Accelerated life testing

The GIDEP Reliability-maintainability Data Bank (RMDB) has failure rates, failure modes, replacement rates, mean time between failure (MTBF) and mean time to repair (MTTR) on components, equipment, subsystems and systems. The RMDB includes field experience data, laboratory accelerated life test data, reliability and maintainability demonstration test results. The... 

After obtaining the prototypes, tests must be made to determine the utility. Generally these include a short time destructive test to determine the strength and to check out the basic design. Another test that is done is to use the product in the projected environment with stress levels increased in a rational manner to make for an accelerated life test. Other tests may include consumer acceptance tests to determine what instructions in proper use are required, tests for potential safety hazards, electrical tests, self-extinguishing tests, and any others that the product requires. In the case of high risk products, the test program is continued even after the product enters service. 

The methodology described In this paper has evolved over the past ten years but still remains very elementary It was developed to minimize the exceptional hazards associated with the design and Implementation of accelerated life tests Many accelerated life tests can be characterized as expensive failures, due to the use of poor experimental designs. Inadequate scientific and statistical expertise, and Insufficient peer review prior to Implementation The methodology outlined below Is Intended to reduce such failures ... 

Accelerated drug approval, 13 700-701 Accelerated life testing, for reliability, 26 991... 

Recent studies performed with deactivated anodes show [55] that electroless or electrolytic platinum deposition on failed anodes, not only lowered the polarisation behaviour of these anodes (see Fig. 5.20), but also demonstrated an equivalent lifetime as that of a new anode in accelerated life tests in the sulphuric acid solution (see Fig. 5.21). These results unequivocally demonstrate that the deactivation of anodes, for which the Ru loading is still high, is a direct consequence of the depletion of Ru from the outer region of the anode coating. Note that this process of surface enrichment by conducting electroactive species will not lead to reactivating a failed anode, if there is a TiC>2 build-up at the Ti substrate/coating interface. 

Comparing to the accelerated life test where only the life distribution under a given stress level is recorded, the accelerated degradation test keeps track of the evolution of a damage metric (Fr), which allows the experimental validation of the correlation approach if the selected damage metric is observable. For example, the projected life distribution under normal stress can sometime... 

Methods for acute-to-chronic extrapolations have been developed and are available as computer programs such as the acute-to-chronic estimation (ACE Mayer et al. 1994 Ellersieck et al. 2003) software, which makes use of 3 methods — regression, multifactor probit analysis, and accelerated life testing — to consider the relationship between exposure concentration, degree of response, and time course of response (Mayer et al. 1994 Sun et al. 1995 Lee et al. 1995). All methods produce confidence intervals around the LC and/or EC percentage point estimate. 

Sun K, Krause GF, Mayer FL, Ellersieck MR, Basu AP. 1995. Predicting chronic lethality of chemicals to fishes from acute toxicity test data theory of accelerated life testing. Environ Toxicol Chem 14 1745-1752. 

Comparisons of electrochemical impedance spectroscopy of freshly prepared electrodes and after accelerated life test can give us some information of the deactivation mechanism. 

Various testing procedures have been used to determine and ensure that the epoxy encapsulant will meet the device requirements. This testing can be divided into three categories analytical characterization, functional testing and accelerated life tests. The characterization includes the following ... 

The accelerated life tests that are normally used are as follows ... 

These accelerated life tests include the proper electrical testing at designated intervals. 

Example 3.2. Decomposition of a herbicide in a CSTR Accelerated life tests of an experimental herbicide in oleic solution in a 500-ml CSTR at 125° C give the results shown in the first three columns of Table 3.4. The analytical method is said to have a possible error of 0.005 M however, the feed concentration CA° is not affected because a stock solution of exactly known composition was used. The flow rate is accurate to 0.02 mL s . Fluid-density variation is negligible. 

Table VI. Failures Upon Accelerated Life Testing of Devices Encapsulated with GE s Developmental Molding Compound. Digital Devices on A-42 Leadframes...

Both CMOS and bipolar devices encapsulated with the new transfer molding compositions performed well under thermal cycling between -65°C and + 150°C and also under accelerated life testing at 145°C, 85% RH and 18V bias. Further optimization of this type of molding composition is expected to improve its performance as a protective material for integrated circuitry. 

Gel batteries are also produced in 6-V and 12-V monoblocs with capacities between 5 and 180 Ah. These are also mainly used for telecommunications applications. They have flat positive plates, and provide a service-life of more than 12 years. The results of an accelerated life test of 12-V, 16-Ah batteries at 40°C and a float voltage of 2.22-V per cell are shown in Fig. 13.9. It can be seen that the capacity decreased below the 80% level after about 35 months and reached 50% after about 40 months. This equates to an expected life of more than 12 years at 20°C. The influence of discharge rate and temperature on the available capacity is shown in Fig. 13.10. Most of the applications of this battery-type require discharge currents between 1 and 4 times the 10-h discharge rate. Therefore, this battery-type has been optimized to a high energy density for discharge times between 10 and 2h. 

E. Baker, Prediction of Long Term Heat Pipe Performance From Accelerated Life Tests, AIAA Journal (11/9) September 1979. 

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