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12
УкраГнський державний лкотехшчний ун1верситет
2. ТЕПЛОМАСООБМ1НН1 ПРОЦЕСИ В ДЕРЕВООБРОБН1Й ГАЛУЗ1
УДК 674.047 Проф. Я.1. Соколовський, д-р техн. наук - УкрДЛТУ
НАПРУЖЕННЯIДЕФОРМАЦП У ДЕРЕВИН1В ПРОЦЕС1
СУШ1ННЯ
Розроблено методи синтезу та анал!зу напружено-деформiвним станом дереви-ни у процесi сушiння з урахуванням и реологiчноí поведшки, яю дозволили встано-вити та кшьюсно описати закономiрностi впливу пгроскошчно'' вологи, i"i градieнту i форми зв'язку вологи з матер!алом, структурно' ашзотропи, геометричних розмiрiв та густини на розподш в'язкопружних i залишкових напружень для перiодiв пада-ючо' та стало' швидкостей сушiння деревини зi сталими i змiнними потенцiалами тепломасоперенесення.
Prof. Ya.I. Sokolovskyy, Dr.H.S., Dr.Ph. - USUFWT Stresses and Strains of Wood in the Drying Process
Developed metods of synthesis and analysis of stressed-strained state of wood in drying process with taking account of its rheological behaviour, which allowed to set and quantitatively to describe influence conformities of gigroscopic moisture, its gradient and form of connection with material, structural anisotroption, geometrical dimensions and density on distribution of viscous-elastic and residual strains for falling and constant speeds of wood drying with constant speeds of wood drying with constant and changeable potentials of mass heat transfer.
Key words: wood, drying, stressed, strained, viscous-elastic, heat-mass-exchange.
Introduction
For rational directing of wood drying process provided with necessary quality indexes is an important problem to make physical-mathematical model of rhe-ological state of wood taking into account mechanism of regenerating strains in time, and also to develop methods of synthesis and analysis of strain relaxational processes in these materials taking into account changeable potentials of mass heat transfer, interrelation between stresses and parameters of external and internal mass heat transfer, anisotroption of properties, structure transformations. Limitation of these researches is one of the basic suppressing factors for rational choice and basing of technological regime of wood drying processes with simultaneous improving of its mechanical properties.
Thermodynamical approach and mathematical model
In base of synthesis and analysis of offered physical-mathematical model of strains and stresses development in technological wood drying processes is laid methodology of system-structural approach, that stipulated basing of parameters choice of phenomenological model description and setting of suitable heat, mass, energy and impulse laws. On base of thermodinamical analysis was described structure of relations, set mutual influense of different phenomena and factors specifically creeping processes, relaxation and shrinkage on deformation of arboreal
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Сучасш теоретичш розробки в деревообробному i меблевому виробництвах
materials. There was described generaliged function of free energy (thermodyna-mical potential of researching system), as material state function with changeable potentials of mass heat transfer, that determines by components of summary (elastic, viscous-elastic and residual) strains tensors or stresses, chemical potential or moisture content and temperature T, and entropys. State function is expressed through invariants from determining parameters, specifically strains tensors.
There was synthesized physical-mathematical model of strain-relaxational processes in wood during process in general case directed in form of diffrential equations system [1, 2]: balance and motion equations
oj = p32Ui/3T2 ; Cij = oji; (1)
= div(^ttgradt)+ div(^tugradU) + div(^pgradp)+1d^tt ; (2)
T div(Aatgradt)+ div(^uugradu) + div(^1pgradp)+ U; (3)
dT = div(^,tgradt)+ div(^,ugradU)+ div(Vppgradp)+ Pq ; (4)
G(t,U,P)=^(3V + 2M)-SP ; vq
state equations:
i = 2|m(1 - ffl)eij + (£ij [ V+ 3 m® ] - vVq + |Sij; (5)
M = Y - £ij dU G(t, U,P) + £ij£ij dU m(1 - + £ ij dU 2 + M ®/3); (6)
1 3U ' ' 1J 1J 3Ur ' ' ij 3Uv t
S = f — dt + £ ij — G(t,U,P)-£ij£ij — m(1 -ffl)+£2 — (V 2-M®3). (7)
t0
For enclosing of equation system (1)-(7) were used conditions of strains compatibility, kinematical equations of mass heat transfer potentials, and also initial and boundary conditions which are typical for different drying process stages.
Was obtained equations system (1)-(7) which allows to describe temperature-moisture and stress-strained fields in wood drying process with taking into account viscous-elastic properties of material and strains regeneration mechanism in time.
On basis of relation setting between balance equations (2)-(4) and generalized law of Hooke for viscous-elastic materials was obtained law of rheological wood behaviour with changeable temperature-moisture fields as viscous-elastic material, for which transformation in time one kind of strains into another is typical Inasmuch for determination of characteristics of rheological wood behaviour in suitable change diapasons u and t were developed methods of experimental research on creeping and relaxation with use of integral functions (creeping and relaxation nucleus), then rheological regularity of wood straining can be given in form (8).
o
2. Ten^OMacooSMiHHi npouecn b gepeBoo6po6mn ra^y3i
93
yKpaiHCbKHH gepwaBHiiñ .nicoTexHiHHHH yHÍBepcHTeT
e(,U,t) = [ «)+J [ R2 (c-Tlu1t) ^
H + (j-T1U1t)dU^
fflt pT
-aU. (8)
Offered rheological equation (8) was endorsed by experimental results for cases of creeping and reverse creeping strains for different levels of temperature and moisture.
Experimental researches of rheological wood properties
Taking into account experimental researches refering to studies of stress-strained wood state in drying process, were determined tasks of rheological researches: to inquire into rheological behaviour of wood on creeping, relaxation and reverse creeping with taking into account anisotroption in range of change of moisture (8 %, 15 %, 20 % Wrr) and temperature (200 C, 400 C, 800 C, 950 C); to set regularities of development of elastic, viscous-elastic and residual strains and to describe quantitively function of creeping and relaxation, which are necessary for computation of stress-strained state of drying wood; to substantiate application of speed up methods of temporal analogies, which allow by results of short-time researches to forecast rheological properties of wood along fibres for long-time term. Each experiment was carried out on separately taken sample of ping-tree, fir-tree, birch and oak for constant loading tension and compression, that does not exceed limits of long-time resistance.
Results of experimental senses of creeping function y (t, w, t=20 °C) of pine-wood for tangential direction of deformation directed in table 1, where y(t = 0)= En-1; y(t = ~)= Et-1; EM,Et-momentary and continuous modulus of elasticity, ^-characteristic, that allows to estimate degree of wood creeping.
On analysis base of experimental data of strains creeping, obtained for constant and changeable senses of moisture content and temperature, was studied strains mechanism and displayed different types of interaction of given above factors on wood deformation[34]. Considerable growth of strains components of experimental wood species irrespective of loading method is observed with augmentation of moisture from 8 % to Wrr. Further change of strain e changes insignificantly, that qualitively agree with experimental data for elastic component. Augmentation of viscous-elastic and residual components caused by acceleration of kinetic energy disipation at the expence of intermolecular interactions of lignin and cellulose molecules in wood and by their conformation changes. For wood with moisture W > Wrr dependently on temperature change is observed a insignificant distinction between sense of strains of creeping and revers creeping in radial and tangential directions is obsreved an influence of initial moisture content of material on full strain and its components.
Creeping of strains of moisture samples under loading is greater that viscous-elastic component in unloading process, that is during loading goes accumulation of residual strain, which is absent in elastic loading regime. Was set, that elastic and viscous-elastic components of strain for tension across fibers do not depend on initial loading, and its augmentation causes strains augmentation, in the same time
when decrease of temperature for creeping process does lead to essential change of strains. Were set dependencies of elastic characteristics (Young's modulus and Poisson coefficient) of pine-wood for orthotopic scheme of anisotroption dependent on temperature and moisture changes.
Table 1. Deformation indexes of pine-wood
y,10"3 MPa time of deformation t* 103, y' - tension, y" - compression
0.05 12 24 36 48 60 78 90 120
Y W=8 % 1.07 1.21 1.33 1.43 1.50 1.54 1.58 1.63 1.68
y" 1.04 1.22 1.32 1.40 1.53 1.56 1.60 1.62 1.69
9 419 478 517 561 599 612 619 639 662
Y W=15 % 0.92 1.09 1.21 1.34 1.40 1.44 1.47 1.50 1.52
y" 0.97 1.07 1.26 1.36 1.42 1.44 1.46 1.50 1.54
9 346 378 432 483 503 510 520 533 545
Y W=20 % 0.86 1.05 1.18 1.27 1.36 1.37 1.40 1.42 1.43
y" 0.85 1.06 1.19 1.28 1.34 1.36 1.39 1.43 1.43
9 266 333 372 401 420 426 435 448 448
y' W=Wrr 0.64 0.82 0.93 0.99 1.03 1.06 1.06 1.07 1.07
y" 0.64 0.81 0.93 1.01 1.03 1.05 1.05 1.06 1.08
9 167 212 242 259 268 272 273 275 280
Were set regularities of temperature and moisture influence on important index of rheological wood behaviour, as time of anisotroption dependent on temperature and moisture changes.
Were set regularities of temperature and moisture influence on imporntant index of rheological wood behaviour, as time of relaxation Tp (w,t). Is observed that moisture change influences more essentially on Tp (w,t) for wood straining along fibres. Specifically, for pine-wood (t=20 °C), moisture from 20 % to 10 % stipulates decreasing Tp (w,t) almost in 42 times. For tangential direction for the same condition Tp(w,t) decreases in 2,5 times. Temperature growth causes decreasing of Tp (w,t). However speed of tp falling with t growth is smaller than speed of change Tp (w,t) dependently on w. By measuring results in identical temperature-moistural conditions was obtained a dependency Tp (w,t )= A(t)exp(- bw) , and coefficient A, B determined for each wood spice.
Results of strains researches of creeping and reverse creeping of wood across fibres allowed to build necessary for synthetis and analysis of stress-strained lumber state (8) of creeping functions with taking into account accumulation of residual strains:
Ki(T-T';U,t)=^o + ^akexp(-«k(t-T)); K2(-r--r';U,t)= Pexp(-l(t-t^)). (9) k=1
Was developed an algorithm of determining parameters y0, ak, ak, P and substantiated a choice of their amount from minimum of quadratic deviation of approximation of experimental curves e(t,w,T). Application of more complicated function of creeping because of high changeability of strain properties of wood essentially complicates mathematical apparatus and it unconvenient for practice.
2. Ten^oMacooSMiHHi npouecn b gepeBoo6po6mn ra^y3i 95
YKpaÏHCbKHH gepxaBHHH .mcoTexHiqHHH yHÏBepcHTeT
For research of rheological behaviour of wood along fibres and generalization of existing experimental data was offered an approach with use of fixed scale function, which provide invariance of strain process concerning temperature and moisture changes. Were built generalized curves of creeping for researched species of wood in half-logarithmical coordinates (e,\nr) and determined scale function ln a (t,w), that characterizes creeping curves dependency on generalized, directed for base senses of temperature t0=40° and moisture W0=8 %. Was set that function is unlinear for each from arguments and is stipulated by their mutual influence. In general case ln a(t,w) is described by polynomial and coefficients are determined by method of minimum squares.
On base of observed peculiarities of wood straining along fibres for different temperature and moisture senses was offered rheological equation
1 n
e(r) = £0 (o,t,W) + - X bi (1 - exp(-®(t,W)/Toi )). ni=1
(10)
Were set spectrums of relaxation times and function a(t,w). Specifically, for t=
■(W)-(W^W)btl^5(0[^EET|WWVE: (Wîf »0. -p(WoXW„/W)b (11)
Senses of coefficient b for different species of wood and method of loading are directed in table 2.
Table 2. Senses of coefficients b for determining of relaxation time
pine'
¡-tree
fir-tree
birch
oak
compression
0.63
0.51
0.42
0.7
tension
4.73
4.3
3.85
4.8
b
Computation of flat stress-strained state of wood in drying process
With use of elastic theory methods was researched flat (two-dimensional) stress-strained wood state in drying process with taking into account anisotroption of mechanical and heat physical properties, stipulated by structural construction of wood [5,6]. Was considered an orthotopic plate of wood, which in two mutual perpendicular direction is characterized by anisotroption of mechanical and moisture properties, and a plane of orthotroption coincides with co-ordinates system planes, beginning of which is situated in the center of transversal section (fig. 1).
Task of determining of moisture stresses in drying wood by integration of equilibrum equations (1) turns into decision of differential equation with boundary conditions:
6 X
Fig. 1. Scheme of task organization of determining of stress-strained state of drying wood
Науковий вкник, 2002, вип. 12.5
VF = -Э 2 (вуЛи)/Эх2-Э 2 (вхЛи)/Эу2, (12)
V = ЕуЭ4/Эх4 + (g-1 - 2vxy|ey )э VЭх2Эу2 + ЕхЭ 4 /Эу4 ; ffx = 0, X = ±li = Li/2 = 0, Y = ±l2 = L^2;
ву = (Vyo-вхоУ(х2 + у2)/(l2 +12)+вхо)(30-W)/30 ; вх =вхо(30-WV30 ;
MW,t), Pyo(W,t) - tangential and radial coefficients of shrinkage, ли=и* -и(х,у,т) - function of change of hygroscopic moisture content. For U>U was taken ли =0, that accords with lack of shrinkage in moisture zone. Because change of inf1exibi-lity in wood starts from 25.. .30 % then и* = 0.25.
Function of stresses F is related with components of stresses Ьу formulae
ах =Э 2f/ Эу2;ау = 32f/ Эх2; тху = -32f/ЭхЭу . (13)
Numerical decision was obtained with use of conjugate with distribution of temperature-moisture field designed function ft that provide a minimum of potential energy of dicing wood Ьу dint of determination of unknown coefficients a and k from fixed system of equations
£ £ (Vfteftn Kk = (-Э 2 (вуЛи)/Эх2 -Э 2 (вхЛи) Эу2 ), (14)
where (A<p,y) and right part (14) are scalar. Residual strains, stipulated by dependence between modules of elasticity Ex, Ey, vxy and moisture (effect of regeneration) are defined for formulas:
^хзал _ °х °х max
/3 ; ^узза _ ^y ^ymax /3 ■
(15)
Numerical decision of written in criterional form of mass heat transfer equations (2),(3) and boundary conditions was obtained by intheratical locally one-dimentional method. On fig.2 and 3 are presented the modeling results of stress-strained state of drying wood.
3,2 У, cm
Fig. 2. Distribution of tangential stresses ТХу(Т: у=2; l1=4 см; l2=8 см, 1 - F0~2.47; 2-F0~3,63; 3 - F0„4,02; 4 -F0~6,32; tc=84 °C; (p=0,62; a=22,5 Wm(M t); P=310-6м/с; Pyo=7,1 %; Pr=3,4 %; p0=460 Kg/м3
k
УкраГнський державний лкотехшчний унiверситет
//
/ 7 \
// t л э
ч- s
-х
1 5 10 15 20 25 30 35 х
1,0 2,0 3,0 4,0 5,0 6,0 7,0 f„ Fig.3. Change of normal stresses ax: 1 - 1, Fig 1; 2 - 2, Fig 2; 3 - 6;4 - 7; tc=84 °C; (p=0,62; a=22,5 Wm(M21); в=310-6м/с; f\==7,1 %>; вх0=3,01 %; p0=460 Kg/м3
On basis of offered single approach was solved practically important for wood drying process class of task of stress-strained state determining. Was set a distribution of moisture and residual strains for parabolic distribution aw = w ... Was observed influence of distribution of properties and geometrical size of lumber on normal and tangential stresses. Maximum senses normal stresses reach in the medium layer of drying wood, and tangential-in undersurface zones, and on the surface and in the center of the board they are insignificant.
Were found components of stresses for case, when initial moisture of lumber is higher than transition moisture content in the first period (bound moisture stands of from surface zones, and in central -W>Wm). Was obtained distribution of tangential and normal stresses of zone of lumber in drying process, which essentially depends on modulus of elasticity of wood along fibres. Was estimated influence on normal stress of ввдношення change of hygroscopic zone to board thickness were found coefficients of stress intensivities on possible cracking surface dependently on even and quadratic distribution of hygroscopic moisture. Was observed influence of intensive drying (moisturing) on components of stresses, for example, in shrinkage process of thin layer (veneer) glued on massive base.
Research of stress-strained wood state in drying process with taking into account of viscous-elastic properties and peculiarities of strain regeneration in time. Developed methods of synthesis and analysis, which are formalized with the aim of using of obtained experimental data of rheological wood behaviour allow quantitively to set important in technology of wood drying regularities of distribution influence of hygroscopic moisture, its gradient, anisotroption of constant and changeable coefficients and internal sources of mass heat transfer, geometrical size of lumber on development of viscous-elastic and residual stresses in wood on different drying process stages.
Obtained dependences for determination of stress-strained state of drying wood are represented in structural form [7,8]. For irregular drying process regime we have:
aB (X,Fo) = Kt>^e(U,X)(l/2KIm (l+eKoPnLu(l/3 - X2 )-
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Сучасш теоретичш розробки в деревообробному i меблевому виробництвах
Науковий BicHHK, 2002, вип. 12.5
"-К" XX Cm 1 -v? jcosVi^nX - ^^ I exp(-^n2Fo)(uo - Up); (16)
aKon=1=1 )
аЗ (X,Fo)=К^Ди,Х)} (3U(X,Fo)/3t-3U(t)/3t) £ S1(U,t)Ko (т -T',U,t)d-r' (16) 0 i=1
Developed methods of synthesis and analysis allowed to set regularities of distribution of moistural and residual stresses in wood with constant and changeable coefficients of mass heat transfer for period of falling velocity of drying. Were considered cases of initial parabolic and cosinusoidal distribution of moisture content. For drying process of hardwood species moisture content in which can be described by cosinusoidal law, stress-strained state determines by correlations [9]:
aB(Y,T) = f(U,t)g(Uo,Up,B;)exp(-^2BiiF/(ш+ n2 )) (17)
0"3 (y,t) = -(exp(T/Tpen )/ h(Tpen ,Bi,a '))f ( U,t )g(Uo,Up,Bi )* * (E(U,t)- E T (U,t))/ET (U,t)Tpen (exp(h where f ( U,t) = F( U,t )/(1 + p 0U0 )p( U,t);
g(U0,Up ,Bi )= 4(u0 -Up )Bi(ncosXn/2-1)/n(n2 + 4Bi);
h(Tpen ,Bi,a ') = У Трел-n2aB/ R2 Ц + n2 ).
Was observed influence of maximum stresses on cracking criterion. К^, accepted as concerning gradient between local and mean moisture content and initial moisture content [7]. For determining of maximum-admissible senses К^, in case of parabolic distribution of moisture content (regular regime) was obtained integral equation
Т K(T-T',U,t )K'TpdT'+ K' = 2^max feMWo ) -0 p 3 E(U,t)Uoe(U,t)K
- At О^^рел (1-Трел exp(T/Tрел))). (18)
tc - tM
Was learned stress-strained state of wood with taking into account deepening of moisture evaporation zone in period of falling drying velocity [10]. In connection with complication of temperature-moistural fields determining was accepted an assumption, that moisture content of moisture zone is constant, and in evaporation zone is equal to equilibrium sense. On base of analysis of results was showed presence of turners in stresses for different heat physical senses of deepening zone of moisture evaporation, and also augmentation of size of compression stresses for some senses of evaporation zone in dry region of wood plate (without taking into account zone of tensional stresses).
On base of carried out researches were studied basic regularities of development of viscous-elastic and residual stresses in wood during drying process with taking into account distribution of hygroscopic moisture, forms of moisture connection with material, physical and mechanical characteristics, conventional density (species) and geometrical size of lumber. Character of dynamics of residual
YKpaiHCbKHH gepxaBHHH .mcoTexHiqHHH yHiBepcHTeT
stresses is stipulated by uneven development of moistural strains and creeping stains and reverse creeping dependently on forms of connection of moisture with material, and velocity of their development for constant change of moisture content is proportional to moisture gradient change. Peculiarity of forming of stresses in viscous-elastic region of straining is displacement of spectrum of maximum senses on lumber surfaces concerning maximum senses in central layers, caused by uneven distribution of level-by-level moisture and by dependence of time of maximum senses ^m&x
reaching from relaxation time which for fixed senses of Et and Em are associated by correlation Tmax (x)=i,38t| /aBmaxY - velocity of changing of moisture strains. Augmentation of conventional density sense causes growth of maximum stresses, especially on surface and in under surface lumber zones, and also retardation of velocity of stresses relaxation. Specifically, for parameters of drying agent t, t,W % for wood with p0=550 kg/m3 o(t=10) - o(t=20), is 0.18 MPa to XL2=0, and for p0=450 kg/m3 analogic size is 1.37 MPa was set considerable influence of structural anisotroption on stress-strained state of logs under action of uneven distributed moisture. In this case unlike isotropic, where components of stresses are insignificant, even distribution of moisture causes growth of stresses. Was shown compressional character of radial stresses for r/R<0,53 (R-radius) and ten-sional in under surface zones. Was observed change the sign of tangential stresses (tensional character for R/r < 0,42 and for central zone), if coefficient of shrinicage in tangental direction is greater than in radial direction.
Connection of components of stressed-strained state of drying wood
with parameters of internal and external mass heat transfer
For quantitative description of connection was analyzed and described interacting mass heat transfer flows on border of drying wood and moisture environment with taking into account behaviour peculiarities of bound moisture with material. Was taken into account that process of mass heat transfer in drying wood simultaneously goes in liquid, airvaporous and hard phases. With aim of concretiza-tion of thermodinamical components were made researches of them dependently on hygroscopic moisture of material, its structural properties with following normalization of sum of the flows, on general geometrical surface. Integral components of surfaces are determined from equality of volumetric and surface heterogeneities component of surface skeleton is a constant, and component of surface of liquid and gas-vaporous phases depend on moisture content of material.
Was synthesized model of connection of stress-strained state of drying wood with parameters of external and internal mass heat transfer processes [12], and also dependences of heat-physical and mechanical characteristics of material with parameters of moistural air allow to determine maximum senses of parameters of drying agent directly at the expense of stresses, that do not exceed bound durability and provide integrity of material. Were obtained engineering correlations for p and t0 choice with taking into account constant and changeable coefficients of mass heat transfer dependently on rheological properties of wood. Specifically, for parabolic distribution of moisture content in wood (period of constant velocity of drying):
t = 0,13(238 +1)lnB lnB = 2ampo (l + lnUo K (19)
C 1+ 238 +1n ln^ EM(U,t)KNuDpPnc ' V ' 1785
For cosinusoidal distribution of moisture content in wood (period of falling-drying velocity) was set:
0,018* H2sH4'8Uost * (20) T Vs(1 - 3.1lnVto)
Kb (X,Fo)(1 + ^0U0)(Uц + (uц - Un )cos xn2)
B; cos xn2 - 2Bi/n i 4BiFo 4(U0 -Up)(H(U,t) + K(U,t) i--- expI--
+1
* ^-PS ^ iJL " — (U n + (U ц - U n )cosxn 2 )
P0 Nuu IP0 PT
Was researched influence of parameters of moistural air on stress-strained state of wood in drying process with taking into account mechanical-sorptional creeping of material, caused by decreasing of moisture content in drying wood. Was observed a greater deformation change of wood in case of growth of relative moisture of air p in compare of its decreasing. Influence of temperature of moistural enviroment is more essential on development of residual strains and strains, caused by wood shrinkage.
Due to researches results was developed a system of automatic regulation of drying agent parameters with taking into account stress-strained state of wood.
Symbols: p - density; u - moving; t - time; u0, up, un, uy - moisture content: initial, equilibrium on surface, in the center; c- thermal capacity; x- coefficients of mass heat transfer: Poisson, Lame, filtration, kinematic viscousity, thermal conductions of dry wood; e, r -criterion and heat of phase transition; Kt,H, Ei, Gxy -volumetric modulus of elasticity, modules of shift elasticity; R(t - t', U, t), K(t - t', U, t), S1, S2 - functions of rheological behaviour (functions of relaxation, creeping and functionals of relaxation times); S -temperature gradients; K K0, Pn, W, F0, B^ Rb-criterions of Kirpichov, Kosovich, Posnov, Lykova, Fourier, Bio, Rebinder; cm, v,^-characteristic number; A, B-parameters of approximation; Si -Kronecker symbol.
References
1. Sokolovskyy Ya.I. The relationship of deformation-relaxational and heat-mass-exchange processes in cappilary porous bodies.// The reports of NANU, a Mechanics series, 9: 76-80, 1998. (in Ukrainian language).
2. Sokolovskyy Ya.I. Interrelation of deformation relaxational and heat-mass-exchange processes under drying of capillary-porous bodies.// INTERNATIONAL APPLIED MECHANICS, 9: 101-107, 1998.
3. Sokolovskyy Ya.I. Experimental researches of viscous-elastic properties of wood.// Nau-kovyi visnyk, 7: 91-99. - Lviv, USUFWT, 1997 (Ukrainian language).
4. Sokolovskyy Ya.I. Research of flat stressed-strained state of wood in drying process.// Nau-kovyi visnyk, 8: 161-168. - Lviv, USUFWT, 1997 (Ukrainian language).
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УкраГнський державний лкотехшчний ун1верситет
5. Sokolovskyy Ya.I. Analysis of stressed-strained of lumber in drying process.// Naukovyi visnyk, 8.1: 156-165. - Lviv, USUFWT, 1998 (Ukrainian language).
6. Sokolovskyy Ya.I. Technological stresses and strains of wood in drying process.// Naukovyi visnyk, 9.3: 168-176. - Lviv, USUFWT, 1999 (Ukrainian language).
7. Sokolovskyy Ya.I. Identification of stressed-strained state of lumber with taking into account deepering of moisture evaporation zone.// Naukovyi visnyk, 9.5: 89-93. - Lviv, USUFWT, 1999(Ukrainian language).
8. Sokolovskyy Ya.I. Mutual connection of stressed-strained state of drying wood with parameters of internal and external processes of mass heat transfer.// Naukovyi visnyk, 9.6: 64-68. -Lviv, USUFWT, 1999 (Ukrainian language).
9. Sokolovskyy Ya.I. Stressed-strained state of logs in drying process.// Naukovi zapysky Ukrainskoi akademii drukarstva. Naukovo-tehnichnyi zbirnyk, 2: 20-22.- Lviv, 2000 (Ukrainian language).
10. Sokolovskyy Ya.I. Computation of stressed-strained wood state with cosinusoidal law of distribution of moisture content.// Visnyk Tehnologichnogo universytetu Podilla. Tehnichni nauky, part 2: 191-193. - Hmelnyckyy, 2000 (Ukrainian language).
11. Sokolovskyy Ya.I., Andrashek J.V. Methodics and results of experimental researches of rheological behaviour of wood.// Naukovyi visnyk, 9.13: 15-26. - Lviv, USUFWT, 1999
11. Sokolovsky Ya.I., Poberejko B.P., Filinjuk R.V. Technological stresses and strains of wood in the proscess of drying// XIII Konferencja Naukowa Wydzialu Technlogiji Drewna SGGW "Drewno-material o wszechstronnym przeznaczinib i zastosowaniv". - Warszawa. - 1999. - p. 377-389.
12. Pat. 23818 A, Ukraine, MKHF26 B25/22. System of automatic regulation of drying process with taking into account its physical-mechanical state./ Sokolovsky Ya.I., Safarov V.O., Knysh Yu.V. (Ukraine)/; Published 16.06.98 (Ukrainian language).
УДК 674.047 Проф. П.В. Бглей, д-р техн. наук - УкрДЛТУ
АНАЛ1З ОСНОВНИХ СПОСОБ1В СУШ1ННЯ КАП1ЛЯРНОПОРИСТИХ КОЛО1ДНИХ МАТЕР1АЛ1В
Розглянуто фiзичнi особливост та ефективнють кондуктивного, радiацшного, електричного та конвективного способiв сушшня катлярнопористих колощних ма-терiалiв.
Prof. P. V. Biley - USUFWT Analysis of basic of colloid materials drying methods
Considered the physical peculiarities and effectiveness conduction, radiation, electric and convection drying methods of colloid materials.
Капшярнопорисп коло'1дш матерiали охоплюють широкий спектр ре-човин, в основному, оргашчного походження. Деревина, яка входить до цього класу матерiалiв, мае складну анатомiчну будову i фiзико-механiчнi властивость Особлившть будови деревини полягае в тому, що при початково-му зволоженш вона мае явно виражеш коло'1дш властивоста, а в подальшiй полiмолекулярнiй конденсаци - властивостi капiлярнопористого тша.
Процес видалення вологи з катлярнопористих колощних матерiалiв супроводжуеться порушенням ii зв'язку з тiлом, на що потрiбно витрачати значну кiлькiсть енерги. Тому, класифiкацiя форм зв'язку тш з вологою побу-дована за принципом штенсивносл цього зв'язку. У цьому ж напрямку до-цшьно провести аналiз ефективностi рiзних способiв сушiння та 1х комбша-
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Сучасш теоретичн1 розробки в деревообробному i меблевому виробництвах
