ACT has substantial experience in designing, fabricating and testing heat pipe assemblies to various shock and vibration loadings. ACT has in house mechanical shock and vibration test equipment as shown in Figure 2. ACT’s heat pipes and loop heat pipes have been tested to diverse shock and vibration conditions including:
- 4,500 lbf force sustained vibration loads
- Up to 9,000 lbf shock loads
- 0-3,000 Hz Frequency Range
- Over 100g’s peak acceleration
- Vibration: Sine, Random, Sine on Random, Random on Random
- Shock: Haversine, Half-Sine, Saw-Tooth, & Trapezoid
- Replication of Measured Field Data
- Gunfire Vibration
- Shock Response Spectrum
ACT’s shock test rig can produce a peak acceleration of Gpk=123g. The vibration capabilities include a frequency of 267 Hz, Grms=24g, and Gpk=45g. Examples of shock and vibration test profiles are shown in Figure 3.
Testing has confirmed that vibration loading has little or no impact on the performance of ACT’s heat pipes. Shock and vibration testing showed no evidence of overstress or fatigue on the heat pipes or solder joints. Some examples of vibration tests are listed below:
- Hybrid Two Phase Loop System. ACT tested a pumped two phase system with internal wick components to military vehicle shock and vibration requirements. Figure 4 (a) shows the PSD profile of the body and frame in a Future Combat Systems (FCS)-like military vehicle. The PSD curve produces a maximum vibration level of about 5 Grms. Figure 4 (b) shows the shock profile of the same vehicle with a half-sine pulse of 10 G’s for 50~75 ms. This thermal performance was identical before and after the tests.
- Heat Pipe Loop Assembly- This assembly was tested to the shock and vibration specifications shown in Figure 4 under full thermal loading with no degradation in performance during testing.