探討碳纖複合材料疊層板之壓縮強度

Abstract

本研究主要目的為預估不同疊層碳纖維複合材料疊層板(Composite laminate)之壓縮強度。首先藉由改變實驗夾持方法、負載方式並搭配有限元素法(Finite element analysis)與紐結(Kinking)預估模型探討實驗因素與試片因素對碳纖維複材壓縮強度的影響，以定義出合適之壓縮測試方法與試片尺寸。接著以此方法量測疊層順序為L1[0/90/45/-45]2s、L2[0/45/-45/90]2s、L3[45/0/-45/90]2s與L4[45/-45/0/90]2s碳纖複材疊層板。實驗結果發現，當0度疊層順序被安排於試片外層時，其壓縮強度較弱，且由破壞試片可知，其壓縮表現會受到不同的相鄰疊層角度而影響。接著本研究使用有限元素法考慮材料非線性、介面破壞性質(Fracture properties)與纖維初始偏差角(Fiber initial misalignment)建立含纖維偏差半均質模型(Semi-homogenized model)，以層間脫層、樹脂破壞與平面外紐結破壞模式為基礎，預估碳纖複材疊層板壓縮強度。結果發現0度層在外之疊層板具較低壓縮強度。此外，分析模型亦探討纖維初始偏差角與預估模型長度對壓縮強度的影響，結果顯示上述兩因素皆與疊層板壓縮強度為負相關，而其中又以纖維初始偏差角對壓縮強度的影響較為顯著。

The research aims to characterize compressive strength of composite laminates with different stacking sequences. First of all, by changing experiment clamp method and loading mode and also combine with finite element method(FEM) and kinking prediction model to investigate experiment factors and specimen factors, that are able to influence composite material compressive behavior. Then defining an appropriate test method to measure compressive strength of composite laminates with stacking sequences L1[0/90/45/-45]2s、L2[0/45/-45/90]2s、L3[45/0/-45/90]2s and L4[45/-45/0/90]2s. Experimental results indicated that the laminates with 0 degree plies as outer layers exhibit lower compressive strength and the main failure mechanism is the out-of-plane microbuckling. In order to understand the failure strength of the composite laminates, a semi-homogeneous model with the consideration of interfacial delamination, material nonlinearity, and fiber initial misalignment was generated. Based on the model predictions, it was found that the fiber misalignment and fiber waviness length may significantly influence the compressive strength of composite laminates. In addition, the laminates with 0 degree plies in the surface demonstrate lower compressive strength, which is coincided with the experimental observation.