The difference between environmental test and reliability test
In a sense, any test department under certain environmental conditions can be regarded as environmental test, but in fact only in the process of product development to assess the design or production of products to the predetermined working environment adaptability as the goal of the test is called environmental test.
This does not involve quantitative indicators of how long a product can maintain its own adaptive capacity. Obviously, if the product does not adapt to the intended environment, it is not reliable at all.
In another sense, environmental tests and other tests are beneficial to improve the reliability of the product, at least from these tests can get some fault information.
Although both environmental test and reliability test are carried out under the condition of applying environmental stress to the product, they are quite different in terms of test purpose, the number of environmental factors used, the determination criterion of test time, the selection criterion of environmental stress and the decision criterion of test termination. For example, in the environmental test, the storage time of specimens at high and low storage temperatures is 48h or 24h(or the time when the storage temperature can completely expose all possible defects during the fixed storage of the product), while the time of reliability test is calculated according to the test profile, and the time is generally 30~60mins
Although the calculation method of vibration stress is the same, the significant difference is very large. Although the test can be accelerated, because the reliability test is under the action of temperature and vibration, compared with the environmental test with high vibration level, the impact on the product is obviously different. It can be seen that these two tests cannot replace each other. However, the reliability test of air-to-air missile can be considered from the aspects of economy and effective mode when dealing with the environmental profile of short time and high quantity, and only the free vibration test of the product can be carried out, and the test results can be directly applied to the product reliability engineering. Based on the representative standard of environmental test GJB 150 “Military Equipment Environmental Test Method” (equivalent to MIL-STD-8100) and reliability test standard GB89 “Reliability Appraisal and Acceptance Test” (equivalent to ML-STD-781), as shown in Table 2, the environmental test and reliability test are compared. The comparison is the identification test. In fact, the reliability acceptance test and the appraisal test are basically the same. There are only some differences between the growth and identification tests.
Therefore, the reliability test must be able to evaluate or improve the time when the product can work normally by means of environmental adaptability is to assess the ability of the product to work normally under extreme environmental conditions. These two kinds of tests can only complement each other but not replace each other in product development and production.
Environmental test should be a form of independent reliability test, and complement each other, combined with mature environmental test technology and corresponding research results, play a due role in improving product reliability.