MDF弹性模量、泊松比和剪切模量静态测试方法探讨

Discussion on static testing method of material MDF constants of elastic modulus,Poisson's ratio and shear modulus

提出了一种静态测试MDF泊松比μ和弹性模量E的新方法,即悬臂板静态弯曲法。首先,阐述了悬臂板静态弯曲法测试MDF泊松比和弹性模量的原理。根据MDF悬臂板受集中力作用下静态弯曲应力、应变分析,确定了静态测试MDF泊松比的十字应变片粘贴位置。为说明悬臂板静态弯曲法测试MDF弹性模量和泊松比的正确性,采用轴向拉伸法、四点弯曲法进行MDF的弹性模量和泊松比值的验证试验。最后,针对MDF为各向同性材料特点,通过方板静态扭转试验测得的剪切模量G,验证悬臂板静态弯曲法测试弹性模量和泊松比的正确性。结果表明:悬臂板静态弯曲法中,用于测试泊松比的应变片粘贴位置由板内横向应力σy=0的位置所确定;悬臂板静态弯曲法和轴向拉伸法测试的MDF的泊松比和弹性模量吻合得相当好,悬臂板静态弯曲法测试泊松比和弹性模量的正确性得到轴向拉伸试验的验证;悬臂板静态弯曲法测试MDF弹性模量E、泊松比μ的正确性还得到方板静态扭转试验的验证,即根据悬臂板静态弯曲法测试得到MDF的弹性模量和泊松比,并按G=E/2(1+μ)推算剪切模量G是可行的。

In this paper,a new method for static testing of MDF Poisson＇s ratio μ and elastic modulus E was presented,namely static bending cantilever plates method. First of all,the principle of measuring MDF Poisson＇s ratio and elastic modulus by the static bending method of cantilever plate was expounded.According to the static bending stress and strain analysis of MDF cantilever plate under concentrated force,the cross strain gauge position of static testing MDF Poisson＇s ratio was determined. Secondly,to illustrate the correctness of the MDF elastic modulus and Poisson＇s ratio of the cantilever plate static bending test method,the elastic modulus and Poisson＇s ratio of MDF were tested by axial tension method and four-point bending method. Thirdly,in view of the fact that MDF is an isotropic material,the correctness of E and μ tested by the static bending test of the cantilever plate was verified by shear modulus G tested by the square plate static torsion test. The conclusion showed that strain gauge position of the cantilever plate MDF specimen used for the testing static Poisson＇s ratio was determined by the position of the plate transverse stress σy= 0; the Poisson＇s ratio and the elastic modulus of the MDF tested by the static bending cantilever plate method and the axial tensile test were in good agreement. The correctness of the static bending cantilever plate method for the testing of Poisson＇s ratio and elastic modulus was verified by axial tensile test; the correctness of static bending cantilever plate method for the testing of MDF elastic modulus E and Poisson＇s ratio μ verified by the square plate had been static torsion test,that is E and μ were tested based on the static bending cantilever plate method for the testing ofMDF,and according to G = E/2（ 1 ＋ μ）,the calculated shear modulus G is feasible.