Another approach is to set a sufficient number of vibration cycles (usually using sinusoidal vibrations), such as 10° cycles. For products without fatigue limit issues, such as electrical or electronic products, sometimes the number of cycles is increased beyond 10° cycles.
4) Lifetime Testing: Lifetime testing is a real-time, high-precision simulation of the product’s environmental life cycle. Unlike durability testing described earlier, lifetime testing not only focuses on fatigue damage but also on the product’s performance degradation and failure. Therefore, lifetime testing is a type of test that cannot be accelerated and must continue until the product fails (including structural damage and performance degradation). Alternatively, the product’s intended lifespan can be specified, and testing continues until the predetermined lifespan is reached. Lifetime testing may involve not only vibration environments but also other environmental factors like temperature, humidity, and altitude, if such factors are deemed to significantly impact the product’s lifespan based on pre-test life analysis, to obtain a realistic life cycle.
5) Reliability Testing: This is used to obtain the statistical failure rate of the product, with the ultimate goal of determining the product’s Mean Time Between Failures (MTBF). Reliability testing can be developmental or qualification testing. While reliability testing shares many similarities with lifetime testing, it can be conducted with multiple test samples exposed to various test segments of the life cycle, unlike lifetime testing, which typically involves a single test sample exposed to the entire life cycle.
6) Environmental Stress Screening (ESS): ESS is not an environmental test. It is a process used early in the product manufacturing process to eliminate components, parts, or assemblies with hidden defects. The principle for selecting the power spectral density of random vibration is to “screen out the most potential defects in a short time without causing new damage to the items being screened.” Specifically, this involves applying stress levels higher than the operational profile but never exceeding the product’s design stress limits.
7) Developmental Testing: This is used to determine the product’s characteristics, expose design and structural defects, and evaluate corrective measures to ensure the developed equipment can meet the vibration environment life cycle requirements. Developmental testing primarily follows functional testing requirements, but sometimes also references environmental adaptability testing requirements.
8) Qualification Testing: This is used to determine whether the product can withstand the specified vibration environmental requirements. Qualification testing generally includes functional and durability tests, or a combination of both.
The above classifications refer to the specifications of vibration test types according to the national military standard GJB150.16A-2009B2.1. The third chapter also introduces commonly used classification methods within the industry. These descriptions are intended to illustrate that different test names correspond to different testing requirements. In actual engineering practice, test conditions and requirements depend on the test’s objectives. Different objectives will lead to different environmental test conditions, requirements, and process controls, so there is no need to be rigidly constrained by test names.