Impact damage characteristics of steel fiber reinforced cement matrix composites based on digital image correlation

The surface displacement field and strain field of steel fiber reinforced cement matrix composites at three-point bending falling ball impact test were calculated and studied by the digital image correlation (DIC) technology. The impact times of initial crack was determined by the displacement near the crack point. And the whole horizontal strain was statistically analyzed to obtain damage factor(D_f) characterization curve under impact. The influence law of bending impact damage with different fiber dosage was further investigated. The experimental results indicate that compared with the effect to the initial crack impact times, the steel fibers effect to the crack impact times is more obvious; D_f curve can better reflect the impact of shock load and the bending impact of the specimen is destroyed, based on the damage factor characterization curve, the impact bending process has tardiness, acceleration and tardiness stages; The more fiber content, the slower D_f curve development, the greater the proportion of the tardiness stage of the three impact damage stages. And steel fiber toughening effect mainly displays in the tardiness stage.