Introduction to the Dimensional Stability of Composite Materials
This comprehensive text brings together the best quantitative methods and currently known data for understanding how composites become unstable over time.
TABLE OF CONTENTS Introduction to the Dimensional Stability of Composite Materials
Chapter 11: Measurement Techniques
11.1 INTRODUCTION
Table 1.1 showed the strain range of interest to the dimensional stability of engineering materials, from nanometers per meter (nanotechnology) to 0.2% offset strain (engineering yield strengths). Table 11.1 lists a range of candidate measurement techniques that cover the required temperatures, stress levels, environmental conditions, precision and accuracy [1]. These techniques include methods to determine linear displacements, area distortions and even volumetric or 3-dimensional shape changes.
| Technique | Resolution (m) | Range (m) or ? ?(%) | Accuracy m or % Range | Contacting [*] |
|---|---|---|---|---|
| A. Metrology | ||||
| Air Gage | 10 ?7 | 10 ?3 | 1% | SG |
| Micrometers | 3 10 ?5 | 10 ?1 | 10 ?4 | C |
| Vernier Scales | 3 10 ?5 | 1 | 2 ?10 ?5 | C |
| Dial Gages | 10 ?5 | 10 ?2 | 10 ?5 | C |
| Profile Projectors | 8 10 ?6 | 1 | 10 ?5 | L |
| Telemicroscopes | 10 ?6 | 1 | 10 ?6 | L |
| Micrometer Slides | 10 ?6 | 10 ?1 | 10 ?6 | SG |
| B. Electrical Transducers | ||||
| Resistance Strain Gages | 10 ?7( ?) | 20% | 10 ?7( ?) | C |
| Semiconductor Strain Gages | 10 ?9( ?) | 1% | 10 ?8( ?) | C |
| Capacitance | 10 ?11 | 10 ?4 | 10 ?1 0 | SG |
| LVDT's (dilatometers) | 2 10 ?6 | 10 ?2 | 10 ?8 | SG |
| Electronic Gages | 10 ?9 | 10 ?5 | 10 ?9 | C |
| Resistance Transducers | 10 ?5 | 3 | 1% | C |
| Variable lmpedance | 10 ?8 | 10 ?2 | 0.01% | SG |
| Variable Reluctance | 10 ?6 | 10 ?3 | 3% | C |
| C. Electro-Optical Techniques |
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