Negative Coefficient of Thermal Expansion ALLVAR alloys offer a solution to thermal mismatch and pre-load uncertainty
The image to the left demonstrates how pre-load fluctuations stay below ± 200N simply by using an ALLVAR Alloy washer or spacer. Without the ALLVAR washer or spacer, LAV/Lplate=0, the clamping force is significantly reduced as temperature decreases. With an ALLVAR thickness of 20% of the plate thickness, LAV/Lplate=0.20, there is a near constant load kept across the same temperature range. This is a huge difference from the 50% pre-load reduction with a 120°C temperature change.
With ALLVAR NTE washers and spacers, you can:
- Control Pre-Load Uncertainty by
- Increase Demonstrated Factor of Safety Margins
- Attack Extreme Environments head-on
Getting More Technical
ALLVAR Alloy washers and spacers have Negative Thermal Expansion (NTE) through their thickness, as displayed in the graph on the left. This NTE can compensate for thermal expansion mismatch between fasteners and the joined materials.