【摘要】：在玻璃鋼錨桿中,纖維是載荷的主要承擔(dān)者,桿體受拉纖維斷裂失效后,在斷點(diǎn)發(fā)生纖維脫粘和桿體裂紋擴(kuò)展是兩種主要破壞形式。另外,玻璃鋼錨桿生產(chǎn)中,經(jīng)歷由高溫到低溫的固化過程,產(chǎn)生熱殘余應(yīng)力也是不可避免的。本論文主要對(duì)玻璃鋼錨桿拉伸過程中,纖維拉脫、桿體裂紋擴(kuò)展兩種破壞失效形式以及玻璃鋼錨桿桿體在固化過程中的熱殘余應(yīng)力分布進(jìn)行了數(shù)值模擬。本論文所進(jìn)行的數(shù)值模擬是采用通用有限元模擬軟件ANSYS與自主開發(fā)程序相結(jié)合的方法,以玻璃鋼錨桿的尺寸為基礎(chǔ)建立初始條件、邊界條件、失效準(zhǔn)則、材料和狀態(tài)方程來進(jìn)行。主要研究?jī)?nèi)容如下:對(duì)單根纖維拉脫模擬分析了理想界面、不同界面層厚度和不同界面層彈性模量對(duì)單根纖維拉脫的影響。研究結(jié)果表明:在單根纖維拉脫過程中,下端脫粘點(diǎn)和上端面都會(huì)出現(xiàn)應(yīng)力集中,且下端脫粘點(diǎn)的應(yīng)力集中范圍和程度要大于上端面。適當(dāng)增加界面層厚度、減小界面層的彈性模量,界面上應(yīng)力分布更均勻,有利于減少應(yīng)力集中的范圍和程度,界面產(chǎn)生塑性變形的能力增大,界面脫粘載荷增大,從而可以避免桿體發(fā)生脆性破壞,提高其強(qiáng)度和韌性。對(duì)桿體裂紋擴(kuò)展模擬分析了纖維斷裂后裂紋擴(kuò)展的模式和界面強(qiáng)度對(duì)損傷演化發(fā)展的規(guī)律。研究結(jié)果表明:強(qiáng)界面情況下,纖維斷點(diǎn)處產(chǎn)生的裂紋沿垂直于纖維軸向的基體中擴(kuò)展,纖維上應(yīng)力迅速增大,纖維上容易出現(xiàn)應(yīng)力集中,材料往往出現(xiàn)脆性破壞,但已斷纖維和鄰近纖維上的應(yīng)力都會(huì)迅速恢復(fù);弱界面情況下,纖維斷點(diǎn)處產(chǎn)生的裂紋在已斷纖維和其鄰近基體的界面上沿纖維軸向進(jìn)行擴(kuò)展,界面脫粘,鄰近纖維上應(yīng)力集中的范圍和程度都比較小,材料表現(xiàn)出較好的韌性,已斷纖維和鄰近纖維上的應(yīng)力恢復(fù)得慢;在中等界面的情況下,纖維斷點(diǎn)處產(chǎn)生既會(huì)發(fā)生纖維脫粘也會(huì)發(fā)生裂紋擴(kuò)展,使材料既能保持一定的強(qiáng)度,又表現(xiàn)出一定的韌性。對(duì)固化過程中桿體中熱殘余應(yīng)力分布模擬分析了固化溫度、纖維彈性模量、基體彈性模量、纖維體積分?jǐn)?shù)和界面層彈性模量等工藝參數(shù)對(duì)玻璃鋼錨桿桿體中熱殘余應(yīng)力分布的影響規(guī)律。研究結(jié)果表明:固化溫度升高,纖維彈性模量增大,基體彈性模量增大,纖維體積分?jǐn)?shù)增加,都會(huì)引起玻璃鋼錨桿桿體中熱殘余應(yīng)力增大。界面層彈性模量增加,玻璃鋼錨桿桿體中的熱殘余應(yīng)力集中向界面層中轉(zhuǎn)移,熱殘余應(yīng)力集中減少。當(dāng)界面層的彈性模量與纖維的彈性模量相差比較小時(shí),桿體中的熱殘余應(yīng)力會(huì)大大降低。
[Abstract]:In FRP anchor rod, fiber is the main load bearer. after the fracture failure of tensile fiber, fiber debonding and crack propagation are the two main failure forms. In addition, in the production of FRP anchor rod, it is inevitable to produce thermal residual stress through the curing process from high temperature to low temperature. In this paper, two failure modes of fiber drawing, crack propagation and thermal residual stress distribution of FRP anchor rod during curing are simulated. The numerical simulation carried out in this paper is based on the size of FRP bolt by combining the general finite element simulation software ANSYS with the independent development program to establish the initial conditions, boundary conditions and failure criteria. The material and the equation of state are carried out. The main research contents are as follows: the effects of ideal interface, different thickness of interface layer and elastic modulus of different interface layer on pullout of single fiber are analyzed by simulation of single fiber drawing. The results show that the stress concentration occurs at the lower end and the upper end during the drawing process of a single fiber, and the range and degree of the stress concentration at the lower end of the debonding point are larger than those at the upper end. By properly increasing the thickness of the interface layer and reducing the elastic modulus of the interface layer, the stress distribution on the interface is more uniform, which is beneficial to reduce the range and degree of stress concentration, increase the ability of plastic deformation at the interface, and increase the debonding load of the interface. Thus, the brittle failure of the rod can be avoided and its strength and toughness can be improved. The mode of crack propagation and the law of interfacial strength on the development of damage evolution after fiber fracture are simulated and analyzed. The results show that under the condition of strong interface, the cracks at the broken point of the fiber propagate along the matrix perpendicular to the axial direction of the fiber, the stress on the fiber increases rapidly, the stress concentration on the fiber tends to appear, and the material often appears brittle failure. However, the stress on the broken fiber and the adjacent fiber will recover rapidly. In the case of weak interface, the cracks at the broken point of the fiber propagate along the axial direction of the fiber along the interface between the broken fiber and its adjacent matrix, and the interface debonding is small in the range and degree of stress concentration on the adjacent fiber. The material shows good toughness and the stress recovery on broken fiber and adjacent fiber is slow. In the case of medium interface, fiber debonding and crack propagation will occur at the broken point of the fiber, which makes the material not only maintain a certain strength, but also show a certain toughness. The thermal residual stress distribution in the bar during curing was simulated and analyzed, such as curing temperature, elastic modulus of fiber and elastic modulus of matrix. Effects of technological parameters such as fiber volume fraction and elastic modulus of interface layer on thermal residual stress distribution in FRP anchor rod. The results show that when the curing temperature increases, the elastic modulus of the fiber increases, the elastic modulus of the matrix increases, and the volume fraction of the fiber increases, the thermal residual stress in the FRP anchor rod increases. With the increase of elastic modulus of interface layer, the concentration of thermal residual stress in FRP bolt rod is transferred to the interface layer, and the concentration of thermal residual stress is reduced. When the difference between the elastic modulus of the interface layer and the elastic modulus of the fiber is small, the thermal residual stress in the rod body will be greatly reduced.
【學(xué)位授予單位】：中國(guó)礦業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ327.1;TD353.6

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