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Deepak Sharma, Ph.D.

Research Interests

  • Design of bio-inspired cellular structures.

  • 3D printing of designed cellular structures.

  • Numerical and experimental analysis of the mechanical properties of the cellular structures.

  • Topology optimization of the cellular structures.

  • Incorporation of best-performing cellular structures in the aero-engine parts to reduce weight and improve performance. 

Bio-inspiration: Lightweight yet strong cellular structures

Sea-sponge (Euplectella aspergillum)


Introduction and motivation

Bio-inspired lattice structures are derived from the skeleton of the hexactinellida sponge Euplectella aspergillum porous structure, also commonly known as venus' flower basket. It is a marine sponge found in the deepwater of the Pacific Ocean. The surface of the cylindrical skeleton consists of a regular square lattice with a series of vertical and horizontal silica struts. Each silica strut is composed of bundles of spicules which during its lifespan progresses from an easily deformable phase, consisting of loosely bonded spicules, through various stages of skeletal consolidation, eventually resulting in the rigid form.

The internal structure of each spicule is like ceramic fiber-reinforced composite. The cell spacing between vertical and horizontal struts is about 2.5 mm, while the diameter of each strut is about 0.25 mm. Secondly, these struts are incorporated with a set of diagonal elements, interconnecting in a way that generates a series of alternating closed and open cells. The function of diagonal struts is to prevent the buckling of sponge under the high-pressure present deep inside the sea and helps to absorb vibrations caused by the vortexes, which forms during the flow of seawater from one end to the other end of the sponge. The formation of vortexes during the flow is known as von Kármán vortex shedding. The combination of horizontal, vertical, and diagonal struts results in a near-optimal strut-based design. Therefore, in this study, an attempt has been made to experimentally and numerically evaluate the energy absorption performance and deformation mechanism of designed lattice structures under quasi-static compressive load.

In this study total of nine different structures are designed, first the effect of the ratio of diagonal (t) to vertical (d) strut thickness is studied (t/d = 0.5, 0.75, 1). The best performing t/d ratio is considered to study the relative density effect and last the unit size effect is studied using the best t/d ratio and relative density.




Finite element analysis shows local buckling characteristics of the bio-inspired lattice structure which is necessary for energy absorbers


Efficiency curves show maximum energy absorption efficiency of 0.39

Energy absorption curves 


Cyclic loading/unloading curves show reusability

Ashby chart shows better performance of our designs

Bird feather (Columba Livia)

Bird feather.jpg

Bird feather used to derive cellular structures 

Introduction and motivation

In pursuit of lightweight materials, researchers have studied the internal architecture of the bird's feathers.  The complete architecture of a feather vane can be divided into three zones. First is the main shaft, which consists of the rachis and calamus. The main shaft is porous from the inside, which makes lightweight feathers and helps to carry aerodynamic loads without much flexure or damage. The second is the sequential array of barbs that branch from rachis on both sides of the main shaft. Barbs contribute to the overall stiffness of the feather as they are the most rigid component of any feather. The third is the series of interlocked barbules that branch from barbs. Barbules are of two types distal and proximal. Distal barbules have tiny hooklets along the length and proximal barbules have a grooved structure. The barbules interlock adjacent barbs and produce a highly ordered lattice with a tightly woven design. The interlocking mechanism allows for a cohesive and compact structure for aerodynamic efficacy and makes flight possible. Pictorial images, HRSEM images, and cut-view of design inspired by bird’s feather are shown in the Figure above.

In this study, novel cellular structures inspired by the bird feather are printed using FFF technology, and their compressive behavior is investigated for the first time. The fabricated samples were analyzed for possible defects and size variations. Mechanical properties such as compressive elastic modulus, compressive strength, and energy-absorbing capacity were experimentally and numerically evaluated for the structures with different shaped and sized struts.

stress strain bird feather.jpg

Stress-strain response of circular and square barbule, and honeycomb structures with different relative densities.

Deformed structures bird feather.jpg

Circular, square and honeycomb deformed structures at different strains with 36 % relative density.

Numerical analysis.jpg

Comparison between finite element analysis of bird feather and honeycomb structures in uniform stress distribution in bird feather structures.

Bird feather inspired sandwich panels


In-plane three-point bending testing of bird-feather inspired sandwich panels


Out-plane three-point bending testing of bird-feather inspired sandwich panels

Engineering crack path with venation patterns


Venation patterns in nature


Experimental and DIC results shows change in crack path with change in design


Bionic tubes for grid-stiffened structures


Fracture mechanics of as-printed and heat-treated bionic tubes



Peer-reviewed International Journals:

1. Sharma D, Hiremath SS. Additively Manufactured Mechanical Metamaterials based on Triply Periodic Minimal Surfaces: Performance, Challenges, and Application. Mechanics of Advanced Materials and Structures 2022;29(26):5077-5107.

2. Sharma D, Hiremath SS. Bio-inspired Repeatable Lattice Structures for Energy Absorption: Experimental and Finite Element Study. Composite Structures 2022;283:115102.


3. Sharma D, Hiremath SS. Engineering the Failure Path with Bird Feather Inspired Novel Cellular Structures. Engineering Fracture Mechanics 2022;264:108350.

4. Sharma D, Hiremath SS. Compressive and Flexural Properties of the Novel Lightweight Tailored Bio-inspired Structures. Thin-walled Structures 2022;174:109169.

5. Sharma D, Hiremath SS. In-plane and out-plane flexural properties of the bird feather-inspired panels: Experimental, digital image correlation, and finite element study. Aerospace Science and Technology 2022;127:107731.


6. Sharma D, Hiremath SS, and Kenchappa NB. Bio-inspired Ti-6Al-4V mechanical metamaterials fabricated using selective laser melting process. Materials Today Communications 2022;33:104631.

7. Sharma D, Hiremath SS. Experimental and FEM Study on the In-plane and Out-plane Loaded Reversible Dual-material Bio-inspired Lattice Structures with Improved Energy Absorption Performance. Composite Structures 2023;303:116353.

8. Sharma D, Hiremath SS, and Kenchappa NB. Effect of Heat Treatment on the Variable Amplitude Fatigue Life and Microstructure of the Novel Bio-inspired Ti-6Al-4V Thin Tubes Fabricated Using SLM Process. Fatigue & Fracture of Engineering Materials and Structures. 2023;46(3):975-986.

9. Sharma D, Hiremath SS. Compressive fatigue response of Al-Si10-Mg bionic thin tubes under constant and variable amplitude loading. International Journal of Fatigue. 2023;168:107478.


10. Sharma D, Hiremath SS. In-plane elastic properties of the Euplectella aspergillum inspired lattice structures: Analytic modelling, finite element modelling and experimental validation. Structures. 2023;48:962:975.

11. Sharma D, Hiremath SS. Design of Euplectella aspergillum based bionic thin tubes for impact absorbing application under different loading conditions. Journal of Materials Research and Technology. 2023;23:3790-3810


1. Sharma D, Hiremath SS. A positive displacement pump and a method of fabrication thereof. Patent no. 420151, Indian Patent, 2023.

2. Sharma D, Hiremath SS. A system and a method for manufacturing triply periodic minimal surface structure. Application no. 202241044725, Indian Patent, 2022.

3. Sharma D, Hiremath SS. A system and method for bionic impact absorption device. Patent no. 431156, Indian Patent, 2023.

4. Sharma D, Hiremath SS. A System and method for a hydraulic flow divider. Application no. 202241060987, Indian Patent, 2022.

5. Sharma D, Hiremath SS. Bionic grid stiffened structures for structural application. Application no. 373506-001, Indian Design Patent, 2022.

Peer-reviewed International Journal not Related to Thesis:

1. Sharma D, Hiremath SS. Review on Tools and Tool Wear in EDM. Machining Science and Technology 2021;25(5):802-873. 



Peer-reviewed International Journals:

1. Sharma D, Mohanty S, Das AK. Surface modification of titanium alloy using hBN powder mixed dielectric through micro-electric discharge machining. Surface and Coatings Technology 2020;381:125157.

Book Chapter:

1. Sharma D, Siddique AR, Kumar V, Mohanty S, Das AK. A Study on the Effect of Polarity Change on Various Parameters on Ti6Al4V in Powder-Mixed Micro-EDM Using Multi-objective Grey Fuzzy Optimization. In: Narayanan R., Joshi S., Dixit U. (eds) Advances in Computational Methods in Manufacturing. Lecture Notes on Multidisciplinary Industrial Engineering. Springer, Singapore 2019.

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