船用FRP補強板之極限破壞強度研究

Abstract

因複合材料具有強度高、質量輕之優點，所以廣為快艇結構採用以達輕量化、高速化之目的。唯其剛性太低為主要的缺點，因此複合材料結構往往有變形量太大之問題，於是需要適當的補強以增加剛性，快艇結構中常見的補強材為帽型樑。另外快艇於波浪中高速航行時，船艏會露出水面後再急速衝入水中，造成相當大之衝擊力，在此種劇烈的縱向運動下，增加補強材後的補強效果及對極限負荷之影響，應對其做深入之探討。 本文之實驗方面，利用試片、夾具壁與活塞形成水密艙區，再藉由外力推動活塞以增加水壓直至試片達最終破壞，利用不同型式之外力可模擬出結構物承受靜態與動態水壓破壞之行為，藉由實驗結果便可以提供數值模擬分析之比較驗證。 數值計算方面，以GFRP積層單板破壞之分析方式為基礎，採用了將樹脂層和纖維層分開考慮之數值模式，各種纖維的破壞法則與破壞後的剛性修正亦在此基礎下建立，接著利用有限元素分析軟體ABAQUS結合使用者副程式USDFLD對補強板結構進行動態與靜態破壞分析，以瞭解破壞位置及模式、補強材之補強效果等，另外結構物的破壞進展由於無法由實驗得知，只能藉由分析來觀察。經由本研究所建立之分析與實驗方法，可以更加掌握補強板之特性，對日後相關之設計將有很大之助益。

Since FRP(Fiber Reinforced Plastic) has the advantages of high specific strength, it can reduce the weight of the ship when applying to the ship structure. However, the structures constructed by FRP have the problem of relatively low modulus of materials, this leads to the large deflection of FRP laminates. Therefore, we need to stiffen unsupported plates by appropriate mechanism. The most prevalent longitudinal adopted by craft structures is the top-hat stiffeners. On other side, the craft will be exposed above the water and lead to heavy slamming force while sailing in high speed in the sea. Therefore, we should examine the effects and ultimate load of stiffened plate. In actual experiment,an experimental apparatus for the purpose of creating failure on the test pieces under hydrostatic pressure and hydrodynamic pressure identical to the exerting pattern of slamming loads is used. Then we can verify the results of numerical method from experiment. In the numerical analysis, based on the failure analysis of the GFRP laminates, the model that the sections are separated into fiber layers and matrix layers are considered in simulating the stiffened plates. We also established the suitable failure criterion and stiffness modification factor curve in stiffened plates. The finite element analysis is performed by software ABAQUS in cooperated with user subroutine USDFLD to proceed the numerical failure analysis of the stiffened plates. By this we can identify the failure location and mode of the structure as well as the effects of stiffening. Because the failure progress of stiffened plates is unable to understand, we only can observe by numerical analysis. Through the numerical methods and experiment of this research, we can know well the property of stiffened plates. It is positive for relevant design at a later date.