In the March edition of this column, Purdue University’s Dr. R. Byron Pipes suggested “Accelerating the Certification Process for Aerospace Composites” (see "Editor's Picks," at top right) by certifying simulation software rather than manufactured parts (short.compositesworld.com/cdmHUB). This may seem radical, but it is, in fact, a logical concept that is not only possible but also has real potential to reduce and, perhaps, even eliminate the need for physical testing.
But there is a barrier to its implementation: Today’s software-based simulation tools are readily available but they are at different maturity levels, don’t communicate with each other seamlessly and have gaps in processes where no commercial or academic codes exist. Aerospace companies must write their own proprietary codes or develop best practices on the shop floor to compensate for this shortcoming, which ultimately causes delays in manufacturing.
The time and money an OEM invests in composite material testing and part development is extensive. The process is manual, and each OEM has its own processes to certify their parts. There is no “cookbook” for OEMs to use. The slightest design or material change increases cost, reduces productivity and, as a result, lengthens part lifecycles, making it difficult for the OEM to keep its competitive advantage. It is unrealistic, then, to think an OEM or its supply chain could assess the functionality, accuracy and consistency of each simulation tool that is available today. There are simply too many to test and many composites manufacturing methods for which each would have to be validated. The cost alone would be prohibitive, and the effort would further increase time to market.
Theoretically, using the Internet to harvest data for both physical and virtual testing is ideal because all sorts of composite data is easily accessible. Whether data is collected from public sources or is purchased for a fee, it would be easier and faster than physical part testing. But right now, it’s not very practical: Often, virtual and physical test data is gathered from multiple sources that offer different results for the same material, resin and/or manufacturing process. This creates uncertainty about the data’s accuracy. Also, suppliers publish material properties that become the basic information required to run virtual simulations. But this information is typically insufficient, requiring OEMs and suppliers to collect additional performance parameters.
Yes, independent companies also analyze material properties and then publish data on them for a fee. Although this sounds ideal, it is not. There are no uniform criteria for gathering the data. To compensate, OEMs have to purchase multiple material databases. Many times, this approach is still insufficient. Today, there aren’t any better alternatives. The aerospace industry is forced to combine data from multiple sources, a time-consuming and error-prone process.
Although the industry has a long way to go to bring the composites software toolset to maturity and remove the uncertainties associated with composites manufacturing, there are things that can be done to narrow the gap between the virtual and real worlds. One option that would facilitate the maturity process is to have all the toolsets, regardless of maturity level, accessible to all interested parties on an Internet-based platform.
One such platform is the Composites Design and Manufacturing HUB (cdmHUB.org). This Web site’s objective is to accelerate the development of, and knowledge about, a comprehensive toolset available to the entire composites community. It’s intended as a platform for the birth, development, refinement, integration and commercialization of the simulation tools necessary to bring composites certification and manufacturing simulation to a level consistent with high-performance composites simulation tools for geometric and structural modeling, such as CATIA, NASTRAN, ABAQUS and ANSYS.
The cdmHUB has been built using the proven HUBZero architecture. The National Science Foundation (NSF) provided more than $30 million in funding to develop the original nanoHUB technology and the HUBZero platform at Purdue University. Today there are 20 HUB organizations at Purdue using the same platform and RAPPTURE software, a toolkit that supports Rapid application infrastructure. (For more, visit https://nanohub.org/infrastructure/rappture/).
Supported by NSF, nanoHUB.org is the largest and most successful HUB. To date, it boasts 10,000 users worldwide. It has more than 350,000 simulations with more than 210 engineering tools to simulate important nano phenomena used in nanoelectronics, materials science, thermal science, physics and chemistry. More than 2,500 content items, such as tutorials, seminars and full classes, are available to the community. The user community consists of students at all levels, research professionals, faculty and industrial users. Tools range from molecular modeling and simulation to photonics.
The primary goal of the cdmHUB is to accelerate the rate of development of composites simulation tools by an order of magnitude. That will require development of a comprehensive set of simulation tools that connect composites from their birth in manufacturing to their lifetime prediction. With these tools, composites professionals can advance the certification of composite products by analysis validated by experiments, but to do so, current and future generations of engineers must be taught how to use the tools. To do that, software developers must work with industry, academia and government, and a platform like cdmHUB is the vehicle that will make that possible. This cloud-based platform, then, can be the “meeting place” for the composites community, where sustaining sponsors, simulation tool providers, and developers and tool users can work together toward this common goal.
The cdmHUB brings to that community a host of benefits:
- Education in the use of commercial and emerging simulation tool use
- Development of new simulation tools for composites manufacturing
- Evaluation of technology-readiness levels of emerging tools
- Establishment of protocols for simulation tool validation and verification
- Access to data sets required in composites manufacturing simulation
- Forecasts of the unmet needs in simulation tool functionality
- New tool development for composites design, manufacturing and processing simulation
- Development of research needs analysis for simulation tools
As noted by Dr. Waruna P. Seneviratne, technical director/scientist at the National Institute for Aviation Research (NIAR, Wichita, Kan.), building-block analysis validated by testing is a rational multilevel developmental model used by many aerospace companies to certify metallic and composite structures. The cost and time involved in performing experimental tests escalates as the OEM moves from lamina coupons level to details level and, eventually, to component level. So there is the potential for significant cost and time savings, if some of the higher level testing could be reduced through the use of validated analytical models.
Dr. Seneviratne points out that if we are to fully realize the advantages of analysis supported by test, then we must investigate the accuracy and validity of the current state-of-the-art virtual analysis tools in terms of predicting the results of experimental physical tests. When these tools are validated, such analytical models can then be used to model more complex geometries and reduce the burden of certification testing requirements.
Realistically, a lot of work must be done just to get all the existing composites simulation tools gathered into one cyber-community so they can be assessed and brought to the same maturity level. The cdmHUB is designed for that very purpose. In the near future, the aerospace community will be able to log on to the cdmHUB to begin that process.
But … why stop at the aerospace industry? These same tools can be used in the automotive, marine, consumer goods and other industries. What we accomplish here will benefit everyone.
Editor’s Note: HPC will update cdmHUB.org progress as details become available.