1. Deformation response of nanoglass-metallic glass nano-laminate composites.
Student working on the project: Hirmukhe Sidram
Collaborator: Dr. Eswara Prasad Korimilli, Discipline of MEMS IIT Indore.
Nanoglasses are novel metallic glass based amorphous materials consisting of nano-meter sized glassy grains separated by fine glassy interfaces. The presence of interfaces facilitates nucleation of multiple shear bands distributed in entire volume of the material, which, in turn, results in prolonged homogeneous deformation in nanoglasses, in contrast to metallic glasses. However, nanoglasses exhibit lower yield strength in comparison to metallic glasses. Various strategies have been investigated to enhance ductility without compromising strength. The most promising is the development of nanoglass-metallic glass composites. Although few molecular dynamics studies have been performed reporting these composites as strong yet ductile materials, the mechanics of deformation and fracture is not well understood. We are trying to understand the physics of deformation and fracture in these materials through experiments and finite element simulations.
2. Mechanical behavior of piezo-electric materials
Student working on the project: Vaibhav Kathavate (joint student with Dr. Eswar prasad Korimilli, Discipline of MEMS IIT Indore)
Collaborator: Dr. Eswara Prasad Korimilli, Discipline of MEMS IITI; Praveen Kumar, Armament research and development establishment (DRDO), Pune.
Piezo-electric materials are of great technological importance due to their special property of electromechanical or mechanoelectrical conversion under an applied electric potential or mechanical load, respectively. However, these are brittle ceramic materials, and prone to lose their “piezo property” under repeated loading conditions. Although there have been studies in characterizing the piezo properties under cyclic loading conditions, a clear description of role of local stresses on the global piezo effect is not yet fully understood. We are trying to understand this problem by using both experimental and computational approaches. Indentation techniques are being used for experiments while simulations are being performed using ABAQUS software.
3. Understanding the mechanics of SMAT process in FCC metals
Students working on the project: Harshdeep Sharma (recently joined the project) from discipline of ME and Vikesh Kumar (joint student with Dr. Santosh Hosmani from MEMS).
Collaborator: Dr. Santosh Hosmani, Discipline of MEMS IIT Indore.
Surface mechanical attrition treatment (SMAT) has attracted significant interest owing to its ability to increase the material hardness, yield stress, fatigue life, and corrosion resistance. This process is derived from the conventional shot peening process which induces multi-directional impacts with a relatively low bead speed. There are various processing parameters such as shot size, height and their velocity influencing the microstructure and hence mechanical properties of the treated materials. In order to achieve desired properties in treated material, one needs to determine a suitable value of these parameters, which is expensive and cumbersome through experiments. Finite element simulations employing crystal plasticity theories may help not only understanding the physics of SMAT process, but also in optimizing the processing parameters. In this project, we are trying to implement crystal plasticity theories in finite element framework. This in-house developed finite element program would be utilized to analyze the SMAT process and optimizing the parameters.
4. Mechanical response of metallic glass composites
Collaborator: Prof. R. Narasimhan, Department of mechanical engineering, IISc Bangalore.
Metallic glasses have shown attractive mechanical properties such as high strength, good corrosion resistance and excellent formability making them potential candidates for various applications including defence, sports, medical, nano and micro-devises. The proverbial ‘Achilles heel’ that is preventing widespread deployment of metallic glasses in structural components is the lack of tensile ductility. This is due to localization of plastic flow into shear bands. Numerous materials engineering strategies are being pursued to circumvent this problem. Amongst these, the composites approach, herein a secondary crystalline dendritic phase is introduced into the microstructure, is most promising. While the dendritic phase imparts the required ductility, a concomitant reduction in strength, by virtue of the fact that its yield strength is much lower than that of the metallic glass matrix, is inevitable. Although few experimental studies have been undertaken to analyzes the fracture behavior of metallic glass composites, many fundamental questions are still unanswered. In this project, we are trying to understand the fracture response of metallic glass composites through finite element simulations.