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Catastrophic events: actual risk versus sociental impact
World Abstracts on Microelectronics and Reliability
Low cycle fatigue reliability expressions. RONALDG. LAMBERT. IEEE Proc. Reliab., 47 (1982). Simple closed-form analytical expressions have been developed to accurately predict the fatigue life and other useful reliability parameters for structural elements that are intentionally or inadvertently stressed above the material's elastic limit into the inelastic stressstrain region. The unique feature of these expressions is that both the applied strain and the material's ductility are treated as simultaneous random variables. The developed expressions predict average and minimum cycles to first failure, probability of failure, instantaneous failure rate, hazard rate, and average number of cumulative failures of given designs and manufacturing processes. Examples are given for multilayer board plated-through holes and solder joints during thermal cycling.
Quasi-random stress screening using the QRS-100. GREGG K. HOBSS and ROBERT MERCADO.IEEE Proc. Reliab., 79 (1982). High-rate production programs of electro-optical devices required economical and efficient screening systems to be selected. This paper describes the selection process used in arriving at the conclusion to purchase two QRS-100 systems from Screening Systems, Inc., and the results obtained with those systems.
Diagnostic programming: costs and benefits. CAESAR F. CHAVEZ. IEEE Proc. Reliab., 25 (1982). Diagnostic programs detect and isolate hardware faults within a computer system and are thereby valuable tools for aiding maintenance personnel. It can be shown that significant cost savings may result from the usage of diagnostic programs. Proof of this premise requires the development of a Life Cycle Cost model, including assumptions relating to fault diagnosis, service, and system architecture.
Catastrophic events: actual risk versus sociental impact. ROGER L. MCCARTHY, ROBERT K. TAYLOR and JAMES P. FINNEGAN. IEEE Proc. Reliab., 11 (1982). Attention drawn to catastrophic events is not commensurate with the low risk posed to society from these events as compared to other less dramatic, more common type of accidents, but whose cumulative toll is far greater. The disparity between perceived impact and true impact results in misallocation of both safety and reliability and resources. A technique for prioritizins high severity rare events with other more frequent lesser severity events is presented. FMEA technique for microcomputer assemblies. RICHARD L. KENYON and RICHARD J. NEWELL. IEEE Proc. Reliab., 117 (1982). This paper documents a methodology which can be used when preparing a Failure Modes and Effects Analysis (FMEA) for microcomputer assemblies. It uses a fault generator, microcomputer, and the production firmware (software) for the unit. The example presented is for a propulsion microcomputer assembly which provides total propulsion system control for a mass transit vehicle. Difficulty in the preparation of conventional single point FMEA's arises from the sheer volume of faults that may be subject to examination. If analyses were to be made of the hardware and firmware, the complexities associated with the preparation would not allow for its completion in a timely manner.
Reliability management of nuclear power plant. KATSUSHIGE ONODERA, MINORU MIKI, KEIZO NUKADA and HIDEO NAKAMURA. IEEE Proc. Reliab., 151 (1982). Statistics show that the average frequency of forced shut-down of nuclear power plants is 6-8 times per plant year in U.S.A., 3-4 in West Germany and about 1 in Japan. Although Japan seems to have reached a good frequency, plant manufacturers wish to improve this frequency by making more reliable plants. This paper describes several activities of plant manufac-
397
turer, Hitachi, Ltd., relating to the reliability management of nuclear power plant, such as standardization of design, reliability classification of equipment, and reliability assessment methods.
Regression models for detecting reliability degradation. JACK TOMSKY. IEEE Proc. Reliab., 238 (1982). Two regression models are described that assume repeated measurements over time and concurrently attempt to detect and evaluate component degradation with respect to time. The following statistical results are obtained for each model: 1. 2. 3. 4.
Estimation of parameters Hypothesis test for the slope Confidence band for the regression mean Tolerance band for the population.
These results are illustrated by two numerical examples, one for each model.
Repair-discard concepts in design. Dr. JAMESK. SEGER. IEEE Proc. Reliab., 21 (1982). Many items of aircraft equipment are capable of being repaired when they fail. Whether or not these items should be repaired or discarded upon failure is a complex problem that has important implications for design, life cycle cost, and operational requirements. Treating any of these factors separately can lead to seriously suboptimal results. A procedure is presented here that offers a unified approach to repair-discard decisions. The procedure addresses design, cost, and operational requirements, and it is compatible with the logistic support analysis (LSA) process as called out in MIL-STD-1388.
Common cause hazard analysis for random glitches. JOHN P. RANKIN. IEEE Proc. Reliab., 1 (1982). This paper describes an approach to common cause hazard analysis of electrical systems that is based upon checklists. The checklist method has proven to be practical, effective and easier to learn and use than fault tree reduction techniques. A common cause hazard is taken to be any design susceptibility to occurrence of single events which can lead to co-existing failure of multiple channels or interdependent subsystems such that the system is disabled. These occurrences are typically thought to be rare events of great improbability until their true nature is known or experienced. The paper draws upon real cases wherein the technique determined the causes of operational problems that had been thought to be random, unrepeatable glitches prior to the analysis. R/M/LCC effects of commercial off-tbe-shelf equipment. PRESTON R. MACDIARMID, ANTHONY D. PETTINATO and BRUCE G. JOHNSON. IEEE Proc. Reliab., 40 (1982). This paper addresses the effects of using commercial off-the-shelf equipment in military environments. Comparisons are made of military vs commercial reliability approaches and an analytical approach for choosing the most appropriate acquisition strategy is presented. Life cycle cost comparisons are made of commercial off-the-shelf equipment vs similar militarized equipment in military environments. Examples are presented of assessing risks under varying applications and choosing the best acquisition strategy.
Optimizing spare module burn-in. DAVID M. MARKO and THOMASD. SCHOONMAKER.IEEE Proc. Reliab., 83 (1982). An approach is presented to optimize spare module burn-in and thereby minimize a segment of life-cycle cost, defined herein as burn-in costs plus field failure costs. The approach is based on the hazard rate concept of declining failure rates with burn-in time. Increased costs associated with added burn-in are compared to field savings from failure reductions until an optimal approach is identified. The method permits the manufacturer to use his own failure and cost data. Burn-in time is, thus, optimized for each manufacturer's specific circumstances. An example is presented.
Low cycle fatigue reliability expressions. RONALDG. LAMBERT. IEEE Proc. Reliab., 47 (1982). Simple closed-form analytical expressions have been developed to accurately predict the fatigue life and other useful reliability parameters for structural elements that are intentionally or inadvertently stressed above the material's elastic limit into the inelastic stressstrain region. The unique feature of these expressions is that both the applied strain and the material's ductility are treated as simultaneous random variables. The developed expressions predict average and minimum cycles to first failure, probability of failure, instantaneous failure rate, hazard rate, and average number of cumulative failures of given designs and manufacturing processes. Examples are given for multilayer board plated-through holes and solder joints during thermal cycling.
Quasi-random stress screening using the QRS-100. GREGG K. HOBSS and ROBERT MERCADO.IEEE Proc. Reliab., 79 (1982). High-rate production programs of electro-optical devices required economical and efficient screening systems to be selected. This paper describes the selection process used in arriving at the conclusion to purchase two QRS-100 systems from Screening Systems, Inc., and the results obtained with those systems.
Diagnostic programming: costs and benefits. CAESAR F. CHAVEZ. IEEE Proc. Reliab., 25 (1982). Diagnostic programs detect and isolate hardware faults within a computer system and are thereby valuable tools for aiding maintenance personnel. It can be shown that significant cost savings may result from the usage of diagnostic programs. Proof of this premise requires the development of a Life Cycle Cost model, including assumptions relating to fault diagnosis, service, and system architecture.
Catastrophic events: actual risk versus sociental impact. ROGER L. MCCARTHY, ROBERT K. TAYLOR and JAMES P. FINNEGAN. IEEE Proc. Reliab., 11 (1982). Attention drawn to catastrophic events is not commensurate with the low risk posed to society from these events as compared to other less dramatic, more common type of accidents, but whose cumulative toll is far greater. The disparity between perceived impact and true impact results in misallocation of both safety and reliability and resources. A technique for prioritizins high severity rare events with other more frequent lesser severity events is presented. FMEA technique for microcomputer assemblies. RICHARD L. KENYON and RICHARD J. NEWELL. IEEE Proc. Reliab., 117 (1982). This paper documents a methodology which can be used when preparing a Failure Modes and Effects Analysis (FMEA) for microcomputer assemblies. It uses a fault generator, microcomputer, and the production firmware (software) for the unit. The example presented is for a propulsion microcomputer assembly which provides total propulsion system control for a mass transit vehicle. Difficulty in the preparation of conventional single point FMEA's arises from the sheer volume of faults that may be subject to examination. If analyses were to be made of the hardware and firmware, the complexities associated with the preparation would not allow for its completion in a timely manner.
Reliability management of nuclear power plant. KATSUSHIGE ONODERA, MINORU MIKI, KEIZO NUKADA and HIDEO NAKAMURA. IEEE Proc. Reliab., 151 (1982). Statistics show that the average frequency of forced shut-down of nuclear power plants is 6-8 times per plant year in U.S.A., 3-4 in West Germany and about 1 in Japan. Although Japan seems to have reached a good frequency, plant manufacturers wish to improve this frequency by making more reliable plants. This paper describes several activities of plant manufac-
397
turer, Hitachi, Ltd., relating to the reliability management of nuclear power plant, such as standardization of design, reliability classification of equipment, and reliability assessment methods.
Regression models for detecting reliability degradation. JACK TOMSKY. IEEE Proc. Reliab., 238 (1982). Two regression models are described that assume repeated measurements over time and concurrently attempt to detect and evaluate component degradation with respect to time. The following statistical results are obtained for each model: 1. 2. 3. 4.
Estimation of parameters Hypothesis test for the slope Confidence band for the regression mean Tolerance band for the population.
These results are illustrated by two numerical examples, one for each model.
Repair-discard concepts in design. Dr. JAMESK. SEGER. IEEE Proc. Reliab., 21 (1982). Many items of aircraft equipment are capable of being repaired when they fail. Whether or not these items should be repaired or discarded upon failure is a complex problem that has important implications for design, life cycle cost, and operational requirements. Treating any of these factors separately can lead to seriously suboptimal results. A procedure is presented here that offers a unified approach to repair-discard decisions. The procedure addresses design, cost, and operational requirements, and it is compatible with the logistic support analysis (LSA) process as called out in MIL-STD-1388.
Common cause hazard analysis for random glitches. JOHN P. RANKIN. IEEE Proc. Reliab., 1 (1982). This paper describes an approach to common cause hazard analysis of electrical systems that is based upon checklists. The checklist method has proven to be practical, effective and easier to learn and use than fault tree reduction techniques. A common cause hazard is taken to be any design susceptibility to occurrence of single events which can lead to co-existing failure of multiple channels or interdependent subsystems such that the system is disabled. These occurrences are typically thought to be rare events of great improbability until their true nature is known or experienced. The paper draws upon real cases wherein the technique determined the causes of operational problems that had been thought to be random, unrepeatable glitches prior to the analysis. R/M/LCC effects of commercial off-tbe-shelf equipment. PRESTON R. MACDIARMID, ANTHONY D. PETTINATO and BRUCE G. JOHNSON. IEEE Proc. Reliab., 40 (1982). This paper addresses the effects of using commercial off-the-shelf equipment in military environments. Comparisons are made of military vs commercial reliability approaches and an analytical approach for choosing the most appropriate acquisition strategy is presented. Life cycle cost comparisons are made of commercial off-the-shelf equipment vs similar militarized equipment in military environments. Examples are presented of assessing risks under varying applications and choosing the best acquisition strategy.
Optimizing spare module burn-in. DAVID M. MARKO and THOMASD. SCHOONMAKER.IEEE Proc. Reliab., 83 (1982). An approach is presented to optimize spare module burn-in and thereby minimize a segment of life-cycle cost, defined herein as burn-in costs plus field failure costs. The approach is based on the hazard rate concept of declining failure rates with burn-in time. Increased costs associated with added burn-in are compared to field savings from failure reductions until an optimal approach is identified. The method permits the manufacturer to use his own failure and cost data. Burn-in time is, thus, optimized for each manufacturer's specific circumstances. An example is presented.