An intelligent viaduct, designed to heal its own cracks using bacteria encapsulated in calcium lactate, has failed in its mission. The cracks did not heal, and the concrete lost its self-healing capacity. The question engineers must answer is whether the microcapsules ruptured prematurely during pouring or if the material's porosity prevented biological activation.
Forensic diagnosis using microtomography and finite elements 🧪
To resolve this failure, a multidisciplinary workflow was employed. First, VGSTUDIO MAX processed the X-ray microtomography data, generating a 3D volumetric model of the cracks and embedded capsules. This analysis revealed that 30% of the capsules were already fractured before the concrete cracked, releasing the healing agent prematurely. Subsequently, the geometry was exported to Ansys to simulate residual stresses. The finite element simulation confirmed that mechanical fatigue during setting and plastic shrinkage generated stress peaks exceeding 12 MPa on the capsule walls, surpassing their rupture limit.
Lessons for fatigue simulation in composite materials 🔧
The combination of GOM Inspect for surface deformation analysis and Ansys for cyclic fatigue simulation allowed correlating high-porosity zones with capsule rupture. The failure was not of the bacteria, but of the container. This case demonstrates that structural validation of microcapsules through 3D simulation is critical to avoid premature failures in self-healing materials. The fatigue of the sacrificial material must be modeled before field application.
In the finite element simulation of a viaduct with self-healing concrete, how to model the kinetics of bacterial activation when microcapsules break due to cyclic fatigue and calcium lactate is released non-uniformly over time?
(PS: Material fatigue is like yours after 10 hours of simulation.)