58th AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, AIAA SciTech Forum, (AIAA 2017-1832)
Aerospace structures are required to be lightweight. Thin-walled beams are very common aerospace structures because they are light and possess the ability to operate in complex loading environment with combined axial, bending, shearing and torsional loads. These thin-walled structures may have either open or closed cross sections with a variety of sectional shapes such as I, C, V, Z and circular sections. Eventually, they all come under the category of dimensionally reducible structures. Unlike existing models for analyzing the thin-walled beam sections in the literature, the Variational Asymptotic Method (VAM) allows for a beam formulation that is free of ad hoc assumptions. This work is a summary of efforts put towards modeling thin-walled beams using VAM. Using nonlinear composite beam theory developed by the second author and coworkers, this work presents verification of results for a thick- to thin-walled Z-section beam obtained from VAM when compared with thin-walled beam theory solutions and solutions obtained from commercially available finite element tools. This work also demonstrates that while typical thin-walled beam theory is asymptotically correct, the VAM is advantageous over thin-walled beam theory solutions in capturing more information for a given cross section. This work also addresses a concern of interaction of small parameters that occurs in very thin-walled beams while being solved using VAM. An approach with shell and plate theories as the starting point has been presented through this work.
A Multifunctional Composite System for Rotorcraft Structures - An Investigation of Energy Harvesting and Storage Characteristics
Sustainability 2015 - AHS Montréal-Ottawa Chapter
The objective of the project is to propose a multifunctional composite material system for next generation rotorcraft’s structural components. In particular, a hybrid composite termed as Piezo-Battery Fiber Reinforced Composite (P-BFRC) comprising of piezoelectric and battery fibers is proposed for the rotorcraft blades, which are arranged in an appropriate optimized fashion. For the fuselage skin panels, use of Battery Fiber Reinforced Composite (BFRC) is proposed. In the rotor blades and the regions where vibration amplitudes are larger, the P-BFRC structure aims to extract electrical energy from the structural vibrations using the piezoelectric panels and store it within the battery panels embedded in the structure itself. In the fuselage, the battery composite skin panels, upon charging from ground station, can serve as power source for operation for several rotorcraft’s electrical and electronic components. Importantly, the proposed multifunctional structure is optimized such that the structural characteristics of the existing rotorcraft is not compromised, while simultaneously performing its multiple functions. In other words, introducing such multifunctional material does not increase overall weight nor reduce the structural load carrying capability. In addition, the proposed material system intend to make minimal modifications in the existing system as far as structure and power management systems are concerned, thereby a re-design of entire structural/power system is not necessary. Preliminary analyses have been conducted for to study the energy harvesting and storage characteristics of the multifunctional structure. This work focuses on detailed quantification of energy harvesting and storage capabilities of the proposed multifunctional system through appropriate electro-mechanical models. Altogether, the multifunctional structural system is found to be a promising step towards a cleaner and sustainable aviation.
American Helicopter Society, Forum 72, May 16-18, 2016, West Palm Beach, FL
The objective of the project is to propose a multifunctional composite material system for next generation rotorcraft’s structural components. In particular, a hybrid composite termed as Piezo-Battery Fiber Reinforced Composite (P-BFRC) comprising of piezoelectric and battery fibers is proposed for the rotorcraft blades, which are arranged in an appropriate optimized fashion. The optimized layout will depend on the characteristic of vibrations in the rotor blades and associated structural components. For the fuselage skin panels, use of Battery Fiber Reinforced Composite (BFRC) is proposed. In the rotor blades and the regions where vibration amplitudes are larger, the P-BFRC structure aims to extract electrical energy from the structural vibrations using the piezoelectric panels and store it within the battery panels embedded in the structure itself. In the fuselage, the battery composite skin panels, upon charging from ground station, can serve as power source for operation for several rotorcraft’s electrical and electronic components. Importantly, the proposed multifunctional structure is optimized such that the structural characteristics of the existing rotorcraft is not compromised, while simultaneously performing its multiple functions. In other words, introducing such multifunctional material does not increase overall weight nor reduce the structural load carrying capability. In addition, the proposed material system intend to make minimal modifications in the existing system as far as structure and power management systems are concerned, thereby a re-design of entire structural/power system is not necessary. Preliminary analyses have been conducted for to study the energy harvesting and storage characteristics of the multifunctional structure. This work focuses on detailed quantification of energy harvesting and storage capabilities of the proposed multifunctional system through appropriate electro-mechanical models. Altogether, the multifunctional structural system is found to be a promising step towards a cleaner and sustainable aviation.