SIZE EFFECTS ON TENSILE FRACTURE PROPERTIES - A UNIFIED EXPLANATION-BASED ON DISORDER AND FRACTALITY OF CONCRETE MICROSTRUCTURE
SIZE EFFECTS ON TENSILE FRACTURE PROPERTIES - A UNIFIED EXPLANATION-BASED ON DISORDER AND FRACTALITY OF CONCRETE MICROSTRUCTURE
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DOI：
10.1007/bf02473124
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发表时间：
1994-12-01
影响因子：
3.8
通讯作者：
FERRO, G
中科院分区：
文献类型：
--
作者：
CARPINTERI, A;FERRO, G
测试使用正交配置的三个独立千斤顶进行，使得可以施加纯拉伸力，因此，如果控制住二次弯曲应力，则构成与正常测试设备允许的值相当的误差程度。该方法能够绘制应力与应变曲线，其下降（软化）分支直至拉伸试样的横截面断开的点。主要目的是避免任何虚假的影响，这些影响可能对反复出现的尺寸对表观抗拉强度和虚拟断裂能的影响提供错误的解释。一旦次要影响被排除，只有混凝土微观结构的无序和断裂仍然可以解释这些基本趋势。在抗拉强度的情况下，尺寸递减表示材料韧带、色相、孔洞、缺陷、裂纹、集料、夹杂物等的自相似弱化。同样，在断裂能的情况下，维数增量表示断口表面的自相似弯曲度，以及微裂纹在与形成大裂纹正交方向上的自相似重叠和分布。
Tests were carried our using three independent jacks orthogonally disposed, making it possible to apply a purely tensile force, so that the secondary flexural stresses, If kept under control, constitute a degree of error comparable with the values allowed for normal testing apparatus. The method enables a stress versus strain curve to be plotted with the descending (softening) branch up to the point where the cross-section of the tensile specimen breaks away. The principal purpose is to avoid any spurious effect that might provide a fallacious explanation of the recurring size effects on apparent tensile strength and fictitious fracture energy. Once the secondary effects have been excluded, only the disorder and fractality of the concrete microstructure remain to explain such fundamental trends. In the case of tensile strength, the dimensional decrement represents self-similar weakening of the material ligament, hue to por es, voids, defects, cracks, aggregates, inclusions, etc. Analogously, in the case of fracture energy, the dimensional increment represents self-similar tortuosity of the fracture surface, as well as self-similar overlapping and distribution of microcracks in the direction orthogonal to that of the forming macrocrack.