Generally, large-span bridges crossing shipping channels get damaged at the piers when they collide with ships resulting in causalities and property loss. To enhance the integrity and safety of bridges, researchers have focused on developing various collision detecting technologies. For example, artificial neural network technology and embedded piezoelectric sensors have been used to collect real-time collision information. However, the former uses a recognition program that requires sufficient data to train to enhance its accuracy while the latter is expensive to implement since it requires installation of the sensors throughout the possible collision regions in the pier members. Therefore, developing new monitoring sensors for ship-bridge collision is highly desirable to enable real-time collection of collision information, which will provide a basis for damage estimation and rescue strategies.
Scientists from Dalian University of Technology comprised of Qiaofeng Zheng (Master), Professor Baoguo Han and Professor Jinping Ou from the School of Civil Engineering investigated the use of quantum tunneling composites (QTC) in monitoring ship-bridge collision. The composites work on the principle of detecting the variation of electrical voltage across the composite when subjected to load impact. Unlike other conductor polymers, they transform from an insulator into a metal-like conductor upon deformation of the composites drawing the metal particles inside to each other without actual contact, a phenomenon referred to us the tunneling effect. Their work is currently published in the journal, Smart Materials and Structures.
The research team started their work by fabricating flexible nickel/ rubber quantum tunneling composites with cushioning ability for ship collision monitoring. Next, they investigated and compared the effects of rubber matrix and thickness on the sensitivity of the quantum tunneling composites. Eventually, their sensing and positioning capabilities to collisions were explored to determine potential quantum tunneling composites application in bridge-ship collision monitoring.
It was necessary to design and conduct collision tests between steel ball and quantum tunneling composites sensors to simulate ship-bridges collision. Quantum tunneling composites especially those with T4-matrix exhibited relatively large sensing range exceeding 50MPa with a corresponding high-stress resolution ranging between 0.017 to 0.13Mpa as compared to that for steel ball. This was considered enough to achieve full-time ship-bridge collision monitoring. The systems accurately positioned the collisions due to instant and repeatable responses to the impact load. Additionally, its ability to absorb kinetic energy during collisions significantly enhanced its cushioning capabilities.
Generally, quantum tunneling composites have numerous advantages: large sensing range, high detection prediction, energy-saving, cost-efficacy, and excellent cushioning capability among others. From the results, the ship-bridge collision monitoring system can be effectively applied in detecting collision occurrence and duration. Furthermore, determining the collision load and collision position will provide enough cushioning to protect the bridge piers and ships. The collected collision information will be used for post-accident damage estimation that would provide the basis for evacuation activities during accidents. This will extremely save time during rescue works. The study by Dalian University of Technology researchers will, therefore, pave way for future advancement of the monitoring system including the development of wireless transmission systems and incorporating the system with existing bridge piers.
Zheng, Q., Han, B., & Ou, J. (2018). Ship-bridge collision monitoring system based on flexible quantum tunneling composite with cushioning capability. Smart Materials and Structures, 27(7), 075018.Go To Smart Materials and Structures