RESEARCH
EXPERTISE AND INTERESTS

• Solid mechanics
• Fracture mechanics
• Mechanics of novel / non-traditional materials such as:

- layered materials

- functionally graded materials (FGM)

- syntactic structural foams and cellular structures

- additively printed polymer and metallic materials

- micro-/nano-composites and hierarchical materials

- interpenetrating phase composites (IPC)

- interpenetrating polymer networks (IPN)

- soft materials

• Photomechanics / optical metrology
• Non-destructive testing and evaluation (NDT & E)
• Optical/digital image processing

RESEARCH SUMMARY

Broadly my research deals with (a) exploration of fracture and failure mechanics of advanced materials using experimental and computational methods, and (b) development of novel full-field optical sensors for experimental mechanics and metrology. Early on in my career I developed full-field optical techniques based on laser speckles and geometric moiré methods for mapping three-dimensional deformations near cracks and stress concentrations. Subsequently, I developed a real-time optical method called Coherent Gradient Sensing (CGS) suitable for dynamic fracture studies when used in conjunction with ultrahigh-speed photography. CGS since its invention has found other applications such as metrology of thin films/structures as well and has become a commercial metrology tool used by the electronic industry. Concurrently, CGS also contributed to the in-depth understanding of dynamic fracture mechanics of glass polymers, high strength steels and dissimilar material interfaces. In my group, an infrared interferometric sensor has been developed to perform rough surface metrology and flaw detection. It has also been successfully demonstrated to perform real-time fracture mechanics investigation on plastically deformed homogeneous materials and bi-material (e.g., solder-copper) interfaces. My group has been credited with extending the vision-based method of Digital Image Correlation (DIC) to study fast-fracture events under rapid loading conditions using ultrahigh-speed imaging systems. More recently, a new vision-based method called Digital Gradient Sensing (DGS) has been developed by my group for failure characterization and NDE of optically transparent and specularly reflective solids.

My current interests include development and high-strain rate failure characterization of non-traditional materials such as functionally graded materials, hierarchical micro-/nano-composites, structural foams, soft materials, layered structures, lightweight structures, and 3D printed materials. Modeling the failure behavior using computational methods are integral to many of my research projects.  Over the years my research has received sponsorship of NSF, DOD, and NASA and has resulted in over 250 research articles in refereed journals and conference proceedings.