A Short History of Early Days of Modern Composite Materials

Stephen W. Tsai, Research Professor Emeritus, Stanford University

(This article is based on “Three decades of composites activities at US Air Force Materials Laboratory,” Stephen W. Tsai, Composites Science and Technology, 65 (2005) 2295-2299, Three decades of composites activities at US Air Force Materials Laboratory. The article was updated in 2015 and is published with the kind permission of Dr. Tsai.)

In the decades of 1960s–1980s, Air Force Research Laboratory Materials Laboratory, near Dayton, Ohio, pioneered many programs and training of personnel that led to major advances in the understanding and utilization of composite materials and structures. The early involvement of industry resulted in rapid identification of the advantages and technical hurdles to be overcome. Through extensive use of postdoctoral appointments, ROTC at universities, visiting and exchange scientists, the Laboratory was able to reach many talented young people who in the years following have assumed leadership in teaching, research and applications of composite materials worldwide well into the 2010’s. A recount of the activities during these three decades is timely because most of the “young” men and women who had spent time at the Laboratory will be ready to retire in the next few years. It is however how small the group of these dedicated people was and the impact that they are continuing to make after over 50 years.

1. Advanced Composites

Project Forecast was an exercise conducted under General Bernard Shriver, Commander of US Air Force Systems Command at the beginning of 1960s. It was intended to assess the potential impact of boron fiber and its composite materials. Having a stiffness twice that of steel, the unidirectional composite would have a stiffness higher than steel but only 1/4 of the weight. That prompted a famous claim that building made with such material could be five times taller, and bridge span, five times longer. Although this forecast has not come true, it did launch composite materials for serious aerospace applications. While glass has phenomenal strength its stiffness is not sufficiently high to be used for load-carrying aircraft structures. Thus a new class of composites, dubbed advanced composites, based on boron fiber and subsequently carbon fibers has been under intensive development ever since. Critical decades of the 1960s through the 1980s were the times when advanced composites emerged. The single most successful class of composites from the standpoint of general acceptance is carbon/epoxy composites. Many other composites were also pursued but have failed to achieve the prominence of CFRP.

The Air Force advanced development program on composites was conceived and implemented by Alan M. Lovelace, then the Chief Scientist and later the Director of AF Materials Laboratory, near Dayton, Ohio, and his point person George Peterson, head of the advanced composites division. A deliberate decision was made to induce industrial participation in the beginning state of this new technology. Then viable infrastructure within each company in support of this technology could be developed concurrently rather than sequentially. Early pioneers from industry included Charlie Roger of General Dynamics/Fort Worth, Sam Dastin of Grumman, and others at North American, Northrop, and McDonnell–Douglas for airframe, and Pratt and Whitney and General Electric for aircraft engines. These industrial projects started in the mid 1960s. The first demonstration was the F-111 horizontal stabilizer by General Dynamics. By the mid 1970s composite components for production began to appear in the horizontal stabilizer of F-14, F-16 and F-15. NASA/Langley later joined the AF and started promoting the use of composites for commercial airplanes. Al Lovelace later became NASA administrator and, after retirement from government, was president of General Dynamics commercial launch service, and is now retired living in Florida. George Peterson retired from the Air Force and lives near Dayton, Ohio. Charlie Rogers retired and so did Sam Dastin. Charlie lives in Fort Worth area and Sam in Las Vegas. At General Dynamics, Fort Worth, there were many young Turks that made important contributions to composites design and testing. Max Waddoups, James Ashton , and R. Byron Pipes were among the most active innovators and doers. They all left GD in the 1970’s and continued to lead development of composites in the years following. Byron in particular went to the University of Delaware and started one of the first composites centers that remains an active entity today. Byron himself moved from the University of Delaware to other universities and is now at Purdue and currently leading a newly established national center in composites manufacturing.

2. Mechanics of Composites

Robert T. Schwartz was the head of nonmetallic materials at AFML that spearheaded in-house research in fibers, matrices and their composites. He initiated micromechanics and many related in-house and contractual programs. In 1966, Jim Whitney was a textile engineer trying to develop the first micromechanics analysis. He was later assisted by another newly hired, freshly minted Ph.D from Drexel in Nick Pagano. Both Jim and Nick have retired. Jim lives in Dayton, and Nick in Columbus. A contract program of the nonmetallic division of AFML with MIT had a graduate student Su Su Wang that performed mechanics analysis and testing of composites. Su Su later headed composites centers at the University of Illinois and is now at the University of Houston leading composites applications for wind and off-shore engineering.

In the years following, Jim earned his doctorate from Ohio State University and did a solution of unsymmetric laminates. Subsequently, he and Jim Ashton of General Dynamics, coauthored a book on anisotropic plates. Among many of Jim Whitney’s accomplishments, he started the American Society for Composites in the 1970s. Jim retired from AFML and now lives in Dayton.

In the mean time, Nick teamed up with Byron Pipes, and wrote a pioneering paper on delamination of composites. Hundreds of papers have appeared since and, as of this date, delamination remains a favorite topic of many researchers. Nick is now retired and lives in Columbus.

Through the years the mechanics tradition continues at nonmetallic division of AFML. The torch is being carried by Steven Donaldson , a Purdue graduate with subsequent Ph.D from Stanford. He also retired from the lab 10 years ago, and began his teaching career at the University of Dayton. He is assisted by Ajit Roy , a Ph.D from the University of Minnesota, who served as post doc with the Lab before eventually joining it. Ajit is still active at the lab. It has long been recognized that composite materials and structures can be most effectively optimized by mechanics principles. They strive for realistic modeling of deformation and failure to supplement and reduce empiricism.

3. Young Officers

AF Materials Lab is often chosen by Reserve Officer’s Training Corps (ROTC) graduates from universities. Among the successful ones include Al Lovelace and George Peterson, mentioned earlier. Since the advent of advanced composites, several officers have made important contributions. One was Robert Rapson who started working for George Peterson in his advanced composites division. Bob progressed in his career with the Lab and served the head of nonmetallic materials, headed by R.T. Schwartz when advanced composites was conceived. Bob Rapson is among the top executives of the Lab.

John Halpin began his research in anisotropic behavior using rubber specimens. His experimental demonstration of the shear coupling effect earned him a doctorate from the University of Akron. He also started the Halpin–Tsai equation and later was a proponent of a wear out model to characterize composites durability.

Other officers include Lawrence Drzal who came to the Lab with a doctoral degree from Case Western Reserve. He set up a surface science lab when he came in the early 1970s. His pioneering work in interfacial strength of composites and bonded joints has been well documented and recognized. He left the AF Lab and started with Michigan State University where he still is a professor of chemical engineering. In recent years, Larry has expanded his composites research to include natural fibers.

Another officer, Karen Knoll, came from MIT. She designed a Read Only Memory module for a hand held computer (Texas Instrument TI-59). She was also instrumental in writing operating instructions for classical laminated plate theory and quadratic failure criteria. It was an exceptionally user-friendly tool by the standard of the late 1970s, an era before personal computers. After Materials Lab, Karen worked for industry in Houston and later in Florida.

Jocelyn Patterson was another MIT graduate that helped the Lab to promote simplified design methodology of composites. She later went to Stanford and received her Ph.D and did her research in thermal/curing warping of composite components. She now works IDA near Washington, and was recently promoted to Major General in the USAF reserve.

Jerry Flanagan also came to the lab from MIT. He worked with exchange scientists Dietmar Wurtzle from the German Aeronautics and Space Institute (DFVLR) in Stuttgart and Thierry Massard from the French Commission of Atomic Energy (CEA) in getting design methodology of composites on some earliest models of personal computers in the early 1980s. Jerry left the lab and started working for Grumman for several years before he joined Material Sciences Corporation. One of his recent contributions is to manage Mil Handbook 17 for the Department of Defense. Dietmar has recently retired for DLR (a more recent name for DFVLR), and Thierry is the Chief Scientist of the military branch of CEA near Paris.

Speaking of MIT, the AFML supported Prof. Jim Mar of the Department of Aeronautics & Astronautics. There were a group of graduate students support in part by this program; among them were Paul Lagace , Hugh McManus , Ed Crawley , Stephen Nolet , Jerry Fanucci , and many others. Through the years, all of them have made impact on composite materials. Paul is the greatest supporter of the International Conference on Composite Materials, Hugh works with composites, Ed because chair of A&A, Steve is known among the best engineers in wind turbines, Jerry until recently owned and operated a successful composites company, KaZak Composites.

Russ Kurtz joined the Lab from Purdue and went on to Pentagon and later became the commander of the high speed test track in New Mexico.

4. NRC Post Doctorate Program

The US National Research Council had an active post doctorate and senior program with AF and NASA laboratories. Many young and senior Ph.D’s spent time at AF Materials Laboratory. One of the earliest ones was H. Thomas Hahn, a Penn State graduate, in 1970. He worked with Steve Tsai and coauthored their first book: Introduction to Composite Materials. Tom left the lab and joint Livermore National Lab in late 1970s and then went on to Washington University, Penn State University and has just retired from UCLA. He was active in a variety of research topics in composite materials behavior and manufacturing processes. He also took over as editor-in-chief of Journal of Composite Materials from Steve Tsai.

Jonathan Awerbuch was a Technion graduate. He did ballistic penetration and acoustic emission. Subsequently he joined Drexel University and is still there. Jack Weitsman was a senior post doc. He covered many topics related to composites with special emphasis on nonlinear behavior of composites under loads and subjected to moisture absorption. He is now with the University of Tennessee.

Ralph Nuismer was a Ph.D from the University of Utah. He and Jim Whitney did the Nuismer–Whitney criteria for stress concentration at the edge of an open hole. The average stress and point stress criteria applied to the open hole stress concentration are still in use.

Michael Hyer of the University of Michigan spent time at AF Materials Lab and has covered the behavior of unsymmetric laminates more thoroughly than almost anyone in the world. He is now with Virginia Tech.

Ippei Susuki came to the lab to study, among many topics related to metals and composites, failure criteria and laminate optimization. Several years later he returned to the Lab for another summer visit. In Japan, he worked for Japan Aerospace Laboratory (ARL, recently renamed JAXA) where he built a combined stress tester from the ground up and made significant contribution in measuring composite laminates and high strength metals subjected to combined stresses. Recently he was in charge of the safety of launching the Japanese rocket. It was a successful launch.

Other notable post docs include Som Soni who started AdTech after he left Materials Lab. He did extensive graphical representation of failure criteria. Ajit Roy came from the University of Minnesota and worked on linear and nonlinear behavior of composites. He is now a permanent member of the Lab. Seng Tan was another post doc and solved a wide variety of problems. He headed a small company named Wright Materials Research until his untimely death in 2014. Peter Sjoblom was a graduate form the Technical Institute of Linkoping in Sweden and was involved in many composites programs including design software. He later joined the University of Dayton Research Institute and was a major contributor to the determination of bird strike resistance of gas turbine fan blades. He retired from UDRI a few years ago and heads a company near Dayton that is doing work in composite materials.

Prof. K.P. Rao from Indian Institute of Science in Bangalore was a senior post doc. He contributed to the study of waffle plates and developed a simplified design program. He returned to Bangalore and has recently retired. He is now a consultant at Infosys in Bangalore working on Boeing 787 and Airbus 380 projects. Prof. T.S. Ramamurthy was another senior post doc from the same institute and also retired. He did work on bolted joints. N. Balasubramanian did failure theory and retired from Everest Eternitt Company in Bangalore. Prof. H.V. Lakshminarayana was involved in fracture mechanics of composite structures, and has now retired from M.S. Ramaiah Institute of Advanced Studies. All these outstanding people came from Bangalore, more than 20 years before it became famous in the US for its software and out-sourced service centers.

5. University of Dayton Research Institute

In-house research of AFML depended heavily on the close working relation with the professional staff and technicians of UDRI. On top of the list of the professional staff is Ran Kim who since the early 1970 had built a world-class testing facility. He provided continuity and upheld the technical integrity among government personnel, visiting and exchange scientists and postdocs through the years.

Other equally famous alumni of this group included C. S. Hong, who later became the president of the Korea Advanced Institute of Science and Technology (KAIST), a legislator in the Korean government (National Assembly) before his eventual retirement from KAIST. Georges Verchery was also a visiting scientist. After his stay with the Lab, he held several teaching positions in France and was also the Science Attache of the French Embassy in Tokyo. Won J. Park of Wright State University also participated actively in simplified design of composites. He is now professor emeritus.

Antonio Miravete from Zaragoza, Spain, came as a newly wed. He did the laminate optimization and presented stunning graphical representation of ply drops. He has been professor at the University of Zaragoza for nearly 20 years. Antonio chaired ICCM/9 in Madrid in 1993. He now heads a company doing consulting in composite materials. Norbert Himmel, also a newly wed, did three-dimensional elasticity solution for his doctoral thesis. He returned to Germany and worked for Institute of Composite Materials, in Kaiserslautern in Germany before retirement a few years ago.

The Lab was also benefited by having several students during summer vacation from Purdue and the University of Michigan. Steve Wanthal was one of them. After having received his Ph.D from Purdue under Prof. Henry Yang, he started his work with McDonnell–Douglas and now Boeing in St. Louis.

6. Exchange Scientists

There were a number of exchange scientists working in composite materials at the Materials Lab. Jan Erikson from the Swedish defense research institute (FOA) spent many months working with Tom Hahn on the fatigue of composites. Thierry Massard from France helped in introducing personal computers for composites design. He and Jerry Flanagan worked tirelessly in programming many tools including an automated laminate optimization at the beginning days of personal computers (in the early 1980’s). Our division chief at the time was upset by how much time Thierry and Jerry sat in front of monitors. He had no idea that the majority of the workforce today, including students and faculty at colleges and universities, are spending more time in front of computer monitors or screens than any other activity. Thierry and Jerry were just decades ahead of time.

Thierry returned to France and steadily moved on the management chain of the Commission on Atomic Energy of France. He also ran International Conference on Composite Materials in Paris (ICCM/12) in 1999.

There were three exchange scientists from the German Research Institute of Space and Aeronautics (DFVLR) in Stuttgart. Rodolfo Aoki was the first one and was instrumental in testing and evaluation of composites; Dietmar Wurzel was interested in novel design of composites; and Christopher Kindervater was into crash worthiness of composite structures with special emphasis on helicopters. Rodolfo and Dietmar retired from by the successor of organization called German Aeronautics Research (DLR). Chris is still active and served as the head of DLR’s Stutgart’s lab before returning to active research in composite materials.

7. Famous Sponsored Programs

Two very important sponsored programs during the 1970s and 1980s were performed by George Springer at the University of Michigan and later at Stanford University.

The first was the moisture absorption and its impact on properties of composites. He not only set this area of research on a solid foundation in his innovative treatment of the boundary conditions of a diffusion process but also provided data to validate the analytic predictions. For the last 30 years, research on the moisture effect has assumed a life of its own. It refuses to die. Nearly all subsequent efforts were variations of George’s initial effort.

Another equally important program was the cure modeling of composites. This too was done by George. Up till then (and to some extent it still is) curing was regarded as an art, purely empirical. George was able to systematically model the processes of heating, consolidation, void migration and residual stress upon cooling. Once the processes were modeled, optimization became straightforward. He later extended the work to include thermoplastic, microwave cure, and “smart cure” by expert system. Among many of his students, Al Loos and Woo Il Lee are still active in the field. Al is now a professor at Michigan State University after having stayed at Virginia Tech for many years. Woo Il Lee is a professor of mechanical engineering and Vice President (since July 2014) at Seoul National University.

8. Workshops

Many of us were involved in many workshops promoting the use of composites. Dozens were held in the US, nine European and six Far Eastern countries. Many people who were connected with AFML in various capacities were contributors to these workshops.

The longest lasting one was at the University of California, Berkeley, where 17 workshops were held over a span of 20 some years. The attendance varied from 40 to 140. Hundreds of students participated in this series. Many recall the instructions, software practice sessions, wine tasting and Chinese dinners.

Another few workshops were sponsored by SAMPE. In 1989, it was attended by over 300 and the year after was over 400. It did not take a rocket scientist to figure out that there was a lot of money to be harvested. So SAMPE decided to have more than one workshop. In the years that followed, there are 10 workshops presented each year.

9. Macintosh Computers

The first Macintosh computers made its debut in 1984. It had many innovations with its intuitive user interface and easy of use that set a standard that had influenced nearly every electronic device since. This computer had an important connection with composite materials through its spreadsheet that came with the first Macintosh. It is the Multiplan, a forerunner of Microsoft Excel. The often used MicMac (for micro- and macromechanics analysis tool) had its beginning in this spreadsheet in 1984. It has spread among many composites engineers and it is still the backbone of all the graphs and tables in books written later by this author. It is the backbone tool of our online Composites Design Workshop. An iPad app of MicMac is available and can be downloaded without charge.

10. Ten Classic Publications

We wish to honor some of the more influential papers for composite materials research since it the beginning of the advent of CFRP. This list was presented by Byron Pipes of Purdue University at ICCM-16 in Kyoto in 2007.

Hashin, Z., Shtrikman, S. (1963). "A Variational Approach to the Theory of the Elastic Behavior of Multiphase Materials". J.Mech.Phys.Sol. 11: 127–140.

Mori, T., Tanaka, K. (1973). "Average Stress in the Matrix and Average Elastic Energy of Materials with Misfitting Inclusions". Acta metall. 21: 571–574.

S.B. DONG, K.S. PISTER and R.L. TAYLOR, "On the theory of laminated anisotropic shells and plates", Z Aerosp. Sci. 29, pp. 969-975, 1962.

Tsai, S. W. and Wu, E. M. (1971). A general theory of strength for anisotropic materials. Journal of Composite Materials. vol. 5, pp. 58–80.

Pagano, N. J., and Pipes, R. B., "The Influence of Stacking Sequence on Laminate Strength," Journal of Composite Materials, Vol. 5, (1971), pp. 50-57.

Loos, A. C. and G. S. Springer, "Curing of Epoxy Matrix Composites," Journal of Composite Materials, Vol. 17, March, 1983, pp. 135‐169.

Johnston, P. Hubert, G. Fernlund, R. Vaziri, A. Poursartip, “Process Modelling of Composite Structures Employing a Virtual Autoclave Concept”, Science and Engineering of Composite Materials, 1996, 5, 3/4, 235-252.

Rybicki EF and Kanninen MF, "A finite element calculation of stress intensity factors by a modified crack closure integral," Eng. Fract. Mech.,(1977), 9, 931–938.

T.K. O'Brien, "Fracture Mechanics of Composite Delamination," in ASM Handbook Volume 21, Composites ASM International, 2001, pp. 241-45.

T.W. Chou, E. T. Thostenson and Z.F. Ren, "Advances in the Science and Technology of Carbon Nanotubes and Their Composites: A Review, " Composites Science and Technology, 61, 1899 (2001).

11. Reflection

It was clear that AFML through its programs and personnel put advanced composites on their way to success. Many applications of composites for military and commercial aircraft can be traced to the investment made by the Lab. While other agencies and companies around the world all made their marks, AFML stood out as a source of ideas and experts. It is amazing how many of their people are still active in composites, most of them in universities around the world. While General Shriver’s prediction of tall building and long bridge spans might not be precisely right, the foresight and implementation by Lovelace, Peterson and Schwartz made a difference. For all the engineers who have passed through AFML, we appreciate their contributions and lasting commitment to stay with this technology. Their students and colleagues will no doubt carry the torch to see composites reach another plateau.

Have composites reached its middle age? We should think not. The new Boeing 777X will have the longest and biggest composites wing ever made. But its fuselage will not be composites. What does that say about composites after it was touted a great advance for passenger comfort for Boeing 787? For engines, composites are as strong as ever. For automotive it is really in the beginning. This is being spearheaded in Europe. If what Daniel and I are proposing in design and testing become mainstream, the barrier for using composites will be reduced significantly. Many applications not even imagined today will come to past. That would be our greatest reward. It will also give us guidelines for investment and research.

Another historical account worth mentioning is that George Springer, Dick Christensen and Steve Tsai were graduate students at Yale in 1959. Thirty years later, they all become members of Aeronautics & Astronautics at Stanford majoring in composite materials. An incredible coincidence.

?Acknowledgement

This writing is based primarily on memory. When people and activities are cited, omissions would be unavoidable. Please accept apologies for my less-than-perfect memory.