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本文对无损检测片状模塑料(SMC)试样和鉴别支配复合材料强度的基本微观特征所需的技术进行了探讨。发现有两种试验方法对表征SMC的行径特别有用。一种是温度记录器法,它是应用——灵敏的热成像系统,以探测低幅循环环加载过程中的滞后热局部变差;另一种是超声技术,它是采用超声波速度来表征局部机械性能的变化。两者均能在试验前查出SMC材料终极损坏区。已观察到这两种试验方法之间具有良好的一致性。藉助这两种查出弱区的方法,便可以进一步研究可能造成所发现的弱化的原因。业已发现,在同一SMC样品中,纤维增强材料和填料存在相当大的差异,在单个层板中观察到这些局部差异高达27％。据发现,富集树脂区与无损鉴定为可能的损坏区密切相对应。剪力波试验结果指出与试样的不均匀性相比,纤维取向成为局部力学性能差异之根源的可能性较小。
This article explores the techniques required for nondestructive testing of SMC specimens and for identifying the basic microscopic features that govern the strength of the composite. Two test methods were found to be particularly useful for characterizing SMC behavior. One is the temperature logger method, which is an application-sensitive thermal imaging system to detect local variations in hysteresis over low cyclic loading cycles; the other is the ultrasound technique, which uses ultrasound velocity to characterize local Changes in mechanical properties. Both can detect the ultimate damaged area of SMC material before testing. It has been observed that there is good agreement between these two test methods. With these two methods of identifying weak areas, one can further investigate the causes that may have contributed to the weaknesses found. It has been found that there is a considerable difference between the fiber reinforcement and the filler in the same SMC sample, with up to 27% of these local differences observed in a single laminate. It has been found that the resin-rich zone corresponds closely to the damaged zone where no-damage identification is possible. The shear wave test results indicate that the fiber orientation is less likely to be a source of local mechanical differences than the inhomogeneities of the specimens.