A Guide to Wall Shear Stress Measurement - #9 - Conventional Assembly

Posted by Jared Anderson on Jul 13, 2020 4:48:57 PM

Previous sections of this guide provided information on wall shear stress measurement techniques and transduction methods. This section, and the one that follows, discuss shear stress sensor construction methods and how they impact and/or enable sensor capabilities. When it comes to the actual construction of shear stress sensors, there are two main categories: conventionally-built and micromachined.

Conventional Methods

Conventionally-built sensors may be constructed from one or more standard machining processes including turning, boring, milling, shaping, grinding, etc. Sensor components are generally formed via subtractive processes and are then combined together via hand or machine assembly to create a sensor.

The bulk starting materials and comparably large tool sizes limit the dimensional resolution of the sensors, restricting them to larger sensor dimensions compared to micromachined sensors. These larger dimensions for conventional sensors generally result in reduced dynamic performance (particularly bandwidth and gain-bandwidth product), though higher sensitivities and lower noise floors are sometimes achieved with larger sensing areas. Dimensional control using conventional methods is limited and thus tolerances are larger, resulting in greater uncertainty and variance between sensors versus what may be achieved with micromachined sensors.

On the upside, conventionally-built sensors can be made to be very rugged to ease handling and installation challenges and to meet rugged operational requirements. An example of conventionally built macroscale shear-stress sensors are the products produced by Ahmic Aerospace [26].

Micromachining methods will be discussed in the next section.

Table of Contents

  1. Overview
  2. Comparing Techniques - Indirect Measurements
  3. Comparing Techniques - Direct Measurements
  4. Transduction Method - Piezoresistive
  5. Transduction Method - Piezoelectric
  6. Transduction Method - Capacitive
  7. Transduction Method - Optical
  8. Transduction Method - Summary and Guidelines
  9. Sensor Construction - Conventional
  10. Sensor Construction - MEMS
  11. Summary and References

References

[26]      “Sensors — Ahmic Aerospace.” [Online]. Available: http://www.ahmicaerospace.com/products. [Accessed: 10-Aug-2018].

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