R&R study of using a stress wave timer to measure the elastic modulus of structural dimension lumber

The repeatability and reproducibility (R&R) analysis is of great importance in measurement of a material property in science and engineering. Stress Wave Timer is a portable and efficient instrument, which has been widely applied to measure the modulus of elasticity (MOE) of lumber. The study was aimed at analyzing the R&R of using Metriguard 239A Stress Wave Timer to measure the MOE of the structural dimension lumber of lodgepole pine (Pinus contorta var. latifolia), and providing a scientific measurement, i.e. a measurement plus an uncertainty, for any accredited testing laboratory and quality control department in a manufacturer. It was found that the R&R of using Metriguard 239A Stress Wave Timer to measure the MOE of lumber was very reliable when the standard operation procedure was strictly applied. The uncertainty of an MOE measurement was 335 MPa at a confidence level of 95%. The average MOE measured was 12,098 MPa.