July 10, 1919 



Hardwood Record — Veneer & Panel Section 



23 



Mechanical Test Made on Plywood 



Trying Out the Mechauiical and Physical Properties of Veneer Peuiels 



Editor's Note 



IW'Uiw is :i siimiii;ir>' nf :i rcpui-t on ti'sts (if panels niailo 

 b'lil-est I"rniluits Lal>oi-ati>r.v at Mailisiiii, Wis. A tVw of thi' 

 (tinitt»Mi IxM'Miise (if flicii' liiL'hly rcclinical nature, (ir f(ir i 



li.v L. .1. .Markwanlt aiul Ariiiin Klineinlorf. eiijiiiieers in the 

 niatheniatical fiiritiulas and two or three piettires ju-e 



i\ck (if sjiace. 



The terms veneer, laminated wood, laminated veneer, 

 veneer panel and plywood are often used indiscriminately 

 for the w^ood construction in which several sheets of thin 

 wood are glued together so that the grain of successive 

 sheets crosses at an angle. At the Forest Products Labora- 

 tory veneer is taken to mean the individual sheets of com- 

 paratively thin wood which are cut on special veneer ma- 

 chinery, and plywood is used for the combination of sev- 

 eral sheets or plies of veneer glued together usually at 

 right angles. 



Plywood differs from ordinary wood in several im- 

 portant properties; primarily in strength, resistance to 

 splitting, and shrinkage. The tensile strength and modu- 

 lus of elasticity of ordinary wood parallel to the grain 

 are from 15 to 20 times greater than these properties at 

 right angles to the grain. The shear strength on the other 

 hand, is higher across the grain than parallel to the grain. 

 In plywood the ratio of the strength in the two directions, 



parallel and perpendicular to the edge of a panel, may be 

 varied over wide ranges by changing the number or thick- 

 ness of plies or the combination of species. The strength 

 in tension or in bending in the two directions is readily 

 made equal or it may be made greater in one direction 

 than in another. The resistance to splitting is very much 

 higher for plywood than it is for an ordinary board of the 

 same thickness, and the shrinkage is usually only about 

 one-tenth as much for plywood as it is for ordinary wood 

 across the grain. 



The unique possibility of varying the strength proper- 

 ties by changing the number of plies or their thickness, 

 its high resistance to splitting, combined with the facility 

 with which large, flat panels are made, has given plywood 

 a prominent place as a material of construction for air- 

 planes. In order to use plywood intelligently in airplane 

 design, it is necessary to have numerical data bearing upon 



(C(>MfiMi(('(/ oti f^dge 26) 



Sp(tOlOB 



All ollM In «nj on« T.«n.l »«r« of th. .»m<i thlonnse. .n-l 

 AH oil., in ^,^^ ^^ .uoc.B.lv. rlls. (it rli'Jit .nirl.. 

 All i..t.rl.l rofry out - P.rHn. Olu, ,..,d throughout 



Kl«ht thloKh.BC. of plywood. r»nnln» froir /^i to 



the BKco .p.cl.. 

 ' wore taated 



Av.Sp.Gr. c; :A»«ra«« : 

 I'lywoo' B.sad I Per Cnti- 

 on 0v.n-3ry rti( ol.tur.: 

 & Vol - at T.Bt : ■ - 



eduxn snbiiw ' 



Column UenMr.t .odulu. Modulu. of Kinetic 



Parallel* : p.pp^nd.lculap* ; .'aral lei" ; Parpsnl leu 



:»o. of: Lbs. Par: Wo. of;Lbe. Pan 

 (ToBtB : .=*q. lr.,:TeBta : bq . In.: 



( bB . Par £q. 



Ity ; Ter-olla L tranrth : 



Idr*; rJar.llel" :r'eroen'llculBr- ; 



li-. no. of:LbB. P«r:lio. cfiLbB. Per:»o. of: 

 :T»etB : 'q. In.:ToBtB : Sq. In.:Te»tB : 



lolltllni 

 Rao'.Bt.'-c. 



Par CBht Of 

 Blrcho<» 



»ah, Blaok 



Ash, Coirnerolal "Tiltc 



BABBWOCd 



b.^Cll 



Slrch, Yallow 



Cedar, Joanlah 

 Cherry (al 

 Chaetnut 

 Cottonwood 

 CypraBB, tiald 



DOURlBH Fir 

 ?.l5:. Cork 

 Flir, rhlte 

 Jur, BlacV 

 3U'^, Gotten 



OtL" , (<ed 

 H-=»ber-j 

 Herlook, lveBt>^rn 

 MaKT.olla f-1 

 liB?;0!«n/, ifri;;'! ' •) 



kahoRany, Phlllii^lna 1^1 



Kahorany, Trua 



haple, boft 'el 



■ eT^? «, Sucrar 



Cal!, Cor-er:ii: Bad 



Dale, Cor-erclal vhlta 

 Jlne, vhite 

 Poblgr, lellow 

 rted^Jool 

 SorucBi ^ltV9 



Syoa-ore 

 -alnut, Black 



f ■= 1 Probably dIp:^ uherry 



'>^ =rohably (Kver^roin) ai^olla 



'o) Probably Khaya Sp. 



H) Probably TanRulla 



'■5" Probably Silver ,apl; 



10. P 

 "•6 





10." 

 10. ' 



!0.7 

 11. 1 



P.O 

 ?.3 



1?0 



no 



TOO 

 l-o 



I'O 



i»a 



HP 

 10 



lo." 



lOf 



77^0 



nqro 

 71?'- 

 1^350 

 1 flooo 



■^4"0 



12^ GO 



B'6u 



7a ^ 



ou-0 

 (=070 





10400 

 7QP0 

 Oflc-O 



1-0 

 1"0 



1770 

 "flrn 



:'»7o 



1400 



1110 



"Parallel and oerpor : 1 : J - in 

 appllca'.lon of tf-e ri^r;^ 



•"Ihe relatl" 



1 till >* r^Bid'ai 09 o. 



1070 

 1.4 00 



I"10 



-ir<l 



•"HO 



1440 

 1140 



1"7 



107 



IT 

 TOO 



11' 

 111 



40-n 



4fC0 

 '740 - 

 T770 



« 101 



60 



5i' 



par * 1b 1- 



^B fttcen r-Utl" 



Is I iprel V on the 



•> 1 '. ! -: 



ff* 



«« 



'14 



i 



1- 



'7 



pt' :t .-1 . 



70 S3m 

 TABLE 1-STRENGTII i>l' VARIOUS SPECIES 0\- THREE PLY PAXELS 



uMjpD bUlcS T-'AilTlll'.NT OK ..-SlJl-'lJn- 



►vB .1 PBJCUGis ;.Ai;jpAT uc 



FOB'.-T ■ T'l-" 4i 



•.CISO.-J, ■■ 1 .'"^-'"IN 

 ,..._..^Y r. '-"l" 



