光学非均匀纤维复合材料对径受压圆盘应力分布－光学关系研究

本文报道利用显微激光分析仪研究微透明实际纤维复合材料对径受压圆盘径向应力分布的新尝试。结果表明,从I-θ曲线中提取出来的傅里叶变换四次基波的模A_‖4等于均质双折射材料在暗场下的等色线亮度的1/2.当用传统方法无法再获得实际纤维复合材料的条纹图象时,仍然可以利用显微激光分析仪得到A_‖4,且借助于A_‖4,可通过作图法求出对径受压圆盘的径向应力分布,所得结果与H.Okabo的理论计算相吻合。实验表明,采用上边方法可对透光度低达万分之六(0.06%)的实际纤维复合材料进行测试。

STRESS DISTRIBUTION-OPTICAL RELATIONSHIP STUDY OF OPTICALLY HETEROGENEOUS FIBER COMPOSITE DISK DIAMETRICALLY COMPRESSED

This paper reports the application of Laser Microscopic Analyser (LMA) to the stress analysis of optically heterogeneous fibre reinforced composites.The composite samples were all disks of 20mm diameter and diametrically compressed in experiments.The transmitted polarised light intensity under the bright field of plane polariscope (I‖) were measured.The light intensity vs.azimuth curve(I‖-θ) was analysed with Fourier transform.The relative intensity of the 4th amplitude,e.g.the amplitude of cos (4θ),A‖4,of the I‖-θ curve was found to be proportional to the brightness of the isochromatic line under the dark field of circular polariscope for optically homogeneous birefringent model,including transparent photoelastic composites with well matched refractive indices between fiberes and resin matrix.On the condition of optically heterogeneous fibre composites,the transparency was too low to show any photoelasic pattern.The 4th amplitude,however,was still readily available with the use of LMA.By the means of A‖4,the stress distrbution on the radius perpendicular to the compressing direction was obtained.The results agree with the theoretic results from H.Okabo.The material used for this measurement is E-glass fibre reinforced rubber-epoxy resin,with fibere volume fraction of 60%,and with an apparent transparency of only 0.06%.