High-ductility cement-based material uniaxial stretching die, test piece manufacturing method thereof and test method thereof

Abstract

The invention discloses a high-ductility cement-based material uniaxial stretching die, a test piece manufacturing method thereof and a test method thereof. The die comprises a bottom plate, a lower test die assembly, a lower frame, a middle test die assembly, an upper frame, an upper test die assembly, first fibers and second fibers. The lower test mold assembly, the middle test mold assembly andthe upper test mold assembly are assembled to form a consistent structure and a plurality of dumbbell-shaped test piece areas are formed in inner cavities; and the lower test mold assembly, the middle test mold assembly and the upper test mold assembly are fixed on a bottom plate by bolts. The lower frame and the upper frame are fixed on the bottom plate through screws; and the first fibers and the second fibers are arranged at the narrow-down parts of the test piece areas uniformly vertically and horizontally. In addition, the test piece manufacturing method includes steps of casting and dieremoval; dumbbell-shaped test pieces of the first fibers and the second fibers are encrypted at variable cross-sections. According to the invention, multiple test pieces can be cast at a time and assembling and mold disassembling become convenient; the fibers which are uniformly arranged vertically and horizontally to add ribs at the variable cross-sections of the test pieces, so that the tensilestrength of the test piece is enhanced; and the strain-hardening behavior of the high-ductility cement-based material is favorably evaluated.

Description

technical field [0001] The invention relates to the field of testing the mechanical properties of high-ductility cement-based materials, in particular to a high-ductility cement-based material uniaxial stretching mold and a test piece manufacturing method and testing method. Background technique [0002] High ductility cement-based material ECC is a special high-performance fiber-reinforced cement-based material. ECC materials are designed based on fracture mechanics and micromechanics theory, and the mechanical properties of ECC are improved by adjusting the fiber, matrix, and interface properties between fiber and matrix. Under bending, the ECC material exhibits ultrahigh deformability, with metal-like strain-hardening behavior. [0003] To study the strain-hardening behavior of ECC materials, uniaxial tensile tests and bending tests are mostly used. During the uniaxial tensile test, because the traditional thin plate tensile test piece is prone to stress concentration n...

AI Technical Summary

Problems solved by technology

[0004] However, if figure 1 As shown, where the width of the "dumbbell-shaped" or "dog-bone" specimen changes, there is stress concentration during the stretching process due to the change of the interface area, and there is an early cracking phenomenon that affects the test results, which is easy to cause the uniaxial tension of the ECC material. The stress and strain in the tensile test are smaller than the actual value, which affects the evaluation of the strain-hardening behavior of ECC materials

Images