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Exploration, Design, and Additive Manufacturing of Bio-inspired, Functionally-gradient Composites with Optimized Mechanical Properties

   Department of Mechanical, Aerospace & Materials Engineering

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  Dr R Akhtar, Prof P Y Chen  No more applications being accepted  Funded PhD Project (Students Worldwide)

About the Project

This project is part of a 4 year Dual PhD degree programme between the National Tsing Hua University (NTHU) in Taiwan and the University of Liverpool in England. As Part of the NTHU-UoL Dual PhD Award students are in the unique position of being able to gain 2 PhD awards at the end of their degree from two internationally recognised world leading Universities. As well as benefiting from a rich cultural experience, Students can draw on large scale national facilities of both countries and create a worldwide network of contacts across 2 continents.

Technological advancements have created a surging demand for materials with area-specific properties and functionalities. Functionally gradient materials (FGMs), a new generation of advanced composites that exhibit a gradual change in structure and composition over volume, can fulfil such stringent requirements. Developing such functional material is often challenging because, on one hand, conventional manufacturing techniques lead to materials with homogeneous microstructure and composition, but on the other, practical applications require heterogeneous stress, strain, and temperature states.

Biological materials offer abundant examples of gradient design principles that can aid the development of functional gradient materials and structures. The highly impact-resistant dactyl club of Mantis shrimp and the soft to stiff property transition of mussel byssus for its attachments in rocks are some well-known instances of natural FGMs. In our recent investigation [1], using high-resolution micro-CT scans and nanoindentation measurements, we discovered a porous gradient microstructure and elastic modulus in the Elaeocarpus Ganitrus endocarp, revealing that it is an FGM. The structure and property gradient imparts exceptional compression and impact resistance to the endocarp. The micro/nanostructural strategies discovered in this study hold great potential to be used as a novel structural design methodology to synthesize FGMs.   

This project aims at investigating natural functional gradient design strategies and manufacturing 3D printed functionally gradient composites by observation, structural characterization, mechanical testing, multi-scale modeling/simulation, property/functionality design and optimization, and polymer additive manufacturing. To obtain gradient design principles, the multi-scale structural features of shark skin-denticle interface, bird feathers, and bat wing bone will be characterized by micro-CT scans, confocal laser scanning microscopy (CLSM), SEM, and atomic force microscopy (AFM). The micro-scale localized mechanical properties will be measured by nanoindentation. Utilizing machine learning techniques like generative adversarial networks (GANs) and genetic algorithm (GA), design software like Solidworks, Netfabb, etc., optimized structures will be modeled. A state-of-the-art multimaterial polyjet 3D printer (J55 prime, Stratasys) will be used to manufacture the FGMs inspired by natural gradient designs. Subsequently, the specimen’s tensile, compression, and bending mechanical performance will be evaluated by universal testing machines. In addition, a 2D triangular lattice spring model (LSM) and FEM simulations will be adopted to conduct the stress-strain analysis of the gradient stiff-soft composites. We will collaborate with Prof. Shu-Wei Chang (Dept. of Civil Engineering, National Taiwan University) and Prof. Tsung-Hui Huang (Dept. of Power Mechanical Engineering, NTHU) on multi-scale modeling/simulation and A.I./M.L.-based optimizations. 

Finally, the resulting FGMs and methodologies will be utilized to develop prototypes and applications like graded facial prosthetics, lightweight and shock-absorbing structural materials, flexible devices, etc.

When applying please ensure you Quote the supervisor & project title you wish to apply for and note ‘NTHU-UoL Dual Scholarship’ when asked for details of how plan to finance your studies.

For enquires on the application process or to find out more about the Dual programme please contact: [Email Address Removed].

Funding Notes

This project is a part of a 4-year dual PhD programme between National Tsing Hua University (NTHU) in Taiwan and the University of Liverpool in England. It is planned that students will spend 2 years at NTHU, followed by 2 years at the University of Liverpool.
Both the University of Liverpool and NTHU have agreed to waive the tuition fees for the duration of the project and stipend of TWD 11,000/month will be provided as a contribution to living costs (the equivalent of £280 per month when in Liverpool).


1. A. Ghimire and P.-Y. Chen, Seed protection strategies of the brainy Elaeocarpus Ganitrus endocarp: Gradient motif yields fracture tolerance. Acta Biomaterialia (2022) 138, 430-442.
2. P.-Y. Chen, J. McKittrick, M.A. Meyers. Structural biological materials: Functional adaptations and bioinspired designs. Progress in Materials Science (2012) 57, 1492-1704.
3. M.A. Meyers, J. McKittrick, P.-Y. Chen. Structural biological materials: Critical mechanics-materials connections. Science (2013) 339, 773-779.
4. P.-Y. Chen. Tough lessons from diabolical beetles. Nature (2020) 586, 502-504.
5. A. Ghimire. Y.-Y. Tsai, P.-Y. Chen, S.-W. Chang. Tunable interface hardening: Designing tough bio-inspired composites through 3D printing, testing, and computational validation. Composites Part B (2021) 215, 108754.
6. C.-C. Tung, Y.-S. Chen, W.-F. Chen, P.-Y. Chen. Bio-inspired, helically oriented tubular structures with tunable deformability and energy absorption performance under compression. Materials & Design (2022) 222, 111076.
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