The Elastic Constants of Plywood

DIRECT observation (see Fig. 1) on a strip of veneer cut at an angle other than 0 deg. or 90 deg. to the grain shows that a bending moment parallel to the long axis of the strip is accompanied by a twist, in addition to the usual bending, and further, that the resistance to bending is higher when the accompanying torsion is prevented than when it is permitted. Similar phenomena are observed when the strip is subjected to a pure twist about the long axis; the distortion is again a combination of flexure and torsion, and a higher resistance to torsion is obtained when the accompanying bending is suppressed than when it is permitted.