Current Research: Composite Materials

A. Haque, Ph.D., Associate Professor

Department of Aerospace Engineering & Mechanics

Phone: (205)348-2694     Fax: (205)348-724    Email:  ahaque@coe.eng.ua.edu

Nanocomposites

Polymer nanocomposite is a new class of material in which resin is usually tailored by nanosized reinforcements such as silica, carbon nanotube and carbon nanofiber to exhibit improved mechanical, thermal, electrical and fire resistance properties. The research in this area is primarily focused in studying morphologies, computational stress analysis at the interface and performance evaluation of polymer and carbon/carbon nanocomposites. The major problems in this area are controlling dispersion of nanoparticles, understanding stress transfer at the interface and developing appropriate experimental tools for performance evaluation of this new class of materials. Various functionalization routes and dispersion techniques are studied for understanding the distribution, composition and behavior of nanoscale structures under a wide variety of naturally occurring physical/chemical conditions, including nanoscale interactions at the interface between organic and inorganic solids, liquids and gases, and structures. Some affordable processing routes such as vacuum assisted resin infusion method are also studied for manufacturing continuous fiber reinforced hybrid nanocomposites.  Theoretical models are also developed for stress transfer analysis at the interface of carbon nanotube and nanofiber reinforced polymer matrix composites.

Dispersion Equipment

Interface Modeling (Anlytical -3-D Cyl. Model)

Biodegradable Composites

The research in this area is focused in studying bio-composites in order to develop environmentally friendly tough and lightweight materials.  These bio-composites are going to replace glass fiber reinforced composites currently used in vehicle components. We are going to incorporate cellulose fibers (industrial hump, kenaf, jute, palm, coir, wood) to process both petroleum-based and plant-based “green” biodegradable composites. The plant based plastics will be processed from soybean, wastepaper, corn and sugar through innovative research.  The major challenge of this research is to develop new method for processing natural fiber-reinforced thermoplastics which will closely resemble  current manufacturing practice-such as producing a thin sheet of bio-composite that can be stamped like sheet metal. The researcher at the AIME center, UA has already studied the potential applications of ionic liquids (ILs) as “green” solvent which can replace environmentally undesirable solvents currently used for dissolution of bioresource. Various fiber treatment methods such as pregrafting, presence of the hydroxyl groups of cellulose and polymeric coatings are also under investigation for improved adhesion to matrix materials. Finally, both mechanical and thermal properties of this biodegradable fiber reinforced composites are predicted and evaluated through various analytical models and experimental test methods.

Natural fibers 

Melt processing using Hot-press

Impact and High Strain Rate Loading

The research in this area is primarily focused in understanding the rate effects and failure behavior of both isotropic and anisotropic materials under high strain rate loading particularly using Split Hopkinson Pressure Bar (SHPB) Method. We are involved in developing constitutive equations for modeling the dynamic behavior and failure of anisotropic materials under impact and short duration loading. Most of the constitutive equations developed for simulating high strain rate effects are empirical, and require experimental data for verification of various parameters used in the model. The interaction of many parameters in composites related to material constituents, processing, fiber architecture, lay-up sequence and orientation made the formulation of constitutive equations more difficult under impact and high strain loading. The research in this area addresses the influence of these parameters in high strain rate behavior of composites. Microstructural damage progression at various stress levels and high strain rate loading is an interesting topic which need to be addressed for accurate representation of the physical system. The classical SHPB apparatus has been incorporated by a wave-trapping mechanism to apply a predetermined level of impact loading and to restrict the repeated loading. This facilitates in identifying the microstructural damage progression during the loading period. Current research is also focused in studying various constraints and environmental effects (moisture, temperature) on dynamic response of composites.
 

Split Hopkinson

Performance and Durability

The safe design of a structure requires extensive test data on mechanical performance of materials under static, cyclic and creep loading conditions. The effects of environment such as moisture and temperature also play a major role in the overall performance of structures made of composite materials.  In this research major focus is to develop a performance data base for composite materials under tensile, compression, bending, shear, fatigue and creep loading in order to study and understand the behavior of these materials. These data are also extensively used in developing fatigue and creep life prediction models for both polymer and ceramic matrix composites. An extensive research is also carried out in analyzing the physical system made of composite materials under various loading conditions using finite element method. The performance data generated in the laboratory are applied in our computational analytical and numerical models.   

Servohydrolic Testing Equipment with Environmental Chamber