Internal failures

Spall is the process of internal failure or rupture of condensed media through a mechanism of cavitation due to stresses in excess of the tensile strength of the material. Usually, a dynamic failure is implied where transient states of tensile stress within the body are brought about by the interaction of stress waves. Free surfaces are assumed to be well removed from the material point of interest and play no role in the spall process. 

Failure costs - Internal failure costs are essentially the cost of failures identified and rectified before the final product gets to the external customer, such as rework, scrap, design changes. External failure costs include product recall, warranty and product liability claims. 

Pc - internal failure cost due to rework at the end of the production line Pc - external failure cost for return from customer inspection 10 Pc - external failure cost for warranty return due to failure with customer in use. 

It can be seen that the various boxes in the flowchart can be associated with different stages of the stepladder model. For example, the first box on the left corresponds to skill-based behavior and its associated internal failure mechanisms. The second box illustrates the situation (Stereotype Fixation) where the worker erroneously does not change to a rule-based mode when encountering an unusual situation in the skill-based mode (see also the discussion of the GEMS model in Section 2.6.3). 

Internal failure cost is the cost when you discover, before release a laboratory report or an analysis certificate that something has gone wrong. 

The two predominant mechanisms of failure in adhesively bonded joints are adhesive failure or cohesive failure. Adhesive failure is the interfacial failure between the adhesive and one of the adherends. It indicates a weak boundary layer, often caused by improper surface preparation or adhesive choice. Cohesive failure is the internal failure of either the adhesive or, rarely, one of the adherends. 

Heat exchangers and similar vessels shall be protected with a relieving device of sufficient capacity to avoid overpressure in the case of an internal failure. 

The FDA is hampered not only by its own internal failures, but also by its reliance on the potentially fraudulent activities of the pharmaceutical companies in developing and marketing their products. Because the FDA never evaluates the primary data generated by the drug companies,... 

What gets measured gets done. The health of the quality system and the effectiveness of the quality plan need to be monitored. Therefore selecting the right set of quality metrics is important.Traditionally quality costs are broken down into preventive, appraisal, internal failure, and external failure costs. A commonly used indirect measure of internal failure costs is not-right-first time. Cycle time is another useful indirect measure of quality. Process quality can be measured. Processes can be rated on a 1-5 scale where ... 

Cost must be understood in the context of quahty. If quahty means conformance to requirements, then quality costs must be understood in terms of costs of conformance and costs of nonconformance, , as illustrated in Figure 19-1. In industrial terms, costs of conformance are divided into prevention costs and appraisal costs. Costs of nonconformance consist of internal and external failure costs. For a laboratory testing process, calibration is a good example of a cost incurred to prevent problems. Lhcewise, quality control is a cost for appraising performance, a repeat run is an internal failure cost for poor analytical performance, and repeat requests for tests because of poor analytical quality are an external failure cost. 

Prevention costs Appraisal costs Internal failure costs External failure costs... 

A quantitative risk assessment (QRA) is an integrated, quantitative analysis (including uncertainty) of accident scenarios, their likelihood, and possible consequences. Current QRAs examine human actions as well as systems failures, external events as well as internal failures, and worker risk as well as public risk. A salient feature of a QRA is that it is integrated, in that it ... 

In composite propellants, a relatively strong bond between binder and filler is important for obtaining high tensile strength. However, the edges and surfaces of the inclusions serve as sites of dangerously high stress concentrations, which could cause internal failure of the softer matrix material. Most studies (I, 2, 6-9) have dealt with the problem of matrix fracture induced by the inclusions. Here, we present the mode of matrix fracture called cavitation,... 

Internal failures must be thrown out or recycled. These should all be detected in products where a batch can be sampled and tested. External failures are much more serious and costly, although it is not always easy to quantify the cost. In the case of a "normal" product, the customer will return it. If he is really unhappy he will not buy it again. If a batch of medicine is faulty, the F.D.A. (to name but one national authority) may recall it. If the agency is really unhappy about the company s structures, procedures, and methods, it may well take stronger action. 

Internal failure Disposal of defective materials and/or equipment Extra training costs Repeat analysis Time spent on internal investigation Time/revenue lost because of interruption of sample diroughput... 

Internal failure costs are incnrred to discover and remedy unacceptable data before they leave the laboratory. 

The ultimate consequence of this approach is that quality improvement wUl lead to cost reduction (Crosby 1979 Garvin 1984b), which is achieved by lowering internal failure costs (e.g., scrap, rework, and spoilage) and external failure costs (e.g., warranty costs, complaint adjustments, service calls, and loss of goodwill and future sales) through prevention and inspection. 

Line Pulls and Associated Failures. If an internal failure occurs, the line is stopped and the problem is resolved. This causes downtime and associated problems with getting the correct parts or correcting the problems that have been encountered. 

The simulated crushing response of the EA web segment is shown in Figure 10.10. It should be noted that the model is shown with the upper plate removed to allow the internal failure mode to be observed. The corrugated core exhibited a failure mode similar to that observed for hat-shaped crush elements tested in [43] where the two C-sections splayed out from the corrugated core as the crush element progressively failed. A comparison of the experimental and predicted load—displacement response... 

Problem A set of non-redundant (loot) equipment is used to implement a safety instrumented function. Within the equipment, automatic diagnostics complete execution every one second. The instrument is programmed to take the process to a safe state when an internal failure of the equipment is detected. A dangerous condition occurs every one minute on average. What is the mode of operation and can the automatic diagnostics be given credit in the probability of failure calculation ... 

Many companies have an internal expert who has studied these sources, as well as their own internal failure records, and maintains the company failure rate database. Some use failure data compilations found on the Internet. While the data in industry databases is not product specific or application specific, it does provide useful failure rate information for specific industries (nuclear, offshore, etc.) and a comparison of the data provides information about failure rates versus stress factors. 

Figure 9-2. Current Levels used to Indicate Internal Failure in Transmitters...

The Micro-Motion 1700/2700 Coriolis flowmeter (Figure 9-12) received its lEC 61508 assessment in 2005. The basic technology is frequency based providing high inherent safety as most internal failures wiU result in lack of frequency and are therefore detectable by the transmitter. 

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