D. Mallikarjuna Reddy

Bio: D. Mallikarjuna Reddy is an academic researcher from VIT University. The author has contributed to research in topics: Composite number & Rotor (electric). The author has an hindex of 6, co-authored 25 publications receiving 77 citations. Previous affiliations of D. Mallikarjuna Reddy include General Electric & Indian Institute of Technology Madras.

Low velocity impact analysis on composite structures - A review

Abstract: This paper is a review of low-velocity impact analysis of composite structure. Low impact velocity and damage mode due to impact load and failure criteria’s are explained. The effects of the composites constituents on impact properties, test method to measure the strength of the composite structure are studied with impact properties are explained in terms of residual strength of the composite.

Damage Detection and Identification in Structures by Spatial Wavelet Based Approach

Abstract: The objective of current work is to show the effectiveness of using wavelet transform for detection and localization of small damages. The spatial data used here are the mode shapes and strain energy data of the damaged plate. Because the wavelet coefficients are performed with various scale indices, local perturbations in the mode shapes and strain energy data can be found in the finer scale that are positioned at the locations of the perturbations. The continuous wavelet transform (CWT) using complex Gaussian wavelet with four vanishing moments is used to get the spatially distributed wavelet coefficients so as to identify the damage position on a square plate. The mode shape and strain energy data of the square plate with damage of different sizes are obtained by using ANSYS 9.0. The damage is simulated by reducing the thickness of one element out of 625 elements used for modeling. It is observed that by using modal data as input, damage can be identified if the reduction in thickness in one of the elements is at least 10%. Use of strain energy data as input to the wavelet analysis provides detection up to less than 10% damage. Lipschtiz (Hoelder) exponent (α) and Intensity factor (K) is derived from the coefficients to quantify the relation between damage and change in wavelet coefficients derived from modal and elemental strain energy data. The variation of maximum absolute wavelet coefficients versus percentage of damage for different mode shapes and scales are studied Influence of boundary conditions of the plate on damage identification has been studied, especially for damage near boundaries. Another objective of this paper is to apply wavelet transform to highlight the detection and localization of damage in beam and stiffened panel using experimental modal data as input to the wavelet analysis. This in real time has potential to be used in structural damage monitoring.

Innovative method of empirical mode decomposition as spatial tool for structural damage identification

Abstract: Summary A new approach to sensitize detecting structural damage using empirical mode decomposition (EMD) of the spatial signals is proposed. The difference of undamaged and damaged spatial strain and strain energy data for the beam and bridge modes is processed through the EMD, which yields the respective IMF1, which shows that damage location can be identified distinctively for as low as 0.01% reduction in elemental stiffness of beam discretized with 30 elements. An analysis was also carried out for a two-dimensional bridge model (I-40). It can detect damage sensitivity up to 0.5% loss in stiffness of the bridge. EMD as a spatial analysis tool seems to be the most sensitive among all methods currently available. Copyright © 2014 John Wiley & Sons, Ltd.

Wind turbine blade edge monitoring system

Abstract: A monitoring system and associated operational method are operatively configured with a wind turbine for detecting separation of shell members along an edge of a wind turbine rotor blade. The system includes any configuration of sensors disposed within an internal cavity of the rotor blade, with the sensor oriented relative to a leading or trailing edge of the blade and configured to detect a physical characteristic within the blade that is indicative of onset of a separation between the shell members along the monitored edge. A controller is configured to receive signals from the sensor and to initiate an automatic response to a detected separation.

Advanced Fiber Materials for Wearable Electronics

Abstract: Abstract Fiber materials are highly desirable for wearable electronics that are expected to be flexible and stretchable. Compared with rigid and planar electronic devices, fiber-based wearable electronics provide significant advantages in terms of flexibility, stretchability and breathability, and they are considered as the pioneers in the new generation of soft wearables. The convergence of textile science, electronic engineering and nanotechnology has made it feasible to build electronic functions on fibers and maintain them during wear. Over the last few years, fiber-shaped wearable electronics with desired designability and integration features have been intensively explored and developed. As an indispensable part and cornerstone of flexible wearable devices, fibers are of great significance. Herein, the research progress of advanced fiber materials is reviewed, which mainly includes various material preparations, fabrication technologies and representative studies on different wearable applications. Finally, key challenges and future directions of fiber materials and wearable electronics are examined along with an analysis of possible solutions. Graphical abstract

System and method for ground based inspection of wind turbine blades

Abstract: A ground based wind turbine blade inspection system and method consists of a thermal imaging camera configured to detect propagating defects by acquiring thermal imaging data from a wind turbine blade when it is substantially at thermal equilibrium with respect to surrounding air and analyzing the thermal imaging data with a processor to identify thermal effects associated with latent defects caused by internal friction due to cyclic gravitational stresses and wind loads during normal turbine operation. The system permits latent defects to be identified using a ground-based in situ inspection before they become visually apparent, which allows repairs to be made economically while the blade is in place.