Shankar Mall

Bio: Shankar Mall is an academic researcher from Air Force Institute of Technology. The author has contributed to research in topics: Fretting & Fracture mechanics. The author has an hindex of 45, co-authored 281 publications receiving 6712 citations. Previous affiliations of Shankar Mall include Air Force Research Laboratory & University of Dayton.

Introduction to carbon nanotube and nanofiber smart materials

Abstract: The potential use of carbon nanotubes and nanofibers as smart composite materials is discussed in this paper. An overview of the properties of carbon nanotube materials is presented, and then four applications under development are briefly discussed. The first application is electrochemical actuation in dry and aqueous environments. The second is a carbon nanotube polymer piezoresistive strain sensor developed for structural health monitoring. Third, nanotubes are used with an electrolyte for harvesting power from structural vibration. Fourth, a carbon nanotube bioelectronic sensor is discussed. Tying all this together, a vision is presented for using nanoscale smart materials to synthesize intelligent electronic structures with prescribed elastic and electrical properties for a wide range of new applications. Hurdles to be overcome to achieve this goal are also discussed.

Fretting fatigue crack initiation mechanism in Ti–6Al–4V

Abstract: r Fretting fatigue crack initiation in titanium alloy, Ti-6Al-4V, was investigated experimentally and analytically by using finite element analysis (FEA). Various types of fretting pads were used in order to determine the effects of contact geometries. Crack initiation location and crack angle orientation along the contact surface were determined by using microscopy. Finite element analysis was used in order to obtain stress state for the experimental conditions used during fretting fatigue tests. These were then used in order to investigate several critical plane based multiaxial fatigue parameters. These parameters were evaluated based on their ability to predict crack initiation location, crack orientation angle along the contact surface and the number of cycles to fretting fatigue crack initiation independent of geometry of fretting pad. These predictions were compared with their experimental counterparts in order to characterize the role of normal and shear stresses on fretting fatigue crack initiation. From these comparisons, fretting fatigue crack initiation mechanism in the tested titanium alloy appears to be governed by shear stress on the critical plane. However, normal stress on the critical plane also seems to play a role in fretting fatigue life. At present, the individual contributions/importance of shear and normal stresses in the crack initiation appears to be unclear; however, it is clear that any critical plane describing fretting fatigue crack initiation behaviour independent of geometry needs to include components of both shear and normal stresses.

American Society for Testing and Materials

Abstract: The American Society for Testing and Materials (ASTM) is an independent organization devoted to the development of standards.

Digital Twin in Industry: State-of-the-Art

Abstract: Digital twin (DT) is one of the most promising enabling technologies for realizing smart manufacturing and Industry 4.0. DTs are characterized by the seamless integration between the cyber and physical spaces. The importance of DTs is increasingly recognized by both academia and industry. It has been almost 15 years since the concept of the DT was initially proposed. To date, many DT applications have been successfully implemented in different industries, including product design, production, prognostics and health management, and some other fields. However, at present, no paper has focused on the review of DT applications in industry. In an effort to understand the development and application of DTs in industry, this paper thoroughly reviews the state-of-the-art of the DT research concerning the key components of DTs, the current development of DTs, and the major DT applications in industry. This paper also outlines the current challenges and some possible directions for future work.