玻璃钢锚杆拉伸及固化过程细观力学数值模拟研究
发布时间：2019-06-06 01:15
【摘要】：在玻璃钢锚杆中,纤维是载荷的主要承担者,杆体受拉纤维断裂失效后,在断点发生纤维脱粘和杆体裂纹扩展是两种主要破坏形式。另外,玻璃钢锚杆生产中,经历由高温到低温的固化过程,产生热残余应力也是不可避免的。本论文主要对玻璃钢锚杆拉伸过程中,纤维拉脱、杆体裂纹扩展两种破坏失效形式以及玻璃钢锚杆杆体在固化过程中的热残余应力分布进行了数值模拟。本论文所进行的数值模拟是采用通用有限元模拟软件ANSYS与自主开发程序相结合的方法,以玻璃钢锚杆的尺寸为基础建立初始条件、边界条件、失效准则、材料和状态方程来进行。主要研究内容如下:对单根纤维拉脱模拟分析了理想界面、不同界面层厚度和不同界面层弹性模量对单根纤维拉脱的影响。研究结果表明:在单根纤维拉脱过程中,下端脱粘点和上端面都会出现应力集中,且下端脱粘点的应力集中范围和程度要大于上端面。适当增加界面层厚度、减小界面层的弹性模量,界面上应力分布更均匀,有利于减少应力集中的范围和程度,界面产生塑性变形的能力增大,界面脱粘载荷增大,从而可以避免杆体发生脆性破坏,提高其强度和韧性。对杆体裂纹扩展模拟分析了纤维断裂后裂纹扩展的模式和界面强度对损伤演化发展的规律。研究结果表明:强界面情况下,纤维断点处产生的裂纹沿垂直于纤维轴向的基体中扩展,纤维上应力迅速增大,纤维上容易出现应力集中,材料往往出现脆性破坏,但已断纤维和邻近纤维上的应力都会迅速恢复;弱界面情况下,纤维断点处产生的裂纹在已断纤维和其邻近基体的界面上沿纤维轴向进行扩展,界面脱粘,邻近纤维上应力集中的范围和程度都比较小,材料表现出较好的韧性,已断纤维和邻近纤维上的应力恢复得慢;在中等界面的情况下,纤维断点处产生既会发生纤维脱粘也会发生裂纹扩展,使材料既能保持一定的强度,又表现出一定的韧性。对固化过程中杆体中热残余应力分布模拟分析了固化温度、纤维弹性模量、基体弹性模量、纤维体积分数和界面层弹性模量等工艺参数对玻璃钢锚杆杆体中热残余应力分布的影响规律。研究结果表明:固化温度升高,纤维弹性模量增大,基体弹性模量增大,纤维体积分数增加,都会引起玻璃钢锚杆杆体中热残余应力增大。界面层弹性模量增加,玻璃钢锚杆杆体中的热残余应力集中向界面层中转移,热残余应力集中减少。当界面层的弹性模量与纤维的弹性模量相差比较小时,杆体中的热残余应力会大大降低。
[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.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ327.1;TD353.6
本文编号：2493957
[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.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ327.1;TD353.6
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