The Academy Lecture
WOOD AS NATURAL SMART MATERIAL
“Smart Materials” (SM) creation is one of the most perspective trends in society development. SM provideuseful reactions to different exterior actions. The dominant feature of artificial SM is the “shape memory” effect. Thisphenomenon is based on quazi-residual frozen strains (FS). They were detected by us at constrained shrinkage in theearly 1960s. In 1971 in collaboration with Y.Lapshin the integral law of wood deforming under loading and moisturecontent and/or temperature changing was formulated. Different character of deforming at drying and wetting weretaken into account. This law was applied for calculation of wood drying stresses; the developing of drying schedules;nondestructive stress control by differential shrinkage method; and for conditional treatment after drying. In 1952wood internal stresses measurement method was proposed, it raised this key problem research to a quantitative level.Stress memory and strain memory effects for wood were found. Wood has ability to recollect the type of load (tensionor compression) which it had undergone. For example, the size of unloaded dried wood specimen decreases at heating.In order to recognize in complex strains the kind of constituent strain (thermo-frozen or hygro-frozen) they were“marked” by the type of loading that had induced the strain. This approach in particular was applied in working outthe method of removing veneer waviness by creation of counter frozen strains of both types. The research conducted incollaboration with the Institute of Solid State Physics using method of IR spectroscopy showed that at drying of loadedwood the degree of orientation in amorphous areas of cellulose increases; expected by us increasing of wood stiffnesswas experimentally proved. Lately we have suggested the classification of hygromechanical strains which includesthe notions “reduced wood shrinkage” and “frozen shrinkage”. Thus it takes into account decreasing of shrinkagecoefficient at sufficiently high level of tension loading. These terms reflecting the nature of wood behaviour at dryingis more correct than “mechano-sorptive creep” (MSC). MSC can be observed at cyclical change of moisture content inloaded wood. “Hygrofatigue” of wood plays main role in this process. It can be seen from the suggested conception ofthermo-hygrofrozen strains, that at drying or cooling of loaded wood its total strain doesn’t decrease, in spite of theincrease of the stiffness of wood. This phenomenon can be found in the studies of other researches. Furtherinvestigations of deformative conversions will permit to improve wood technology and create new smart woodcomposites.
Boris Ugolev is Professor of Moscow Forest State University (MSFU), Mytischi, Russia, from which he graduated in1948 with diploma of mechanical engineer. His education includes PhD (1953), DSc. (tech., 1968), Professor (WoodScience) of Moscow Forest Engineering Institute (now Moscow State Forest University). His research carrier startedas a postgraduate student and then he was a research scientist associate at the Central Institute of Wood-working,Moscow-Khimki. In 1957 he returned to his alma mater where he is working until now.For forty years he was Head of Wood Science Department. His textbooks have been published many times since 1975.He is the author of more than 300 books, articles and patents. His fields of research are to the wood physics andmechanics. For more than half a century he has been studying wood behavior at drying. Besides, he together with hispupils, made an essential contribution to the development of rheology, nondestructive testing methods, research ofdensity, strength, moisture content, shrinkage, colour, luster and other properties of wood. He is a scientific adviser tovarious encyclopedia, member of editorial boards of Woodworking Industry (Russia) and Wood Research (Slovakia).For many years he works in the field of home state and international standardization of wood testing methods, timberquality and terminology. He is the President of Regional Coordinating Council of Wood Science for East Europeancountries.In 1991 he was elected Fellow of IAWS and retained membership in IAWS Board of Directors from 1998 till 2004. Hewas also a member of IUFRO and RILEM Working Groups. He took part in conferences and Plenary Meetings ofAL n° 48 B.UgolevJune 20092IAWS (1975, 1997, 2003). He delivered tutorial lesson at the third IUFRO Wood Drying Conference, Vienna, 1992and presented Honorary keynote on the ninth IUFRO conference, Nanjing 2005. He delivered lectures in manyEuropean countries, USA and Canada. He was the Professional Guarantor of RCCWS International Symposiums on«Wood structure, properties and quality» in Mytishi, Moscow, Petrozavodsk, St.Petersburg, Russia (1990, 1996,2000, 2004). He has been awarded a title «The prominent Scientist of Russia» (1995), elected an Honorary member ofthe Russian Academy of Natural Science (1996), awarded the medal of Zvolen Technical University, Slovakia (1998),elected Dr.h.c. of the University of West Hungary (2006).
The Lecture was presented on 19th June 2009 during the 2009 IAWS Plenary Meeting in Saint Petersburg -Moscow