Study of materials behavior in extreme environments and development of new materials for such environments has become a vital research area for materials scientists and engineers in the 21 st century. Mechanical properties of materials under dynamic loading are considered as an important area of research and development in defense, automotive and aerospace industries. Under dynamic loading conditions, the inertial effects come to play an important role in the deformation behavior of the material. Many materials exhibit strain rate sensitivity at higher strain rates, i.e., flow stress dependence on strain rates. In addition, the failure mechanisms under high strain rate loading conditions are generally different than those occur in low strain rate. Furthermore, the deformation and failure mechanisms are controlled by the microstructure of the materials. This course will be important to mechanical, materials and civil engineers to understand materials behavior for ballistic applications, explosive forming or welding applications, automotive and aerospace applications.
INTENDED AUDIENCE: Mechanical Engineers, Civil Engineers, Materials EngineersPREREQUISITES: Solid Mechanics and basic Materials Science course
COURSE LAYOUT Week 1: Introduction: dynamic deformation and failureWeek 2: Introduction to waves: elastic waves; types of elastic waves; reflection, refraction and interaction of wavesWeek 3: Plastic waves and shock waves: Plastic waves of uniaxial stress, uniaxial strain and combined stress; Taylor’s experiments; shock wavesWeek 4: Shock wave induced phase transformation; Explosive-material interaction and detonationWeek 5: Experimental techniques for dynamic deformation: intermediate strain rate tests; split Hopkinson pressure bar; expanding ring test; gun systemsWeek 6: Review of mechanical behavior of materials (especially metals): Elastic and plastic deformation of metals; dislocation mechanics;Week 7: Plastic deformation of metals at high strain rates: Empirical constitutive equations; relationship between dislocation velocity and applied stress; physically based constitute equationsWeek 8: Plastic deformation in shock waves: Strengthening due to shock wave propagation; dislocation generation; point defect generation and deformation twinningWeek 9: Strain localization/shear bands: Constitutive models; metallurgical aspectsWeek 10:Dynamic Fracture: Fundamentals of fracture mechanics; limiting crack speed, crack branching and dynamic fracture toughness; spalling and fragmentationWeek 11:Dynamic deformation of materials other than metals: Polymers; ceramics; compositesWeek 12:Applications: Armor applications; explosive welding and forming