## 2 Infield and Outfield Environmental Tests of Rubber Materials
### Test Process and Results  
The typical low-temperature parking temperature range of the aircraft is \(-\)40 to 10 \({}^{\circ}\)C. In the infield and outfield environments for this temperature range, the tensile springback tests and isobaric elongation tests are carried out on the two kinds of specimens. The pretest was carried out before the test to compare the elongation and springback of the specimens at different low-temperature environment times. When the experimental scheme is freezing for 15 min (or more) plus loading for 15 min (or more), the experimental data is basically stable. The appropriate test time is determined to ensure the stability of loading and unloading state and reduce the fluctuation range of field temperature. In the outfield experiment, we should grasp the required environmental temperature range to carry out the experiment, and there are a small number of temperature points greater than 10 \({}^{\circ}\)C after the average--these data are also adopted. The specimens were pretreated: heated for 45 min at 50 \({}^{\circ}\)C and held for 24 h to ensure that they were in the same state. The sample test shows that the properties of the sample have no change after pretreatment. In the outfield tests, the thermometer was used for temperature measurement, and this outfield thermometer was calibrated and checked by the calibrated temperature test chamber before. When the ambient temperature measured by the thermometer is close to the temperature to be tested (\(<\)0.5 \({}^{\circ}\)C), the experiment is started. Considering the instability of the external temperature in the outfield test, the temperature of the tests was measured  
Figure 3: Rubber specimens. (**a**) Material A (**b**) Material B.  
Figure 2: Environmental test chamber. (**a**) Device appearance (**b**) Experimental area. three times, and the average value was taken as the test temperature when the temperature fluctuation was no more than 1 \({}^{\circ}\)C.  
The process of infield and outfield tests is shown in Figure 4.  
When the specimen is subjected to constant pressure tensile test, a small change in the cross-sectional area may lead to a large range of tensile length. In order to solve the experimental error caused by the cross-sectional area error, the tensile test was carried out at room temperature (25 \({}^{\circ}\)C) with the same loading weight before the low-temperature test. The results of the low-temperature tensile test and the normal temperature tensile test were compared to eliminate the error caused by the cross-sectional area. In the data processing of the tensile test, the concept of low temperature elongation is adopted. The low-temperature elongation is the ratio of the low-temperature tensile test length to the room temperature tensile test length of a specimen. The processing method of the tensile test data is shown in the Figure 5. Because the measured value of the rebound test specimen is the rebound length, which has nothing to do with the cross-sectional area of the specimen, only the tensile test data are equivalently processed. Figure 4: Infield and outfield tests. (**a**) Tensile springback test outfield at night (**b**) Isobaric elongation test outfield (**c**) Tensile springback test outfield (with clamp loosed) (**d**) Tensile springback test infield (with clamp loosed). Through the test, the steady-state response data of the elastic properties of the two typical sealing rubber materials at the low-temperature infield and outfield were obtained. The results are shown in Figure 6. The test results show that material A and material B harden at low temperatures in both the infield and outfield environments; that is, the elasticity of the material becomes worse at low temperatures, and both rubbers are in the glass transition region at \(-40\,^{\circ}\)C, but they do not reach their glass transition temperature. For material A, there is a difference between the infield and outfield elasticity, and the elasticity is worse in the infield low-temperature environment.