SIMULATION OF FRACTURING PROCESS OF WOOD BY FINITE ELEMENT METHOD

An existing FEM program for elastic-plastic problems was converted to the one which can be accomodated to the change of stiffness matrix and the release of stress at fractured elements. With this program, the fracturing processes of two testing types of wood (spruce) were simulated; the standard JIS shearing test (JIS Z2114) and the standard JIS bending test (JIS Z2113). The results are summarized as follows.(1) The shearing strength obtained by the calculation was 90.6kgf/cm2. This value agreed with the actual testing data. The fracture initiated and propagated along the grains. This simulated result accorded well with the real fracturing process in the shearing test.(2) The bending strength obtained by the calculation was 1297kgf/cm2, which was larger than the actual value because the finite element mesh was rough and thus the scale factors for yielding were estimated as large values. The fracture initiated at the bottom of the specimen, grew to the neutral axis and turned its direction to the grain. This simulated result accorded well with the real fracturing process in the bending test.