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基于粒子群优化算法及Newton-Raphson迭代方法的数字图像相关粗-细搜索方法,该文观测了单向压缩砂样变形破坏过程中的变形场及侧向位移的分布及演变规律。该方法对于应变达到10%~15%时适用,对于位移的大小没有限制。研究发现,当载荷不大时,砂样的变形就变得不对称、不均匀,砂样一侧呈弧形,而另一侧呈S形。当狭窄的应变局部化带出现之后,在砂样两侧位于相同高度上,有的测点的水平方向位移发生了加速。位移矢量增量的演变经历了4个阶段:第1阶段为均匀的压缩变形阶段;在第2阶段,应变不均匀分布区内部的位移增量呈现连续的变化,属于非均匀的变形阶段;在第3阶段,应变局部化带两侧的点向相反的方向运动,而带内的位移增量基本向下;在第4阶段,应变局部化带一侧的点快速沿带发生错动,而另一侧的位移增量则不明显。随后,宏观剪切裂纹面马上形成。
Based on the particle swarm optimization algorithm and Newton-Raphson iterative method for digital image correlation rough-thin search, the distribution and evolution of deformation field and lateral displacement in the process of deformation and failure of unidirectional compacted sand samples were observed. This method is applicable when the strain reaches 10% to 15%, and there is no limitation on the magnitude of the displacement. The study found that when the load is not large, the deformation of the sand sample becomes asymmetric and uneven, one side of the sand sample is arc-shaped and the other side is S-shaped. When the narrow strain localization zone appears, the same height is located on both sides of the sand sample, and the horizontal displacement of some measuring points is accelerated. The increment of displacement vector undergoes four stages: the first stage is the uniform stage of compressive deformation; in the second stage, the displacement increments within the region of uniform strain show a continuous change, which belongs to the non-uniform deformation stage; In the third stage, the points on both sides of the strain localization zone move in the opposite direction, while the incremental increment in the zone is basically downward. In the fourth stage, the point on the side of the strain localization zone moves rapidly along the zone, The other side of the incremental displacement is not obvious. Subsequently, the macro-shear crack surface immediately formed.