PROJECTS

Role : Principal Investigator

Cost: Rs. 3,800,000

Collaborator : DMRL Hyderabad and NMRL Mumbai

Duration: 2021-2024

Abstract

The high strength aluminium alloys are most commonly used for structural and marine applications. Aluminium alloys are lighter in weight which means less power requirements, good corrosion resistance and generally have low maintenance. Of all the available aluminium alloys, Al-5xxx series (non-heat treatable) and the Al-6xxx (heat treatable) series are generally recommended for the applications exposed to salt water. Al-5086 magnesium-aluminium alloys are focus of attention in the proposed research work. The principal strengthening mechanism of these alloys is due to strain hardening. For constructing large ship structures, it is often required to make joints, for which welding is mostly preferred. Among all the welding techniques, friction stir welding (FSW) technology has gained significant popularity. Most of the studies till date have been devoted to the understanding of mechanical properties of these joints at room temperature but the investigation of the material behaviour at sub-zero temperature (< 0 0C) has been rarely investigated. Moreover, the big structures are often subjected to complex variable loadings for e.g. ships, where the load complexity is induced due to external forces and sea waves. It is thus desired to ensure the structural integrity of these structures under such environmental conditions. For such applications, it is important to characterize the fatigue properties at different ambient temperatures (near sub-zero) and in corrosive environment, which have not been investigated much till date.

Role : Principal Investigator

Cost: Rs. 3,300,000

Collaborator : None

Duration: 2020-2022

Abstract

In this project, I aim to investigate and contribute to the understanding of fatigue damage characteristics of additively manufactured IN718 alloy, specifically used in high temperature applications. The proposed research framework is innovative with respect to current status of research and will be useful in making suitable recommendations to the industries for enhanced performance. The powdered IN718 alloy will be additively manufactured using and outsourced to an external company. The samples will be prepared for microstructural and texture characterization using the optical microscope and the Field Emission Scanning Electron Microscope (FE–SEM). Strain controlled monotonic tensile tests at a constant strain rate will be performed and the data will be used to estimate the stress levels for the fatigue tests. Low cycle fatigue tests will be done to obtain the hysteresis loops and the cyclic stress-strain curve and the data will be used for the modelling of constitutive equations of the material. ABAQUS software along with MATLAB will be used for modelling purposes. Load controlled high-cycle fatigue tests will be carried out at different load ratios (R). The residual stresses will be measured using XRD analysis and their role will be quantified in fatigue damage. The fractured surfaces will be examined using the scanning electron microscope (SEM) for the identification of damage initiating factors by locating and analyzing the crack initiation sites. The procedure will be helpful in understanding the effect of different stress ratios on the damage mechanisms in this material. Based on the obtained results, certain recommendations could be made for better performance of the structural components.

Role : Principal Investigator

Cost: Rs. 4,697,000

Collaborator : DMRL Hyderabad

Duration: 2020-2023

Abstract

The monotonic tensile properties of the additively manufactured (AM) alloys have been evaluated in most of the research studies for limited class of metals. Titanium alloys (Ti-6Al-4V) is one of the most investigated material because of its wide range of industrial applications. These alloys are known to have good high temperature mechanical properties. Only a handful of studies exist dealing with fatigue of additively manufactured metals and limited data is available on its creep performance at high temperatures. The fatigue properties are generally associated with scattered data, and additive manufacturing is likely to enhance this scatter because of several defects associated with it. These defects are also likely to affect creep properties, which has not yet been studied much. In the project, it is proposed to investigate the fatigue and creep behavior of Ti-6Al-4V alloy. The overall aim is to investigate and understand the fatigue damage characteristics of additively manufactured Ti – alloy (Ti-6Al-4V) using selective laser melting (SLM) along with the effect of defects on the fatigue lives at high temperature. The creep behaviour of the additively manufactured Ti-6Al-4V alloy will also be investigated. The role of defects on crack initiation sites during high temperature fatigue under mean stress is not yet fully understood due to limited data. The most critical defects that will be addressed are the porosities/lack of fusion and the residual stresses. Experimental fatigue tests at different mean – stresses under different ambient temperature will be conducted and the data will be used to formulate a model for the prediction of high temperature fatigue and creep behaviour of additively manufactured Ti-alloy using finite element analysis (FEA) in ABAQUS^TM.

Role : Principal Investigator

Cost: Rs. 3,300,000

Collaborator : PMG Engineering Pvt. Ltd.

Duration: 2020-2023

Abstract

Given the advancement in the fields of computational power and machine learning, the “algorithmic” generation and evaluation of design options has been made possible, although there is still a long way to go to replicate human behaviour. Generative design is not just about efficiency. It is much more about creativity. Instead of designing fixed forms and solutions, it involves designing goals, constraints, and systems of geometry. Instead of reviewing a few dozen design options with intuition, it involves exploring a few thousand design options with data. Generative design allows us to go beyond human linear thinking and typical rules-of-thumb to discover new possibilities. Many researchers now-a-days across the world are working on this problem in design of products and systems. The aim of this study is to explore this area of industrial/ academic importance to develop novel approaches and solutions for generation and evaluation of design options with direct application to industries.

Role : Principal Investigator

Cost: Rs. 2,000,000

Collaborator : None

Duration: 2019-2021

Abstract

Friction stir welding (FSW) is a solid state joining process with a potential to join hardened aluminum alloys of different types: 2xxx, 6xxx,7xxx & 8xxx series, similar and dissimilar both, which was not possible using conventional fusion welding process. The process finds applications in aerospace, ship building including large fuel tank for space launch vehicle, cargo decks for high-speed ferries, and roofs for railway carriages etc. FSW consists of a non-consumable rotating tool with specifically designed pin and shoulder, whose frictional heat is used to soften the metal and allow the tool to traverse along the joint seam. As a result, three distinct microstructural zones are developed in the welded part: nugget zone (NZ), thermo-mechanically affected zone (TMAZ), and heat-affected zone (HAZ). The nugget region is characterized by intense plastic deformation and higher temperature resulting in fine and equi-axed recrystallized grains. Thermo-mechanically affected zone experiences medium temperature where metal is deformed plastically while the heat affected zone experiences only the heat without any deformation. The high temperature (about 400 – 450 ℃) and intense plastic deformation developed during FSW of aluminum alloys results in significant change of microstructural features in the stir zone i.e. very fine microstructure, dissolution and coarsening of grains. These microstructural changes affect the mechanical and fatigue properties of the joints. Thus, it is very important to quantify the change and to be able to predict this change in properties of joints for safer design of the structural component and to prevent catastrophic failure.

Role : Lead Researcher

Cost: ~ 1 Trillion JPY

Collaborator : University of Tokyo and UACJ Ltd.

Duration: 2016-2019

Abstract

The project aimed to develop a set of modules required for research and development of materials and components by relating materials, processing, microstructure and performance. Of several modules of this project, I worked on fatigue module with an aim to develop an extensible computational framework by integrating the advanced computational techniques such as crystal plasticity modelling for crack initiation prediction, extended finite element method for crack growth etc. so as to be able to predict fatigue performance of material using its chemical composition and minimum experimental data. The fatigue behavior and crack growth of aluminum welds (5xxx series) were investigated with an aim to study the composition of crack initiation and crack growth in total fatigue life of the material containing pores and finally be able to predict the total fatigue life including the mean stress correction and then to implement it in the computational framework using crystal plasticity modelling and extended finite element method. In 5xxx series aluminum alloys, it was found that the strength could be improved by increasing the content of Magnesium. Thus, one such improved strength alloy was investigated for its fatigue performance. Several fatigue tests were conducted at different stress ratios to characterize mean stress effect. For crack growth study, standard CT specimens were used and crack closure measurements were done using DIC (Digital Image Correlation) technique. Short crack study is very challenging in such metals because defects favors crack initiation owing to their stress concentration. Thus, a new approach for specimen design was made to monitor short crack and to study the effect of micro-structure. Crystal plasticity (CP) model has been developed and a framework for CP simulations is under process.

Role : Researcher

Cost: ~ 50000 Euros

Collaborator : Laboratoire de Mécanique des Solides (LMS) and IFPEN France

Duration: 2013-2016

Abstract

IFPEN designed a clip connector to be used in offshore oil deep drilling. It was found that a typical riser assembly (riser pipe plus clip connector) when immersed in sea water, not only experiences external pressure from sea water but also the internal pressure of fluid flowing through it as well as the mass of the riser assembly, buoyancy force and sea waves and currents which induce cyclic bending with a random amplitude. Hence fatigue comes into picture i.e. multiaxial fatigue with variable amplitude. The aim was to investigate its multiaxial fatigue performance in air and in corrosive environment. Multiaxial fatigue is a challenging problem in field of fatigue because of the requirement of expensive multi-axial machines and large complex shape specimens. At first, the complex multiaxial variable amplitude loading was simplified to constant amplitude in-phase biaxial tension with mean stress. However, most of the multiaxial fatigue criteria are based on tension-torsion fatigue data and do not discriminate the influence of biaxial tension from that of a mean stress. Thus mean-stress and biaxiality effects were investigated separately. For mean stress effect, uniaxial fatigue tests were run at various R ratios (σmin/σmax) on cylindrical specimens. To investigate the effect of positive stress biaxiality, combined cyclic tension and internal pressure tests with various proportions of each loading were run on tubular specimens, at fixed R ratio. Several popular fatigue criteria failed to describe all fatigue data. Endurance criteria that include a linear mean stress term or contain a hydrostatic tension term failed to predict the variations of the endurance limit. A new criterion based on Gerber’s parabola was proposed. Similar tests were run to investigate the influence of salt water (3.5% NaCl) on fatigue lives under: 1) free corrosion and 2) cathodic protection. The experimental setup was designed during the project to simulate these tests.

Role : Principal Investigator

Cost: Rs. 1,298,000

Sponsor : Jindal Steel and Power Ltd. Raigarh

Year: 2021-22

Role : Principal Investigator

Cost: Rs. 2,124,000

Sponsor : Oberoi Thermit, Noida

Year: 2020-22

Role : Principal Investigator

Cost: Rs. 2,124,000

Sponsor : Ora India Pvt. Ltd. Kanpur

Year: 2020-22

Role : Principal Investigator

Cost: Rs. 1,062,000

Sponsor : Railtech Welding & Equipment Pvt. Ltd Chattisgarh

Year: 2020

Role : Principal Investigator

Cost: Rs. 2,478,000

Sponsor : BHEL Haridwar

Year: 2020-21

Role : Principal Investigator

Cost: Rs. 2,596,000

Sponsor : BHEL Haridwar

Year: 2020-21

Role : Co-Principal Investigator

Cost: Rs. 1,239,000

Sponsor : SP Singla Construction Pvt. Ltd. Haryana

Year: 2020-21

Role : Co-Principal Investigator

Cost: Rs. 1,209,000

Sponsor : BSNL National Network Center, New Delhi

Year: 2020-21

Role : Principal Investigator

Cost: Rs. 3,068,000

Sponsor : PMG Engineering Pvt Ltd, New Delhi

Year: 2020-21

Role : Principal Investigator

Cost: Rs. 177,000

Sponsor : Namami Industries, Rajkot

Year: 2020

Role : Principal Investigator

Cost: Rs. 118,000

Sponsor : Asahi India Glass Ltd. Hardwar

Year: 2019

Role : Co-Principal Investigator

Cost: Rs. 59,000

Sponsor : Price Pipes and Fittings, Hardwar

Year: 2019