Indian Institute of Technology Hyderabad (IITH) is a premier institute of science and technology established in 2008. IITH has been consistently ranked in the&nbsp;<a href="https://iith.ac.in/reports/" rel="noopener noreferrer">top 10 institutes</a>&nbsp;in India for Engineering&nbsp;<a href="https://www.nirfindia.org/2021/EngineeringRanking.html" rel="noopener noreferrer" target="_blank">according to NIRF</a>&nbsp;making it one of the most coveted schools for science and technology in the country.

IITH offers&nbsp;<a href="https://iith.ac.in/academics/under-graduate/">undergraduate programs</a>&nbsp;in all the classical engineering disciplines, applied sciences, design, as well as several modern interdisciplinary areas. Students are given a flexibility to explore a broad set of areas, and potentially pursue a minor or double major in a discipline that is not their own. Students who wish to seek a deeper understanding of their own discipline are strongly encouraged to get involved in cutting-edge research with the help of a faculty to mentor them, and earn an Honors in their own field.

The very foundation of IIT Hyderabad is based on&nbsp;<a href="https://iith.ac.in/research/">research and innovation</a>. The vibrant research culture is evident from the number of patents and publications that IITH produces consistently every year. IITH offers&nbsp;<a href="https://iith.ac.in/academics/programmes-offered/">graduate programs</a>&nbsp;at both a masters, and a doctoral level, in several diverse areas. There are separate programs for technology, design, science, and liberal arts. The&nbsp;<a href="https://iith.ac.in/academics/post-graduate/">MTech program</a>&nbsp;is offered in various modes and durations to cater to the ever-growing need of postgraduate level professionals in the country.

IITH encourages and supports&nbsp;<a href="https://iic-iith.netlify.app/index.html" rel="noopener noreferrer" target="_blank">innovation and entrepreneurship</a>&nbsp;at every stage. The minor program in entrepreneurship is open to all students of IITH, and many of the courses are offered by industrialists who are entrepreneurs themselves. There are various&nbsp;<a href="https://iith.ac.in/research/centres-incubators/">innovation centers and incubators</a>&nbsp;that promote entrepreneurship and help mentor young innovators. IITH has been very successful in building tie-ups with leading academic institutions around the globe.

IITH enjoys a very special relationship with Japanese universities and industries that goes beyond academic and research collaborations. In fact, some of the iconic buildings in IITH campus will carry the signature of Japanese architecture.

IITH creates a unique holistic ecosystem for education that offers interactive learning, a very flexible academic structure, cutting-edge research, strong industry collaboration, and entrepreneurship. This is an environment which enables students and faculty to translate their dreams into realities.

IIT Hyderabad

Lockdowns are found to be effective against rapidly spreading epidemics like COVID-19. Two downsides to strategies rooted in social distancing and lockdowns are that they adversely affect the economy and prolong the duration of the epidemic. The extended duration observed in these strategies is often due to the under-utilization of medical facilities. Even though an under-utilized health care system is preferred over an overwhelmed one, an alternate strategy could be to maintain medical facilities close to their capacity, with a factor of safety. We explore the practicality of this alternate mitigation strategy and show that it can be achieved by varying the testing rate. We present an algorithm to calculate the number of tests per day to maintain medical facilities close to their capacity. We illustrate the efficacy of our strategy by showing that it reduced the epidemic duration by 40% in comparison to lockdown-based strategies. © 2023 Elsevier Ltd

World University root node

Department of Mechanical and Aerospace Engineering

Journal of Theoretical Biology

An adaptive testing strategy for efficient utilization of healthcare resources during an epidemic

The design of bistable arches is challenging due to their inherent nonlinear behaviour.It is known that the arch profiles of bistable arches in their two force-free equilibrium states are related to each other through a bilateral relationship.The closed-form analytical form of the bilateral relationship helps in designing the as-fabricated profile of the bistable arches when their toggled shape is completely specified.However, in certain cases, the arch profiles cannot be designed solely using the bilateral relationship.In this paper, we address such cases and present a design method to obtain arch-profiles using shape optimization in conjunction with the bilateral relationship.Such cases include: (1) arch-profiles that are partially specified in the first or/and second states; (2) arch-profiles that extremise the travel have a prescribed change in slope and have a specific ratio of travel between stable and unstable states.Towards this, the arch-profiles are represented using a set of finite variables corresponding to the mode weights of the basis set in which their shape is described.We formulate the optimization problem for each design case with the constraint to restrict the solutions in design space where the arches are bistable.After describing the procedure for numerically solving the optimization problem, design of arch-profiles using this method is illustrated through examples. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

Lecture Notes in Mechanical Engineering

Design of Bistable Arch-Profiles by Using Bilateral Relationship and Shape Optimization

This paper presents an analytical approach to predict the mechanical behavior of different types of screw lap shear joints using a spring-mass model. The spring-mass model captures the axial, bending, bearing, and shear stiffnesses of the components and their masses at the joint. The springs in the model represent the stiffness arising from each of these modes of deformation. We derive the expressions of the individual stiffnesses analytically and use the spring-mass model to obtain the overall joint stiffness. We show that this joint stiffness accurately predicts the experimentally observed mechanics of counter-bore and countersink screw lap joints. The experimental validation is carried out in nine different joint configurations. The analytical model is also validated with the aid of linear finite element analysis. Furthermore, the influence of individual stiffness components on the overall joint behavior is studied by varying the thickness and width of the plates. © 2022 Taylor &amp; Francis Group, LLC.

Mechanics Based Design of Structures and Machines

Modeling of counter-bore and counter-sink screw lap joints

Mechanical logic gates, whose embodiments were demonstrated in the past with rigid bodies connected with kinematic joints, are revisited in this work using compliant mechanisms. In particular, an OR gate is designed using pinned-pinned bistable arches. The compliant OR gate consists of five bistable arches arranged in such a way that a central arch acts as the output with 0 and 1 stable states while two pairs of arches, with their own 0 and 1 states, act as inputs. The arch-profiles of all arches are designed so that the forces of switching and switching back between the two stable states and the travel between the two stable configurations are as per the desired functionality. An analytical method, which is based on linear superposition of buckling mode shapes of a straight pinned-pinned column, was used to design the arch-profiles. Finite element analysis was used to validate the OR logic behaviour of the entire setup. A macroscale prototype was made using 3D printing to demonstrate the working of the OR logic. Since mechanical gates are useful at the micro-scale, using fixed-fixed arches instead of pinned-pinned arches is beneficial from the viewpoint of microfabrication. © 2021, Springer Nature Singapore Pte Ltd.

A Mechanical OR Gate Using Pinned-Pinned Bistable Arches

A passive monolithic compliant grasping mechanism that works based on the eversion of an elastically deformable bistable shell is conceptualized. It comprises grasping arms made of beam segments that work in conjunction with the everting shell. The grasper is capable of picking up a stiff object of any shape up to a maximum size and weight. The bistable shell everts upon contact with the object to enable the grasping arms envelop the object forming an enclosure. The mechanism then stays in that configuration until it is actuated again to turn the shell back to its original configuration and thereby opening the enclosure to release the object. The stiffness of the arms decides the payload of the mechanism. The size of the arms decides the largest object that can be grasped and held. The arms have distributed compliance so that they can conform to the shape of the object without applying undue force on it. © 2021, Springer Nature Singapore Pte Ltd.

A Passive Universal Grasping Mechanism Based on an Everting Shell

We analyse spatial bistable arches and present an analytical model incorporating axial, two transverse bending and torsion energy components. We extend the St. Venant and Michell relationship used in flexural-torsional buckling of planar arches and use it in modelling spatial arches. We study deformation pathways in spatial arches and their effect on critical characteristics of bistability such as back and forth switching forces, and the distance travelled by a point of the arch. We show that not considering spatial deformation leads to incorrect inferences concerning the bistability of planar arches too. Thus, this model serves as a generalized framework for the existing analysis on planar arches since they belong to a subset of spatial arches. Additionally, the effects of eccentric loading on spatial deformations are explored for arches with a range of as-fabricated shapes and boundary conditions, and the results are validated with finite-element analysis. © 2019 The Author(s) Published by the Royal Society. All rights reserved.

Fulltext

Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences

Analytical modelling of spatial deformation pathways in planar and spatial shallow bistable arches

Arch-profiles of bistable arches, in their two force-free equilibrium states, are related to each other. This bilateral relationship is derived for arches with fixed-fixed boundary conditions in two forms: a nonlinear single-variable equation for analysis and a closed-form analytical expression for design. Some symmetrical features of shape as well as necessary and sufficient conditions for bistability are presented as corollaries. Analysis and design of arch-profiles using the bilateral relationship are illustrated through examples. Copyright © 2019 by ASME.

Journal of Mechanisms and Robotics

Analysis and Design of Fixed-Fixed Bistable Arch-Profiles Using a Bilateral Relationship

An improved design of an electrothermally actuated two-terminal bistable microswitch is the focus of this paper. The proposed design has bimodal bistability which is obtained by using a pair of arches, a V-beam electrothermal actuator, and a novel initially retracting actuator. All these elements are monolithically integrated in a single planar releasable layer. The salient feature of the design is the usage of only a single pair of electrodes to switch between ON and OFF states, even though there are two actuators. In order to reduce the stress, the two actuators are mechanically decoupled but are electrically coupled to satisfy the two-terminal actuation. The switch design is experimentally verified by realizing on a silicon-on-insulator (SOI) wafer using a single-layer micro-fabrication technique. An actuation voltage of 11.8 V with 200-ms pulse-width, drives the switch from OFF to ON state and a 50-ms pulse of the same voltage across the same terminals, brings it back. [2018-0293] © 2019 IEEE.

Journal of Microelectromechanical Systems

A two-terminal bistable electrothermally actuated microswitch

Arch-profiles in the two force-free stable equilibrium states of shallow bistable arches are related to each other. We derive a two-way, i.e., bilateral, relationship between stress-free initial profile and stressed toggled profile so that pinned–pinned bistable arches of arbitrary profiles can be efficiently analyzed and designed. The derivation relies on representing the initial and toggled profiles with two sets of mode weights corresponding to the buckling mode shapes of a pinned–pinned column. Furthermore, we prove that the fundamental mode weights should be non-zero for an arch to be bistable. The following corollaries arise from the aforementioned relation: (1) symmetry in initial and toggled profiles remains unchanged; (2) all the mode weights other than the fundamental mode weight have the same sign in both stable states; (3) magnitudes of corrugations in stable force-free arch-profiles are approximately equal. Derivations and proofs of the principal relationship and its corollaries as well as examples of analysis and design of bistable arches of arbitrary arch-profiles are presented in the paper. © 2018 Elsevier Ltd

International Journal of Solids and Structures

A bilateral relationship between stable profiles of pinned–pinned bistable shallow arches

The boundary conditions, as-fabricated shape, and height-to-depth ratio of an arch characterize its bistability. We investigate this by modeling planar arches with torsion and translational springs at the pin joints anchored to the ground. A pinned-pinned arch, a special case of the model, has superior bistable characteristics as compared to a fixed-fixed bistable arch, which is also a particular case of the model. Arches with revolute flexures at the ends retain bistable characteristics of the pinned-pinned arches while being amenable for easy fabrication. However, equilibrium equations for such arches become intractable for analytical solution unlike the extreme cases of fixed-fixed and pinned-pinned arches. Therefore, a semi-analytical method for analysis and shape-synthesis of bistable arches with general boundary conditions is developed in this work. This is done by numerically determining critical points in the force-displacement curve. These critical points correspond to switching and switch-back forces and travel between the two states thereby enabling synthesis for desired behavior. We present design and optimization examples of bistable arches with a variety of boundary conditions and as-fabricated shape without prestress. We also propose two approaches to design a new class of asymmetric bistable arches. © 2017

Mechanism and Machine Theory

Design of bistable arches by determining critical points in the force-displacement characteristic

This paper describes a simplified method to analyze and design a bistable pinned-pinned arch with torsion springs at the pin (revolute) joints. Finite, but not zero, values of torsion spring constants offer the dual advantage of being amenable to monolithic compliant bistable arches wherein torsion springs are realized with equivalent revolute flexures; and giving enhanced range of travel between the stable states and reduced switching forces. However, the equilibrium equations become intractable for analytical solution unlike the extreme cases of fixed-fixed and pinned-pinned arches. Therefore, a new method for analyzing and designing novel bistable arches is presented here by determining critical points in the force-displacement curve. First, the equilibrium equations for post-buckling analysis are derived by writing the deflected profile as a linear combination of the buckling mode shapes of the corresponding straight beam with torsion springs at the pinned ends. These equations are then used to find the critical points with maximum, minimum, and zero forces. The critical points not only provide an approximate view of the bistable force-displacement curve but also enable synthesis of arches with desired behaviour. By using this semi-analytical method, we present an example of an arch with reduced switching force, large switch-back force, and enhanced travel between the two stable states. © Springer Nature Singapore Pte Ltd. 2017.

Lecture Notes in Electrical Engineering

Design of bistable pinned-pinned arches with torsion springs by determining critical points

In this paper, an initially straight beam with torsional springs at its two hinged ends is subjected to an axial force and its buckling mode shapes are found. Any shape which is a linear combination of the modes is taken as the as-fabricated stress-free form and then subjected to a transverse actuating force. Post-buckling analysis is used to compute the force-displacement characteristic of such a beam and thereby check if bistability exists. Two special cases of the torsion spring constants being very large and zero are presented. The former is a known result where a cosine curve is the fundamental buckling mode that does not give bistability unless its asymmetric second mode shape is avoided by a physical constraint. When the spring constant is zero, a single sine curve profile, which is the fundamental mode, can be made bistable without having to physically constrain the asymmetric buckling modes. This is realized when pinned-pinned boundary condition is used, which further allows the element to have enhanced range of travel between its two stable states, reduced switching force, and provision for secondary lateral actuation. To realise a monolithic compliant bistable element without any kinematic joints, torsion springs are substituted with equivalent revolute flexures. Physical embodiments of three types of bistable curved beams, namely, fixed-fixed, pinned-pinned, and revolute flexure-based, are presented. © 2015, Indian Institute of Technology, IIT. All rights reserved.