考虑纤维弯曲缺陷拉挤GFRP桥面层合板破坏机理多尺度数值模拟

Pultruded glass fiber reinforced polymer (GFRP) composites have a good potential application for light-weight and built-up bridges due to its high-strength and light-weight nature. In terms of huge demanding and cost factor, pultrusion manufacturing process is considered as the most common methods and glass fiber reinforced polymer (GFRP) composites are always recommended in newly constructed bridge decks for meeting the established design criteria with reasonable cost. The pultrusion process has a relatively lower quality control resulting in uneven reinforcement distribution and fabric folds perpendicular to pultrusion direction. Those initial imperfections lead to the damage mechanism of lamina and inter-lamina of pultruded lamination more complicated. .The research is to reveal the fiber/fabric intial imperfection effects on damage mechanism of pultruded GFRP lamination, to establish an effective numerical method simulating initial imperfection and to provide a suggested limits of initial defects during GFRP bridge deck manufactury by comprehensively utilizing model tests, micro and macro mechanics analysis and multi-scale numerical simulation. CT scan techniques will employed to identify fiber/fabric intial imperfection. Based on the identified imperfections, model tests including lamina, inter-lamina and lamination with different initial defect will be conducted. Meanwhile, numerical homogenization methods will be applied to reveal the damage mechanism of laminas with different initial defects. Cohesive strategies will be employed to simulate the initiation and propogation of the interface cracks. Furthermore, a progressive damage simulation method on pultruded laminates with initial defects will be established and the relationship between initial defects and the modulus/ strength of pultruded laminates will be revealed.

拉挤GFRP桥面板轻质、高强，在实现桥梁结构轻型化和装配化方向有着广泛的应用前景。因土木工程结构材料用量大和工程造价限制，常用玻璃纤维及其织物作为增强材料，用能连续生产的拉挤工艺制造FRP型材。由于拉挤工艺的限制，层合板中纤维及其织物易产生初弯曲，使得单层板损伤机理不明，且层间界面因织物初始缺陷呈弯曲状分布，层间损伤机理复杂。.本研究拟综合模型试验、宏细观力学分析和多尺度数值模拟，采用CT扫描纤维单丝和织物纵横向弯曲初始缺陷形状，开展含不同初弯曲缺陷的单层板、层间界面和层合板力学性能试验，基于多尺度均匀化方法评估不同纤维弯曲初始缺陷下单层板细观损伤机理，依据裂纹粘聚力本构关系预测弯曲层间界面裂纹萌生和裂纹扩展，开展考虑初弯曲缺陷的层合板渐进损伤数值模拟；其目标是建立能够考虑纤维初弯曲缺陷的GFRP层合板多尺度数值模拟方法，提出拉挤GFRP桥面层合板纤维初弯曲控制限值。

拉挤GFRP桥面板轻质、高强，在实现桥梁结构轻型化和装配化方向有着广泛的应用前景。拉挤GFRP型材呈正交各向异性，通过试验手段来评估力学性能时间和经济成本高。因此，本课题综合模型试验、宏细观力学分析和多尺度数值模拟，开展了如下研究：（1）针对桥梁工程用拉挤FRP型材，制作了 10 组 FRP 单层板试件，获得了密度及纤维体积含量、纵横向拉伸、纵横向压缩、面内剪切、纵横向弯曲和纵横向热膨胀系数材料性能；（2）通过细观力学公式和双尺度均匀化非线性有限元预报了FRP 单层板的工程弹性系数和强度，修正混合定律法和多尺度均匀化理论可较好预测 FRP 单层板工程弹性系数，混合定律法通过修正可较好的预测纵向拉伸强度和纵向压缩强度，经验公式法及桥联理论可较好预测横向拉伸强度，应变放大因子法可较好预测横向压缩强度，经验公式法可较好预测面内剪切强度；双尺度均匀化非线性有限元模拟结果与试验结果完全吻合；（3）开展了胶层拉伸和剪切性能试验，获得了层间界面的基本性能，并采用 Cohesive 单元有效模拟了管型桥面板脱胶失效过程；(4) 对拉挤 GFRP 桥面板型材试件进行了局部荷载试验研究，并采用多尺度方法研究了GFRP 桥面板型材在局部荷载作用下的失效机理，所提出的模拟方法可以有效预测结构的破坏模态，且屈曲前荷载-位移曲线与荷载-应变曲线与试验结果吻合较好。