Department of Mechanical Engineering

&ldquo;IIT Jodhpur is committed to impart quality education to facilitate the creation of qualified, competent and responsible human resources to meet the emerging technological challenges of the world. It is working towards creating an equitable learning platform that is positive, accessible and effective in the face of the modern societal and scientific advancements.

Flexibility in curriculum, in all its academic programs, encompassing elements of teaching, research, creativity, innovation and entrepreneurship is the most unique feature of IIT Jodhpur. The Department of Science and Technology (DST), under the National Mission on Cyber Physical Systems, has identified IIT Jodhpur as a Technology &amp; Innovation Hub in the area of Augmented Reality and Virtual Reality. The institute has also been nominated as the coordinator for the Jodhpur City and Knowledge Cluster by the Office of Principal Scientific Adviser, Government of India.

The sprawling 852-acre IIT Jodhpur campus is a majestic tribute to the deep-rooted diverse cultural heritage of the region. The campus is an architectural masterpiece, which is slated to become an international exemplar of sustainability with net-zero energy, and advanced water and waste management strategies.&rdquo;

IIT Jodhpur

An analytical investigation was carried out for composite rotor blades with straight and swept tips to determine aeroelastic stability, response and loads in forward flight. Nonlinear equations were derived using Hamilton's principle. Composite blades with two-cell, soft-in-plane, hingeless configuration were analyzed. Results obtained from numerical calculations demonstrate the influence of composite ply orientation, tip sweep and anhedral on antrium, hub loads, blade response and stability.

World University root node

Collection of Technical Papers - AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

Aeroelastic stability, response and loads of swept tip composite rotor blades in forward flight

This paper is the third in a series in which we study the superconvergence of finite element solutions by a computer-based approach. In [1] we studied classical superconvergence and in [2] we introduced the new concept of η%-superconvergence and showed that it can be employed to determine regions of least error for the derivatives of the finite element solution in the interior of any grid of triangular elements. Here we use the same ideas to study the superconvergence of the derivatives of the finite element solution in the interior of complex grids of quadrilaterals of the type used in practical computations. © 1994.

Applied Numerical Mathematics

η%-Superconvergence in the interior of locally refined meshes of quadrilaterals: superconvergence of the gradient in finite element solutions of Laplace's and Poisson's equations

This paper presents the mathematical details of the formulation for the sensitivity derivatives for the structural dynamic, aeroelastic stability, and response characteristics of a rotor blade in hover and forward flight. The formulation is denoted by the term semi-analytical approach, because certain derivatives are evaluated by a finite difference scheme. Using this formulation, sensitivity derivatives for structural dynamic and aeroelastic stability characteristics were evaluated for a composite rotor blade. Useful conclusions regarding the relative merits of the semi-analytical approach, when compared to a pure finite difference approach, are obtained. In addition, influence of ply orientation angles on the vibratory hub loads in forward flight is also considered. © 1994.

Mathematical and Computer Modelling

A new sensitivity analysis for structural optimization of composite rotor blades

In this paper we study the pollution-error in the h-version of the finite element method and its effect on the local quality of a-posteriori error estimators. We show that the pollution-effect in an interior subdomain depends on the relationship between the mesh inside and outside the subdomain and the smoothness of the exact solution. We also demonstrate that it is possible to guarantee the quality of local error estimators in any mesh-patch in the interior of a finite-element mesh by employing meshes which are sufficiently refined outside the patch. © 1994.

Finite Elements in Analysis and Design

Pollution-error in the h-version of the finite-element method and the local quality of a-posteriori error estimators

This paper is the first in a series in which we discuss computational methodologies for checking the quality of a posteriori error estimators for finite element approximations of linear elliptic problems. In this first part we study the asymptotic properties of error estimators in the interior of patchwise uniform grids of triangles. A completely numerical methodology for the analysis of the quality of estimators is presented. Results from the application of the methodology to the study of the quality of several well-known error estimators are reported. In subsequent papers we shall discuss methods to study the properties of estimators for meshes of quadrilaterals, non-uniform grids, at boundaries, grid-interfaces and near-singular points. © 1994.

Computer Methods in Applied Mechanics and Engineering

A model study of the quality of a posteriori error estimators for linear elliptic problems. Error estimation in the interior of patchwise uniform grids of triangles

The planform structure of turbulent Rayleigh-Bénard convection is obtained from visualising a liquid crystal sheet stuck to the bottom hot surface. The bottom plate of the convection cell is Plexiglas and the top plate is glass. Water is the 3est liquid and the Rayleigh number is 4 × 107. The planform pattern reveals randomly moving hot streaks surrounded by cold regions suggesting that turbulent Rayleigh-Bénard convection is dominated by quasi-two-dimensional randomly moving plumes. Simultaneous temperature traces from two vertically separated thermocouples indicate that these plumes may be inclined forward in the direction of horizontal motion. The periodic eruption of thermals observed by Sparrow et al [3] and which forms the basis of Howard's model is not observed. © 1994.

International Communications in Heat and Mass Transfer

Planform structure of turbulent Rayleigh-Bénard convection

A fundamental study of vibration reduction in helicopters using higher harmonic blade pitch control was performed. The nonlinear equations of motion for a coupled rotor/flexible fuselage system have been derived using computer algebra on a special purpose symbolic computing facility. The trim state and vibratory response of the helicopter are obtained in a single pass by applying the harmonic balance technique and simultaneously satisfying the trim and the vibratory response of the helicopter for all rotor and fuselage degrees of freedom. The influence of the fuselage flexibility on the vibratory response is studied. New insight on vibration reduction in coupled rotor/fuselage is obtained from the sensitivity of the hub shears to the frequency and amplitude of the open loop HHC signal in the rotating frame. It is shown that conventional higher harmonic control through the swashplate, is capable of suppressing either the hub loads or only the fuselage vibrations, but not both simultaneously. It is demonstrated that for simultaneous reduction of hub loads and fuselage vibrations, a multiple frequency higher harmonic control input signal provided in the rotating frame is required. © 1993.

Coupled rotor-fuselage vibration reduction using open-loop blade pitch control

This paper presents a detailed mathematical derivation of the sensitivity derivatives for the structural dynamic, aeroelastic stability and response characteristics of a rotor blade in hover and forward flight. The formulation is denoted by the term semi-analytical approach, because certain derivatives have to be evaluated by a finite difference scheme. Using the present formulation, sensitivity derivatives for the structural dynamic and aeroelastic stability characteristics, were evaluated for both isotropic and composite rotor blades. Based on the results, useful conclusions are obtained regarding the relative merits of the semi-analytical approach, for calculating sensitivity derivatives, when compared to a pure finite difference approach.

Collection of Technical Papers - AIAA/ASME Structures, Structural Dynamics and Materials Conference

New sensitivity analysis for structural optimization of composite rotor blades

This paper describes the development of a new structural optimization capability aimed at the aeroelastic tailoring of composite rotor blades with straight and swept tips. The primary objective is to reduce vibration levels in forward flight without diminishing the aeroelastic stability margins of the blade. In the course of this research activity a number of complicated tasks have been addressed: (1) development of a new, aeroelastic stability and response analysis; (2) formulation of a new comprehensive sensitive analysis, which facilitates the generation of the appropriate approximations for the objective and the constraints; (3) physical understanding of the new model and, in particular, determination of its potential for aeroelastic tailoring; and (4) combination of the newly developed analysis capability, the sensitivity derivatives and the optimizer into a comprehensive optimization capability. The first three tasks have been completed and the fourth task is in progress. © 1992, by P.P. Friedmann, C. Venkatesan, and K. Yuan.

4th Symposium on Multidisciplinary Analysis and Optimization, 1992

Development of a structural optimization capability for the aeroelastic tailoring of composite rotor blades with straight and swept tips

A new model has been developed for the integral analysis of high Schmidt number (or equivalently high Prandtl number) laminar buoyant jets discharged horizontally. This model assumes top-hat density profile across the inner core of jet and Gaussian velocity profile. Entrainment coefficient corresponding to pure laminar jet has been taken in the analysis. The prediction of the jet trajectory agree well with experimental data in the regions where the jet remains laminar. © 1992.