Impact of Thermal Stress on Attachment and Stability of High Temperature Strain Sensors

Journal Article · Sat Sep 11 00:00:00 EDT 2021 · IEEE International Ultrasonics Symposium (IUS)

DOI:https://doi.org/10.1109/ius52206.2021.9593423· OSTI ID:2290240

Leff, David ^[1]; da Cunha, Mauricio Pereira ^[2]

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1. University of Maine, Orono, ME (United States); University of Maine
2. University of Maine, Orono, ME (United States)

Static and dynamic strain sensing is required in high-temperature (HT), harsh-environments (HE) for industrial, aerospace, and energy sector applications to ensure equipment and process safety, reduce the cost of operation and maintenance, and increase process efficiency. Challenges that arise in HT HE sensing applications include device mounting, packaging, integrity, and stability to HT HE conditions. In previously reported work, static and dynamic strain surface acoustic wave resonator (SAWR) sensors were fabricated on langasite (LGS) and mounted on Inconel 625 strain beams for wireless testing up to 400°C. In this work, it has been identified that after subjecting the mounted SAWR strain sensor to thermal cycling between 100°C and 425°C, the measured sensitivity to dynamic strain decreased by 73% due to cracking at the adhesive/LGS interface, further deteriorating after additional thermal cycles. Strain modeling of the mounted LGS sensor chip up to 400°C revealed the existence of concentrated strain at the borders of the LGS chip. Microcracks caused by dicing make the chip boarders the most susceptible location for cracks to initiate when the sensor is subjected to thermal stress. In an attempt to mitigate the high strain at the LGS chip borders due to heating, adhesive shaping is proposed in this work. Simulations indicate a strain reduction of 50% at the border is achieved using both circular and triangular adhesive shapes, while also reducing the maximum strain over the entire adhesive/LGS interface by around 30%. Furthermore, the technique is thus promising for improving the integrity, reliability, and stability of static and dynamic strain sensors, particularly while operating under HT HE with several hundreddegree Celsius temperature excursions.

• Research Organization: University of Maine, Orono, ME (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: FE0031550
• OSTI ID: 2290240
• Journal Information: IEEE International Ultrasonics Symposium (IUS), Journal Name: IEEE International Ultrasonics Symposium (IUS); ISSN 1948-5719
• Publisher: IEEE
• Country of Publication: United States
• Language: English

Related Subjects

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acoustic wave
dynamic strain sensor
high-temperature
thermal stress