scholarly journals fmdtools: A Fault Propagation Toolkit for Resilience Assessment in Early Design

2020 ◽  
Author(s):  
Daniel Hulse ◽  
Hannah Walsh ◽  
Andy Dong ◽  
Christopher Hoyle ◽  
Irem Tumer ◽  
...  
Keyword(s):  
Hazard Analysis ◽  
Early Design ◽  
Reliability Based Design ◽  
Complex Engineered Systems ◽  
Fault Modelling ◽  
Aerospace Systems ◽  
Engineered Systems ◽  
Recovery Schemes ◽  
Analysis Environment

Incorporating resilience in design is important for the long-term viability of complex engineered systems. Complex aerospace systems, for example, must ensure safety in the event of hazards resulting from part failures and external circumstances while maintaining efficient operations. Traditionally, mitigating hazards in early design has involved experts manually creating hazard analyses in a time-consuming process that hinders one's ability to compare designs. Furthermore, as opposed to reliability-based design, resilience-based design requires using models to determine the dynamic effects of faults to compare recovery schemes. Models also provide design opportunities, since models can be parameterized and optimized and because the resulting hazard analyses can be updated iteratively. While many analysis frameworks have been presented for early hazard assessment, these frameworks are difficult to apply without reference implementations, and most currently-available fault modelling tools are meant for the later stages of design. This paper describes fmdtools, a Python-based resilience-based design and analysis environment that solves these problems by enabling the designer to represent the system in the early design process, simulate the effects of faults, and quantify corresponding resilience metrics. This toolkit is then demonstrated in the hazard analysis and architecture design of a multi-rotor drone.

scholarly journals Fmdtools

2021 ◽  
Vol 12 (3) ◽  
Author(s):  
Daniel Hulse ◽  
Hannah Walsh ◽  
Andy Dong ◽  
Christopher Hoyle ◽  
Irem Tumer ◽  
...  
Keyword(s):  
Hazard Analysis ◽  
Theoretical Frameworks ◽  
Early Design ◽  
Reliability Based Design ◽  
Complex Engineered Systems ◽  
Aerospace Systems ◽  
Engineered Systems ◽  
Recovery Schemes ◽  
Early Phases

Incorporating resilience in design is important for the long-term viability of complex engineered systems. Complex aerospace systems, for example, must ensure safety in the event of hazards resulting from part failures and external circumstances while maintaining efficient operations. Traditionally, mitigating hazards in early design has involved experts manually creating hazard analyses in a time-consuming process that hinders one’s ability to compare designs. Furthermore, as opposed to reliability-based design, resilience-based design requires using models to determine the dynamic effects of faults to compare recovery schemes. Models also provide design opportunities, since models can be parameterized and optimized and because the resulting hazard analyses can be updated iteratively. While many theoretical frameworks have been presented for early hazard assessment, most currently-available modelling tools are meant for the later stages of design. Given the wide adoption of Python in the broader research community, there is an opportunity to create an environment for researchers to study the resilience of different PHM technologies in the early phases of design. This paper describes fmdtools, an attempt to realize this opportunity with a set of modules which may be used to construct different design models, simulate system behaviors over a set of fault scenarios and analyze the resilience of the resulting simulation results. This approach is demonstrated in the hazard analysis and architecture design of a multi-rotor drone, showing how the toolkit enables a large number of analyses to be performed on a relatively simple model as it progresses through the early design process.

scholarly journals Automated Generation of Fault Scenarios to Assess Potential Human Errors and Functional Failures in Early Design Stages

2020 ◽  
Vol 20 (5) ◽  
Author(s):  
Lukman Irshad ◽  
H. Onan Demirel ◽  
Irem Y. Tumer
Keyword(s):  
Human Error ◽  
Human Action ◽  
Time Step ◽  
Critical Function ◽  
Human Errors ◽  
Early Design ◽  
Complex Engineered Systems ◽  
Early Design Stages ◽  
Engineered Systems ◽  
Improved Performance

Abstract Human errors are attributed to a majority of accidents and malfunctions in complex engineered systems. The human error and functional failure reasoning (HEFFR) framework was developed to assess potential functional failures, human errors, and their propagation paths during early design stages so that more reliable systems with improved performance and safety can be designed. In order to perform a comprehensive analysis using this framework, a wide array of potential failure scenarios need to be tested. Coming up with such use cases that can cover a majority of faults can be challenging for engineers. This research aims overcome this limitation by creating a use case generation technique that covers both component- and human-related fault scenarios. The proposed technique is a time-based simulation that employs a modified depth first search (DFS) to simulate events as the event propagation is analyzed using HEFFR at each time-step. The results show that the proposed approach is capable of generating a wide variety of fault scenarios involving humans and components. Out of the 15.4 million scenarios that were found to violate the critical function, two had purely human-induced faults, 163,204 had purely non-human-induced faults, and the rest had a combination of both. The results also show that the framework was able to uncover hard-to-detect scenarios such as scenarios with human errors that do not propagate to affect the system. In fact, 86% of all human action combinations with nominal human-induced component behaviors had underlying human errors.

Designing in Excess Capability to Handle Uncertain Product Requirements in a Developing World Setting

2016 ◽  
Author(s):  
Jeffrey D. Allen ◽  
Christopher A. Mattson ◽  
Kendall Thacker
Keyword(s):  
Service Life ◽  
Communication Systems ◽  
Developing World ◽  
User Requirements ◽  
Space Craft ◽  
Original Design ◽  
Complex Engineered Systems ◽  
The World ◽  
Engineered Systems

Products designed for the developing world often go unused or under used by the intended individuals. Designers with experience in developed areas of the world naturally apply their values to the products they design. This results in a misjudgment of the actual requirements of individuals in developing areas. When the products do not have the ability to adapt to the actual user requirements, long-term adoption is not achieved. The ability of a product to adapt to new or changing requirements has been shown to extend the service life of large complex engineered systems (e.g., aircraft carriers, aircraft, communication systems, and space craft). These systems must remain in service for extended periods of time, even though the environments and requirements may change dramatically. The ability of these complex systems to adapt to meet these new requirements is a valuable attribute. Applying these proven techniques to products designed for the developing world can address the issue of misunderstood requirements. Adaptability is achieved, in this paper, by incorporating appropriate excess capabilities into the original design. These excess capabilities can be identified and analyzed using a numerical search methodology. This paper presents a methodology for increasing the adaptability, and therefore adoptability of products designed for the developing world by incorporating strategically determined excess capabilities.

Model Validation in Early Phase of Designing Complex Engineered Systems

2018 ◽  
Author(s):  
Elham Keshavarzi ◽  
Kai Goebel ◽  
Irem Y. Tumer ◽  
Christopher Hoyle
Keyword(s):  
Model Simulation ◽  
Early Stage ◽  
Design Stage ◽  
Early Design ◽  
The Real ◽  
Early Design Stage ◽  
Complex Engineered Systems ◽  
Search Tool ◽  
Engineered Systems

In design process of a complex engineered system, studying the behavior of the system prior to manufacturing plays a key role to reduce cost of design and enhance the efficiency of the system during its lifecycle. To study the behavior of the system in the early design phase, it is required to model the characterization of the system and simulate the system’s behavior. The challenge is the fact that in early design stage, there is no or little information from the real system’s behavior, therefore there is not enough data to use to validate the model simulation and make sure that the model is representing the real system’s behavior appropriately. In this paper, we address this issue and propose methods to validate the model developed in the early design stage. First we propose a method based on FMEA and show how to quantify expert’s knowledge and validate the model simulation in the early design stage. Then, we propose a non-parametric technique to test if the observed behavior of one or more subsystems which currently exist, and the model simulation are the same. In addition, a local sensitivity analysis search tool is developed that helps the designers to focus on sensitive parts of the system in further design stages, particularly when mapping the conceptual model to a component model. We apply the proposed methods to validate the output of failure simulation developed in the early stage of designing a monopropellant propulsion system design.

scholarly journals Forensic Engineering Use Of Fault Tree Analysis

2006 ◽  
Vol 23 (2) ◽  
Author(s):  
Frank H. Johnson ◽  
DeWitt William E.
Keyword(s):  
Fault Tree ◽  
Fault Tree Analysis ◽  
Tree Analysis ◽  
Complex Engineered Systems ◽  
Track Record ◽  
Forensic Engineering ◽  
Fire And Explosion ◽  
Engineered Systems ◽  
Analytical Tools

Analytical Tools, Like Fault Tree Analysis, Have A Proven Track Record In The Aviation And Nuclear Industries. A Positive Tree Is Used To Insure That A Complex Engineered System Operates Correctly. A Negative Tree (Or Fault Tree) Is Used To Investigate Failures Of Complex Engineered Systems. Boeings Use Of Fault Tree Analysis To Investigate The Apollo Launch Pad Fire In 1967 Brought National Attention To The Technique. The 2002 Edition Of Nfpa 921, Guide For Fire And Explosion Investigations, Contains A New Chapter Entitled Failure Analysis And Analytical Tools. That Chapter Addresses Fault Tree Analysis With Respect To Fire And Explosion Investigation. This Paper Will Review The Fundamentals Of Fault Tree Analysis, List Recent Peer Reviewed Papers About The Forensic Engineering Use Of Fault Tree Analysis, Present A Relevant Forensic Engineering Case Study, And Conclude With The Results Of A Recent University Study On The Subject.

Uniform asymptotic stability, an initial treatment

2012 ◽  
Author(s):  
Rafal Goebel ◽  
Ricardo G. Sanfelice ◽  
Andrew R. Teel
Keyword(s):  
Asymptotic Stability ◽  
Equilibrium Point ◽  
Single Point ◽  
Fundamental Property ◽  
Uniform Asymptotic Stability ◽  
Closed Set ◽  
Long Term Trends ◽  
Engineered Systems

This chapter focuses on the uniform asymptotic stability of a closed set. Asymptotic stability is a fundamental property of dynamical systems—one that is usually desired in natural and engineered systems. It provides qualitative information about solutions, especially a characterization of the solutions' long-term trends. The asymptotic stability of a closed set, rather than of an equilibrium point, is significant since the solutions of a hybrid system often do not settle down to an equilibrium point. Furthermore, the asymptotic stability of an equilibrium point is a special case of asymptotic stability of a closed set. Namely, an equilibrium point is a closed set containing a single point.

scholarly journals Design of Complex Engineered Systems

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Christina L. Bloebaum ◽  
Anna-Maria R. McGowan
Keyword(s):  
Complex Engineered Systems ◽  
Engineered Systems

Quantifying the Resilience-Informed Scenario Cost Sum: A Value-Driven Design Approach for Functional Hazard Assessment

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Daniel Hulse ◽  
Christopher Hoyle ◽  
Kai Goebel ◽  
Irem Y. Tumer
Keyword(s):  
Functional Model ◽  
Scoring Function ◽  
Modeling Languages ◽  
Concept Selection ◽  
Complex Engineered Systems ◽  
Propagation Behavior ◽  
Engineered Systems ◽  
Selection Framework ◽  
And Function ◽  
Probability Information

Complex engineered systems can carry risk of high failure consequences, and as a result, resilience—the ability to avoid or quickly recover from faults—is desirable. Ideally, resilience should be designed-in as early in the design process as possible so that designers can best leverage the ability to explore the design space. Toward this end, previous work has developed functional modeling languages which represent the functions which must be performed by a system and function-based fault modeling frameworks have been developed to predict the resulting fault propagation behavior of a given functional model. However, little has been done to formally optimize or compare designs based on these predictions, partially because the effects of these models have not been quantified into an objective function to optimize. The work described herein closes this gap by introducing the resilience-informed scenario cost sum (RISCS), a scoring function which integrates with a fault scenario-based simulation, to enable the optimization and evaluation of functional model resilience. The scoring function accomplishes this by quantifying the expected cost of a design's fault response using probability information, and combining this cost with design and operational costs such that it may be parameterized in terms of designer-specified resilient features. The usefulness and limitations of using this approach in a general optimization and concept selection framework are discussed in general, and demonstrated on a monopropellant system design problem. Using RISCS as an objective for optimization, the algorithm selects the set of resilient features which provides the optimal trade-off between design cost and risk. For concept selection, RISCS is used to judge whether resilient concept variants justify their design costs and make direct comparisons between different model structures.

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