ASTM D6874-22a

SIGNIFICANCE AND USE 5.1 The dynamic modulus of elasticity provided by these test methods is a fundamental property for the configuration tested. 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. 5.2 The modulus of elasticity, whether measured statically or dynamically, is often a useful predictor variable to suggest or explain property relationships. 5.3 Results from these test methods can be related to other measurements of modulus of elasticity, such as static methods (see Annex A1 and Appendix X4). 5.4 These methods use calculations that assume specimens are prismatic in cross-section and are uniform in modulus of elasticity and density. 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 (that is, 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 Testing specified to be undertaken in accordance with this Method shall include any requirements regarding the following for each Class: 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 t... SCOPE 1.1 These test methods cover the non-destructive determination of the following dynamic properties of wood and wood-based materials from measuring the fundamental frequency of vibration: 1.1.1 Flexural (see Refs (1-3))2 stiffness and apparent modulus of elasticity (Etv) 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 (Esw) using stress wave propagation time in the longitudinal direction. 1.2 The test methods can be used for a broad range of wood-based materials and products ranging from logs, timbers, lumber, and engineered wood products. 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 (for example, columns but not products with distinct subcomponents such as wood I-joists). 1.3 The standard recognizes three implementation classes for each of these test methods. 1.3.1 Class I—Defines the fundamental method to achieve the highest degree of repeatability and reproducibility that can be achieved under laboratory conditions. Note 1: Testing should follow Class I methods to develop training and validation data sets for method conversion models (see Annex A2). 1.3.2 Class II—Method 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. Note 2: Practical deviations include, for example, environmental and test boundary conditions. Class II methods allow for corrections to test results to account for quantifiable effect such as machine frame deflections. 1.3.3 Class III—Method permitting the broadest range of application, with permitted modifications to suit a wider ra...