**Commenced**in January 2007

**Frequency:**Monthly

**Edition:**International

**Paper Count:**6

# Search results for: Accelerated life test

##### 6 A Data Driven Approach for the Degradation of a Lithium-Ion Battery Based on Accelerated Life Test

**Authors:**
Alyaa M. Younes,
Nermine Harraz,
Mohammad H. Elwany

**Abstract:**

Lithium ion batteries are currently used for many applications including satellites, electric vehicles and mobile electronics. Their ability to store relatively large amount of energy in a limited space make them most appropriate for critical applications. Evaluation of the life of these batteries and their reliability becomes crucial to the systems they support. Reliability of Li-Ion batteries has been mainly considered based on its lifetime. However, another important factor that can be considered critical in many applications such as in electric vehicles is the cycle duration. The present work presents the results of an experimental investigation on the degradation behavior of a Laptop Li-ion battery (type TKV2V) and the effect of applied load on the battery cycle time. The reliability was evaluated using an accelerated life test. Least squares linear regression with median rank estimation was used to estimate the Weibull distribution parameters needed for the reliability functions estimation. The probability density function, failure rate and reliability function under each of the applied loads were evaluated and compared. An inverse power model is introduced that can predict cycle time at any stress level given.

**Keywords:**
Accelerated life test,
inverse power law,
lithium ion battery,
reliability evaluation,
Weibull distribution.

##### 5 A Partially Accelerated Life Test Planning with Competing Risks and Linear Degradation Path under Tampered Failure Rate Model

**Authors:**
Fariba Azizi,
Firoozeh Haghighi,
Viliam Makis

**Abstract:**

**Keywords:**
Expectation-maximization (EM) algorithm,
cause of
failure,
intensity,
linear degradation path,
masked data,
reliability
function.

##### 4 A Stochastic Diffusion Process Based on the Two-Parameters Weibull Density Function

**Authors:**
Meriem Bahij,
Ahmed Nafidi,
Boujemâa Achchab,
Sílvio M. A. Gama,
José A. O. Matos

**Abstract:**

**Keywords:**
Diffusion process,
discrete sampling,
likelihood
estimation method,
simulation,
stochastic diffusion equation,
trends
functions,
bi-parameters Weibull density function.

##### 3 Effect of Progressive Type-I Right Censoring on Bayesian Statistical Inference of Simple Step–Stress Acceleration Life Testing Plan under Weibull Life Distribution

**Authors:**
Saleem Z. Ramadan

**Abstract:**

This paper discusses the effects of using progressive Type-I right censoring on the design of the Simple Step Accelerated Life testing using Bayesian approach for Weibull life products under the assumption of cumulative exposure model. The optimization criterion used in this paper is to minimize the expected pre-posterior variance of the P^{th} percentile time of failures. The model variables are the stress changing time and the stress value for the first step. A comparison between the conventional and the progressive Type-I right censoring is provided. The results have shown that the progressive Type-I right censoring reduces the cost of testing on the expense of the test precision when the sample size is small. Moreover, the results have shown that using strong priors or large sample size reduces the sensitivity of the test precision to the censoring proportion. Hence, the progressive Type-I right censoring is recommended in these cases as progressive Type-I right censoring reduces the cost of the test and doesn't affect the precision of the test a lot. Moreover, the results have shown that using direct or indirect priors affects the precision of the test.

**Keywords:**
Reliability,
Accelerated life testing,
Cumulative exposure model,
Bayesian estimation,
Progressive Type-I censoring,
Weibull distribution.

##### 2 A Combined Approach of a Sequential Life Testing and an Accelerated Life Testing Applied to a Low-Alloy High Strength Steel Component

**Authors:**
D. I. De Souza,
D. R. Fonseca,
G. P. Azevedo

**Abstract:**

Sometimes the amount of time available for testing could be considerably less than the expected lifetime of the component. To overcome such a problem, there is the accelerated life-testing alternative aimed at forcing components to fail by testing them at much higher-than-intended application conditions. These models are known as acceleration models. One possible way to translate test results obtained under accelerated conditions to normal using conditions could be through the application of the “Maxwell Distribution Law.” In this paper we will apply a combined approach of a sequential life testing and an accelerated life testing to a low alloy high-strength steel component used in the construction of overpasses in Brazil. The underlying sampling distribution will be three-parameter Inverse Weibull model. To estimate the three parameters of the Inverse Weibull model we will use a maximum likelihood approach for censored failure data. We will be assuming a linear acceleration condition. To evaluate the accuracy (significance) of the parameter values obtained under normal conditions for the underlying Inverse Weibull model we will apply to the expected normal failure times a sequential life testing using a truncation mechanism. An example will illustrate the application of this procedure.

**Keywords:**
Sequential Life Testing,
Accelerated Life Testing,
Underlying Three-Parameter Weibull Model,
Maximum Likelihood Approach,
Hypothesis Testing.

##### 1 Appling Eyring-s Accelerated Life Testing Model to “Times to Breakdown“ of Insulating Fluid: A Combined Approach of an Accelerated and a Sequential Life Testing

**Authors:**
D. I. De Souza,
D. R. Fonseca,
D. Kipper

**Abstract:**

**Keywords:**
Eyring Accelerated Model,
Sequential Life Testing,
Two-Parameter Weibull Distribution,
Voltage Stresses.