Earlier lectures

September 2020

Novel developments in clamped geometries for fracture toughness testing

Speaker: Prof. Nagamani Jaya Balila

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Abstract of the lecture

Stable fracture toughness test geometries are useful in not only determining the monotonic fracture toughness, but also in capturing the R-curve behaviour and damage tolerance of materials under cyclic loading and extreme environments. The doubly clamped boundary condition offers such crack stability even in the most brittle materials. This talk will cover all aspects of clamped beams and wires in tension and bending as fracture toughness test geometries including their geometric factor solutions for linear elastic and elastic-plastic cases. Finite element simulations are used to explain the mechanics of crack stability for various beam and wire aspect ratios and crack configurations. Their varied applications in bulk materials, architectured systems, thin film multilayers and graded coatings will be shown.

Related publications

  1. A. K. Mishra, A. Lambai and V. Jayaram, B. Nagamani Jaya, “The edge-notched clamped beam bend specimen as a fracture toughness test geometry”, Theoretical and Applied Fracture Mechanics, 105, 2020, 102409 (DOI: 10.1016/j.tafmec.2019.102409)
  2. B. Nagamani Jaya, Sanjit Bhowmick, S. A. Syed Asif, Oden L. Warren and Vikram Jayaram, “Optimization of clamped beam geometry for fracture toughness testing of micron-scale samples” Phil Mag Special Issue on Nanomech IV, Vol 95, 2015, 1945-1966 (DOI: 10.1080/14786435.2015.1010623)
  3. B. Nagamani Jaya and Vikram Jayaram, “Crack stability in edge notched clamped beam specimen under bending: modeling and experiments”, International Journal of Fracture, Vol 188, Issue 2, 2014, 213-228 (DOI: 10.1007/s10704-014-9956-2)
  4. B. Nagamani Jaya, Vikram Jayaram and Sanjay K. Biswas, “A new method for fracture toughness determination of graded (Pt,Ni)Al bond coats by microbeam bend tests”, Philosophical Magazine Special Issue on Nanomechanical Testing in Materials Research and Development III, Vol 92, Issue 25-27, 2012, 3326-3345. (DOI: 10.1080/14786435.2012.669068)

Fascinating flows in simple and enigmatic marine animals

Speaker: Prof. Vivek N Prakash

Abstract of the lecture

Animals are characterized by their movement, and their tissues are continuously subjected to dynamic force loading. Tissue mechanics determines the ecological niches that can be endured by a living organism. In the first part of my talk, I will present our surprising discovery of motility-induced tissue fractures and healing in a simple, early divergent marine animal - the Trichoplax adhaerens. I will demonstrate how fracture mechanics governs dramatic shape changes and asexual reproduction in this animal. In the second part of my talk, I will focus on the role of fluid mechanics in marine invertebrates. Many marine invertebrates have larval stages covered in linear arrays of beating cilia, which propel the animal while simultaneously entraining prey. In starfish larvae, we discovered that these ciliary arrays give rise to a beautiful pattern of slowly evolving vortices. I will elucidate how these vortices create a physical tradeoff between feeding and swimming in heterogeneous environments. For more information, please visit: Prakash Lab at Miami.

August 2020

Chaotic footprints of a flapping wing: A computational perspective

Speaker: Dr. Chandan Bose

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Abstract of the lecture

The lecture will discuss the investigations made on the complex vortex interactions in a flapping wing. The flow-field transitions from periodic to chaotic through a quasi-periodic route as the plunge amplitude is gradually increased. This study unravels the role of the complex interactions that take place among the main vortex structures in making the unsteady flow-field transition from periodicity to chaos.

Machine intelligence in mechanical and aerospace sciences: Today & beyond

Speaker: Dr. Rajnish Mallick

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Abstract of the lecture

AI and ML have been topics of huge interest in the recent times. Machine learning techniques are being applied vastly to understand the uncertainities in the models - both solid and fluid mechanics. During the lecture, we will discuss on how artificial intelligence is being in used in the aerospace industry.

Homogenization of heterogeneous materials for aerospace applications

Speaker: Prof. Guruprasad P J

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Abstract of the lecture

Micromechanical analysis of heterogeneous can be effectively carried out using the variational asymptotic method (VAM) unit cell homogenization technique. The governing equations obtained by adopting this technique can be solved using numerical methods by conformal discretization of the domain. In the case of heterogeneous materials, conformal discretization of the domain becomes difficult and time-consuming. It is preferable to have a non-conformal discretization procedure for problems involving complex geometries, for example, woven composites. A novel numerical framework for the micromechanical analysis of heterogeneous materials based on VAM is proposed, where the level-set method is used to define the interface as well as to decompose the domain into voxel regions of inclusions and matrix. The point interpolation method (PIM) is used to connect these voxel regions. The PIM-VOXEL framework thus developed is validated using examples having complex geometries taken from open literature for predicting elastic, thermal, thermo-elastic, and visco-elastic properties. The proposed methodology alleviates the requirement for conformal meshing without compromising the accuracy and is capable of automation for homogenization and localization applications. Finally, the application of the numerical framework to capture damage initiation and progression in woven composites is demonstrated.

Related publications

  • Rajeev, G. N., Sundararajan, T., B. and Guruprasad, P. J., 2018. A novel framework using point interpolation method with voxels for variational asymptotic method unit cell homogenization of woven composites. Composite Structures, 202: 261-274 (Link)

  • Pandi, P. Berger, H. and Guruprasad, P. J., 2020. Investigating the influence of interface in a three phase composite using variational asymptotic method based homogenization technique. Composite Structures, 233: 111562 (Link)

  • Pandi, P. and Guruprasad, P. J., 2020. Determination of the influence of interfacial thermal resistance in a three phase composite using variational asymptotic based homogenization method. International Journal of Heat and Mass Transfer, 155: 119889 (Link)

July 2020

Inspirations and equations derived from VAM for mechanics of student life

Speaker: Prof. Dineshkumar Harursampath

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Abstract of the lecture

The lecture will discuss various aspects of modeling in aerospace structures. In particular, the lecture will focus on the modeling of composite materials using the Variational Asymptotic Method (VAM).

Related publications

  • D. Harursampath, Introduction to the Special Section on Asymptotic Analyses, Dynamics and Aeroelasticity, AIAA Journal, Vol. 57 (10), 2019, pp. 4118-19 (Link)

  • D. Harursampath, A. B. Harish and D. H. Hodges, Model Reduction in Thin-Walled Open-Section Composite Beams using Variational Asymptotic Method. Part II: Applications, Thin-Walled Structures, 117, 2017, pp. 367-77 (Link)

UEL in Abaqus

Speaker: Dr. Niraj K Jha

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Abstract of the lecture Dr. Jha will present a methodology for the development of UEL in Abaqus CAE. In this regard, the lecture will focus on modeling of the constitutive behavior of hyperelastic materials. In addition, the lecture will also demonstrate the development of cohesive elements as well. Over the course of the lecture, he will present theoretical formulations followed by code review. The intended audience of this lecture is Master / Ph.D. / Industry participants who are beginning to use UEL routines in Abaqus CAE.