Reliability failure modes/mechanisms

Nonelectronic Parts Reliability Data 1991 (NPRD-91) and Failure Mode/Mechanism Distributions 199V (FMD-91) provide failure rate data for a wide variety of component (part) types, including mechanical, electromechanical, and discrete electronic parts and assemblies. They provide summary failure rates for numerous part categories by quality level and environment. 

Failure Mode/Mechanism Distributions 1991, Reliability Analysis Center, P.O. Box 4700, Rome, NY, 1991. 

FMD-97 Failure Mode /Mechanism Distributions. Reliability Analysis Center, 1997 (Ref. 5)... 

Failure Mode/Mechanism Distributions. Reliability Analysis Center, 1997. 

The ultimate goal for reliability studies is to optimize the total reliability of the product. This involves reliability of the various elements of the system (electronic/electrical components, mechanical components, PWB, and solder joints), through different failure modes (mechanical, electrical, electrochemical, etc.), under the actual use conditions (which often involves complex loading conditions with multiple loadings simultaneously imposed, such as cyclic temperatures, humidity, atmospheric chemical exposure, electrical field, vibration, mechanical shock, etc.) (Ref 26). The interactions between... 

Process Reliability Simulation VIP The process reliability simulation VIP is the use of reliability, availability, and maintainability (RAM) computer simulation modeling of the process and the mechanical reliability of the facility. A principal goal is to optimize the engineering design in terms of life cycle cost, thereby maximizing the project s potential profitability. The objective is to determine the optimum relationships between maximum production rates and design and operational factors. Process reliability simulation is also applied for safety purposes, since it considers the consequences of specific equipment failures and failure modes. 

This section describes a methodical procedure that allows reliability issues to be approached efficiently. MEMS reveal specific reliability aspects, which differ considerably from the reliability issues of integrated circuits and macroscopic devices. A classification of typical MEMS-failure modes is given, as well as an overview of lifetime distribution models. The extraction of reliability parameters is a Tack of failures situation using accelerated aging and suitable models. In a case study, the implementation of the methodology is illustrated with a real-fife example of dynamic mechanical stress on a thin membrane in a hot-film mass-airflow sensor. 

Some combinations of answers to these three questions rarely occur in the life of a product, but others are specific for certain failure modes and can therefore give valuable hints as to the underlying mechanism. A good visualization of this approach is the reliability triangle [1], in which solid fines indicate typical combinations of when, how, and why (Fig. 5.9.5). 

The reliability of an adhesive and its impact on the performance of an electronic assembly should be considered in the initial selection of the adhesive and the design of the system. The function that the adhesive must perform for a specific application, the environment it is expected to encounter, and its duration are all important. Various approaches may be used to predict and assure reliability. Key among these approaches is a basic understanding of possible failure modes and mechanisms. Most failure modes attributed to adhesives are now well understood and documented so that they can be avoided in the initial selection and qualification of the adhesive and in its processing. 

It should be noted that in using MIL-HBK-217, the rehability predictions are based on empirical data for different component types and do not necessarily take into account the rehabihty of adhesive attached and interconnected components. The effect of the adhesive and its various possible failure modes and mechanisms on the reliability of devices under both operating conditions and long-term accelerated conditions should be considered a part of the equation. 

In addition, it should be demonstrated analytically that the mechanical systems can withstand a single active failure including failure of any auxiliary electric power source and not prevent delivery of sufficient cooling water to maintain the plant in a safe shutdown condition. A technique suitable for this analysis is a Failure, Modes, and Effects Analysis (FMEA). IEEE Std. 353-1975, "Guide for General Principles of Reliability Analysis of Nuclear Power Generating Station Protection Systems," provides additional guidance on the preparation of FMEAs. 

In an operational context, there is a need to adjust and optimize existing maintenance programs. In order to facilitate this, one has to be specific on failure causes and mechanisms. A Failure Mode Effect and Criticality Assessment (FMECA) module has thus been included in the RAM tool. With the FMECA module in place, the ageing and downtime modelling are further improved compared to the basic RAM model in Section 5.1. Critical failures are split into different failure modes with the related Mean Time to Failures (MTTFs) and failure causes. A description of maintenance measures is linked to each of the failure modes. Information regarding the different cost elements of maintenance and operation are registered in the maintenance-planning module, or the Reliability Centred Maintenance (RCM) module. Interval optimisation for each of the preventive maintenance tasks is derived as the interval that produces the minimum total cost. 

Engel, P.A. 1993. Failure models for mechanical wear modes mechanisms. IEEE Trans, on Reliability 42(2) 262-267. 

The durability of fuel cells needs to be increased by about five times the current rates (e.g., at least 60,000 h for the stationary distributed generation sector) in order for fuel cells to present a long-term reliable alternative to the current power generation technologies available in the maiket. The degradation mechanisms and failure modes within the fuel cell components and the mitigation measures that could be taken to prevent failure need to be examined and tested. Contamination mechanisms in fuel cells due to air pollutants and fuel impurities need to be carefully addressed to resolve the fuel cell durability issue. 

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