Modeling the dynamic fracture in concrete: an eigensoftening meshfree approach

The objective of this work is twofold. First, we develop an eigensoftening algorithm to capture the gradual process of failure in materials with a softening behavior as an extension of the eigenerosion approach. Both methods are validated against the physical measurements in three-point bending tests of concrete with a drop-weight device, including impact and reaction forces, loading-line displacements as well as strain histories from gauges. The comparison shows that the eigenerosion algorithm significantly overestimates the tensile stresses and the strain peaks, while it captures the forces and crack pattern accurately. Predictions made by the proposed eigensoftening algorithm agree very well with experimental results in all aspects. Second, the energy evolution and partition in the beam predicted by the eigensoftening algorithm at various impact rates is analyzed to quantify the rate dependent fracture properties of concrete. It is demonstrated that, at impact loading conditions, the area below the reaction-deflection curve is much larger than the dissipated fracture energy.