A Horizontal Machine for Testing Structural Wood Elements in Tension

摘要

The machine provides an efficient facility for conducting evaluations of tensile strength properties of structural size lumber relatively fast, easily, and safely. The grips provide axial alinement of clear material and rotate freely when eccentrically located knots are present. The hydraulic loading system provides a uniform, controllable velocity of the movable head, and the electronic weighing system provides an accurate measurement of the tensile load. The face width of the grips, the distance between faces, and the distance between the movable and the stationary grips are such that various structural specimens, ranging in size from 1 to 2 inches thick, 4 to 10 inches wide, and 8 to 16 feet long, can be tested provided the load does not exceed 150,000 pounds. The grips are wedge shaped and beveled to automatically lateral pressure against the specimen and yet minimize stress concentrations. An extensometer accurately provides an average measurement of strain in the specimen between the grips, permitting one observer to read and record the elongation. Finally, the entire work area in which the operators must handle the specimens and extensometer and observe data provides for efficient operation. All of these features aid in the accurate, safe, and economical generation of tensile properties of structural size members. (Author)