CAJ | 학술논문

为了研究焊接结构破坏过程中的宏细观损伤演化特征及其表征方法，以含细观裂纹的焊接构件为对象，采用X-CT（ X射线计算机断层扫描）和电测技术同步记录试样内部细观结构和宏观力学性能变化过程。实验发现，试样变形过程中试样在弹性模量减小的同时，其内部细观裂纹不断萌生、扩展和聚合，扩展形态表现出显著的分形特征，且分形维数随试样塑性变形呈线性增加的趋势。综合考虑裂纹扩展形态的分形维数度量与裂纹扩展的物理意义，提出了一种多尺度损伤表征方法，以同时描述结构宏观损伤特性与内部细观裂纹扩展特性，并用传统的损伤量化方法进行验证。结果表明，新的多尺度损伤表征方法能够很好地描述细观裂纹到宏观损伤的多尺度演化过程。
위료연구한접결구파배과정중적굉세관손상연화특정급기표정방법，이함세관렬문적한접구건위대상，채용X-CT（ X사선계산궤단층소묘）화전측기술동보기록시양내부세관결구화굉관역학성능변화과정。실험발현，시양변형과정중시양재탄성모량감소적동시，기내부세관렬문불단맹생、확전화취합，확전형태표현출현저적분형특정，차분형유수수시양소성변형정선성증가적추세。종합고필렬문확전형태적분형유수도량여렬문확전적물리의의，제출료일충다척도손상표정방법，이동시묘술결구굉관손상특성여내부세관렬문확전특성，병용전통적손상양화방법진행험증。결과표명，신적다척도손상표정방법능구흔호지묘술세관렬문도굉관손상적다척도연화과정。
This paper aims to explore behavior of cracking and develop the method for of multi-scale damage characterization.A welded specimen with meso-cracks was taken as research objects.X-CT ( Micro focus X-ray Computed Tomography System ) was employed to record the tomograms of cracking and macro-scale response was measured synchronously using electrical measurement device. The experimental results show that the specimen's modulus decreases on the same time when meso-cracks initiation, propagation and coalescence happens during the deformation process.The behavior of crack growth shows typical fractal pattern, and the fractal dimension is linearly increasing along with plastic strains of the specimen.Considering both the fractal dimension measurement of crack growth morphology and the physical significance of crack growth, a new multi-scale damage charac-terization method is proposed to describe the behavior of damage both in meso-and macro-scale of cracking.The proposed method was verified by current theories of damage mechanics.The results show that, the new method can well describe multi-scale damage evolution process in which damage starts from meso-cracks to macroscopic crack.