ABSTRACT

The use of hemp fiber has increased in recent decade due to the increasing demand for sustainable, recyclable, and biodegradable materials. Hemp fibers are obtained from the stem of a plant for the reinforcement of composites. In this work, experimental modal analysis was performed on a hemp fiber (Cannabis sativa) reinforced plate with a free-free condition. Preliminary results of modal parameter identification of multiple damage detection are presented. To consider multiple damage effects, an undamaged plate including six damaged scenarios are considered. For each scenario, natural frequencies with mode shape were identified with accuracy using accelerometer sensors and impact hammer. Measured the natural frequencies and mode shape for undamaged and damaged plates are compared with each other. To establish the correlation between undamaged and damaged plate, modal assurance criterion (MAC) are considered. In addition, coordinated multiple modal assurance criterion (COMAC) considered that were highly sensitive to the severity of damage scenarios with sufficient mode consideration. It is clearly observed that a COMAC plot results show more sensitive compared to MAC plot results. It reveals that even small level damage present in the specimen can be easily examined through coordinate modal assurance criterion.

摘要

由于对可持续、可回收和可生物降解材料的需求不断增加，近十年来大麻纤维的使用有所增加。大麻纤维是从植物的茎中获得的，用于增强复合材料。在这项工作中，对大麻纤维 ( Cannabis sativa) 具有自由自由状态的加强板。给出了多损伤检测模态参数辨识的初步结果。为了考虑多重损坏效应，考虑了包括六个损坏场景的未损坏板。对于每种情况，使用加速度传感器和冲击锤准确识别具有振型的固有频率。将测量的未损坏和损坏板的固有频率和振型相互比较。为了建立未损坏板和损坏板之间的相关性，考虑了模态置信度 (MAC)。此外，协调多模态置信度 (COMAC) 考虑到对损坏情景的严重性高度敏感，并有充分的模态考虑。可以清楚地观察到，与 MAC 绘图结果相比，COMAC 绘图结果更敏感。它表明，通过坐标模态置信度可以很容易地检查试样中存在的小水平损伤。