关键词: 定向刨花板, 弹性模量, 剪切模量, 动态测试, 方板扭转试验

Abstract: [Objective] In recent years, there have been few researches on the shear modulus test method for oriented strand board (OSB). It has been related to the acoustic emission method and the transverse vibration of the cantilever member to test the OSB shear modulus. This paper studies the OSB from the experimental aspect. Anisotropy, from the theoretical analysis and experimental aspects to explore the dynamic and static method for testing the in-plane shear modulus of OSB, involves the new concept of OSB free plate and cantilever plate shape coefficient, the principle of square plate static torsional strain method and its principle test implementation.[Method] Using ANSYS program to calculate the vibration shape coefficient of the OSB free plate and the cantilever plate test, it is given that the mode shape coefficient is dependent on the relational expression of length-to-width ratio and width-to-thickness ratio and verify the correctness of simulation calculation, dynamic test and static torsion test plate. The dynamic test of shear modulus about the OSB is made from a piece of the whole OSB board material, and the specimens were divided into three directions, namely, making specimen along the whole plate longitudinal(0° or x)direction, transverse(90° or y)direction and to the direction of 45° along with specimen longitudinal direction making. The test piece for testing the OSB shear modulus by square plate torsion test is made along the entire plate in the longitudinal or transverse direction. This study tests the dynamic elastic modulus of the OSB plate specimens about the longitudinal, transverse and 45° direction, and also tests the OSB plate specimen's dynamic in-plane shear modulus and shear modulus of 45° direction.[Result] The measured longitudinal elastic modulus of OSB plate is 2.89 times of its transverse elastic modulus, and the shear modulus of the 45° is smaller than that of in-plane shear modulus. It was given that the shear modulus through square plate torsion test which is suitable orthotropic material, and the calculation formula needs to use ±45°direction's difference of strain measurement value of the shear modulus calculation, for the OSB plate, the measured static shear modulus and dynamic shear modulus test very well.[Conclusion] The OSB plate's elastic modulus presents a direction tendency. The longitudinal elastic modulus is maximum, the transverse elastic modulus is minimum, and the 45° direction elastic modulus is the medium; the free plate torsional vibration shape method and cantilever plate torsional mode method are suitable for dynamic testing of OSB plate in-plane shear modulus, and its correctness is verified in square plate torsion test shear modulus; 0° and 90° OSB plate dynamic are measured almost equal, and can be used to estimate the OSB plate in-plane shear modulus value G_xy; OSB plate should not deal according to unidirectional composite processing, and in the theoretical analysis should be according to the orthotropic plate processing, OSB 45°direction of shear modulus G_45° < G_0° or G_90°; square plate torsion test for testing OSB in-plane shear modulus, should be in the center of the surface two square plate along the two diagonal paste ±45° degrees of strain gages, according to the difference of ±45° direction strain measurement calculation; shear modulus by dynamic test agrees with the shear modulus by square plate torsion test, which shows that the torsional vibration method is feasible in the test of OSB sheet shear modulus.

Key words: oriented strand board(OSB), elastic modulus, shear modulus, dynamic test, square-plate torsion test