Table 1. — Mechanical properties of roble bianco ( Tabebuia pentaphylla ) , white 
oak Qjuercus alba), and white ash (Fraxinus amsricma)- (continued) 
Property 
Sp 
:ies_ 
Roble bianco 
(Tabebuia 
pentaphylla) 
: White oak 
(Qucrcus 
V/hite ash 
( Fraxinus 
air.ericana) 
Compression perpendicular to the grain 
Stress at proportional limit 
Green p.s.i. 
Air-dry 2 p.s.i. 
Tension perpendicular to grain 
Green p.s.i, 
Air-dryl p.s.i. 
She ar 
Green p.s.i, 
Air-dry 2. p.s.i, 
Cleavage . . : 
Green lb. per in, of width: 
Air-dryl lb. per in. of width: 
Toughness^. in. -lb. per specimen: 
790 
940 
790 
*560 
1,250 
1,450 
380 
*270 
147.0 
-This table shows results of tests on roble bianco made by the Yale School of 
Forestry in cooperation with the Office of Naval Research and the Bureau of 
Ships, U. S. Navy Dept. Average strength values for all logs are presented 
(32). The results of tests on white oak and white ash, cited in the same 
Yale report, were taken from U. S. Dept. Agriculture Tech. Bull. 479 (14) . 
Strength values for roble bianco from Venezuela are not included in this 
table, but have been determined on limited material at a different moisture 
content by Kynoch and Norton (10). 
2 
-Source and number of logs: Roble bianco, British Honduras, 3 logs, 
Honduras, 3 logs, and Panama, 3 logs; white oak, United States, 20 logs; 
v/hite ash, United States, 23 logs. 
3 
-Air-dry values adjusted to 12 percent moisture content except where designated 
(*), in which case the actual moisture content at time of testing (see 
isture Content in table) applies. 
L 
-The load in pounds required to embed a 0.444-inch steel ball to half its 
diameter. 
-Toughness values are the average of tests of green and air-dry specimens 
5/8 by 5/8 by 10 inches loaded on the tangential face over an 8- inch span. 
^Value obtained for plank material received from the New York Naval Shipyard. 
Rept. No. 1980 
(Sheet 2 of 2) 
