溫度效應及扭轉損傷對Gr/PEEK積層板軸向靜態強度與疲勞壽命影響之研究

STUDY ON TEMPERATURE AND TORSION-DAMAGED EFFECTS ON STATIC STRENGTH AND FATIGUE LIFE OF THE GRAPHITE/PEEK COMPOSITE LAMINATES

在本研究中，使用實驗觀察方式對熱塑性複合材料（Gr/PEEK）受到溫度或扭轉損傷後，其靜態拉伸強度與疲勞壽命所受到影響進行研究。由實驗結果很清楚得知，溫度效應對於靜態拉伸強度並沒有影響，但對於疲勞壽命卻有所損害。而扭轉損傷將會降低拉伸強度與疲勞壽命。同時，由實驗結果可發現，經扭轉損傷再經溫度影響所造成的損傷會比經溫度影響後再經扭轉損傷所造成的損傷嚴重。另一方面，對已受到損傷的試片在200°C進行熱壓修補，並且研究修補後的試片其靜態拉伸強度與疲勞壽命。很明顯的，熱壓修補後的試片其脫層面積會變少。因此，對於遭受扭轉損傷或者經溫度影響的試片，經200°C熱壓修補後疲勞壽命將會增加。而溫度與扭轉之間施加在試片上的順序，對於修補後的試片在疲勞壽命上的影響不大。

By experimental observation, the effects of temperature and torsiondamage on ultimate strength and fatigue life were investigated, respectively, for the Graphite/PEEK laminate in this study. It is evident from the experimental results that there is no influence on residual strength after exposure to temperature changes. But temperature change effects are detrimental to the fatigue life. It can be found that the ultimate strength and fatigue are decreased life after torsion damage. Furthermore, by comparing the experimental results, it is found that the damage from temperature change effects after twisting is more serious than the damage from twisting after temperature changes. Meanwhile, the damaged specimens are repaired by thermoforming at a temperature of 200oC. The corresponding static strength and fatigue life are also investigated in this study. Obviously, due to torsion-damage or temperature change effects, the area of delamination can be improved by thermoforming. Hence, the thermoforming method can increase the fatigue life of a specimen that has experienced temperature changes or twisting. It is noted that temperature and twist action has less influence on fatigue life for the repaired specimens.