What is the main purpose of environmental test? What does environmental testing include?

Date：2021-08-04 14:19:04 Views：4198

With the rapid development of science, technology, economy and trade, the development and utilization of natural resources, the environment encountered in the storage, transportation and use of various products is becoming more and more complex and harsh. From tropical zone to cold zone, from plain to plateau, from ocean to space and so on, both users and producers are concerned about the performance, reliability and safety of products in the above environment, so as to ensure that products can work satisfactorily. Therefore, environmental tests must be carried out.

The so-called environmental test is to expose the products to the natural environment or artificial simulation environment, so as to evaluate the performance under the storage, transportation and use conditions they will actually encounter. Environmental test can provide information on design quality and product quality, which is an important means of quality assurance.

Environmental test is an activity to ensure that the product maintains functional reliability in all environments of expected use, transportation or storage during the specified service life. It is to expose the product to natural or artificial environmental conditions and undergo its action, so as to evaluate the performance of the product under the environmental conditions of actual use, transportation and storage, and analyze and study the influence degree and action mechanism of environmental factors. Environmental test equipment is a method for enterprises or institutions to verify the quality of raw materials, semi-finished products and finished products under the conditions of transportation, handling, vibration, etc. The purpose is to verify whether the materials and products meet the expected quality objectives in R & D, design and manufacturing by using various environmental test equipment. It is widely used in Colleges and universities, aviation, aerospace, military, shipbuilding, electrician, electronics, medical treatment, instruments and meters, petroleum instruments, petrochemical industry, medical treatment, automobile and motorcycle and other fields.

Environmental test runs through the development, production and use of products, usually design, environmental test, improvement, re environmental test and production. The more authentic and accurate the environmental test, the better the reliability of the product.

1) For product research test:

The research test is mainly used in the design and development stage of products to assess whether the selected components, parts, design structure and process can meet the actual environmental requirements and existing problems. In order to save time and fully expose the weak links of products, accelerated environmental test method is generally adopted.

2) For product type test:

Type test is used to determine whether the product can meet the specified design technical indicators and safety requirements under the predetermined environmental conditions. Type test is the most comprehensive test, and the environmental factors that may be encountered by the product must be taken into account.

3) For production inspection and test:

Production inspection test is mainly used to check the process quality of products and the quality stability during process change.

4) For product acceptance test:

Acceptance test refers to the test of some items that must be carried out to ensure the product quality when the product leaves the factory. The acceptance test is usually carried out by sampling.

5) For safety test:

Environmental test can be used to check whether the product is harmful to health and life, and constant acceleration can be used to check the firmness of product installation and connection, so as to prevent human casualties or other equipment from being thrown out in an emergency. The safety test is usually conducted at a more severe test level than the normal test.

6) For reliability test:

Reliability test is composed of environmental test, life test, phenomenon test and special test, of which environmental test is the main component. American mil-ztd-781d clearly stipulates that environmental test is not only a necessary supplement to reliability test, but also an important means to improve product reliability.

The environmental test equipment can carry out high temperature, low temperature, temperature shock (gaseous and liquid), impregnation, temperature cycle, low pressure, high and low temperature and low pressure, constant damp heat, alternating damp heat, high-pressure cooking, sand dust, explosion resistance, salt spray corrosion, gas corrosion, mold, rain, solar radiation, light aging, etc. according to IEC, mil, ISO, GB, GJB and other standards or user requirements. At present, environmental tests have been standardized abroad, and many countries have also formulated environmental test standards. Generally speaking, the standards are similar. The details are as follows:

(1) Low pressure (high altitude) test:The test is applicable to the situation that the pressure of weapons transported by air in the cargo hold of the aircraft, weapons used on the plateau and air weapons drops rapidly after the aircraft is injured. The purpose of the test is to test the service performance of weapons in low-pressure environment and the impact of rapid pressure drop on weapon performance. The maximum height of the simulation can reach 30000m (m), and the temperature value corresponding to the height shall be taken during the test.

(2) High temperature test:During the test, the weapon was in high temperature air, but not directly exposed to sunlight. The test is aimed at the storage or use of weapons in indoor or confined space or near heat sources such as engine in high temperature season. This test shall be carried out only when the solar radiation test cannot verify the high temperature effect. The purpose of the test is to test the performance of storage or use in high temperature environment.

(3) Low temperature test:The test is applicable to the test pieces that are likely to be used in low temperature environment in the life cycle. The purpose of the test is to test whether the test piece can be stored, manipulated, controlled and operated in a long-term low-temperature environment.

(4) Thermal shock test and cold shock test completed in:The test is applicable to weapons that often experience extremely rapid temperature changes in predetermined use areas or use modes. For example: electronic equipment hoists, missiles, optoelectronic equipment and bombs in bomb silos on aircraft taking off from desert airport and rising to high altitude; Weapons dropped from high altitude into desert areas; Weapons transferred from indoor to outdoor in the Arctic. At present, only the thermal shock test in air is carried out, and the thermal shock test from air to water may be carried out in the future. The purpose of thermal shock test is to test the effect of sudden change of ambient temperature on weapon performance.

(5) Solar radiation (sunshine) test:This is an experiment on weapons and their manufacturing materials exposed to the sun. Solar radiation can cause photochemical and thermal effects. In most cases, this test can replace the high temperature test. The influence of solar radiation on the use or open storage of weapons or related materials can be tested through sunshine test.

(6) Rain test:The test is applicable to weapons that may be exposed to rain during use. Rain test includes rain test when there is no wind and rain test when there is wind. The purpose of rain test is to test the waterproof performance of rain shielding equipment and the performance of weapons during and after rain.

(7) Moisture proof test:The test is applicable to weapons that may be used in warm and humid environment. Tropical areas have different seasons in the whole year and middle latitudes, which is such a warm and humid environment. The purpose of the test is to test the adaptability of weapons to warm and humid environment.

(8) Mould proof test:Warm and humid conditions are the conditions for microbial growth, which widely exist in tropical and middle latitudes. All standard general-purpose weapons and equipment shall be designed to prevent mildew. The purpose of the test is to evaluate the degree of mildew of weapons and the impact of mildew on the performance or use of weapons.

(9) Salt spray test:Salt is widely distributed on the earth. There is salt in the ocean, atmosphere, ground, lake and river, especially in coastal areas, where the salt content is relatively large, and the salt content in the ocean is the largest. There is no weapon that does not come into contact with salt. Therefore, all weapons are in some form of salt environment in their life cycle. The purpose of salt spray test is to test the influence of salt containing humid atmosphere on the performance of weapons, especially the performance of coating protective layer and the compatibility of materials.

(10) Dust test:The test is applicable to all mechanical, electrical, electronic and electrochemical weapons used in air with high dry sand or dust content. The test is divided into dust raising test and sand lifting test. Dust and fine sand are used for dust raising test. Fine dust can enter gaps, cracks, bearings and joints. 149 ~ 850um (micron) sand particles are used in sand lifting test. Large and sharp sand particles can produce erosion and blocking effect and reduce the effectiveness, reliability and maintainability of equipment. The purpose of sand and dust test is to test the use and storage capacity of weapons in sand and dust environment.

(11) Immersion test:Immersion test includes immersion, dripping and pressurized water test. The immersion test is applicable to equipment requiring water tightness and equipment used in full or partial immersion in water. In some cases, this test can replace the rain test to check the water tightness. The purpose of the test is to test the ability of the weapon to immerse in water without water leakage.

(12) Freezing rain test:The test is applicable to equipment that will encounter freezing rain in normal use. The purpose of the test is to test the impact of rain, fog and splashed sea water on the service performance of the equipment after freezing. It is also used to evaluate the deicing device and technology.

By repeating this process, the environmental adaptability of products can be improved; Simulation test is mainly used to verify or evaluate the environmental adaptability level of products or whether they meet the specified requirements, as the basis for design finalization, product acceptance and procurement decision. Therefore, environmental test is an important means to improve, verify and evaluate the environmental adaptability of products.