scholarly journals Margins Associated with Loss of Assured Safety for Systems with Multiple Time-Dependent Failure Modes.

2018 ◽  
Author(s):  
Jon C. Helton ◽  
Dusty Marie Brooks ◽  
Cedric Jean-Marie. Sallaberry
Keyword(s):  
Failure Modes ◽  
Time Dependent ◽  
Multiple Time ◽  
Dependent Failure

scholarly journals Probability of loss of assured safety in systems with multiple time-dependent failure modes.

2012 ◽  
Author(s):  
Jon Craig Helton ◽  
Martin. Pilch ◽  
Cedric Jean-Marie. Sallaberry
Keyword(s):  
Failure Modes ◽  
Time Dependent ◽  
Multiple Time ◽  
Dependent Failure

A New Probabilistic Approach for Accurate Fatigue Data Analysis of Ceramic Materials

1999 ◽  
Author(s):  
Bjoern Schenk ◽  
Peggy J. Brehm ◽  
M. N. Menon ◽  
William T. Tucker ◽  
Alonso D. Peralta
Keyword(s):  
Data Analysis ◽  
Failure Modes ◽  
Probabilistic Approach ◽  
Time Dependent ◽  
Material Strength ◽  
Static Fatigue ◽  
Oak Ridge ◽  
Fatigue Data ◽  
Ceramic Components ◽  
Dependent Failure

Statistical methods for the design of ceramic components for time-dependent failure modes have been developed which can significantly enhance component reliability, reduce baseline data generation costs, and lead to more accurate estimates of slow crack growth (SCG) parameters. These methods are incorporated into the AlliedSignal Engines CERAMIC and ERICA computer codes. Use of the codes facilitates generation of material strength parameters and SCG parameters simultaneously, by pooling fast fracture data from specimens that are of different sizes, or stressed by different loading conditions, with data derived from static fatigue experiments. The codes also include approaches to calculation of confidence bounds for the Weibull and SCG parameters of censored data and for the predicted reliability of ceramic components. This paper presents a summary of this new fatigue data analysis technique and an example demonstrating the capabilities of the codes with respect to time-dependent failure modes. This work was sponsored by the U.S. Department of Energy Oak Ridge National Laboratory (DoE/ORNL) under Contract No. DE-AC05-84OR21400.

A Time Dependent Model for Assessing the Significance of Mechanical Damage

2006 ◽  
Author(s):  
Michael Martin ◽  
Robert (Bob) Andrews
Keyword(s):  
Failure Modes ◽  
Mechanical Damage ◽  
Time Dependent ◽  
External Interference ◽  
Complex Load ◽  
Final Failure ◽  
Dependent Model ◽  
Dependent Failure ◽  
Pipeline Failures ◽  
Type Of Failure

A small but significant number of pipeline failures occur each year and many in populated regions arise as a result of mechanical damage from external interference. These failures generally occur at the time of damage, but a small number are delayed, with the final failure reportedly taking place following periods of up to 40 years from the original damage. This type of failure is of concern to pipeline operators as they occur without warning. The mechanisms governing time-delayed failures are poorly understood due to the extremely limited experimental data available. A greater understanding of the failure mechanism would help operators to improve their strategies for managing external interference damage. In the event of combined dent and gouge mechanical damage, the model described in this paper provides an approach for the assessment of the time dependent failure modes of the defective pipeline. The model, developed using Matlab code, is capable of investigating a complex load history consisting of constant internal pressure hold periods and cyclic fluctuations and can predict time dependent phenomenon such as pressure reversals sometimes experienced following hydrostatic pressure testing. The approach is based on the BS 7910 material specific Failure Assessment Diagram (FAD) in conjunction with R5 (British Energy) creep procedures. The result is a time dependent FAD which allows the combined influence of time dependent material properties (toughness, strength and cold creep) and loading to be investigated.

Analysis of two-machine lines with finite buffer, operation-dependent and time-dependent failure modes

2015 ◽  
Vol 54 (6) ◽  
pp. 1850-1862 ◽  
Author(s):  
Andrea Matta ◽  
Francesca Simone
Keyword(s):  
Failure Modes ◽  
Time Dependent ◽  
Finite Buffer ◽  
Dependent Failure

scholarly journals Methodology for Determining Time-Dependent Lead Battery Failure Rates from Field Data

Batteries ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 39
Author(s):  
Rafael Conradt ◽  
Frederic Heidinger ◽  
Kai Peter Birke
Keyword(s):  
Power Supply ◽  
Failure Modes ◽  
Time Dependent ◽  
Failure Rates ◽  
Reliability Models ◽  
Safety Critical ◽  
Lead Battery ◽  
Reliable Power Supply ◽  
The Individual ◽  
Dependent Failure

The safety requirements in vehicles continuously increase due to more automated functions using electronic components. Besides the reliability of the components themselves, a reliable power supply is crucial for a safe overall system. Different architectures for a safe power supply consider the lead battery as a backup solution for safety-critical applications. Various ageing mechanisms influence the performance of the battery and have an impact on its reliability. In order to qualify the battery with its specific failure modes for use in safety-critical applications, it is necessary to prove this reliability by failure rates. Previous investigations determine the fixed failure rates of lead batteries using data from teardown analyses to identify the battery failure modes but did not include the lifetime of these batteries examined. Alternatively, lifetime values of battery replacements in workshops without knowing the reason for failure were used to determine the overall time-dependent failure rate. This study presents a method for determining reliability models of lead batteries by investigating individual failure modes. Since batteries are subject to ageing, the analysis of lifetime values of different failure modes results in time-dependent failure rates of different magnitudes. The failure rates of the individual failure modes develop with different shapes over time, which allows their ageing behaviour to be evaluated.

Safety Assessment of Pressure Vessels in Service for More Than 20 Years

2020 ◽  
Author(s):  
Chen Xuedong ◽  
Fan Zhichao ◽  
Dong Jie ◽  
Ai Zhibin ◽  
Hu Mingdong
Keyword(s):  
Pressure Vessel ◽  
Failure Modes ◽  
Experimental Studies ◽  
Safety Evaluation ◽  
Pressure Vessels ◽  
Time Dependent ◽  
Economic Losses ◽  
Safety Specification ◽  
Pressure Swing ◽  
Dependent Failure

Abstract In recent years, a large number of pressure vessels for the petrochemical plants built in China in the 20th century have been in service for more than 20 years. The Chinese pressure vessel safety specification TSG 21-2016 “Supervision Regulation on Safety Technology for Stationary Pressure Vessel” stipulates that if the pressure vessels without definite design lives have been in service for more than 20 years, they shall be considered to have reached the design service lives. For these pressure vessels, if they are all blindly scrapped, it will cause huge economic losses. However, if they continue to be used blindly, it may bring great safety risks. In this paper, the failure mode, mechanism and damage evolution law are analyzed through a number of failure accident investigations and experimental studies, for typical pressure vessels such as large LPG spherical tanks, pressure swing adsorbers and coke drums. The classification method of pressure vessel for the time-independent and time-dependent failure modes has been proposed. As for the pressure vessels with time-independent failure modes, the principle to determine target life, and the strategy of inspection and maintenance have been proposed. While for the time-dependent failure modes, the safety evaluation and remaining life prediction methods for the pressure vessels with and without defects have been provided. Finally, the advices on amendment to the relevant regulations on pressure vessels have been proposed. The research findings could provide guidance for rationally determining the safety grades and scientifically extending the service lives of pressure vessels.

Failure Mechanisms of MEMS Thermal Actuators

2006 ◽  
Author(s):  
Nasim Paryab ◽  
Hamid Jahed ◽  
Amir Khajepour
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Failure Mechanisms ◽  
Time Dependent ◽  
Cyclic Loads ◽  
Creep Failure ◽  
Thermal Actuators ◽  
Mems Actuators ◽  
Cause Of Failure ◽  
Dependent Failure

Predicting and eliminating failure modes of MEMS polysilicon thermal actuators as one of the elementary bricks of a more complicated device can save months of time as well as money to repair, reproduce, or even redesign the device. There are validated reports of time-dependent failure in flexural polysilicon MEMS actuators. MEMS thermal actuators are under high temperature and cyclic loads. Therefore, fatigue and creep are suitable candidates in determining failure mechanisms. Here, both fatigue and creep failure mechanisms are studied theoretically and experimentally. A comprehensive finite element modeling is employed to find temperature and stress distribution in the actuators. It is shown, that polysilicon MEMS thermal actuator are less prone to fatigue failure and creep is the main cause of failure in MEMS thermal actuators.

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