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Materials - Mechanical Engineering Research

Materials

Material research aims at developing fundamental understanding of the physical mechanisms and interactions responsible for the behavior of engineering materials.

Covered topics include the synthesis, processing and characterization of conventional and novel materials as well as constitutive modeling and computational analysis at different scales using state of the art techniques.

Materials research finds applications in a wide range of engineering fields including mechanical, civil, aerospace, biomedical, etc. where the search for materials optimized for specific applications is driven by engineering and economic considerations and by increasingly stringent regulations on efficiency and sustainability. It therefore acts as a platform for multidisciplinary research across various disciplines represented in Khalifa University.

 

The materials research group at the department of mechanical engineering is currently overseeing the implementation of the following research projects:

Design and Characterization of light-weight hierarchical iron-based shape memory alloys for aerospace and vehicle design applications

Super-strong and Multifunctional Carbon-Nanotube-Fiber Reinforced Composites for Aerospace Applications

Stochastic deformation and failure processes in heterogeneous materials

Fluid-structure interaction in underwater blast loading


Design and Characterization of light-weight hierarchical iron-based shape memory alloys for aerospace and vehicle design applications

Abstract

Hierarchical materials are characterized by a distinct, organized structure that takes place at one or more length scales. Examples of naturally-occurring hierarchical materials include wood and mollusk shells, for which the existence of small length-scale hierarchy is known to significantly enhance their mechanical properties compared to their constituents. The objective of this project is to develop smart materials with optimized artificial microstructural hierarchy for the purpose of maximizing strength-to-weight ratio and energy dissipation per unit volume for applications in the aerospace, automotive and civil engineering fields. The base materials are chosen to be iron-based shape memory alloys (SMAs), which are emerging as less expensive alternatives to conventional SMAs such as Nickel-Titanium.

Personnel

PI:Dr. Wael Zaki
Co-PIs:Dr. Bashar El-Khasawneh, Dr. Kyriaki Polychronopoulou, Dr. Rachad Zaki
Research Assistants: Cheikh Cisse (PhD student)

Time frame

Sep. 2013 – Dec. 2015

Funding

Khalifa University Internal Research Fund level 2 (AED 2.938M)

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Super-strong and Multifunctional Carbon-Nanotube-Fiber Reinforced Composites for Aerospace Applications

Abstract

In aerospace applications, energy efficiency and safety are two major concerns. Fiber-reinforced composites is replacing conventional engineering materials in structural applications to achieve energy saving, while time-consuming non-destructive methods or complicated sensing techniques are used in structural damage detection. We propose to develop a new class of composite that offers an outstanding structural performance combined with continuous structural health monitoring and on-line damage detection.

This new composite material is based on high-performance carbon-nanotube (CNT) fibers that have demonstrated previously by the PI. These CNT fibers have a very low density of 0.2-0.3 gcm-3, and an extremely high specific strength (~16.5 N/Tex, or ~16.5´106 N×m/kg). They are stronger and lighter than the carbon fibers that are currently used in aerospace composites. We will optimize the fiber spinning process, fabricate super-strong and lightweight composites reinforced by these CNT fibers, and demonstrate their structural capability.

The unique nanostructure of CNTs also allow scientists to add new functions to the resulting composites. It is reported that a reversible color change could be achieved in functional CNT composite. In this study, we will integrate CNTs with polymer to form a novel functional composite capable of undergoing a color change following the application of an electrical current. This electrochromatic composite will provide for the novel in-situ monitoring of structural integrity in an aircraft. Compared with other detection methods, the composite fibers can be easily incorporated into structural materials, enabling damage detection to be completed in a very short time.

These super-strong and multifunctional CNT-fiber-reinforced composites could also lead to new and exciting applications in aerospace and other areas such as energy, body armor, marine, and sport goods.

Personnel

PI: Dr. Lianxi Zheng
Co-PIs and Collaborators: Dr. Kin Liao, Dr. Wesley James Cantwell, Dr. Rehan Umer, Dr. Ibrahim Yildiz, Dr. Yuanqing Li.

Time frame

Sep. 2014 – Dec. 2016

Funding

Khalifa University Internal Research Fund level 2 (AED 2.3M)

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Simulation of deformation and failure of random heterogeneous materials

The complex and irregular microstructure of almost every engineering material results in spatial variations of mechanical and physical properties across multiple length scales. Such irregularity is often totally random in nature due to uncertainties in the manufacturing processes, and can be statistically quantified from observations of the material microstructure. Strong geometric disorder of microstructural features as well as large discrepancies between material constituent properties can lead to significant statistical scatter in the material response, which needs to be included in numerical simulations in order to predict the mechanical behaviour at the appropriate length scale.

This project is a collaborative effort concerned with the development of numerical models able to predict the mechanical response of heterogeneous materials with random spatial variations of material properties across multiple length scales. Current research topics include the following:

  • Predictions of fracture processes and statistical size effects on the strength of fibre-reinforced composites
  • Simulation of the elasto-plastic response of heterogeneous ductile solids featuring spatial microscopic variations of mechanical properties
  • Predictions of the elasto-plastic response of ductile porous solids with random pore distributions

Material Research - Department of Mechanical Engineering at Khalifa University

Personnel

Dr. Andreas Schiffer, Assistant Professor

Dr. Vito Tagarielli, Senior Lecturer, Imperial College London

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Fluid-Structure Interaction in Underwater Blast Loading

The response of submerged structures to underwater blast is an important consideration in the design of military ships and submarines. The structural motion induced in a blast event gives rise to complex cavitation processes in the fluid which significantly affect the loading imparted to the structure, and render predictions of their response extremely difficult. To provide guidelines for blast-resistant design of structural components, we developed numerical and theoretical models able to predict the blast response of fibre-composite plates, foam-cored sandwich panels and multi-walled structural systems, explicitly accounting for the occurrence of cavitation in the fluid. Future research activities include development of a laboratory-scale underwater shock apparatus and design of new light-weight structural systems able to provide optimal protection against blast loading in water.

Material Research - Department of Mechanical Engineering at Khalifa University


Highly nonlinear solitary wave interaction with biological tissues for quantification of bone quality

Osteoporosis is a wide-spread disease affecting millions of people worldwide and in the UAE. Due to the increasing trend of incidents of osteoporosis-induced bone fractures in male and female adults, advanced diagnostic methods for assessing bone quality have recently gained great importance. In this project, the idea of assessing the health status of bone in vivo by a novel portable device is considered. It consists of a linear chain of granular crystals able to support propagation of highly nonlinear solitary waves (HNSWs) whose interaction with the adjacent inspection area is highly sensitive to the bone mechanical properties. The project combines experimental and computational tools and aims at understanding the fundamental physics of the interaction between HNSWs and the inspected biological tissue. The project findings are seen as a preliminary step towards development of a HNSW-based sensory device for non-invasive detection of osteoporosis in human bone.

Personnel

Dr. Andreas Schiffer
Dr. Tae-Yeon Kim

Time Frame

Jan 2016 – Dec 2016

Funding

Khalifa University Internal Research Fund (KUIRF) Level 1 (AED 190k)

Personnel

Dr. Andreas Schiffer, Assistant Professor 

Dr. Vito Tagarielli, Senior Lecturer, Imperial College London

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