The difference between environmental and reliability testing

Although the environmental test and the reliability test are closely related, they are completely different in terms of the test purpose, the amount of environmental stress used, the selection criteria of the environmental force value, the type of test, and the test time.

Objectives:

The environmental test examines the adaptability of the product to the environment, determines whether the environmental adaptability design of the product meets the requirements of the contract, and provides a decision-making basis for acceptance and rejection. The reliability test is to quantitatively evaluate the reliability of the product, that is, the probability of the product completing the specified function within the specified time under the specified environmental conditions.

Number of environmental stresses used:

As far as environmental testing is concerned, GJB150 specifies 19 test items, MIL-STD-810 D specifies 20 environmental test items, and 810F increases to 24 test items, including environmental stresses that have more important effects on products, such as: temperature, humidity, salt spray, vibration shock, pressure, solar radiation, sand and dust, rain, etc. The test product should be selected according to its future use environmental conditions and the degree of influence, and more than 10 environmental stresses should generally be investigated. However, due to the comprehensive simulation of the reliability test, only the comprehensive environmental stress (temperature, humidity, vibration) and electrical stress are combined for the test. It can be seen that the number of environmental stresses used in reliability testing is much less than that in environmental testing.

Criteria for the selection of environmental stress values:

The environmental test basically adopts extreme conditions, and replaces mild with harsh, that is, the most extreme environmental conditions that may be encountered during the life cycle of the product are used as the test conditions. Many tests are destructive and do not require a simulation of the product's operating condition. The reliability test adopts the effectiveness test, that is, it realistically simulates the main environmental conditions encountered in the process of storage, transportation and use, and its dynamic change process. GJB-889 and the corresponding MIL-STD-781 D specify a set of methods to determine the environmental profile according to the task profile, and then simplify the environmental profile to the test profile to conduct a long-term reliability assessment of the product. The reliability test generally does not cause damage to the product, it needs to simulate the working state of the product, and most of the test conditions used simulate the milder stress environment often encountered in the work, and the value is much lower than the environmental test.

Test Type:

Environmental tests usually use single-factor tests and multi-factor combination tests, which act on products in a certain order. The reliability test mostly adopts a comprehensive stress test, which applies multiple environmental stresses to the sample in the same space and at the same time, so as to simulate the influence of environmental conditions more realistically. In order to improve the accuracy and reliability of the test results, environmental testing has also begun to focus on the development of comprehensive testing, and actively develop large-scale multi-functional environmental testing equipment that can simultaneously apply stresses such as temperature, humidity, vibration, radiation, sand, dust, wind, and rain.

Test time:

In the environmental test, the time of each test basically depends on the selected test and the specific test procedure, but due to the different time required for performance testing at each stage, the test time is much shorter than the reliability test. The reliability test time depends on the reliability index value to be verified, the statistical test protocol selected, and the quality of the product itself. The time cannot be determined, until the total number of hours of the tested product reaches the specified value or the judgment of acceptance and rejection can be made.

The main types of environmental tests

1. Climatic and environmental test

(GB2423, GJB150A, GJB4, IEC60068, GJB1032, GJB322A, GJB360A, GJB548, GB4208, GJB899, TB3021, etc.)

A. Temperature test: high temperature test, low temperature test, temperature shock test, temperature change test, rapid temperature change test (temperature change rate up to 15 degrees/min), high temperature aging test, temperature cycle test.

B. Humidity (humidity) test: constant damp heat test, alternating damp heat test, high temperature and high humidity test (double 85 test, double 95 test);

C. Enclosure protection level test:

IP42, IP44, P54, IP55, IP65, IP66, IP67, IP68 protection level certification and testing services;

D. Three-proof test: salt spray corrosion test (neutral salt spray test, alternating salt spray test, acid salt spray test), damp heat test (constant damp heat, alternating damp heat), mold test (mold test, long mold test);

E. Special test: low pressure test (altitude test), high pressure test, solar radiation test, rain test, sand and dust test, etc.

2. Mechanical environmental test

(GB2423, GJB150A, GJB4, IEC60068, GJB1032, GJB322A, GJB360A, GJB548, TB3058, GJB899, GB/T21563, ISO16750, etc.)

A. Vibration test: sinusoidal vibration test (sweep frequency durability test), random vibration test, broadband random vibration test, narrowband random vibration test, sinusoidal + random superposition test;

B. Impact test: half-sine wave mechanical impact test, post-peak sawtooth wave impact, impact response spectrum test;

C. Other tests: drop test (free drop, repeated drop), crash test, acceleration test, etc.

3. Comprehensive environmental reliability test (GB2423, GJB150A, GJB899, etc.)

A. Temperature and humidity combination test, temperature + humidity + vibration comprehensive test (three comprehensive tests)

Electronic, electrical, electrical, railway locomotive installation, military equipment products (environmental test) test standards:

According to domestic and foreign standards, we provide a number of environmental and reliability tests such as photoaging test, temperature and humidity test, gas corrosion test, mechanical vibration test, mechanical shock test, crash test and drop test, dustproof and waterproof test and packaging pressure test, covering most of the items of climate and environmental test, mechanical environment test and comprehensive environmental test, which can meet the requirements of GJB, GB, GB/T, IEC, ISO, EN, MIL-STD, SAE, ASTM, ISTA, JIS, IPC, JEDEC, GM, NISSAN and other international and domestic environmental and reliability test standards, and meet the requirements of relevant military standards.

List of environmental and reliability test standards (excluding GJB)

Climatic and environmental tests

Mechanical Testing:

Comprehensive Testing: