiber composites used in the armor systems. This review aims to comprehend the several influencing factors that significantly impact the target's ballistic impact performance. In addition to experimental study efforts, many analytical, numerical modeling, and empirical technique-based research approaches have also been considered while analyzing the various components. The paper also examines several factors that determine how well natural fiber composite functions, including internal factors like material composition, characteristics of matrix and reinforcement, the kind and choice of fiber/matrix, failure modes, impact energy absorption, and external factors such as residual velocity, and various projectile nose angles. It also emphasizes the ways to improve composites for high performance and ballistic efficiency, as well as the economic cost analysis of switching out synthetic fibers for natural ones in a ballistic composite. Â© 2023 The Authors
Analysis of light weight natural fiber composites against ballistic impact: A review
(KeAi Publishing Communications Ltd., 2023) Doddamani, S.; Kulkarni, S.M.; Joladarashi, S.; Mohan Kumar, M.K.; Gurjar, A.K.
The main factors in the ballistic impact mechanism, an incredibly complicated mechanical process, are the target material's thickness, toughness, strength, ductility, density, and projectile parameters. Creating resilient, high-strength, and high-modulus fibers has made it possible to use natural fibers and their composite laminates for various impact-related applications today. Kinetic energy absorption, penetration depth, and residual velocity were the parameters affecting the performance of natural fiber composites used in the armor systems. This review aims to comprehend the several influencing factors that significantly impact the target's ballistic impact performance. In addition to experimental study efforts, many analytical, numerical modeling, and empirical technique-based research approaches have also been considered while analyzing the various components. The paper also examines several factors that determine how well natural fiber composite functions, including internal factors like material composition, characteristics of matrix and reinforcement, the kind and choice of fiber/matrix, failure modes, impact energy absorption, and external factors such as residual velocity, and various projectile nose angles. It also emphasizes the ways to improve composites for high performance and ballistic efficiency, as well as the economic cost analysis of switching out synthetic fibers for natural ones in a ballistic composite. © 2023 The Authors
Ballistic impact analysis of multilayered armour system using finite element analysis
(Elsevier, 2024) Doddamani, S.; Kulkarni, S.M.; Joladarashi, S.; Mohan Kumar, T.S.; Gurjar, A.K.
The application of finite element analysis (FEA) to the ballistic impact analysis of polymer composites used in armor is covered in this chapter. This study aims to assess polymer composite armor materials' performance and establish their resistance to high-velocity projectile impacts. The use of FEA enables accurate simulations of the impact process that take into consideration the properties of the materials, the geometry of the projectile and the armor panel, and the impact conditions. The investigation' findings shed important light on how the polymer composite armor responds to impacts and its capacity to absorb and dissipate impact energy. For the development of cutting-edge armor materials and the multiscale modeling method of armor design, this information is essential. The chapter ends with recommendations for further research as well as a discussion of the difficulties and restrictions of employing FEA for ballistic impact analysis. © 2024 Elsevier Ltd. All rights are reserved including those for text and data mining AI training and similar technologies.
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 University
Effect of addition of TiC nanoparticles on the tensile strength of Al7075-graphene hybrid composites
(MIM RESEARCH GROUP, 2023) Lingaraju, L.S.; Channabasappa, M.; Doddamani, S.
In the current work, the effect of the addition of titanium carbide and graphene nanoparticles on the tensile strength of the aluminum 7075 matrix composites is investigated. The preparation of the mentioned composites is made using a novel ultrasonic stir casting process. The reinforcements used are 0.25wt% graphene nanoparticles and 0.5wt% to 2.5wt% of titanium carbide nanoparticles. Ultrasonic stir casting techniques are used to enhance the wettability of TiC and graphene nanoparticles. To quantify the microstructure of the prepared composites, SEM and EDS are used. An experimental investigation has been carried out to determine the influence of the addition of TiC and graphene nanoparticles on the tensile strength of the mentioned composite. From the SEM analysis, it is observed that the prepared composites have a uniform distribution of the reinforcements and the EDS analysis confirms the existence of reinforcing elements in the Al7075-TiC/Graphene composites. Experimental results show that the addition of TiC and graphene enhances the hardness and tensile strength. This enhancement is lost with the ductility of the Al7075-TiC/Graphene composites. The fractographic samples of the Al7075- TiC/graphene composites shows cracks in the vicinity of the matrix and reinforcements and also show a brittle fracture. © 2023 MIM Research Group. All rights reserved.
Effect of clamshell powder on the mechanical and damping properties of epoxy-bamboo composites
(SAGE Publications Ltd, 2024) Anand, K.J.; Ekbote, T.; Doddamani, S.; Ashoka, E.
Compared to single natural fibre composites, hybridising natural fibres with filler particles presents a promising avenue for enhancing composites physical, mechanical, and damping properties. This study delves into incorporating clamshell powder, a filler derived from clams’ hard protective outer shells, into polymer composites. The focus is on investigating the potential of clamshell powder as a filler material to augment the mechanical and damping properties of epoxy-bamboo mat composites. The weight ratio of clamshell fillers varied from 0% to 9%, and the compression moulding method was used to fabricate the composites. As per ASTM standards, mechanical properties were evaluated by conducting tensile and flexural tests. Free vibration tests by impact hammer technique were employed to evaluate the natural frequency, damping ratio, and mode shapes of developed composites to measure damping properties. Results revealed that adding clamshell filler significantly improved composites tensile strength, flexural strength, and damping properties. The addition of clamshell elevated the tensile strength by 18.5%, and flexural strength by 24.2% for composite with 6 wt% filler, which can be attributed to the efficiency of load transfer and the interfacial bonding between fillers and epoxy matrix. SEM analysis supported the experimental results obtained. The highest damping value is received for 9 wt% filler, showing 30% enhancement compared to composites without clamshell filler. Modal analyses using ANSYS software further validated the positive impact of clamshell filler. This study underscores the potential of clamshell filler in enhancing the mechanical and damping properties of epoxy-bamboo composites, broadening their applicability in various fields. © IMechE 2024.
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.
Effects of specimen thickness and compositions on the fracture toughness investigations of Al7075-SiC/Al2O3 hybrid composites utilizing Taguchi optimization and FEA analysis
(Springer-Verlag Italia s.r.l., 2025) Bharath, P.B.; Shivakumar, S.P.; Rajesh, A.M.; Prabhuswamy, G.S.; Doddamani, S.
The primary objective of this study is to investigate the influence of process parameters on the fracture toughness of aluminium–silicon carbide/alumina particulate composites. The composite is fabricated using the stir-casting method, and the study aims to explore the relationship between process parameters and the resulting mechanical properties of the material. The research seeks to answer how varying process parameters such as reinforcement composition, specimen thickness, and crack length-to-width ratio affect the fracture toughness of aluminium-based hybrid composites. A comprehensive experimental approach is employed, utilizing compact tension specimens of varying thicknesses, compositions, and crack length-to-width ratios to assess fracture toughness. Taguchi's optimization techniques, including the design of experiments with an L9 orthogonal array, analysis of variance (ANOVA), and regression analysis, are used to analyze the specified parameters. The three key factors and their respective levels considered in the study are reinforcement composition (3, 6, and 9 wt%), specimen thickness (10, 12, and 15 mm), and crack length-to-width ratio (0.45, 0.47, and 0.50). The experimental results indicate that increasing the composition of reinforcements beyond 6 wt% and certain crack length-to-width ratios decreases the fracture toughness of the hybrid composites. Through Taguchi's analysis, it is revealed that for a crack length-to-width ratio of 0.45, specimens with a thickness of 12 mm and 6 wt% reinforcements exhibit the highest fracture toughness. Further analysis underscores that the crack length-to-width ratio (a/W ratio) significantly affects fracture toughness (94%), followed by reinforcement composition and specimen thickness. The study provides valuable insights into optimizing the fracture toughness of aluminium–silicon carbide/alumina particulate composites. The identified optimized parameters 12 mm specimen thickness, 6 wt% reinforcement, and a 0.45 crack length-to-width ratio lead to enhanced fracture toughness. Additionally, finite element simulations support the experimental findings, with less than a 12% error, confirming the robustness of the optimized conditions. This research contributes to a deeper understanding of the interplay between process parameters and mechanical properties in particulate composite materials. © The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature 2025.
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.
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.
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.
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.
Fracture toughness investigations of AA6061-SiC composites: Effect of corrosion parameters
(Elsevier Ltd, 2023) Ramesh, R.S.; M.v, S.K.; Begum, Y.; Doddamani, S.; K, M.K.
The research gap in this problem lies in the limited understanding of how corrosion parameters, such as reinforcement composition, exposure time, and concentration of the corrosive agent, affect the fracture toughness of AA6061-SiC composites. Investigating these factors can provide valuable insights into the corrosion behaviour of AA6061-SiC composites and help optimise their mechanical properties for specific applications in harsh environments. The study aimed to optimise the parameters and find the best combination of composition, normality, and exposure time that improves fracture toughness. The study's results showed that normality (37%), and exposure time (47%) significantly affected the material's fracture toughness. Fracture toughness tests showed Case 1 had higher fracture toughness (18.35 MPa√m) due to lower normality and shorter exposure time, indicating a less aggressive corrosive environment. In contrast, Case 3 had lower fracture toughness (14.86 MPa√m) due to higher normality and longer exposure time, suggesting increased corrosion severity. In particular, increasing the exposure time and concentration of the corrosive agent decreased the fracture toughness. The composite was exposed to a 3.5% NaCl solution, which caused severe damage and formed a protective oxide layer. However, pitting corrosion occurs and causes decreasing in fracture toughness. © 2023 Elsevier B.V.
Influence of sea sand reinforcement on the static and dynamic properties of functionally graded epoxy composites
(Springer Science and Business Media Deutschland GmbH, 2024) Mohan Kumar, T.S.M.; Joladarashi, S.; Kulkarni, S.M.; Doddamani, S.
This study aims to study the static and dynamic properties of the functionally graded epoxy composites with sea sand particles as reinforcement. In this study, functionally graded polymer composites (FGPC) were fabricated by dispersing sea sand throughout the epoxy, exhibiting a spatially varying composition profile within the material. Physio-mechanical properties and high strain rate compression responses were determined for the prepared FGPC by varying the composition of sea sand [0%, 10%, 20%, and 30% (by weight)]. The gradience analysis was performed using the burn-out test and weight method, and the results significantly matched, as well as the variation in gradation could be identified. The density and void content are increased with increased sea sand composition. Tensile and specific strength for neat epoxy shows a 2.41 times increase compared to 30% sea sand-filled epoxy. When loaded from the composite side of FGPC, flexural strength increased by 27.93%, hardness increased by 12.47%, and impact strength increased by 2.35 times for 30% sea sand-filled epoxy compared to neat epoxy. Under dynamic compression loading, FGPC was subjected to split-Hopkinson pressure bar experiments for neat and filled epoxy. These samples were deformed at strain rates in the 103 s?1 while subjected to pressures of 2, 3, and 4 bar. Stress–strain curves and the strain rate were computed using the raw data. High strain rates improve compressive strength, which increases exponentially as the strain rates increase. Scanning electron microscopy micrographs of the fractured specimen are employed to analyze the fracture characteristics. Graphical Abstract: (Figure presented.) © Iran Polymer and Petrochemical Institute 2024.
Investigation of fracture toughness analysis of polymer composites using finite element analysis
(Elsevier, 2024) Doddamani, S.; Begum, Y.; Bharath, K.N.; Rajesh, A.M.; Mohamed, K.K.
This chapter includes a study on using finite element analysis (FEA) to investigate the fracture toughness of polymer composites. This study’s objective is to assess polymer composites' fracture toughness. By considering the material properties and stress distributions, multiscale modeling approaches in FEA enable a thorough assessment of the material behavior under various loading circumstances. The analysis’s findings shed important light on the polymer composites' fracture toughness. The chapter ends with recommendations for further research and a review of the benefits and drawbacks of employing multiscale modeling and FEA techniques to analyze fracture toughness in polymer composites. The results of this work have significant ramifications for polymer composite structure design and optimization, particularly in applications requiring high fracture toughness. © 2024 Elsevier Ltd. All rights are reserved including those for text and data mining AI training and similar technologies.
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.
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 Authors
Investigation on the Hardness of Al6061 Alloys: Implications of Seawater Corrosion
(Springer, 2024) Begum, Y.; Doddamani, S.
This study aims to investigate the impact of seawater corrosion on the hardness of Al-Mg-Si alloys, providing insights into the mechanical alterations induced by exposure to corrosive marine environments. Al-Mg-Si alloys are widely used in marine environments because of their high strength-to-weight ratio and excellent corrosion resistance. However, exposure to seawater can lead to corrosion, which can alter their mechanical properties, including hardness. In this study, Al6061 alloy specimens were exposed to seawater for different periods (3–30 days), and their hardness was measured using Vickers hardness testing. The corrosion rate was determined by weight loss analysis. The results showed that the corrosion rate of Al6061 alloys increased with increased exposure time in seawater, up to 20%. The hardness versus corrosion rate plot analysis indicates an inverse relationship, with scatter points aligning well with a linear regression model. The Vickers' hardness of the samples decreased as the corrosion rate increased. This hardness decline in Al6061 alloys under escalating corrosion rates is attributed to material loss, heightened porosity, and microstructural transformations arising from corrosion product formation. Comprehensive corrosion micrographs unveiled advanced corrosion stages, marked by dynamic pit and crack expansion, oxide layer degradation, pit coalescence, and emergence of distinct corrosion patterns. © The Minerals, Metals & Materials Society 2024.
Investigation on Tribological Behavior of Al7075-TiC/Graphene Nano-composite Using Taguchi Method
(Springer Science and Business Media Deutschland GmbH, 2024) Lingaraju, S.V.; Hatti, G.; Jadhav, M.R.; Dhuttargaon, M.S.; Doddamani, S.
This study addresses the limited understanding of how nano-materials affect the mechanical properties and wear behavior of AMMNCs, focusing on challenges in achieving uniform nano-material distribution and optimizing processing parameters. This study explores the fabrication and tribological performance of Al7075 hybrid metal matrix nano-composites reinforced with TiC and Graphene using ultrasonic stir casting. By varying TiC content (0.5 to 2.5 wt%) and maintaining 0.25-wt% Graphene, the composites were tested under dry sliding conditions. Results indicate that the hybrid nano-composite with 1.5 wt% TiC and 0.25 wt% Graphene exhibits optimal wear resistance and frictional behavior, attributed to improved hardness and reduced surface damage. This results from harder particles intermingling with the softer alloy, which shows increased hardness with reduced delamination, cracks, and fractures of inside surfaces during wear. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2024.
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.