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Shiv Nadar University

In the last few years the research activity in multifunctional composite materials and structures (MFCMS) is remarkably increased. This paper is a review of journal publications that are related to multifunctional composite materials and structures. MFCMS are meant for performing a variety of functions apart from the primary structural function which provides structural functions such as strength, stiffness, stability while non-structural functions provides energy harvesting, self-healing capability, sensing and actuation and sometimes acts as a protective layer etc. Many of the recent developments focused on the applications of MFCMS such as High Altitude Airship (HAA), morphing aircraft wings, energy harvesting, nanomaterials & nanostructures, smart structures, coupled field analysis, biomechanical etc. This paper also focused on the nonlinear mechanics of MFCMS because High Altitude Airship type of problems comes under geometrically and materially nonlinear case, so to analyse this type of problems one of the effective method called Variational Asymptotic Method is used. This method solves the problem by splitting the 3-D nonlinear problem into 1-D analysis through the thickness and 2-D nonlinear shell analysis. This paper concludes with a discussion of future scope and difficulties in design and analysis of multifunctional composite structures. © 2017 Elsevier Ltd.

Mechanical Engineering

(SoE) School of Engineering

Materials Today: Proceedings

A review of recent research on multifunctional composite materials and structures with their applications

The ballistic impact performance of a multi-layer material with aluminum foam as the interlayer was investigated numerically in this study. The multi-layer composite material used in this study consists of three functional layers. The ceramic front layer takes the initial impact and converts most of the kinetic energy of the projectile to the energy dissipated in erosion of the projectile material and ceramic. The backing layer which the projectile comes in contact with is a laminated composite fabric which reduces the intensity of the impact by dissipating energy through various forms of damage. The presence of an interlayer in between the front ceramic plate and a composite backing plate has been observed to change the ballistic performance of the composite armor to a great extent numerically. On studying the effect of different inter layers it was observed that the aluminium foam makes the composite layer experience relatively less damage on impact when compared with a specimen without any interlayer. The studies were conducted keeping in mind the weight compensation in each case which led to thickness changes and various distributions of the layers over the cross section. Cause help. © 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

World University root node

21st AIAA International Space Planes and Hypersonics Technologies Conference, Hypersonics 2017

High velocity impact on multi-layer materials

Low flight endurance is a pitfall commonly identified in most modern-day battery powered micro aerial vehicles. This paper presents the design and analysis of a ducted fan micro aerial vehicle(MAV) having a multifunctional, modular structure in order to address the above problem. The ducted fan rotorcraft has been designed particularly to meet the safety and hover efficiency needs for a prolonged indoor surveillance mission. A detailed literature survey on rotorcraft MAVs and multifunctional structural batteries has been reported and discussed. The paper involves detailed conceptual, preliminary and final design stages of a structurally and aerodynamically optimized axial fan that successfully caters to lower power consumption as compared to similar off the shelf propellers available in the market. The MAV incorporates multifunctionality by merging its structural and energy elements into a single subsystem (PAN-based carbon fiber batteries) thereby enhancing flight endurance. © 2017 by the American Helicopter Society International, Inc. All rights reserved.

6th Asian-Australian Rotorcraft Forum and Heli Japan 2017, ARF 2017

Design of a ducted-fan micro-rotorcraft with structural battery

Orthotropic composite materials exhibits higher specific strength and stiffness; hence extensively used in various industrial and engineering applications such as aerospace, armored and automobile etc. During their service life, these critical engineering components are subjected to thermo-elastic loads. These loading conditions generate local thermal stress concentration near the crack/voids present in the structures, which leads to sudden failure of engineering components. Therefore, the study of crack tip stress field under thermo-elastic loading becomes very important to understand the effect of lamina orientation on the strength of orthotropic composite components. The presented work deals with XFEM formulation and implementation to simulate 3-D orthotropic fracture problems under thermo-elastic loading environment. In XFEM based formulation, meshed topology does not exhibit any geometrical discontinuity. All desired discontinuity can be captured by enriching primary variable approximations by additional mathematical functions (Heaviside and crack front enrichment functions). These enrichment functions are derived from theoretical background of the problem under consideration. The crack surface element enriched by Heaviside function whereas, crack front elements treated by orthotropic crack front asymptotic functions. Mixed mode stress intensity factors are computed by domain based interaction integral approach. Few example of 3-D orthotropic thermo-elastic crack problem is presented to illustrate the effectiveness and robustness of proposed method. © 2015 AIP Publishing LLC.

AIP Conference Proceedings

Thermo-elastic failure simulation of 3-D orthotropic composites by XFEM

This work aims at asymptotically accurate dimensional reduction of non-linear multi-functional film-fabric laminates having specific application in design of envelopes for High Altitude Airships (HAA). The film-fabric laminate for airship envelope consists of a woven fabric core coated with thin films on each face. These films provide UV protection and Helium leakage prevention, while the core provides required structural strength. This problem is both geometrically and materially non-linear. To incorporate the geometric non-linearity, generalized warping functions are used and finite deformations are allowed. The material non-linearity is handled by using hyper-elastic material models for each layer. The development begins with three-dimensional (3-D) nonlinear elasticity and mathematically splits the analysis into a one-dimensional through-the-thickness analysis and a two-dimensional (2-D) plate analysis. The through-the-thickness analysis provides the 2-D constitutive law which is then given as an input to the 2-D reference surface analysis. The dimensional reduction is carried out using Variational Asymptotic Method (VAM) for moderate strains and very small thickness-to-wavelength ratio. It features the identification and utilization of additional small parameters such as ratio of thicknesses and stiffness coefficients of core and films. Closed form analytical expressions for warping functions and 2-D constitutive law of the film-fabric laminate are obtained. © 2015 AIP Publishing LLC.

VAM applied to dimensional reduction of nonlinear multifunctional film-fabric laminates

Asymptotically-accurate dimensional reduction from three to two dimensions and recovery of 3-D displacement field of non-prestretched dielectric hyperelastic membranes are carried out using the Variational Asymptotic Method (VAM) with moderate strains and very small ratio of the membrane thickness to its shortest wavelength of the deformation along the plate reference surface chosen as the small parameters for asymptotic expansion. Present work incorporates large deformations (displacements and rotations), material nonlinearity (hyperelasticity), and electrical effects. It begins with 3-D nonlinear electro-elastic energy and mathematically splits the analysis into a one-dimensional (1-D) through-the-thickness analysis and a 2-D nonlinear plate analysis. Major contribution of this paper is a comprehensive nonlinear through-the-thickness analysis which provides a 2-D energy asymptotically equivalent of the 3-D energy, a 2-D constitutive relation between the 2-D generalized strain and stress tensors for the plate analysis and a set of recovery relations to express the 3-D displacement field. Analytical expressions are derived for warping functions and stiffness coefficients. This is the first attempt to integrate an analytical work on asymptotically-accurate nonlinear electro-elastic constitutive relation for compressible dielectric hyperelastic model with a generalized finite element analysis of plates to provide 3-D displacement fields using VAM. A unified software package 'VAMNLM' (Variational Asymptotic Method applied to Non-Linear Material models) was developed to carry out 1-D non-linear analysis (analytical), 2-D non-linear finite element analysis and 3-D recovery analysis. The applicability of the current theory is demonstrated through an actuation test case, for which distribution of 3-D displacements are provided. © 2014 Elsevier Ltd. All rights reserved.