Wood is one of the oldest and most used structural materials, and its mechanical properties depend greatly on the species, moisture content, and growth characteristics. ASTM D198 attempts to overcome this variability by offering standard procedures for static testing of lumber made in structural sizes. The standard provides that the mechanical property data is produced under controlled laboratory conditions in order to be able to derive engineering design values. It is applied to large specimens of practical size in contrast to the small, clear tests, and thus represents the real performance better for service. The tests are used to determine the modulus of elasticity, ultimate strength, and deformation under load. Information derived from ASTM D198 is therefore very important in wood engineering, structural reliability analysis, and in the development of grade rules for commercial lumber.
ASTM D198 Test Method
| Onset Temperature Determination | The sample is heated at a controlled rate (commonly 10 °C/min), and the temperature at which decomposition begins is recorded. |
| Heat Flow Measurement | DSC measures the energy difference between sample and reference pans as reactions occur, giving insight into exothermic or endothermic processes. |
| Decomposition Energy Analysis | The integrated peak area under the DSC curve quantifies the energy released or absorbed during the decomposition process. |