Fail-Safe and Safe-Life Concepts Effects on the Safety Factor in Mechanical Design

2021 ◽  
pp. 1-6
Author(s):  
Sergio Baragetti
Keyword(s):  
Safety Factor ◽  
Mechanical Design ◽  
Safe Life ◽  
Fail Safe

Fail‐Safe vs. Safe‐Life Philosophy in V/STOL Design

1969 ◽  
Vol 14 (4) ◽  
pp. 2-9 ◽  
Author(s):  
Fred H. Immen
Keyword(s):  
Structural Features ◽  
Tilt Rotor ◽  
Safe Life ◽  
Design Engineers ◽  
Rational Combination ◽  
Life Philosophy ◽  
Fail Safe ◽  
Rotary Wing ◽  
Life Design ◽  
Rigid Wing

V/STOL aircraft combine the technological features of rigid‐wing and rotary‐wing aircraft, incorporating many of the structural features of helicopters. A review indicates that structures analysts of conventional aircraft have concentrated on fail‐safe design; while helicopter design engineers have generally been content to rely on component safe‐life design. The two philosophies are examined and an approach to the rational marriage of helicopter and airplane fatigue technologies is suggested, in order to provide an integrated, economically feasible, statistically rational combination of fail‐safe and safe‐life methodology for tilt‐wing and tilt‐rotor V/STOL aircraft.

Paper 33: The Choice of Fail Safe and Safe Life Fatigue Philosophies in Aircraft Design

1969 ◽  
Vol 184 (2) ◽  
pp. 238-261 ◽  
Author(s):  
A. P. Ward ◽  
H. E. Parish
Keyword(s):  
Fracture Mechanics ◽  
Crack Propagation ◽  
Design Process ◽  
Aircraft Design ◽  
Weight Basis ◽  
Safe Life ◽  
Fatigue Design ◽  
Fail Safe ◽  
Alternative Designs

This paper considers the current fatigue design process and the means of establishing safe lives. The alternative philosophies are discussed together with the required scatter factors. Methods of achieving fail safe designs and the application of crack propagation data are reviewed. Also, since some fatigue designed members will be loaded in a cracked or flawed condition, the theory of fracture mechanics is mentioned. Finally, alternative designs are compared on a weight basis, these leading to different conclusions, depending on the particular function of the structure.

A New Approach to Finding a Risk-Informed Safety Factor for “Fail-Safe” Pressure Vessel and Piping Design

2015 ◽  
Vol 750 ◽  
pp. 3-23
Author(s):  
Jeffrey T. Fong ◽  
N. Alan Heckert ◽  
James J. Filliben ◽  
Pedro V. Marcal ◽  
Stephen W. Freiman
Keyword(s):  
Fatigue Life ◽  
Safety Factor ◽  
Bootstrap Method ◽  
Glass Ceramics ◽  
High Strength ◽  
Engineering System ◽  
New Approach ◽  
Fatigue Life Estimation ◽  
Fail Safe ◽  
The Bootstrap Method

The purpose of this paper is to present a new approach to finding a risk-informed safety factor for the “fail-safe” design of a high-consequence engineering system. The new approach is based on the assumption of a 99.99 % confidence level and a 99.99 % coverage, and the application of the classical theory of tolerance limits, error propagation, and a method of statistical model parameter estimation known as the bootstrap method. To illustrate this new approach, we first apply the methodology to theUTSdata of six materials ranging from glass, ceramics, to a high-strength steel at both 20 C and 600 C, and then to the fatigue life estimation of a BK-7 glass using two available additional sets of laboratory test data. Significance and limitations of our new approach to the “fail-safe”UTSdesign and fatigue life prediction of an aging PVP or aircraft are presented and discussed.

scholarly journals Determining the endurance limit of AISI 4340 steels in terms of different statistical approaches

2021 ◽  
Vol 15 (58) ◽  
pp. 344-364
Author(s):  
Salim Çalışkan ◽  
Rıza Gürbüz
Keyword(s):  
Fatigue Limit ◽  
Curve Fitting ◽  
Endurance Limit ◽  
Load Path ◽  
Confidence Levels ◽  
Safe Life ◽  
In The Beginning ◽  
Fail Safe ◽  
Damage Tolerant ◽  
Aisi 4340

In engineering applications, fatigue phenomenon is a key issue and needs to be analyzed in the beginning of design phase in case of any component exposed to alternating loading on operation otherwise catastrophic fatigue failure may cause. Component can be designed with safe-life, fail-safe, and damage tolerant approach based on whether redundant load path and damage sensitive. Before starting analyzing the structure, material allowable data needs to be presented in a reliable way to predict fatigue life of components. SN curves with presented confidence levels are the robust approach to make a prediction on safe life of a structure in terms of fatigue. In this point, there are so many approaches to determine fatigue limit of materials and issue shall be handled by statistical manner. In literature, different staircase and curve fitting methods were presented to estimate endurance limit of materials and some reliability manuscript published. In this paper, fatigue limit of AISI 4340 steel will be investigated through most convinced staircase and curve fitting approaches and their reliability will be queried.

Designing Safe-Life and Fail-Safe Facade Systems

2014 ◽  
Vol 875-877 ◽  
pp. 934-939
Author(s):  
Michele di Sivo ◽  
Daniela Ladiana
Keyword(s):  
Implementation Process ◽  
Dynamic Loads ◽  
Mechanical Resistance ◽  
Critical Elements ◽  
Safe Life ◽  
Production Processes ◽  
Stone Materials ◽  
Static And Dynamic Loads ◽  
Fail Safe ◽  
Over Time

Safety in façade systems realized with stone materials is linked to a multitude of factors, as regards the stone materials, such as: mechanical resistance values, behavior in specific environmental conditions, inner stress related to applied static and dynamic loads; as concerns the implementation process, in order to achieve safety the following specific aspects emerge: the production processes carried out to realize the elements, the quality in projecting anchorage systems and the modes of material placing. In order to define and maintain over time the desired safety levels, it is important activate a process aiming at controlling the above mentioned factors by carefully determining morphologies and dimensional characteristics, techniques of production and realization of coating and anchorage components so that slab shedding is avoided. In the text, the phases and the critical elements of such process are detected in order to define a safe-life or fail-safe façade system.

scholarly journals Autonomous Driving – How to Apply Safety Principles

Dependability ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 21-33
Author(s):  
H. Schӓbe
Keyword(s):  
Autonomous Driving ◽  
Automated Driving ◽  
Safety Standards ◽  
The Road ◽  
Safe Life ◽  
Level Of Automation ◽  
Human Driver ◽  
On The Road ◽  
Fail Safe ◽  
Automatic Systems

We discuss safety principles of autonomous driving road vehicles. First, we provide a comparison between principles and experience of autonomous or automatic systems on rails and on the road. An automatic metro operates in a controlled and well-defined environment, passengers and third persons are separated from driving trains by fences, tunnels, etc. A road vehicle operates in a much more complex environment. Further, we discuss safety principles. The application of safety principles (e.g. fail-safe or safe-life) is used to design and implement a safe system that eventually fulfils the requirements of the functional safety standards. The different responsibility of human driver and technical driving system in different automation levels for autonomous driving vehicles require the application of safety principles. We consider, which safety principles have to be applied using general safety principles and analysing the relevant SAE level based on the experience from projects for the five levels of automated driving as defined by the SAE. Depending on the level of automation, the technical systems are implemented as fail-silent, fails-safe or as safe-life.

The new CM-Series TEMs: integration of a five-axis motorized, fully computer-controlled goniometer

1993 ◽  
Vol 51 ◽  
pp. 258-259
Author(s):  
Marc J.C. de Jong ◽  
P. Emile S.J. Asselbergs ◽  
Max T. Otten
Keyword(s):  
Mechanical Design ◽  
Computer Control ◽  
Objective Lens ◽  
Access Port ◽  
Vibration Stability ◽  
Transmission Electron ◽  
Computer Controlled ◽  
High Degree ◽  
Five Axis ◽  
Five Axes

A new step forward in Transmission Electron Microscopy has been made with the introduction of the CompuStage on the CM-series TEMs: CM120, CM200, CM200 FEG and CM300. This new goniometer has motorization on five axes (X, Y, Z, α, β), all under full computer control by a dedicated microprocessor that is in communication with the main CM processor. Positions on all five axes are read out directly - not via a system counting motor revolutions - thereby providing a high degree of accuracy. The CompuStage enters the octagonal block around the specimen through a single port, allowing the specimen stage to float freely in the vacuum between the objective-lens pole pieces, thereby improving vibration stability and freeing up one access port. Improvements in the mechanical design ensure higher stability with regard to vibration and drift. During stage movement the holder O-ring no longer slides, providing higher drift stability and positioning accuracy as well as better vacuum.

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