Abstract
Planning is a process which leads from acquired knowledge to new knowledge. Unknown materials, models, environments etc. can generate abnormal operating conditions with the risk of damage. Designers have a number of tools to protect themselves from this eventuality. The first concept that was introduced to guarantee the safety of a project is the safety factor. In general terms, a system has a safety factor when the collapse is expected with conditions markedly more rigorous than those provided as design requirements. However, in a vision closer to reality, the most correct way of addressing the problem consists in recognizing the probabilistic nature of each process in use of a product, involving not only artificial, but also human actions. Every product/service is naturally subjected to failures, but more than failure in itself, are the effects of a failure that give significance to the failure. Then not only the nominal functions (with no failures) but also the functions consequently to a failure must be considered as possible system’s operating conditions. In an initial presentation there will be set forth some basic concepts of system reliability as the probability of no failures, along with the tools most commonly used, such as FMEA which, by virtue of their semi-scientific content, take into account variables not necessarily “measurable” but, nevertheless, lead to a significant reduction of the risk associated with a “failure”.
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Notes
- 1.
In practical applications we must consider only the case of values of stress and strength far from the respective mean values.
- 2.
The demonstration in the following steps:
$$\begin{aligned} MTTF=-\int _0^\infty {t{{d R}\over {d t}}{d t}}=-[tR]_0^\infty + \int _0^\infty {R(t)d t}=\int _0^\infty {R(t)d t} \end{aligned}$$(5.9)The previous demonstration is valid only for \(E[\tau ]<\infty \). See a discussion on this point in Example A 6.9 of [3].
- 3.
We emphasize that the word “Concept”, used in Product development phase [4] as a clear, detailed description of the attributes and benefits of a new product that addresses the needs of the targeted customers.
- 4.
The functions of the item can be identified by a QFD analysis, that must also include anomalous operational conditions.
- 5.
Potential failures modes are due to faults in components.
- 6.
This small team is a group of people with a full set of complementary skills required to complete a task, job, or project. Team members (1) operate with a high degree of interdependence, (2) share authority and responsibility for self-management, (3) are accountable for the collective performance, and (4) work toward a common goal. A team becomes more than just a collection of people when a strong sense of mutual commitment creates synergy, thus generating performance greater than the sum of the performance of its individual members [5].
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Freddi, A., Salmon, M. (2019). Safety Assessment. In: Design Principles and Methodologies. Springer Tracts in Mechanical Engineering. Springer, Cham. https://doi.org/10.1007/978-3-319-95342-7_5
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