ASTM D6874-21

5.1.1?The rapidity and ease of application of these test methods facilitate their use as a substitute for static measurements.

5.1.2?Dynamic modulus of elasticity is often used for surveys, for segregation of lumber for test purposes, for quality assessment of engineered wood products, and to provide indication of environmental or processing effect.

5.4.1?As a result of the above assumptions, the obtained values of modulus of elasticity are dependent on how the specimen is stressed (see Commentary).

5.4.2?Transverse vibration and longitudinal stress wave modulus of elasticity are correlated but not necessarily equal.

5.4.3?These methods provide a means to establish a model to predict one dynamic modulus of elasticity from another dynamic method or a static method (i.e., D198, D4761, etc.).

5.4.4?The methods can also be used to estimate the Class I or Class II modulus of elasticity from the Class III method, or the Class I from the Class II method.

5.5.1?Grades and species permitted to be combined to form the training and validation test sample.

5.5.2?Selection and positioning of manufacturing or growth characteristics to be included or permitted in the test sample.

5.5.3?Moisture content conditioning undertaken prior to testing.

5.5.4?Acceptable moisture content adjustment models.

5.5.5?Any other sampling and data adjustment requirements to obtain a representative sample of the population under consideration.

1.1.1?Flexural (see Refs (1-3))2 stiffness and apparent modulus of elasticity (E_tv) properties using simply or freely supported beam transverse vibration in the vertical direction, and

1.1.2?Axial stiffness and apparent longitudinal modulus of elasticity (E_sw) using stress wave propagation time in the longitudinal direction.

1.2.1?The two flexural methods can be applied to flexural products such as glulam beams and I-joists.

1.2.2?The longitudinal stress wave methods are limited to solid wood and homogeneous grade glulam (e.g., columns but not products with distinct subcomponents such as wood I-joists).

1.3.1?Class IDefines the fundamental method to achieve the highest degree of repeatability and reproducibility that can be achieved under laboratory conditions.

1.3.2?Class IIMethod with permitted modifications to the Class I method that can be used to address practical issues found in the field, and where practical deviations from the Class I protocol are known and their effects can be accounted.

1.3.3?Class IIIMethod permitting the broadest range of application, with permitted modifications to suit a wider range of practical needs with an emphasis on repeatability.

1.4.1?The standard covers only models developed from test data obtained directly from non-destructively testing a representative sample using one test method, and retesting the same sample following a second test method.

1.4.2?Results used for model development shall not be estimated from a model.