Damage Evolution Analysis of Cement-Based 3D Printing Similar Materials Under Different Cyclic Loading-Unloading Conditions (2025-06)¶

In engineering practice, structures such as bridges, tunnels, and embankments often undergo cyclic loading during their service life. Such loading typically has the characteristics of periodicity and intermittency, and different types of loading can cause different degrees of damage, affecting the safety and stability of engineering structures. Rock and concrete, as the main raw materials in structural engineering, often require a large number of laboratory tests to accurately determine their mechanical properties. The repeatability and ease of operation of the sample preparation process need to be given special consideration, and the emergence of 3D printing technology can effectively solve these problems. Based on this, 3D-printed cement-based rock-like materials were prepared using 3D printing equipment, and a continuous and intermittent cyclic loading and unloading test scheme was designed. The test samples were tested using a pressure testing machine, a piezoelectric acoustic emission system, and a digital image correlation (DIC) device to analyze the evolution of damage in the 3D-printed samples under different types of loading. The study shows that the compressive strength of the samples increases first and then weakens as the cyclic upper limit stress increases, and the trend is further exacerbated by intermittent cyclic loading compared to continuous cyclic loading. With 60% of the compressive strength as the dividing line for damage degree, the Kaiser effect is significant under low stress cycling, while the acoustic emission quiet period in high stress cycling is broken, and the Filicity effect gradually becomes obvious. At the same time, the trend of acoustic emission phenomena with the increasing upper limit stress of the cycling also shows an upward trend. Based on the acoustic emission AF-RA value, a new k value can be quantitatively obtained by quasi-definition, which can provide the proportion of tensile and shear cracks in each stage of the sample under different loading forms during loading. In addition, the vertical displacement trend of the sample under loading can be quantitatively obtained by the virtual extensometer in DIC. The research results can provide theoretical support for the safety and stability of structural engineering.