Mechanics and Materials
The faculty and researchers in Mechanics and Materials group perform research that combines the fundamentals and applications of materials science, solid mechanics and constitutive modelling to understand and characterize existing materials, develop advanced materials, enhance manufacturing processes and design mechanical and infrastructure systems. The research capabilities include analytical characterization tools, microscopic systems, rapid prototyping, mechanical testing systems, and a wide range of computational analysis packages.
The research areas in the Mechanics and Materials group include:
- Nonlinear analysis and constitutive modelling of multifunctional materials for energy applications.
- Mechanical behaviour, constitutive modelling, and microstructural alteration of lightweight materials and superplastic materials.
- Fracture mechanics and contact mechanics of functionally graded materials and metal alloys.
- Development of theoretical/analytical techniques for modelling the static and dynamic behaviour of MEMS/NEMS devices.
- Characterization and development nano-structured metallic alloys, composites and cellular alloys.
- Structural health monitoring and damage identification in existing structures.
- Characterization and modelling of infrastructure materials with considerations to coupling effects of mechanical loads and environmental conditions.
Investigating the Superplastic Behavior of Twin-Roll Cast Magnesium Alloys for Effective Use in Automotive Applications
Modeling of Environmental Assisted Degradation Processes in Asphalt Mixtures Using Micromechanical and Continuum Damage Theories
Characterizing the impact loading response of friction-stir welded (FSW) bimetallic joints
Toward Low Temperature Formability of Damage-Tolerant High Specific Strength Magnesium Alloys: Experiments and Modeling
For the past few decades, experimentally developed and calibrated forming limit diagrams (FLDs) have been used to predict the onset of necking or uncontrolled fracture in sheet metal forming. While FLDs have served a useful purpose when other alternatives were not available, the development and use of new alloys and the increased role of manufacturing process simulation have warranted the need for fundamental models that can accurately predict the onset of fracture in sheet metal forming operations. Such models can significantly accelerate the insertion of newly developed materials and can reduce material waste due to uncontrolled failure. A few models for developing failure criteria are reported in the literature; however, these models are for rate independent materials, and most have ignored the effects of crystallographic texture evolution and the effect of texture on flow strength, ductility and dynamic recovery. Therefore, the goal of this study is to develop a coupled plasticity/damage model with associated laws for microstructure evolution and anisotropic plasticity to predict temperature and rate-sensitive damage accumulation at the low stress triaxialities encountered in metal forming processes. This model will be developed to predict failure in wrought and ultra-fine grained magnesium alloys. The project also aims at identifying grain refinement approaches to improve the room temperature formability of the investigated magnesium alloys.
Multiscale Investigation of the Relationship between the Microstructure and Deformability for New Generation Ultra High Strength Multi-Phase Steels for Automotive Applications
The ever increasing cost of energy coupled with environmental concerns, have lead the automotive industry to consider various energy saving measures. Among them, reduction of the vehicle weight as one of the most effective, provided that stringent safety regulations are maintained. Accordingly, the industry world-wide has been adopting various types of advanced high strength steels (AHSS) which, when properly designed, can have both high strength and ductility. AHSS achieve their strength by a combination of factors: grain refinement, solid solution strengthening and precipitation hardening (PH), transformation strengthening and grain boundary strengthening. Although recent advances have demonstrated the feasibility of using AHSS, there is a lack of fundamental understanding of the driving mechanisms for ductility/formability, strength and fracture/crash-worthiness and how they relate to the underlying microstructure, as well as lack of material models that relate properties to the microstructure. The objectives of this proposed work are:
1) to investigate AHSS steel (with emphasis on DP and PH) by an integrated multiscale experimental and modeling approach to understand the local deformation mechanisms,
2) to identify the appropriate mechanical and microstructural properties that have significant influence on the local deformations, and
3) to develop fundamental understandings on key mechanical properties and microstructure features influencing the local formability.
Surgical Threads Simulations Based on a Novel Information-Theory Approach
Texas A&M University at Qatar in partnership with surgeons from Cornell Weill Medical School at Qatar is proposing a research program aimed at creating a physics-based software that will predict the deformation of surgical threads when subjected to conditions commonly encountered during surgery. Of particular interest is be the study of thread tangling, a non-linear and dynamical process detrimental to surgeons during knot formation. The software will use the Cosserat theory of elasticity, a theory particularly suited to describe long and thin flexible structures which take spiral-type configurations in addition to bend and twist. The uniqueness of the proposed work is the method of solution: a discrete optimization-based dynamic programming technique originally developed for information theory problems of text strings which will potentially reduce the computing time. We also plan an experimental phase on bending and twisting deformations of threads to validate the data with the simulations. The proposed research is interdisciplinary in nature with experts drawn from mechanical and electrical engineering, computer graphics and the medical fields. The outcomes of this research will help fill the gap in the area of medical simulations which lag far behind simulations in other fields. The software will train a new generation of medical school students and will diversify Qatar’s economy.
Design and Evaluation of short-term and long-term performance Warm Asphalt Mixtures in the State of Qatar
Asphalt pavement construction is evolving towards sustainability. In recent years, warm mix asphalt (WMA) technology has proven to reduce energy required to manufacture hot-mix asphalt (HMA), emissions and fumes, and damaging aging of the product over its performance life. Techniques commonly used to facilitate mixing of binder and aggregates in WMA include adding organic or inorganic materials that promote foaming and lower viscosity of the binder, chemicals that serve as a surface-active agent to reduce friction at bitumen-and-aggregate interfaces, and waxes that alter binder viscosity. Physical and chemical properties of the resulting mixture can be significantly affected by the construction technique, which can impact performance. The objective of this proposal is to evaluate various warm mix asphalt (WMA) technologies and their applicability to the climatic and traffic conditions in Qatar. A comparative study is proposed to compare the material characteristics and performance-relayed tests of WMA to that of HMA. In addition to performance testing, cost analysis on the effectiveness of using WMA, including life cycle assessment that considers emission impact on the environment, will be performed for the local case of Qatar.
Defined polymers as candidates for pavement subgrade soil stabilization
It is well-established that pavement subgrade soil stabilization has a major influence on pavement construction and durability and that failure to chemically alter certain subgrades in the state of Qatar has resulted in early pavement failures. In previous work sponsored by QNRF, we explored synthesizing defined polymers as candidate binders for Qatar subgrades, with encouraging practical results, which, in some cases, demonstrated quantifiable engineering advantages over traditional stabilizers including Portland cement and lime. The intended proposal will expand on this investigation. The objectives are to: better understand how the structure of the polymer relates to its efficiency as a stabilizer, particularly for Qatari subgrade soil; tailor a polymer to be compatible with a subgrade soil of defined material characteristics; to carry out mechanical testing in both the laboratory and in the field under realistic conditions (curing conditions, temperature and humidity) with the variants of the polymer binders; explore the utility of the polymer modified systems in various pavement structures compared to structures without stabilization and also with traditional stabilization alternatives using state-of-the-art models that predict pavement performance; carry out a comparative and commercial assessment of a possible candidate judged against standard alternatives, such as cement and lime.
Vehicle Tires and Road Accidents
Mechanical Properties and Durability of Treated Palm Fiber Reinforced Mortars
The main objective of this research is to investigate the feasibility of utilizing treated palm fibers in reinforced mortars. To this effect, mortar mixes with various proportions of palm fiber inclusions will be tested and recommendations will be made on the suitable percentage of these fibers which can be safely incorporated within such mixes without any deleterious effects on mechanical and durability properties.