Preface

 First Composites Durability Workshop (CDW) was held at Sakai Memorial Hall of Kanazawa Institute of Technology in November 1998. Over the past 12 years, 15 CDWs were held in all over the world in diverse ways. During this period, sincere discussions have been consistently repeated to establish the durability evaluation method of composite materials based on the scientific basis and to construct durability design method based on this evaluation method. These activities of CDWs formed an international current of the durability research on composite materials. Professor Stephen W. Tsai of Stanford University has been the key figure of these activities. His excellent insight of essence of composite materials and extraordinary zeal to try to acknowledge this material to industrial world as structural material with reliability are the driving force of the activities. In a humane atmosphere that the professor created, I am sure that participants of CDWs could have exhaustive discussions and feel certain progress of own research. I am proud that I could take care of CDWs with him these 12 years. Professor Thomas Hahn of UCLA joined us as the facilitator since CDW-11. The managements of 15 CDWs were completely left to everyone in each venue. We wish sincerely to express our gratitude to everyone who worked devotedly.
 This album is three compositions. Firstly, messages from major participants. Secondary, photo collection of 15 CDWs. Finally, programs and lists of participants of 15 CDWs. Spouse list is under the participant list.
 One of the features of this workshop is participation of the spouse. I wish to express my gratitude to Professor Tsai’s wife Iris for warm consideration to every spouse.
 Wishing further development of CDW in the future, this album was put together as the turning point of 15 CDWs.

Yasushi Miyano, Kanazawa   February, 2011

A Modest Beginning
By
Steve Tsai
Palo Alto California USA

 When Yasushi and I planned to kickoff workshop on our newly won NSF project on composites durability in 1998, Iris’ had objection to another meeting; there were already too many. I assured her that it was just a one-event workshop. It turned out that this workshop had its own durability. Certainly we did not foresee celebrating CDW-15 twelve years later. We have been blessed with many loyal participants. We were also smart to have the participation of our wives in Iris, Noriko, Kristy, Lydia, So-Young and others to play king makers in the selection of location for the next CDW. Mr. Iwashita, then the director of research at KIT, had been the benefactor of the hospitality of each and every CDW until his retirement in 2007. We can see from the pictures here that many participants of CDW-1 are back for CDW-15. It showed the commitment by each and every loyal participant and, often times, his wife. Then there has been a highly focused goal of composites durability. During the past few years, much of our collective effort evolved in ATM (accelerated testing methodology) and MMF (micromechanics of failure.) This multi-scale methodology provides a rational basis for rewriting the basis of design. Recently I read the test matrix for a critical part of a major aerospace component that included: open hole tensile, open hole compression, bolt bearing, and fatigue under shear. It was still incredible that such testing of laminates remained the practice of design for many engineers. Such empirical approach plus use knockdown factors would continue to make composites less competitive. CDW is probably one of the few organizations that practices science-based modeling and testing. Hopefully our mission will continue to expand and be accepted by designers of composite structures. Finally we are so grateful for Yasushi and his colleagues of putting together CDW-15 to celebrate our progress in composites durability since CDW-1. Let us wish there will be many more CDW’s that will be hosted by the younger generation around the world.

Memories of CDW
By
Richard Christensen
Danville California USA

 I have been lucky enough to attend many or perhaps most of the CDW’s. The meetings have always been held in attractive and exciting parts of the world, as befits a truly international involvement. It is this broad and diverse participation that has brought much to the field of failure characterization, involving both short term and long term durability. There has always been a spirit of cooperation that is especially helpful. The track record of these fifteen CDW’s has shown a commendable gradient of progress. I hope to attend many more CDW’s. Congratulations to Professors Steve Tsai and Yasushi Miyano for the foresight and commitment to make it all happen to such good effect.

The Durability of Friendships
By
Ran Kim
Los Angeles USA

 After a long flight to Tokyo, I boarded the Shinkansen train for the last leg of my journey to the inaugural kickoff of the Technical Workshop on Composite Durability, organized by my dear friend Professor SW Tsai of Stanford University and Y. Miyano of Kanazawa Institute of Technology. I was tired from the long flight, but stirred when I witnessed the everlasting grandeur of Mount Fuji. I began to grow with excitement as I anticipate the sharing and exchanging of knowledge with my many lifelong colleagues. But admittedly, I was even more excited to see these colleagues in the roles of lifelong friends from all over the world, and the sharing and exchanging of stories from our lives.
 The workshop’s primary focus was on improving the durability of composites. I was impressed with the high international blend and high caliber of the researchers from countries all over the world. The friendly and congenial atmosphere comforted me with the realization that I was in fact a member of such an impressive group of researchers. The majority of the presentations were impressive, and well prepared. The impact of these presentations profoundly guided the direction and approach of my research. Being surrounded by group of excellent minds from diverse cultural backgrounds opened my mind and heart to multiple points of views on a variety of issues. But for me that was only half of what the Conference has given me.
 The Conference has been not only a gathering of professionals, but a gathering of friends. I have been incredibly blessed by the number of new friendships found, and old friendships renewed. Though we are scattered around the world, we may return every year in some of the world’s most wonderful places such as Kanazawa, Saint-Maxim, Jeju Island, Shanghai, Albuquerque to name a few. As a result, I have attended more than half of the annual workshops held in the many great countries that reflect the great diversity within the conference’s attendees. I attend because it contributes to improving the durability of composite materials and maintain the durability of friendships.

Workshop durability based on long term behavior
By
Georges Verchery
Saint-Etienne France

 In my opinion, the composite Durability Workshops are among the most attractive events for composite materials. I attended one third of the meetings in the CDW series: CDW 5 in Paris-Orly (2002), CDW 8 in Zaragoza (2004), CDW 12 in Saint-Maximin (2007), CDW 13 in Singapore (2008), CDW 15 in Kanazawa (2010), and only stringent commitments prevented me to participate in more CDW's.
 One of the reasons of the attractiveness of CDW's is certainly their friendly atmosphere, but it is not a kind of cosy club! I always found that they are very open-minded and fruitful for discussion. But a deeper advantage may be that they illustrate and help the development of some researches in the long term. Contrary to short view works following the mood or the immediate needs required for applications, basic studies developed over a long range of time are the key to improve the acceptance and the use of composite materials. And CDW's have given the right place for such works, thanks to Steve Tsai and Yasushi Miyano.
 So everyone will certainly join me to wish a long term continuation for the CDW series. Should I add that my wife Monique joined me at every CDW that I have attended. Although it is not for me to explain why she is always ready to come, I would say she made friends with (hard working) attendants' wives and enjoys touring, shopping and chatting with them. And I suppose wives too will join to wish the durability of CDW's.

My memories of CDW-11
By
Woo Il Lee
Seoul Korea

 CDW-11 was held at Seogwipo KAL Hotel in Jeju Island, Korea during June 21-24, 2006. As was the tradition, the workshop had brought together many leading experts in the field and offered an opportunity to promote sharing of new findings and networking. Twenty four technical presentations covered a wide areas regarding durability of composites with 47 participants. I remember one of the first comers mentioned that he was surprised at the level and comprehensiveness of papers for the size of the meeting. The venue for the meeting was located on the south coast of Jeju island, known as the Hawaii of the Far East. This island, roughly the size of Oahu, offers breathtaking scenery and a variety of outdoor activities. Located on the southern coast of the island right by the ocean, Seogwipo KAL Hotel offered a magnificent view with ocean unfolded right from the front lawn. Dr. B. S. Kim (of KIMS) and I made two site visits before the meeting to make sure that everything was in place and the only concern was the weather. Monsoon rain used to start from end of June, and we tried to precede it. However, to our disappointment, it started raining already from the first day. All the participants became eyewitnesses of global warming which, I believe, kept making the arrival of monsoon sooner than the previous year. We originally planned to have an outdoor BBQ by the swimming pool, but we were forced to retreat indoors. Nevertheless, the atmosphere throughout the workshop was very convivial despite the weather. It was due in no small part to the ladies and families who loosened up the atmosphere whenever needed. We had every ingredient for a successful CDW, great company, nice food, and others. The only ingredient we missed was the presence of the ones who started the whole thing ? Steve and Iris. To let them know how much we enjoyed the workshop, we prepared a white board as a memorabilia for them and asked everyone to write down a few words. Between the rains, we even enjoyed outdoors including a guided tour around the island. Financially, we were able to make ends meet thanks to the supports from AOARD, KIMS and others. It was a fun rather than some extra work for us to host the meeting, and probably CDW would be one of few meetings that is fun to organize.

Memory of CDW
By
Sung Kyu Ha
Ansan Korea

 Through the CDW, colleagues have been gathering to share experiences on durability of composites with each other for more than decade.
 Composites are hard to predict its strength, but harder to predict its durability. The Tsai-Wu failure criterion has been one of most effective way for predicting the strength for decades. The ATM plays a major role in predicting the durability of composites. Aging effects due to time and temperature on the durability of composites are interchangeable, and formulated through the ATM, which provides designers to effectively consider the effects of time on the strengths. This methodology has been experimentally proved under various loading conditions including creep and fatigues.
 More fundamentally, the constituents and their interfaces need to be characterized to better explain the overall behavior of composite durability. In this respect, the micromechanics of failure (MMF) has been proposed to better grab the insight into the mechanical behavior of composites. The MMF can be applied to understanding both strength and durability of composites.
 Statistical distribution of each constituent properties and macro behavior should be modeled together the MMF to be used as a practical tool. At this point, the ATM-MMF is being further developed as a methodology for predicting the durability of composites under various environmental and mechanical conditions. The ATM-MMF needs to be implemented into a commercial FEM tool such as Abaqus for composite designers to effectively access this method to their applications.
 The CDW certainly contributed to helping our society better making use of durable composites. It is certain that we keep making our efforts to develop experimental and analytical methods to better characterize composites through the CDW.

Back to the beautiful Sakai Memorial Hall
By
T.E. Tay
Singapore

 I attended and co-chaired a technical session at the first Composites Durability Workshop (CDW) in 1998, and was impressed with the beautiful Sakai Memorial Hall at the Kanazawa Institute of Technology, Japan. The quality of the research presentations, organization and excellent hospitality under the chairmanship of Professor Miyano and Professor Tsai were equally impressive. Subsequent CDWs continued this tradition of excellence and warm hospitality at various wonderful venues throughout the world. With only a few exceptions, I have managed to attend many of the CDWs, but always coming away with fresh ideas for research and strengthening of friendships forged over the years. When the CDW came to Singapore in 2008, it was an honor for me to chair the event and to host such a gathering of distinguished researchers and professors. I believe it is the only CDW that has ever been held in the tropics. At the latest CDW in 2010, it was heartening to note that the familiar tradition of excellence was still being upheld, again in the beautiful Sakai Memorial Hall.

Durability Workshop, Durable Relationship
By
Sangwook Sihn
Dayton Ohio USA

 CDWs have always been special to me because of not only technical contents but also friendly atmosphere among participants and their spouses. I’ve attended seven CDWs out of 15 (CDW-1, 9-13 and 15). Whether held in a small hotel/school meeting room or in a large auditorium with a simultaneous interpreter, CDWs were filled with high-level technical contents with novel experimental and analytical methods as well as innovative tool developments. CDW offered me lots of opportunities to grow technically and to establish new friendship and solidify existing ones. I can also recall fond memories of foods that were provided during welcome reception, lunches and banquet dinners.
 In memorizing the CDW, I cannot but remember the open and caring encounter with Prof. Miyano that profoundly affected my life. It was 1994 when I first met Prof. Miyano at Stanford University. I was a graduate student working with Prof. Tsai on strength prediction of composite bonded joints. Prof. Miyano stayed at Stanford as a visiting professor, and introduced me a methodology, which was later evolved to the ATM, to predict long-term life of composite materials and structures. He spent much time with Q&A’s and discussions on my research topic. After he went back to Kanazawa, we continued the collaboration and discussion. I even visited Kanazawa Institute of Technology (KIT) for three months in 1995, and conducted key experiments for my Ph.D. thesis. He and Mrs. Miyano graciously offered me their place during the stay, and treated me like a son with warm hospitality.
 When Prof. Tsai and Prof. Miyano won an NSF fund and later decided to hold the inaugural CDW at KIT, I was a postdoc and newly-wed. I was impressed by not only the technical presentations, but also flawless preparation by the organizers. Every fine detail was taken care of by hard efforts by the KIT teams led by Prof. Miyano and Dr. Nakada. I think the successful CDW-1 has resulted in the following also-successful 14 more CDWs as of now, and possible many more in the future. I also remember late Tom Gates from NASA was there, sitting in the first row in the Sakai Memorial Auditorium, and gave valuable questions and comments.
 After moving to Dayton, I didn’t think I would attend the CDW anymore until Prof. Tsai graciously invited me and Dr. Ran Kim to CDW-9 in Shanghai and later ones. It can never be overemphasized to appreciate Prof. Tsai, Prof. Miyano and all other organizers to give me invaluable opportunities to make presentations on various topics on composite durability.
 CDW also presented unforgettable memories to my family, Eunmi and Amy. They enjoyed every moment with excellently organized spouse programs and exotic foods in Shanghai, China (CDW-9), St. Maximin in France (CDW-12) and Singapore (CDW-13). Eunmi was also at the CDW-1 at KIT, which was our first international trip after our honeymoon trip. Amy was not in the world yet. They are looking forward to traveling and having more experiences around the world through future CDWs.

Memory of CDW
By
Akira Kuraishi
Gifu Japan

 Professor Miyano’s record showed that I have participated in 7 of the 15 CDWs, starting from the 2nd CDW at Stanford, 3rd at Tokyo, 4th at Albuquerque, 5th at Paris, 6th at Tokyo, 9th at Shanghai, and the latest 15th at Kanazawa. Among the conferences and workshops related to composites, CDW has always been special to me due to my involvement in the research directly related to the NSF program that was kicked off by the first CDW. In the earlier CDWs, where I was participating as a graduate student, CDW was a great opportunity to learn about the research related to composite durability, and also receive valuable comments on our research directions and goals. As research progressed, CDW became an occasion where many researchers with the same goal but different approaches gathered, and discussed how their individual research could collectively contribute to the common goal of understanding the durability of composite materials and structures. These occasions were well utilized by Professor Tsai and Professor Miyano, which is evident in how the accelerated testing methodology (ATM) has gained significant breadth, from fundamental understanding of resin behavior to collaborations with powerful tools such as micromechanics of failure (MMF) and progressive failure analysis. These achievements owe a lot to the warm and frank atmosphere of CDW fostered by the organizers and the participants, which allow us to freely express our visions and opinions.
 Although, my involvement in CDW has changed over the years, I am still thrilled to see how much the research has evolved. I am also pleased to see that the warm and frank atmosphere that characterizes this workshop is still present, and hope that it will continue in the future.
 I cannot complete the memoir of CDW without mentioning the wonderful spouse program that has also contributed to the warm atmosphere of CDW. The organizers have devoted significant effort in making the CDW enjoyable not just to the researchers, but also to the accompanying spouses. Most notably to our family is the latest CDW-15, where my whole family was able to enjoy the beautiful parks and restaurants of Kanazawa. We would like to use this occasion to thank all the organizers, all the participants, and all the accompanying spouses that has collectively made all of the CDWs special. Thank you.

“Mutual Trust and Co-creation” - What I learned from CDW-
By
Nobumasa Iwashita
Kanazawa Japan

 It was in November 1998 when the Composite Durability Workshop was first held on campus of Kanazawa Institute of Technology in the hope that the researchers of the world can contribute to the development of testing method of the durability of composite materials. And now, I would like to give my sincere congratulations to CDW celebrating its 15th meeting this year on the same campus.
 Professor Yasushi Miyano, who was born in Kanazawa, Japan, returned to his hometown in 1977 to be awarded Professor of Kanazawa Institute of Technology after working for Hitachi Research Laboratory, Hitachi, Ltd. During his 33 years of teaching at KIT, he established Materials System Laboratory in 1981. He started its journal Materials System in 1982 and has been highly regarded by researchers of this field.
 Another key person, Professor Stephen W. Tsai of Stanford University has been supporting Professor Miyano and KIT since 1980’s. He has become visiting professor of KIT in 1996. The research collaboration agreement between the Materials System Research Laboratory at KIT and the Structures and Composites Laboratory in the Department of Aeronautics and Astronautics (SACL) at Stanford University was established in 2001 with a great contribution of Professor Tsai. KIT is very grateful to him for such continuous support.
 Though I am not a researcher, I have been allowed to participate in this series of the CDW during the 15-years from which I have learned many things. Professor Tsai left me with strong impressions of his leadership, high level energy, and magnetic charm of his personality. Professor Christensen is also a person of profound character. Furthermore, getting to know their cheerful and hospitable wives will reamin my life-long treasures.
 Sometimes I wonder why I was able to enjoy companionship with many people I met at CDW without being able to speak English. My answer is this. It is because CDW has become a common ground of cooperation among all participants sharing the same research goal supported by mutual trust and strong devotion to foster the study of composite materials.
 Let me wish for continued development of CDW in the future.

How it ends depends on how it begins
By
Isao Kimpara
Kanazawa Japan

 The first CDW (CDW-1) was held at KIT, Kanazawa, November 3 to 5, 1998. It was a memorable start of the successive CDWs up to the CDW-15 which was held again at KIT, Kanazawa, October 17 to 20, 2010, twelve years later. The aim of CDW has continuously been “breaking away from conventional empiricism in composites design” focusing on rational estimation of composites durability. As the CDWs have been small workshops based on single session, they have been quite global due to world-wide ambulation of workshop sites. This tradition will hopefully be transferred to the possible continuation of new CDWs by younger generation in the future. The first-stage activity of CDWs appears to have successfully been summed up at the CDW-15. The next goal of CDW has also been suggested to establish the damage progression mechanism from the first-ply failure at the CDW-15.

CDW-1 and CDW-15
By
Masayuki Nakada
Kanazawa Japan

 I attended on CDW-1 held in 1998 at Kanazawa. Many active researchers attended CDW with it focus on durability of composites. New topics were presented and discussed among participants. I felt the very high level of activity, energy and quality of research.
 CDW-1 held at Kanazawa Institute of Technology (KIT) was organized by Professor Miyano. He was successful in getting support from KIT staff members and many other sponsors. We tried new things for CDW-1. For example, simultaneous interpretation of oral presentations and discussions in between English and Japanese was provided by a professional company. The posters for oral presentations were exhibited in communication plaza which was open in the multi-purpose hall next to the Sakai Memorial Hall. Presenters could discuss with participants during poster session, lunch time and coffee breaks without time limitation. The communication plaza was also open in CDW-15. I think that the communication plaza was instrumental to improve the quality of workshop.
 I have learned many things and met many people in CDW, so my vision and friendship would expand. I thank deeply Professors Tsai and Miyano, I learned many things from them. Their high spirits and warm hearts will remain forever in my mind.

After having 15 CDWs
Yasushi Miyano
Kanazawa Japan

 First CDW was held at Kanazawa in November 1998, since then 15 CDWs were held in all over the world during 12 years. I would like to write down my impression of each CDW.