Resources for learning about aircraft structural design using composites?
Resources for learning about aircraft structural design using composites?
(OP)
Some of you especially those who do work in aircraft structures may be familiar with Bruhn's Analysis and Design of Flight Vehicle Structures. I've heard great things about the book but was also told that it was written for metal structures.
Is anyone familiar with any books written in a similar style to Bruhn but teaches aircraft structural design with composites in a comprehensive manner? A book that relates aircraft structural design to FEA would be even better.
Some of the books I've come across including Jone's Mechanics of Composites Materials only have a chapter or so giving and introduction to the composite structural design process. From the brief look I've taken at Bruhn's book, what I like is the numerous worked out examples covering nearly every structural component of an airplane. His approach seems very practically minded unlike some books which are heavy in theory but light in practice.
Is anyone familiar with any books written in a similar style to Bruhn but teaches aircraft structural design with composites in a comprehensive manner? A book that relates aircraft structural design to FEA would be even better.
Some of the books I've come across including Jone's Mechanics of Composites Materials only have a chapter or so giving and introduction to the composite structural design process. From the brief look I've taken at Bruhn's book, what I like is the numerous worked out examples covering nearly every structural component of an airplane. His approach seems very practically minded unlike some books which are heavy in theory but light in practice.





RE: Resources for learning about aircraft structural design using composites?
If you have to choose just one of Michael Niu's books his "Airframe Stress Analysis and Sizing" is probably most useful. Like many engineers I own all three of his books and would certainly buy more if he produced them. I remember being quite excited when his first ("Airframe Structural Design") came out in 1988. We had someone who was in the States bring back a couple of dozen copies all of which were snapped up in spite of the cost.
Niu is aware of FE analysis and how it impinges on design and analysis but it's not a major issue in his books, though it is mentioned occasionally. I'm not sure what book deals comprehensively with practical aspects of FE.
RE: Resources for learning about aircraft structural design using composites?
I think one of the challenges with composites is that many of the practical methods are semi-empirical (engineering solution). Therefore, the books from academia do not tend carry over well to practical composite structure. This is because academia seeks to find the physical nature of analysis and they shy away from semi-empirical approaches, which can be fluid. Conversely, metals are relatively well suited to many classical solutions. Therefore, much of the work from academia (and the associated books) tend to carry over to practical analysis better. At the very least, this provides a better foundation for practical metal structural analysis, which is why then tend to be more developed.
Brian
www.espcomposites.com
RE: Resources for learning about aircraft structural design using composites?
Cpinz
RE: Resources for learning about aircraft structural design using composites?
I am eagerly awaiting your book on Composite Design/Stress Analysis to come out. I am looking for such a resource which is aimed at practicing engineers.
One of the good thing about Flabel is inclusion of numerous examples to illustrate application of various concepts. I hope you follow similar pattern for Composite Materials.
Just wanted to post this...
Thanks for making an attempt to publish such an above book.
RE: Resources for learning about aircraft structural design using composites?
It eventually became clear that what Flabel did with metals was not going to work as well for composites. This occurs for a variety of reasons, but mostly because of (a) the semi-empirical nature of practical composite analysis and (b) the many failure modes of composites (especially the interlaminar failure modes).
That said, the goal changed to providing: detailed explanations of what to do and pitfalls to avoid, formulas that are effective and commonly used, physical explanations of how to tie everything together, and trying to make it as organized and clear as possible. By focusing on this approach, there was no room left for examples. In addition, original attempts at providing examples muddied the waters and made it a difficult read. Composite analysis tends to be more mathematically involved than metals.
There is still an effort to provide examples. But those will either be done in another book or provided online. I think that by decoupling the reference book from the examples, it will be easier to digest the material.
Brian
www.espcomposites.com
RE: Resources for learning about aircraft structural design using composites?
One more topic possibly if included will be of great help. I assume currently majority of the sizing of composite components will be done using FE. So may be a brief explanation/illustration of how to model laminate panels in FE for most commonly used FE solvers (Nastran, Ansys & Abaqus)? Also how to post process FE results. For example, one firm which is consulting on MRB Stress for composite parts uses FE results to determine interlaminar peel stresses at ply drop-offs/transition, at curvatures & right-angled parts (T-junctions etc).
RE: Resources for learning about aircraft structural design using composites?
The approaches to address interlaminar failure modes are not universal. Stress based solutions can work for some problems, provided they are calibrated via test and the derivatives are not considerably different than the validated range. Curved beams are commonly addressed in this manner. For some problems, the trend is to use interlaminar fracture mechanics since you frequently need to account for possible manufacturing disbonds/defects or delamination after impact. Stress based solutions are not as good for those cases because of the sharp stress gradients (or infinite stress) that may exist (among other reasons). In either case, when interlaminar stresses dominate the structural capability, you will need a lot of testing to validate whatever method you use (or may exclusively use testing with the recognition that predictive methods are relatively undeveloped for these failure modes). You can't simply use an interlaminar strength and combine it with a FEM. Interlaminar strength design values are very much configuration dependent and contrary to what some may believe, are not true material properties. The same can be said for the fracture properties, but to a lesser degree.
Brian
www.espcomposites.com
RE: Resources for learning about aircraft structural design using composites?
RE: Resources for learning about aircraft structural design using composites?
RE: Resources for learning about aircraft structural design using composites?
After that, things become a challenge because the academic and engineering approaches tend to diverge (though some of the academic material carries over). The most complete single resource is probably CMH-17. But that may be difficult to transition to. I think the book by Baker, Dutton, Kelly (mentioned in the 3rd post) does a good job at introducing some of the practical aspects. ASM Volume 21 also has some good information. Some other practical oriented books are by Niu and Kassopglou. After that, you have to start looking at the technical papers. Much of the really good information is found in them, but that is a time consuming task. Furthermore, you have to know which papers are the useful ones.
Note that all of this assumes you have a strong foundation of the basics. If not, you may be better served by first improving skills in mechanics of materials or other areas related to your field. Even if those books concentrate on metals, you will be better prepared to address composites when you are ready to do so. I think there is a general tendency to want to jump into more specialized areas like composites or FEA without having a strong foundation of the basics.
Brian
www.espcomposites.com
RE: Resources for learning about aircraft structural design using composites?
Are you familiar with Krisham K Chawla's Composite Materials?