Research

Current Research

​We aim to design new composite joints by engineering the interface morphology in order to improve mechanical performance and safety. Mechanical performance metrics cover the joint strength and toughness. Different surface preparation techniques suitable for composite are explored, and their effect on strength and toughness is measured. Based on the mechanical test data, a more precise cohesive zone model (CZM) for different surface preparation techniques can be determined. This research is funded by KAUST Competitive Research Grant (CRG) where COHMAS is collaborating with the University of Calabria in Italy.​​​​​ ​​
In contrast to a classical measurement of displacement, full-field measurement based on image correlation technology provides a greater insight into detailed, local material properties as well as failure mechanism. This measurement enables one to build a more accurate material model that possesses an excellent predictive capability. COHMAS Laboratory focuses on the development of robust identification techniques that can efficiently process 3-D full-field data. Here, tools necessary for image correlation are designed for complex microstructures.  ​​​​​​​​​​​​​​
This work aims at developing finite element framework of different length-scales (micro- and mesoscale) in order to study damage mechanism of continuous fiber-reinforced thermoplastic composites. At micro-scale, the unit cell (RVE) is defined rigorously by two-point probability function and Hill-Mandell kinematics. Transverse and shear failure in glass/polypropylene at microscale are simulated. Mesoscale models under in-plane tension and out-of-plane (quasi-static indentation) loads will be developed. ​
​Using carbon based nano reinforcements is currently a popular strategy for the synthesis of advanced materials. Generally, the target is to achieve multi-functionality and to fully customize mechanical, electrical and thermal properties of the resulting formulation.
​Improvement in electrical conductivity is necessary to make conductive films, wires and fibers viable candidates in applications such as flexible electrodes, conductive textiles, and fast-response sensors and actuators. Moreover, a dramatic improvement on tensile strength, Young’s modulus on these materials are also important so that they can be use in wearable electronic with a reliable, long cycle life. ​​​​​
​Micro-scale damage process in thermoplastic composites is studied by capturing the initiation and progression of principal damage modes (transverse crack, and its "migration" into delamination). The first attempt is to study the damage process in unbalanced-unsymmetrical cross-ply laminate at quasi-static rate. The next step is to capture micro-scale damage process in the laminate under impact.  ​​​
We work together with SABIC (Saudi Arabia Basic Industries Corporation) in developing multiscale finite element models for predicting the behavior of continuous fiber reinforced thermoplastic composites. To this end, we fully characterize the thermal and mechanical properties of the thermoplastic polymer (of different formulations), damage mechanisms of thermoplastic composites under in-plane tension and out-of-plane loads (quasi-static indentation and low-velocity impact). We developed in situ technique utilizing fiber Bragg gratings to monitor the processing of thermoplastic composites. The experimental part feeds the model with material data, and validates the developed models. ​​​​​​​​​​​
Composite structures are designed to experience severe circumstances in terms of both mechanical loading and environmental conditions. On the short or long term this will eventually lead to degradations of the structure. Understanding the related mechanisms is fundamental to composite materials. Here, we explore the durability of composite materials, and develop structural health monitoring (SHM) technique utilizing fiber Bragg gratings embedded in the composite system.
Integrity assessment technique can be based on the notable function of carbon reinforced composites, which electric conductivity. Taking advantage of this property, it is expected that structural health monitoring is performed through the detection of the change in electric resistance or potential. Electric resistance is supposed to be changed by mechanical strain as well as damage accumulation. Work is conducted to define optimum experimental solutions (electrode constitution and spatial disposition, current control, etc), and to develop micromechanical modeling (influence of fiber realignment and corresponding contact changes, fiber breakage) and inverse approaches. ​
We develop a specific gluing technique, called as morphing method, to couple continuum and nonlocal mechanics models for predicting the material failure. The morphing method couples both models in the level of constitutive parameters in terms of the conservation of strain energy. This capability makes coupling easier to be applied to a complex structure. In addition, this method is easily transferable and nonintrusive for commercial environments.