Our research group mainly focuses on the following research areas by using some of the state-of-the-art techniques including peridynamics and inverse finite element method (iFEM)
The peridynamic theory provides the capability for improved modeling of progressive failure in materials and structures. Further, it paves the way for addressing multi-physics and multi scale problems. Even though numerous journal articles and conference papers exist in the literature on the evolution and application of the peridynamic theory, it is still new to the technical community.
Damage initiation and its subsequent propagation in fiber-reinforced composites are not understood as clearly as they are, for example, for metals because of the presence of stiff fibers embedded into the soft matrix material, causing inhomogeneity. Under the assumption of homogeneity, a lamina has orthotropic elastic properties. Even though this assumption is suitable for stress analysis, it becomes questionable when predicting failure. Most composite structures include notches and cutouts, not only reducing the strength of the composites but also serving as potential failure sites for damage initiation. They also promote common failure modes of delamination, matrix cracking, and fiber breakage. These failure modes are inherent to the inhomogeneous nature of the composite, thus the homogeneous material assumption taints failure analyses.
CORROSION DAMAGE MODELLING
Due to their unpredictability, rapid growth and difficulty of detection, localised forms of corrosion represent a threat to human life and the environment. The current empirical and semi-empirical approaches used by engineers to hinder corrosion damage have several disadvantages and limitations. In this regard, numerical approaches can be a valuable complement. However, the majority of the numerical techniques currently available in the literature are based on partial differential equations, which become invalid in the presence of field’s discontinuities such as cracks and sharp concentration gradients. In order to overcome these limitations, a recently introduced continuum theory of mechanics based on integro-differential equations, peridynamics, is used modelling of polycrystalline fracture, stress-corrosion cracking, pitting corrosion and crack propagation from corrosion pits in materials exposed to different corrosive environments.
The Arctic is considered as the Middle East of the future. Around 30% of the world’s undiscovered gas and 13% of the world’s undiscovered oil are expected to be stored in the North Arctic Circle. Despite of its advantages, utilization of the Arctic region for sailing brings new challenges due to its harsh environment. Therefore, ship structures must be designed to withstand ice loads in case of a collision between a ship and ice takes place. Such incidents can cause significant damage on the structure which can yield flooding and sinking of the ship. In order to capture the macro-scale behaviour of ice, well-known Finite Element Method (FEM) has been used in various previous studies. The effectiveness of computational techniques such as finite elements in modelling material failure has lagged far behind their capabilities in traditional stress analysis. This difficulty arises because the mathematical foundation on which all such methods are based assumes that the body remains continuous as it deforms. By taking into account all these challenging issues, a state-of-the-art technique, peridynamics will be utilized for ice-structure interaction modelling.
The components of Integrated Circuit (IC) devices are susceptible to moisture absorption at different stages of the production environment which can lead to hygrothermal stresses during the surface mounting process. The moisture concentration in electronic packages can be determined based on the wetness approach. If the saturated concentration value is dependent on temperature or time, the analogy between the wetness equation and the standard diffusion equation is not valid and requires special treatment. Peridynamics is utilized for the solution of wetness field equation in the case of saturated concentration varying with time.
EXTREME LOADING ON STRUCTURES
Efficient quantitative assessment of damage to structures is an active need that hasn’t been satisfactorily addressed. From a defense perspective, damages to structures stem from two main modes of loading: explosions leading to airblast loading on a structure, and direct strikes causing damage through penetration. In some cases both modes coexist. Both of these loading modes have the potential to cause extensive damage on both the external and internal structure. Detection of damage in structures may be straight-forward through visual inspection (cracks, holes, etc.). However, quantification of damage is a daunting task. In addition to the damage that is visible, there exists further damage internal to components and at joints of components. On-site evaluation of damage that is not visible involves expensive specialized equipment, and may not be fully satisfactory in visualization of internal damage. Therefore, damage assessment process stands to benefit from its augmentation by computational modelling and analysis.
STRUCTURAL HEALTH MONITORING
Structural health monitoring (SHM) is a procedure that obtains precise real-time information from a structure regarding its global or local structural state. The main objective of SHM is the detection of unusual structural behaviors, which pinpoint failure or an unhealthy structural condition . Detection of an unhealthy condition not only contributes to the detailed inspection plan of the structure, but also reduces uncertainty concerning the structure that is being monitored. The exercise of SHM serves to both increase human and environmental safety while at the same time reducing maintenance costs. As a consequence, it is necessary to develop a SHM system that uses the measured data obtained from the on-board sensors for any type of practical engineering applications such as bridges, ships, aerospace vehicles etc.