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Basic principles for the selection of environmental test equipment
- Jan 16, 2018 -

1, reproducibility of environmental conditions

The complete and accurate representation of the environmental conditions in nature in the laboratory is an unexpected and impossible thing. However, within a certain tolerance range, people can accurately and accurately simulate the external environmental conditions of engineering products in the process of use, storage and transportation. This passage is summed up in the engineering language, that is, "the environmental conditions created by the test equipment around the tested products, including the platform environment, should meet the environmental conditions and tolerance requirements specified in the product test specification". For example, the temperature box used for military product test should not only meet the requirements of the national standard GJB150.3 - 86, GJB150.4 86, according to the different homogeneity and temperature control accuracy. Only in this way can we ensure the reproducibility of environmental conditions in environmental tests.

2, the repeatability of environmental conditions

An environmental test equipment may be used for the same type of product test and a test project could also be tested in different environmental testing equipment, in order to ensure the environmental test conditions for the same product provided in the same test standard of the comparability of the test results, the inevitable requirement environmental testing equipment provided by the environmental conditions can be repeated. That is to say, the stress level (such as thermal stress, vibration stress and electric stress) of environmental test equipment applied to the tested products is consistent with the requirements of the same test specification. The repeatability of environmental conditions provided by environmental test equipment is guaranteed by the national metrological verification department according to the verification regulation formulated by the state technical supervision institution. Therefore, it is necessary to request that the environmental test equipment can meet all the technical specifications and accuracy requirements of the verification regulation, and it will not exceed the time limit specified in the verification period. Such as the use of electric vibration table is very common in addition to meet the exciting force and frequency range, load capacity and other technical indicators, but also must satisfy the horizontal vibration verification regulation of ratio, acceleration uniformity, harmonic distortion and accuracy requirements, and every time after verification of the life cycle of two years, more than two years must be put into use after re inspection.

3. The measurement and control of environmental parameters

Any environmental testing equipment provided by the environmental conditions must be observed and controlled, it is not only in order to make the environment parameters within the limits of tolerance range, ensure the test conditions of the reproducibility and repeatability of the requirements, but also from the product test of safety is a must, in order to prevent environmental conditions out of control the subjects cause product damage, cause unnecessary losses. At present, in various test specifications, the precision of the parameter test should not be less than 1/3 of the error allowed by the test conditions.

4. Exclusion of environmental test conditions

Every time the environmental or reliability tests are carried out, the categories, values and tolerances of the environmental factors are strictly regulated and the non trial is excluded.

Environmental factors inspection required to permeate, in order to test or test after the judgment and analysis of product failure and failure mode, provide the exact basis of the requirements of environmental testing equipment except for the provisions of the environmental conditions, are not allowed on other product added environmental stress interference. For example, the surface leakage of the table in the verification regulation of the electric vibration table, the ratio of the acceleration signal to noise ratio, and the total root mean square of the acceleration in the belt. The test of random signal, harmonic distortion and so on are all the verification items to ensure the uniqueness of environmental test conditions.

5. Safety and reliability of test equipment

Environmental testing, especially the reliability test, the test cycle is long, the test object is sometimes very high value of military products, test process, test personnel often have to work in the field of testing around the operation of inspection or, therefore environmental test equipment must have safe operation, convenient operation, reliable work, long life and other characteristics, to to ensure the normal test itself. All kinds of protection, alarm measures and safety interlocking devices of test equipment should be improved and reliable, so as to ensure the safety and reliability of the test personnel, the tested products and the test equipment itself.