Wanis Nafo - Previous research

Research Interests

Non-destructive characterization of the mechanical properties of soft and hard tissues and polymers

The identification of mechanical properties of materials without causing permanent damage to their structure has been a long-standing challenge in the field of materials science. My research focuses on implementing a novel approach based on utilizing non-linear solitary waves to overcome this dilemma. By observing the forces and deformations generated by solitary waves in a variety of materials such as silicon rubber, nylon, trabecular bones, soft biological tissues, and polyurethane, it is possible to determine the unique mechanical characteristics of each material. This investigation has yielded valuable insights into the behavior of different materials, and the results have several potential applications in the fields of orthopedics and automotive industry.

Modelling and numerical simulations of surgical implants

Several medical implants experience mechanical complications when deployed in the human body. Recently, a study was performed to investigate the causes of premature cord failure of a new system for correcting spine deformity (Vertebral Body Tethering). Numerical modeling was used to understand the mechanism of the stresses arising from the contact between the screws’ heads and the system’s cord. The outputs of this investigation attracted significant attention in the 56th Scoliosis Research Society meeting (Missouri, USA), and it has won the prestigious John H. Moe award during the meeting.

Stress concentration due to screw malalignment

Mechanics of biological structures

Investigating the mechanics behavior of instrumented spines to understand the patterns of physiological loads, unloading patterns, and their implications on the development of the spine.

Porcine spine instrumented with Magnetically Controlled Growing Rods

Experimental and numerical investigations for characterization and prediction of metals' mechanics under quasi-static and dynamic loading conditions.
Fatigue and fracture mechanics of metals under fatigue loads.

Using Experiments and numerical simulations to investigate the mechanics of PVA hydrogels and their potential applications as alternatives to biological tissues.
Experiments were performed using different loading systems such as Universal Testing System (Instron, USA), and Bio-tester (CellScale, Canada).
Numerical simulations and analytical modeling were performed by various FE solvers packages (Abaqus & Ls- Dyna), and different programming tools (Fortran, Python and Matlab).
Investigating the mechanics of soft materials such as PVA hydrogel, bovine- and porcine liver tissues experimentally and numerically by imposing controlled cavity deformations to their internal structures. The investigation encompasses the elastic and viscous behaviors of these materials.

CT technology, building CAD and FE toolkits

Using industrial and medical CT scan technology systems (e.g., GE phoenix v|tome|x s), I have participated in a variety of projects, including

Investigating the internally deformed structures of specimens tested by the controlled cavitation rheology technique: Nafo, W. & Al-Mayah, A. Exp Mech (2019) 59: 1047. https://doi.org/10.1007/s11340-019-00504-4.
Detecting Iron based and Bismuth based nano-particles in different soil media. This project was performed in collaboration with Prof. Neil R. Thomson: Linley S, Holmes A, Leshuk T, Nafo W, Thomson NR, Al-Mayah A, McVey K, Sra K, Fu FX. Chemosphere. https://doi.org/10.1016/j.chemosphere.2018.10.046.
Performing non-contact measurements to create CAD models and FE mesh in several projects, including:

Xenith NFL helmet: An award-winning FE toolkit was created by the IMMC group led by Prof. Duane Cronin. The model geometry was obtained by scanning the helmet components at the IMI lab.
Human cadaver feet: CAD models were created for human feet as a part of a project that investigates their bone strength. The projectis led by Prof. Naveen Chandrashekar.