【Summary description】 Circular connector is the nerve center of aerospace system, and reliability is an important index of circular connector. It is also the basis to ensure the power transmission, signal control and transmission of the system, and is an important guarantee for the normal operation of aerospace equipment. The significance of reliability of circular connector can provide important basis for the design and application of circular connector.

Circular connector is the nerve center of aerospace system, and reliability is an important index of circular connector. It is also the basis to ensure the power transmission, signal control and transmission of the system, and is an important guarantee for the normal operation of aerospace equipment. The significance of reliability of circular connector can provide important basis for the design and application of circular connector.

Ambient temperature：

At present, the circular connector is usually assembled at room temperature without stress. However, when the circular connector enters the specific working environment, the temperature may change dramatically. Due to the differences in the shape of different parts, thermal expansion coefficient and thermal conductivity coefficient of the circular connector, the stress concentration phenomenon will occur, and even the terrible consequences such as fatigue and fracture will occur. The external environment of sudden cooling and heating is an important factor leading to fatigue failure and even contact fracture.

The metal and insulating materials of circular connector determine the working environment temperature of circular connector. High temperature will destroy the edge material, resulting in the reduction of insulation resistance and withstand voltage performance; for metals, high temperature can make contact pairs lose elasticity, accelerate oxidation and cause coating deterioration. The normal ambient temperature is - 55 ~ 100 ℃, and higher requirements may be required in special occasions.

Contact：

In the process of test and use, although the failure forms of circular connector are various, they mainly include poor contact, instantaneous power failure, poor insulation, short circuit (breakdown), wrong wiring, poor fixation, open circuit, etc. Among them, the contact is the core part of the circular connector, and most of the failures of the circular connector occur on the contact. Therefore, it is necessary to study the reliability of the circular connector with the contact as the focus.

Environmental parameters mainly include environmental temperature, humidity, temperature change, atmospheric pressure and corrosion environment. The environment of aviation circular connector in the use, storage and transportation process has a significant impact on its performance, so we must select the corresponding circular connector according to the actual environmental conditions.

Damp：

The relative humidity is more than 80%. Moisture environment causes the absorption and diffusion of water vapor on the surface of insulator, which easily reduces the insulation resistance below m Ω level. Long term exposure to high humidity environment will cause physical deformation, decomposition and escape of products, resulting in respiratory effect, electrolysis, corrosion and cracks. Especially for the circular connector outside the equipment, the environmental conditions of humidity, water penetration and pollution should be considered. In this case, the sealed circular connector should be selected. The enclosure protection grade of GB4208 is generally used for water tight and dust tight circular connectors.

A sudden change in temperature：

Humidity burst test is to simulate the actual use of circular connector equipment in cold environment into warm environment, or simulate the rapid change of environmental temperature of spacecraft and detector. Rapid temperature changes may cause cracks or delamination of insulating materials.

Atmospheric pressure：

In the high altitude with thin air, the plastic emits gas to pollute the contact pairs, which makes the corona generation trend increase and the withstand voltage performance decrease, resulting in the short circuit fault of the circuit. When it reaches a certain value at high altitude, the properties of plastics become worse. Therefore, the unsealed circular connector must be derated when it is used at high altitude.