High-Temperature Strain Gauging
At Sensor Solutions, we specialise in providing advanced strain gauging services for extreme temperature environments, both cryogenic and very high temperatures. Working at these extremes requires expertise and specialised materials to ensure accuracy and durability.
Challenges of High-Temperature Environments
When temperatures exceed 460 degrees Celsius, organic materials begin to outgas and break down. This poses significant challenges for traditional strain gauges. Backing materials can become soft, components creep, and standard solders melt. To counteract these issues, we use high-temperature solders and Karma alloy foil, which is notoriously difficult to solder. Instead, we employ spot welding for lead attachment, despite the handling difficulties it presents. Our gauges typically use glass-filled epoxy phenolic backings, which, although effective, are brittle and require careful handling to avoid chipping.
Advanced Techniques for Extreme Temperatures
For applications above 400 degrees Celsius, we utilise flame spray ceramic free filament gauges. This technology involves firing a high-powered flame to melt a ceramic rod, which is then sprayed onto the surface, creating a robust insulating layer. This process is performed using specialised equipment, such as the Rock-eye machine, capable of achieving temperatures in the thousands of degrees. This technique is essential for applications like gas turbine blades, where a ceramic layer acts as an insulator.
The strain gauge itself is designed like a wire with support strips. These gauges are adhered using a sticky backing with bars built in, and a ceramic layer underneath. After positioning the gauge, the excess material is peeled away, leaving the filament wire securely held by the ceramic layer. Additional ceramic is flame-sprayed over the top to ensure the gauge is firmly embedded and insulated, preventing degradation at high temperatures.
Cost Considerations
Implementing these advanced strain gauging techniques at very high temperatures is costly. Therefore, wherever possible, we recommend modelling and theoretical validation to minimise practical testing expenses. Accurate models can significantly reduce the need for comprehensive practical tests, thus saving costs.
Cryogenic Temperature Strain Gauging
Similarly, working at very low temperatures presents its own set of challenges. Components behave differently at cryogenic temperatures, and materials must be selected to withstand these conditions without compromising performance.
Application in Aircraft and Rocketry
One of our key applications is for customers who manufacture aircraft gimballed ducting systems, which are used in jet engines and rockets. These systems must operate reliably under extreme conditions, involving both high and low temperatures, as well as significant mechanical loads.
The ducting systems include pipes and gimbals that must rotate and withstand internal pressures and external loads. The gimbal, supported on a robust structure with a U-joint, is subject to comprehensive fluid and thermal analysis. Our clients model these loads and pressures, considering changes in material properties across a thermal range.
Theoretical and Practical Validation
Our approach involves validating these theoretical models with practical tests. Initially, we perform strain gauging at ambient temperatures to confirm the model’s accuracy. Once validated, these models can then incorporate additional thermal calculations, eliminating the need for measurements at extreme temperatures. This approach ensures that the system’s performance is accurately predicted without the prohibitive costs associated with testing at very high or very low temperatures.
Conclusion
At Sensor Solutions, we bring extensive expertise and cutting-edge technology to tackle the most challenging environments. Whether it’s high temperatures that turn materials into a malleable state or the frigid conditions of cryogenic applications, we provide reliable and precise strain gauging solutions. Our combination of advanced techniques, careful material selection, and cost-effective modelling ensures that our clients receive the best possible service, tailored to their specific needs in extreme temperature conditions.
Explore our comprehensive range of services and discover how Sensor Solutions can support your high-stakes projects with unparalleled precision and expertise.
