The Novel Concepts for Reliability Technology

Ryu, Dong Su; Chang, Seog-Weon

doi:10.4028/www.scientific.net/kem.270-273.1791

Cited by 4 publications

(3 citation statements)

References 2 publications

(2 reference statements)

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“…For a 60% confidence level, the first term in equation 23can be approximated as (r + 1) (Ryu & Chang, 2005). If the cumulative failure rate, x, was below about 20 percent, the denominator of the second term ln could be approximated to x by a Taylor expansion.…”

Section: Parametric Accelerated Life Testing Of Mechanical Systemmentioning

confidence: 99%

Estimating the Lifetime of the Pneumatic Cylinder in Machine Tool Subjected to Repetitive Pressure Loading

Woo¹

2018

UCPA

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To estimate the lifetime of pneumatic cylinder in machine tool (or automatic assembly line), new reliability methodology for parametric accelerated life testing (ALT) is suggested. It consists of parametric ALT plan, generalized life-stress failure model with a new effort concept, acceleration factor, and sample size equation. This new parametric ALT enables an engineer to estimate the lifetime of a commercially parts by uncovering the failure through accelerated testing under severe conditions. As a case study, two commercial products of the pneumatic cylinder in machine tool were tested. For company A, we found the hardening and wear of piston seal like that of field at normal conditions. As increasing the pressure, the pneumatic cylinders were tested. Based on the accelerated conditions-0.8 MPa and 1.2 MPa at 23 °C, B1 life at 0.63 MPa and 23 °C was extrapolated as 2.39 × 10 6. On the other hand, for company B, we found the rod cap blocked by slurry like those of field samples. Based on the accelerated conditions-0.8 MPa and 1.4 MPa at 23 °C, B1 life at 0.63 MPa and 23 °C was extrapolated as 2.51 × 10 6. Comparing them with testing data at normal use conditions, we knew that the estimation error for both companies was less than 10%.

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Section: Parametric Accelerated Life Testing Of Mechanical Systemmentioning

confidence: 99%

Estimating the Lifetime of the Pneumatic Cylinder in Machine Tool Subjected to Repetitive Pressure Loading

Woo¹

2018

UCPA

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“…According to the six‐sigma quality policy (i.e. 3.4 defects per million) at the initial time t 0 , Y 0 is equal to 1–3.4 × 10 −6 ; and for five years performance reliability policy, Yt is 0.95. The proposed tolerance allocation model is solved via the discrete search algorithm by adopting MATLAB software.…”

Section: Tolerance Design Of the Led Drivermentioning

confidence: 99%

A Tolerance Design Method for Electronic Circuits Based on Performance Degradation

Zhai

Zhou

2013

Quality & Reliability Eng

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Due to the effects of manufacturing tolerances and environmental conditions, component parameters vary and degrade with time. This may cause performance measures of electronic circuits to deviate from design specifications. Therefore, a tolerance design method based on performance degradation is proposed for electronic circuits, so as to improve the robustness of output characteristics. First, sensitive components causing output fluctuation are determined via orthogonal experiment and PSpice simulation. Then, degradation path models are established to describe the degradation process of sensitive components. The predicted values worked out by the degradation path models are substituted into the simulation model for Monte Carlo analysis. Besides, output characteristics and performance reliability are evaluated according to Monte Carlo simulation. Finally, optimum allocation is carried out for component tolerances as per minimum life cycle cost. The proposed method is illustrated by a case study of light-emitting diode (LED) driver.

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“…4. When the number of failed samples is below four, it follows the Poisson distribution (Ryu and Chang, 2005). At a sixty-percent confidence level, the characteristic life is defined as…”

Section: Derivation Of B X Life and Sample Sizementioning

confidence: 99%

Reliability Design and Case Study of a Refrigerator Compressor Subjected to Repetitive Loads

Woo

O’Neal

Kim

2007

Volume 6: Energy Systems: Analysis, Thermodynamics and Sustainability

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A newly designed crank shaft of a compressor for a side-by-side (SBS) refrigerator was studied. Using standard mass and energy conservation balances, a variety of compressor loads typically found in a refrigeration cycle were analyzed. The laboratory failure modes and mechanisms were compressor locking and crank shaft wear. These were similar to those of the failed samples in the field. Failure analysis, accelerating life testing (ALT), and corrective action were used to identify the key reliability parameters and their level. The design parameters of the crank shaft included the hole locations and the groove of the crank shaft used for oil lubrication, crank shaft hardness, and thrust washer interference. Based on the analysis and design changes, the B1 life of the new design is now over 10 years with a yearly failure rate of 0.01 percent. A procedure was recommended for refrigerator parts design which included five steps.

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The Novel Concepts for Reliability Technology

Cited by 4 publications

References 2 publications

Estimating the Lifetime of the Pneumatic Cylinder in Machine Tool Subjected to Repetitive Pressure Loading

Estimating the Lifetime of the Pneumatic Cylinder in Machine Tool Subjected to Repetitive Pressure Loading

A Tolerance Design Method for Electronic Circuits Based on Performance Degradation

Reliability Design and Case Study of a Refrigerator Compressor Subjected to Repetitive Loads

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