文档介绍：3DryingDefectspage29—,fungalandextractive.・Shrinkage-RelatedDefectsThefactthatwoodshrinksasitdriescanleadtothedevelopmentofseveraldifferentdryingdefects・Duringtheinitialorearlystagesofdrying,,however,isstillabovethefibersaturationpointandhasnotstartedtoshrink•Ineffect、thecorerestrainstheoutershellfromshrinkingasmuchasitnormallywould・・Insomecasesthestressesmaybegreaterthanmaximumstrengthandafissureorsurfacecheckresults・Asdiyingprogresses,theinnercoreultimatelybeginstofallbelowthefibersaturationpointanditshrinks・Thisistennedthesecondstageofdrying・Thetensilesetdevelopedduringthefirststageofdryinghasamajorinfluencesinceitnowrestrainsinturntheinnercorefromshrinkingnormally・Thisresultinastressreversal、pressivestressandtheinnercorebeingunderatensilestress・pressivestressonthesurfacecanfrequentlyclosethesurfacechecksthatwereeasilyvisibleduringthefirststageofdrying、