Additive Manufacturing of electrical strain gauges for the monitoring of embankment failures

<p>Embankments, found in virtually all transportation and river networks, can be subjected to severe scouring and erosion issues due to more intensified climatic change, which may increase their failure risk [1]. Monitoring of embankment conditions with modern means is essential for ensuring the structural stability of nearby infrastructure (eg. roads and rail networks) against any geotechnical and hydraulic hazards [2, 3]. Additive manufacturing (AM), commonly referred to as 3D printing (3DP), is increasingly finding applications in the construction industry and is defined by the American Society for Testing and Materials (ASTM) International Committee as “the process of joining materials to make objects from 3D model data, usually layer upon layer”. This research is demonstrating the application of additive manufacturing technology in producing an electrical resistance strain gauge mechanism [2] to monitor the probability of embankment scouring failure, thus, warning could be given prior any devastating catastrophes, and preventive measures could be implemented accordingly. Electrical resistance strain gauges could be manufactured utilizing a dual-extrusion 3D printer which allows simultaneous depositions of a conductive material and a structural material in one print. Specifically, a range of control parameters are assessed here including different arrangements of the conductive material within the structural material matrix as well as infill percentages. The parameters aforementioned have effects on the gauge factor of the strain gauges produced. Overall, the 3DP sensors could be deployed to monitor embankment slope failure attributed to erosion, flooding and external loading (eg. due to heavy vehicle passage over it, for road embankments), which are important challenges [2, 3].</p><p> </p><p>Acknowledgements</p><p>This research project has been funded by Transport Scotland, under the 2019/20 Innovation Fund (Scheme ID18/SE/0401/014) and the Scottish Road Research Board (Student research competition award 2019).</p><p> </p><p>References</p><p>[1] Koursari, E., Wallace, S., Valyrakis, M. and Michalis, P. (2019). The need for real time and robust sensing of infrastructure risk due to extreme hydrologic events, 2019 UK/ China Emerging Technologies (UCET), Glasgow, United Kingdom, 2019, pp. 1-3. doi: 10.1109/UCET.2019.8881865</p><p> </p><p>[2] Michalis, P., Saafi, M. and Judd, M. (2012) Wireless sensor networks for surveillance and monitoring of bridge scour. Proceedings of the 11th International Conference of Protection and Restoration of the Environment (KatsifarakisKL, Theodossiou N, Christodoulatos C, Koutsospyros Aand Mallios Z (eds)). Thessaloniki, Greece, pp. 1345–1354</p><p> </p><p>[3] Michalis, P.; Konstantinidis, F.; Valyrakis, M. (2019) The road towards Civil Infrastructure 4.0 for proactive asset management of critical infrastructure systems. Proceedings of the 2nd International Conference on Natural Hazards & Infrastructure (ICONHIC), Chania, Greece, 23–26 June 2019.</p>

Damage Evaluation of Lead-Free Solder Joints Based on Micro-Electrical-Resistance Strain Measurement

The relationship between the micro-electrical-resistance strain and the damage was obtained via the theoretical formula deduction, which provides a theoretical foundation for the feasibility of measuring solder joints’ damage based on micro-electrical-resistance strain. Single shear lap creep specimens with a 1 mm2 cross sectional area between thin copper strips were fabricated using lead-free solder (Sn-3.5Ag) to quantify their micro-electrical-resistance strain with in situ micro-electrical-resistance strain measurement under the shear tensile loading. The results showed that the micro-electrical-resistance strain of the solder joints had two stages at the room temperature. And it increased slowly with an almost linear growth trend at the first stage but increased quickly with an almost exponential growth trend at the second stage. The creep damage curves were very similar with the classic creep damage curve.