Accelerated life tests as an integrated methodology for product design, qualification and production control: a case study in the household appliance (original) (raw)
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Designing Accelerated Life Testing For Product Reliability Under Warranty Prospective
2019
For analysing ALT efficiently and to obtain performance data, the experimenter needs to determine the testing method, statistical model, form of the life data and a suitable statistical method. Analysing these measures properly, provides the best estimates of the product's life and performance under usual conditions. There are researchers who combined accelerating life testing and warranty models. GuangbinYang, (2010), provided a method for describing the warranty cost, and its confidence interval. El-Dessoukey (2015) used accelerated life tests along with Exponentiated Pareto distribution to describe age replacement policy under warranty policy. The article describes how to use accelerated life testing procedures for predicting the cost of age replacement of units or products under warranty policy. Under constant stress, the generalized exponential distribution is assumed to cover the lifetimes of the products. The chapter also describes the age replacement policy in the combination of pro-rata rebate warranty for non-repairable units. Model Description and Test Method ALT is a best used method for reliability and life prediction of systems or components.
Novel Statistical Techniques for Conducting Accelerated Life Test to Demonstrate Product Reliability
Defence Science Journal
In Reliability Demonstration Testing (RDT), finding the right sample size is very important since the cost of the prototypes is high and difficult to make. If the sample size for the RDT is test is less, the amount of information obtained from the test will be insufficient, and the conclusion will be meaningless; on contrary, if the sample size is big/huge, the amount of information obtained from the test will be in excess of what is required, resulting in unnecessary costs. Most of the time, the required sample size and test time are decided based on the RDT test design. Resources required for RDT in terms of batch size and long testing-time is practically not feasible, due to limitation of the project schedule and budget. The reliability engineers must have a sound knowledge of type challenge/risk that is allowed for conducting RDT. The research paper with a case study provides the required information about the modern techniques adopted in reducing the sample-size and testing tim...
Applied Sciences
This investigation practically explains the implementation of parametric accelerated life testing (ALT) as an algorithm to recognize design imperfection and rectify it in creating a reliable quantitative (RQ) statement by sample size equation. It covers: (1) a module BX life that X% of a collection of system items is unsuccessful with an ALT plan, (2) design for fatigue, (3) ALTs with alterations, and (4) discernment as to if the final design(s) obtains the targeted BX lifetime. A (generalized) life–stress formulation by the linear transport process is recommended for the mathematical work of the parametric model. As a case study, an ice-maker including gear system in a refrigerator was utilized. The gear teeth made of cast iron (carbon, 3 wt% and silicon, 2 wt%) was fracturing in a refrigerator ice-maker. To reproduce the field failure and rectify the problematic designs in the marketplace, a parametric ALT was carried out. At the first ALT, the gear teeth made of cast iron partly ...
Design and Analysis of Accelerated Life Testing and its Application Under Rebate Warranty
Sankhya A, 2020
The study deals with the advancement of accelerated life testing in the field of product warranty. The expected total cost and expected cost rate for age replacement is estimated under warranty policy using accelerated life testing (ALT) plans. Under constant stress, the lifetimes of the units are assumed to follow generalised exponential distribution. The estimation process is carried through maximum likelihood estimation method. Also, the Age Replacement Policy under Pro-rate Rebate Warranty is discussed. Finally, an application example is presented to illustrate the theoretical results.
Application of Reliability Growth in coupled with Accelerated Life Test Model
The purpose of this paper is to analyze Accelerated Reliability Growth process data during design and development on repairable systems. A model has been developed which will compress testing time and also accelerate failure mechanisms therefore rectifying problems more efficiently so that product reliability can be assessed. In addition, time to failure in stress test do not have to be converted to time to failure in normal condition. By applying this model, it targets to save cost through speedier testing time and reducing number of prototypes needed. Therefore, the total life cycle cost of product will be shortened.
Endurance test of structural parts is an important step in automobile product development. The components, like axle, are designed to survive the life of the vehicle, while operating under design intended load in the field. On the other hand, the validation must be completed on limited number of samples within limited development time allowed by the competitive market. Therefore, the only way to generate failure for component durability prediction is to conduct the test at higher or accelerated load. This work presents an approach to develop optimum accelerated life test (ALT) plan for components under development, analyzing warranty complaints on the base model(s) already operating in the field. The approach allows for components subjected to constant single stress cyclic loading and Type I censoring, with time-to-failure fitting Weibull distribution. First, we present a method to estimate Weibull Shape parameter (Beta) and component reliability in field, by analyzing warranty comp...
Improve the design of mechanical system by using parametric accelerated life testing
2021
To enhance the design of mechanical system, parametric Accelerated Life Testing (ALT) as systematic reliability method suggests to evaluate the design of mechanical systems subjected to repeated stresses. It involves: (1) a parametric ALT plan formed on system BX lifetime, (2) a load examination, (3) a customized parametric ALTs with the design changes, and (4) an assessment of whether the design(s) of product attains the objective BX lifetime. We suggest a general life-stress model and sample size equation. As a test case, based on market data and a customized ALT, the redesign of hinge kit system (HKS) in a refrigerator was investigated. To carry out parametric ALTs, utilizing a force and moment balance analysis, the mechanical impact loading of HKS were computed in operating the refrigerator door. At the first ALT, the HKS failure occurred in the fracture of the kit housing, and oil damper leaked when the HKS broke. The failure modes and mechanisms found in the 1 ALT were alike t...
Experimental tests are a fundamental practice for improving the reliability and the functionality of mass- oriented products. But, since the high level of quality of modern commercial components (e. g., less than 5PPM of failures in the automotive field), accelerated life tests have to be properly integrated by advanced tools for reliability deployment based on failure models and statistical evaluations. On one side, Design of Experiments (DOE) can be used for planning the accelerated experiments; Analysis of Variance (ANOVA) for reducing the variability of measurements; failure models for interpreting the physic of phenomena of damage. On the other side, Failure Reporting, Analysis, Corrective Action System (FRACAS) and Failure Mode and Effect Analysis (FMEA) are irreplaceable to highlight on which criticalities to focus the experimental research, Fault Tree Analysis (FTA) and Reliability Analysis of in-service failure Data (RDA) to foresee the theoretical and authentic behavior of reliability. Only strictly joining the Design for Experiments techniques (DOE, ANOVA, etc.) to the Design for Quality methodologies (FRACAS, FTA, FMEA, RDA) is possible to manage an integrated approach of Total Quality (TQ) and the reliability move besides the current limits.
Accelerated Life Testing to Predict Service Life and Reliability for an Appliance Door Hinge
Procedia Manufacturing, 2015
Appliance manufacturers have traditionally performed physical testing using prototypes to assess reliability and service integrity of new product designs. However, for white goods where service lives are measured in years or decades, the use of endurance testing to analyze long time reliability is uneconomical. As accelerated life testing (ALT) is more efficient and less costly than traditional reliability testing, the methodology is finding increased usage by appliance manufacturers. In the present study, a simulation-based ALT approach was used to predict the service life of a polyacetal hinge cam from a consumer refrigerator. A predictive life stress model based on cumulative surface wear under accelerated stress conditions was developed and used to predict time to failure under consumer use. Results show that the life stress model demonstrated good agreement with performance testing data and reasonably predicts hinge life.