Fatigue-induced cracks are of great concern to the Departments of Transportation. An important number of bridges in the country are fracture critical bridges that are vulnerable to fatigue cracks due to the brittle nature of their failure modes. Localizing and monitoring fatigue cracks is critical for determining retrofitting and maintenance plans. However, the localization process is difficult. This process is typically conducted via visual inspections, and sometime leveraging nondestructive evaluation techniques. Both methods require an inspector to be involved, are time consuming, and do not guarantee that a fatigue crack would be discovered on-time.

A solution is to deploy sensors, but the commercially available solutions do not allow for the discovery of new fatigue cracks, because these sensors are relatively very small in comparison to the geometries (i.e., girders) to be monitored. The recent pooled fund effort TPF-5(328) conducted research on leveraging a large skin-type sensor that could easily be deployed over large areas in order to localize and monitor fatigue cracks. The research project was successful in demonstrating the capability of the technology both in a laboratory environment and in the field.

The objective of this proposed project is to enable large-scale deployments in the United States by addressing further essential development needs uncovered during the previous research to achieve more robust, accurate, and flexible crack monitoring using the wireless skin sensor network.

The work plan is divided into three main research tasks. Task 1 is to deploy the sensing system in the field and collect data. Task 2 is to develop the integrated sensing system. Task 3 is to formulate algorithms and models. The project’s schedule is anticipated to run over a period of five years. The schedule is separated into six deliverables and three research phases. The entire work plan is provided as an attachment at the bottom of this page.

Phase 1 (P1) is expected to run over the first three years of the project with an approximated budget of $550,000. It consists of developing and validating a second generation sensing system (the first generation sensing system is the outcome from TPF-5(328)). Generation II will require the digitalization of the sensing board and development of signal processing algorithms for crack detection based on realistic field data deployment strategies (deliverables 1-4).

Phase 2 (P2) is expected to run over one year subsequent to the completion of P1, with an approximated budget of $250,000. It consists of deploying the Generation II sensing system, which includes on-board software capable of notifying infrastructure operators with fatigue crack alarms (deliverable 5).

Phase 3 (P3) is expected to run over one year subsequent to the completion of P2, with an approximated budget of $200,000. It consists of validating the autonomous functionalities of Generation II (deliverable 6).

Funding Desired annual commitment from each state is $30,000 per year for 5 years for a total of $150,000 per state. Commitment covers travel for an in-person meeting two or three times throughout the life of the project. Specific meetings and locations to be determined during the project.

*February 27, 2020 update : Moving forward as a pooled fund and developing a full proposal of work to cover Phase 1.

Additional partners are always welcome and will be needed to complete desired Phase II and III efforts. Please reach out to the Lead Agency Contact at any time.