- Concept and content of research
Environmental testing is an important part of environmental engineering, which plays an important role in product development, production, safety and use. This is an important way to ensure the environmental change of the product. Environmental testing is the process of applying certain environmental conditions to the product according to certain methods and procedures to test the environmental quality of the product. Environmental conditions include the natural environment, the use environment and the laboratory environment. It can be divided into the following sections according to the characteristics of the environment:
1) Weather factors, including temperature, humidity, atmospheric pressure, rain, snow, ice, frost, sand and sand, salt, corrosive gases, etc.
2) Mechanical factors include vibration, impact, oscillation, constant acceleration, explosion, earthquake and vibration sound.
3) Living things, including mold, insects, sea creatures, etc.
4) Electronic radiation, including radio interference, lightning, electric field and magnetic field, etc., actually includes a new environment when combining these environments.
Environmental tests can be divided into environmental change development tests, environmental characteristics tests, environmental acceptance tests and environmental tests are usually performed according to its functions and functions at different levels. The reliable test also goes through the entire product testing and production process to check whether the product has the original function after a certain period of time.
- Environmental testing and reliability testing
Currently, the authoritative international standards in the field of environmental testing and reliability testing are MIL-STD-810F Environmental testing procedures and engineering guidelines and MIL-STD-781D Reliability testing for engineering development, qualification and production. In theory, any test can be considered as environmental test because the test is always done in some area. Therefore, a reliable test can also be considered as an environmental test. Environmental tests are included in strength, durability, performance, and other basic tests.
Often, people refer to specific testing processes in the product development process as testing environments. From a reliability perspective, the purpose of environmental and other tests is to improve or verify product performance. Performing these tests helps improve product reliability. MIL-STD-781D makes it clear that these tests can be considered part of reliability testing. MIL-STD-785B System and Equipment Development and Reliability Program also emphasizes that “The environmental testing described in 810F should be considered as the first part of the development and growth of reliability. These tests must be done early in the development to ensure that there is enough time and resources to correct the defects revealed in these tests, these corrections must be carried out under environmental pressure, and this information must be included in the process. FRACAS as an important element of trust strategy.
It is clear from the provisions and objectives of the environmental and reliability audit that both aim to show defects in the design, materials, materials and processes of the product. By comparing their research, we can see that. In MIL-STD-810F, maximum value conditions are adopted for environmental pressure standards, while in MIL-STD-781D, a rigorous simulation of the environment is required and environmental conditions are accepted. In addition, there are differences between the two in the amount of environmental stress used in the experiment, the type of experiment, the duration of the experiment, and the criteria for the end of the experiment. In a broad sense, environmental testing and any other test is to improve or evaluate product performance, which makes it better to improve product reliability. It can be seen that environmental testing is closely related to reliability testing. The first is the second foundation, which plays an important role in improving the reliability of the product.
2.1 The relationship between environmental testing and reliability testing
Environmental testing is a variety of tests to identify errors in the environmental design of products, identify the adaptation of products to critical environments during their life cycle, and study the response of products to environmental impacts. . For products that have passed the indoor temperature performance test, various environmental tests will be performed first to ensure that the products will not be damaged and can work well in different harsh environments in the future life. Therefore, environmental testing is more basic than reliability testing. It is done before the reliable test at all stages of product development and production.
Environmental testing is the ultimate test of a product. Only products that have passed the environmental qualification test can undergo the reliability growth test; products that have passed environmental acceptance tests may be subject to reliability acceptance tests. Therefore, it can be said that the environmental analysis is the basis and important element of the reliable test. Reliability testing uses only the results of environmental analysis and environmental conditions. Poor product reliability is often caused by using inappropriate environmental conditions. For example, high temperature will cause heat aging, which causes insulation, low temperature will cause the room to shrink, causing structural damage, sand and dust, and as a barrier, water causes electricity and the effect of vibration to prevent damage.
In order to ensure that the product can perform a specific function under the conditions of the environment in which it is used and obtain the quantitative contribution value required by the contract, it is necessary to first understand the future conditions of the environment product accommodation and use product reliability standards according to the requirement. All forms of trust and policy must be associated with appropriate environmental constraints. In terms of improving product reliability, environmental testing plays an important role. To be critical, without environmental testing, it is impossible to accurately determine the quality of products and ensure product quality. The better the environmental test, the better the reliability of the product. The type and amount of environmental stressors should refer to the results of the environmental assessment. At the same time, both types of tests follow the laboratory test method and are performed in a controlled environment. Environmental equipment and test methods used, including corresponding luminaire manufacturing standards, can be used for reference. Studying the environmental conditions used for environmental testing provides information before creating a reliable test environment.
At the same time, the determination of temperature and vibration values in the reliability test profile is the same as the determination of the corresponding environmental conditions. It can be assumed that the environmental test is the basis and foundation of the reliable test, and many environmental tests should be done before the reliable test to provide information and the basis for the reliable test.
