Standard Test Methods for Mechanical Properties of Lumber and Wood-Base Structural Material

Theory:

ASTM D4761 references and is very similar to ASTM D198 when it comes to mechanical static testing. Types of test can include tensile, shear, and flexure testing. 

 

Wood is one of the predominant construction materials, not just in the United States, but globally. Many emerging countries have still not adopted proper standards for the testing of their lumber. This can and has resulted in catastrophic building failures. Native trees and lumber must be tested since it may behave differently than US pine or oak timber.  

Geometry:

The timber must be sized according to ASTM D198. The most important aspect is the cross-sectional area which is given by the width times the thickness. 

 

Solution:

Self tightening Scissor Grips are the perfect fixture for tensile testing wood samples. The grips use a spring to maintain tension and lateral force on the sample which holds the piece of wood in place. As the test progresses, the wood may compress under the lateral force load. The scissor grips can compensate for these changes in thickness and maintain an ever-tightening grip on the specimen.

 

Flex testing can also be performed with our 4 point wood bending fixture. This is a different tests and required that the machine perform a compression type of test.

 

Analysis:

Ultimate Tensile Strength is the predominant value that is tested for under both ASTM D4761 and D198. There are other calculations which can be made including Elongation.