Further Investigation on the Real Rate Effect of Dynamic Tensile Strength for Concrete-Like Materials

Abstract

Based on dynamic direct tensile tests, splitting tests and spalling tests, it is found that the experimental tensile strength of concrete-like materials greatly increases with loading-rate. This kind of dynamic tensile strength enhancement may be caused by the combination influence of the inertia effect, real rate effect and end friction effect (here the end friction effect is only existed in splitting and spalling tests). To further investigate the influence degree of real rate effect for concrete-like materials in dynamic tensile tests, this paper conducts systematically dynamic tensile experiments, viz. dynamic direct tensile tests, splitting tests and spalling tests. At the same time, numerical dynamic tensile tests are employed to analyze the mechanical characteristics of concrete-like materials. A hydrostatic pressure dependent model, the DruckerPrager constitutive model, is used for concrete-like material specimens, which can consider the influence of inertia effect. In the numerical model, the specimen is set to be rate-independent, thus the predicted dynamic tensile strength of specimens is free of the real rate effect. The end friction effect is also taken into account in the numerical analysis of dynamic splitting and spalling tests. It is found that the dynamic tensile strength of concrete-like materials in numerical simulations does not varies obviously with the loading-rate, indicating that the inertia effect and end friction effect have little contributions to the dynamic tensile strength enhancement of concrete-like materials. Therefore, the real rate effect dominates the dynamic tensile strength enhancement of concretelike materials in laboratory tests, but the inertia effect and end friction effect do not. Keywords Real rate effect, tensile strength, concrete-like materials, experimental and numerical research researchers. The dynamic behavior of concrete-like materials is usually studied by laboratory such as split Hopkinson tension bar (SHTB) or split Hopkinson pressure bar (SHPB). Many experimental results show that the dynamic strength of concrete-like materials subjected to impact loading increases apparently with the loading-rate. The influence of the loading-rate or strain-rate on the dynamic strength enhancement of concrete-like materials obtained from experiments is called as the apparent rate effect. The dynamic performance of mortar under compressive and tensile loading was studied by Yang et al. (2015) based on splitting tests, and the results show that mortar is of rate sensitive. Cai et al. (2015) systematically conducted quasi-static and dynamic compressive tests to analyze the rate effect of granite, and numerical simulation method is employed to determine the true rate effect of granite through the uncoupled assumption of the rate effect, lateral inertia and end friction effect in SHPB tests. Lu et al. (2014) investigated the dynamic compressive behavior of recycled aggregate concrete specimens prepared with five different amount of recycled coarse aggregate [i.e. 0, 25...

Experimental and numerical investigation on the dumbbell-shaped specimen of concrete-like materials under tension

“…The contact between specimens and incident bar and transmission bar can be defined as 'tie'. The quasi-static tensile stress-strain of mortar in the numerical model is consistent with the experiments conducred by Zhang et al(2016), as shown in Figure 16. The amplitude of stress wave in the incident bar is based on the signal collected by the strain gauge on incident bar in laboratory experiments, as shown in Figure 17.…”

“…Yan (2006) conducted direct tensile experiments of concrete dumbbell specimens on MTS810 under the strain-rate with 10-5-10-0.3 s-1. Concrete specimens could be fixed to the bonding surfaces through winding several layers of steel wires and using high strength adhesive in dynamic direct tensile tests by Zhang et al(2016). The tensile strength could also be measured through indirect methods, such as splitting experiments.…”

“…Through that, a more available and effective method is provided for the future research. Based on parameters determined by Zhang et al (2016), dynamic direct tensile test models of dumbbell specimens are also established and the parametric analysis about specimen shapes is conducted in this paper.…”

Quasi-static and dynamic experimental studies on the tensile strength and failure pattern of concrete and mortar discs

“…Thus, there is still lack of an accurate formula for the estimation of DIF of concrete-like materials under dynamic tensile loading. Especially, when the strain rate is in the range of 1–200 s −1 , DIF is difficult to be accurately determined 2 , 3 , 5 , 6 , 9 , 10 since it is rapidly increasing and appears obviously higher than that at a lower strain rate (see Supplementary Fig. S1 ).…”

A Three-Dimensional Numerical Investigation of Dynamic Fracture Characteristics of Rock Specimens with Preexisting Surface Flaws

“…In research examining accurate dynamic characterization of rock test, one of the controversial topics is the loading rate effects. Generally, researchers hold the opinion that the loading rate has effects on the strength of rocks [11][12][13][14]. With an increase in the loading rate, rock dynamic compressive strength presents a significant increase.…”