Breaking Wire Detection and Strain Distribution of Seven-Wire Steel Cables with Acoustic Emission and Optical Fiber Sensors- Mining Engineering portion

1 Graduate Research Assistant

The intent of this study is to provide the interdisciplinary team with a unique opportunity to initiate a new research direction, collect preliminary data, and establish a good track record for collaborative work on the proposed topic. Such an effort will allow the team to prepare a competitive proposal for external funds in the following year. The scope of work includes, but are not limited to, 

(1)     Develop and validate a localization algorithm for breaking wires of a seven-wire steel cables with acoustic emission technology, and

(2)     Develop and validate a simplified model for strain redistribution of the seven-wire steel cables due to wire breakage.

Cable-stayed bridges have been increasingly used as river-crossing links in highway and railway transportation networks. In the event of an abnormal situation, they can not only impact the local and national economy but also threaten the safety of passengers. To assess the structural condition of cables, the strain distribution among multiple wires must be effectively determined as one or more wires are broken due to overstress and/or corrosion. This proposal is focused on a preliminary study of wire breakage detection and associated strain redistribution. The specific objectives are to develop and validate a new algorithm for the localization of broken wires with acoustic emission technology and a new model for the determination of strain redistribution with distributed optical fiber sensor measurements. Both laboratory tests and numerical simulations will be conducted to understand the mechanism of strain redistribution as a result of wire breakage. In particular, a seven-wire steel cable will be tested and analyzed to take into account both the initial stress due to wire twisting and the friction effect between wires. For sensitivity study, various section losses in percentage of sectional area will be considered to understand the effective length of a cable over which the strain condition prior to the loss of wire sections can be recovered.

Relationship to other Research/Projects

This is a new research topic for both investigators. Although Dr. Ge previously applied the acoustic emission technology in mining engineering, this application in structural health monitoring is new. In addition, strain measurements with optical fiber sensors are not new to Dr. Chen. However, this particular application requires a special attention due to the geometric complexity in instrumentation and data interpretation. A seven-wire steel cable often has seven wires twisted under torques. The interface effect among wires plays a significant role in the redistribution of strains in the cable. To the best of our knowledge, there is presently no available model that can accurately simulate the strain transfer from one to other wires due to wire breakages.

Transportation-Related Keywords

Technology Transfer Activities

The findings and results will be summarized and presented at the annual NUTC conference and other professional conferences as well as regular CIES meetings.

Project Deliverables

Anticipated Benefits

River crossing bridges such as the Bill Emerson Memorial Cable-Stayed Bridge and the new I-70 cable-stayed bridge are critical links in the U.S. ground transportation network. It directly impacts the economic development in the state of Missouri and the safety of passengers. Each river-crossing bridge also represents a major capital investment. Therefore, they must be thoroughly inspected as needed but no less than twice a year. The most critical components of these bridges are steel cables that are composed of multiple wires. They are often protected with non-metallic shields and invisible from outside. Therefore, inspections of steel cables are time consuming and costly. The proposed monitoring system can provide an alternative to visual inspection in normal operations. Unless abnormal situations are detected, cable shields are not required to open for in-depth visual inspections, thus saving maintenance costs in long term.

Milestones