Load Duration and Seasoning Effects on Mortise & Tennon Joinery

The difference in stiffness values was also within a reasonable range. Unity values
varied between 0.60 <strong>and</strong> 1.28 with an average perpendicular to grain ratio of 0.91 <strong>and</strong> an
average parallel to grain ratio of 1.08. In general the mathematically combined tests
represented the physically combined tests well.
The eastern white pine base material has a significantly lower bearing strength
perpendicular to grain than the white oak used for the pegs (see Figure 3-4). The
difference in bearing strength meant that the weaker eastern white pine material
dominated the test results; often in the combined tests, little peg damage was visible.
While difficult to quantify, this effect is a consideration.
<strong>Load</strong> (lbs)
5000
4000
3000
2000
1000
Peg Bearing Test
Dowel Bearing Test on
Base Material
Mathematically Combined Test
Linear Portion of Physically
Combined Test
Linear Portion of
Mathematically
Combined Test
Physically Combined Test
0
0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350
Deflection (in)
Figure 3-4 Typical Spring Theory Plot (Base Material <strong>Load</strong>ed Perpendicular to Grain)
Combined tests with the base material loaded parallel to grain resulted in more peg
damage. In the tests with the base material loaded parallel to grain the base material was
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