An innovation that helps speed the design of fishing rods, satellites and cellphone electronics soon will help the U.S. Navy save millions in costs and downtime, while extending the service life of helicopters.
AnalySwift LLC, a Purdue University-affiliated commercial software provider, has received a $240,000 Small Business Innovation Research program grant from the Navy. The SBIR award will help the company further develop its SwiftComp software, technology that provides efficient, high-fidelity modeling of composites.
“We are excited to partner with the U.S. Navy to help address this challenge,” said Allan Wood, president and CEO of AnalySwift. “The Navy is going to be able to use the resulting software technology to properly align a helicopter’s predicted life to actual service life, reduce downtime in redesigns and, ultimately, save money.”
Wood said the software would help meet a need by the Navy and others involved with rotorcraft. The specific project is aimed at advancing the software to better predict the durability of flexbeams made from composite materials, which are materials made from two or more different materials that when combined are stronger, lighter or have other advantages over those individual materials by themselves.
A helicopter flexbeam is the critical component that connects the blade with the hub. Flexbeams made from composites are particularly difficult to design and analyze due to their complexity, including their tapered and curved nature and complex microstructures.
While NAVAIR policy for durability determined by analysis typically requires the analysis to show four times the service life required, the reality is that testing shows actual life well below required service life and what was analytically predicted. This discrepancy between predicted life and tested life has cost both time and money in redesign, with efforts spanning years and costing millions of dollars.
Attempts to address these shortcomings have included changes in the ply layup as well as the locations of ply drops with respect to the neutral axis to improve life. A lack of physical understanding of the physics involved in flexbeam fatigue failure prevents basing the redesign on a more accurate analysis method or understanding than originally used to cleared the failed part.
Instead, the same analysis used to show that the failed part had sufficient life is reused on the newly designed part — historically with little success. That analysis is inadequate because these are complicated composite structures with hundreds of plies, often hybrid materials, and twisted and tapered geometry. Additionally, the loading environment, while understood, is equally complex with axial, bending and torsion loads. This loading leads to multiaxial stress that, combined with the geometry of flexbeams, makes determining stresses/strains at the ply level of first importance, but is often ignored.
“Our specific project aims to enable an efficient high-fidelity tool set with significantly improved durability predictive capabilities for composite flexbeams using user-defined elements,” Wood said. “Success of this proposal will produce a practical solution for efficient yet accurate durability analysis of composite flexbeams.”
In addition to better strength and durability analysis for curved and tapered composite structures such as composite flexbeams, the project aims to enable:
* Significantly reduced time and cost used for design and redesign of complex composite structures.
* More insightful guidance for experiments in understanding the effects of ply drop-offs and other defects of composite flexbeams.
* More explicit modeling of internal features and defects, easy handling of hybrid materials and direct incorporation of new material models.
Although the direct commercial application is durability analysis of composite flexbeams used by the Navy, the proposed work will have many other potential commercial applications:
* Composite helicopter rotor blades, which are usually tapered with ply drop-offs along the span-wise direction.
* Composite wind turbine blades with cross-sections varying significantly.
* Complex composite structures featuring non-uniform cross sections used in aerospace, automotive, and sports.
* Thick composite structures where ply-level stress and durability prediction is critical.
The technology was developed by Wenbin Yu, a professor of aeronautics and astronautics in Purdue’s College of Engineering.
The software also has been licensed to companies and universities worldwide, including those using it for work on satellites and mobile phone components, including printed circuit boards.
“One of the advantages of the SwiftComp software is its ability to carry out efficient high-fidelity multiscale modeling for structures featuring complex microstructures,” Yu said. “SwiftComp takes details of the fundamental building block of materials and structures as input, then outputs the structural properties needed for macroscopic analysis. It can be used for composite beams, plates and shells, and 3D structures, for both micromechanical and structural modeling. This project will help expand the application of SwiftComp even further for composites used in rotorcraft and other applications with curved or tapering structures, as well as applications where a clear understanding of durability is critical.”