Simulation And Analysis Method Of Failure Process Of Engineering Structures Due To Trans-Scale Damage Evolution

Damage analysis methods in single scale are difficult to describe the relationships between micro/meso-scopic damage evolution and structural deterioration due to remarkable size differences size differences between micro/meso-scopic damage within material and global engineering structure. Based on the engineering background, in order to study the micro/meso-scopic damage mechanisms of large-scale engineering structures, the issues on the simulation and analysis of the trans-scale process from micro/meso-scopic damage evolution to structural failure are investigated using multi-scale method.Two classes of damage in engineering structures are respectively researched here. The main research work on damage of concrete components and structures under extreme load can be summarized as follows:1. A new adaptive multi-grid method is developed to simulate concrete damage evolution process. And the developed method is verified by a numerical example. It shows that the process of concrete components from evolving damage to global failure due to load can be simulated, and FE elements can be refined adaptively with damage accumulation. The results show that, the developed method can be used to reduce the error due to high stress gradient caused by damage with lower cost, compared with the traditional FEM with single grid. And it is an effective numerical tool to predict macroscopic damage distribution of concrete components under extreme load.2. A new adaptive image-based multi-scale method is developed to simulate trans-scale damage and failure process of concrete components. And the developed method is verified by numerical examples. It shows that the process of concrete component from meso-scale damage evolution to global failure can be simulated, and image-based meso-scale model can be automatically implemented into the damaged area for incorporating continuous changes in the computational model as a consequence of material evolving damage, without user intervention. The results show that, the developed method can be used to simulate trans-scale damage and failure process of concrete components with lower cost. And it is an effective numerical tool to study relationships between micro/meso-scopic damage evolution and structural deterioration for concrete components under extreme load.3. A new multi-scale modeling and trans-level simulation method is developed to simulate trans-scale damage and failure process of large-scale concrete structures. And the developed method is verified by numerical examples. It shows that the trans-scale process of large-scale concrete structures from meso-damage in material level to local damage and failure in component level and eventually to global failure in structural level can be simulated. Adaptivity ensures level-change due to evolving damage for better effective without user intervention in the computation. The results show that, the developed method can be used to simulate trans-scale damage and failure process of large-scale concrete structures with lower cost. And it is an effective numerical tool to study relationships between mesoscopic damage evolution and structural deterioration for large-scale concrete structures under extreme load.The main research work on damage of steel components and structures under fatigue load can be summarized as follows:4. A multi-scale fatigue model is developed to establish the relationships between continuous macroscopic fatigue damage and collective short cracks for damage of steel components under high-cycle fatigue. Based on the developed model, and image-based simulation method is developed to simulate the short cracks nucleation and growth within material during fatigue process. It shows that the developed multi-scale fatigue model and image-based simulation method can both describe continuous fatigue damage evolution in macro-scale and collective short cracks evolution process in micro-scale. The results show that it is more effective and clear to reveal metal damage mechanisms under high-cycle fatigue from the viewpoint of multi-scale.5. A multi-scale fatigue model is developed to establish the relationships between continuous macroscopic fatigue damage and collective short and long cracks for damage of steel components under low-cycle fatigue or under interaction between high-and low-cycle fatigue. Based on the developed model, and image-based simulation method is developed to simulate collective short and long cracks evolution within material during fatigue process. It shows that the developed multi-scale fatigue model and image-based simulation method can both describe continuous fatigue damage evolution in macro-scale and collective short and long cracks evolution process. The results show that it is more effective and clear to reveal metal damage mechanisms under low-cycle fatigue or under interaction between high-and low-cycle fatigue from the viewpoint of multi-scale.6. A new multi-scale modeling and trans-level simulation method is developed to simulate trans-scale fatigue damage and failure process of large-scale steel structures. Fatigue analysis of stonecutter bridge was carried out using the developed method. It shows that the trans-scale fatigue process of large-scale steel structures from microscopic short cracks nucleation and growth in material level to local damage and failure in component level and eventually to global failure in structural level can be simulated. The results show that, the developed method can be used to simulate trans-scale fatigue damage and failure process of large-scale steel structures with lower cost. And it is an effective numerical tool to study relationships between microscopic damage evolution and structural deterioration for large-scale steel structures under fatigue load.