Uncertainty Topics for Engineering Design Courses

2016 ◽  
Author(s):  
Xiaoping Du
Keyword(s):  
Six Sigma ◽  
System Reliability ◽  
Failure Modes ◽  
Design Stage ◽  
Early Design Stage ◽  
Design For Six Sigma ◽  
Reliability Based Design ◽  
Potential Failure ◽  
Engineering Practices ◽  
Related Design

Uncertainty commonly exists in engineering applications, especially in a design process. Quantifying and managing uncertainty is often a core consideration during the design stage. Due to its importance in engineering practices, uncertainty is gradually introduced and taught in a number of engineering courses. Uncertainty topics, however, are still limited and the teaching materials on uncertainty are still currently lacking. This paper focuses on possible topics that could be introduced in various engineering courses, particularly in design courses. The topics cover the following aspects: identify and take actions on potential failure modes, account for system reliability in the early design stage, quantify the effect of uncertainty, and mitigate the effect of uncertainty in latter design stages. This paper also introduces basics of related design methodologies, such as reliability-based design, robust design, and design for six sigma in order for interested educators to develop familiarity of uncertainty. This paper also reports the implementation and experience of uncertainty education at the Missouri University of Science and Technology.

Function-Based Design of a Spacecraft Power System Diagnostics Testbed

2005 ◽  
Author(s):  
Ryan S. Hutcheson ◽  
Irem Y. Tumer
Keyword(s):  
Power System ◽  
Conceptual Design ◽  
Failure Modes ◽  
Fault Injection ◽  
Design Stage ◽  
Design Phase ◽  
Internal Fault ◽  
Conceptual Design Phase ◽  
Potential Failure ◽  
External Faults

NASA’s Ames Research center is currently designing a testbed to validate and compare potential Integrated System Health Management (ISHM) technologies. The proposed testbed represents a typical power system for a spacecraft and includes components such as a fuel cell, solar cells and redundant batteries. To fulfill design requirements, the testbed must be capable of hosting a wide variety of ISHM technologies including those developed by NASA as well as those developed in the aerospace industry abroad. An internal fault injection subsystem must be built into the system to provide a common interface for evaluating these different ISHM technologies. Additionally, to ensure robust operation of the testbed, the capability to detect and manage external faults must also be present. In order to develop a set of requirements for the internal fault injection subsystems as well as predict external faults, a comprehensive set of potential failures must be identified for all of the components of the testbed. To best aid the development of the testbed, these failures needed to be identified as early as the conceptual design phase, where little is known about the actual components that would comprise the finished system. This paper demonstrates the use a function-based failure mode identification method to identify the potential failures of the testbed during the conceptual design phase. Using this approach, designers can explore the potential failure modes at the functional design stage, before a form or solution has been determined. A function-failure database is used to associate the failures of components from previous design efforts to the testbed based on common functionality. The result is a list of potential failure modes and associated failure rates, which are used to improve the design of the testbed as well as provide a framework for the fault injection subsystem.

System Reliability Analysis With Dependent Component Failures During Early Design Stage—A Feasibility Study

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Yao Cheng ◽  
Xiaoping Du
Keyword(s):  
System Reliability ◽  
Reliability Prediction ◽  
Design Stage ◽  
Early Design ◽  
Early Design Stage ◽  
Design Concepts ◽  
Reliability Bounds ◽  
Lack Of Information ◽  
Dependent Component ◽  
Component Failures

It is desirable to predict product reliability accurately in the early design stage, but the lack of information usually leads to the use of independent component failure assumption. This assumption makes the system reliability prediction much easier, but may produce large errors since component failures are usually dependent after the components are put into use within a mechanical system. The bounds of the system reliability can be estimated, but are usually wide. The wide reliability bounds make it difficult to make decisions in evaluating and selecting design concepts, during the early design stage. This work demonstrates the feasibility of considering dependent component failures during the early design stage with a new methodology that makes the system reliability bounds much narrower. The following situation is addressed: the reliability of each component and the distribution of its load are known, but the dependence between component failures is unknown. With a physics-based approach, an optimization model is established so that narrow bounds of the system reliability can be generated. Three examples demonstrate that it is possible to produce narrower system reliability bounds than the traditional reliability bounds, thereby better assisting decision making during the early design stage.

Link Between Function-Flow Failure Rates and Failure Modes for Early Design Stage Reliability Analysis

2011 ◽  
Author(s):  
Bryan M. O’Halloran ◽  
Robert B. Stone ◽  
Irem Y. Tumer
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Design Method ◽  
Design Stage ◽  
Failure Rates ◽  
High Likelihood ◽  
Functional Failure ◽  
Early Design Stage ◽  
Flow Failure ◽  
Rate Design

This scope of this paper is to provide an extension to the Function Failure Design Method (FFDM). We first implement a more robust knowledge base using Failure Mode/Mechanism Distributions 1997 (FMD-97). Then failure rates from Nonelectric Parts Reliability Data (NPRD-95) are added to more effectively determine the likelihood that a failure mode will occur. The proposed Functional Failure Rate Design Method (FFRDM) uses functional inputs to effectively offer recommendations to mitigate failure modes that have a high likelihood of occurrence. This work uses a past example where FFDM and Failure Modes and Effects Analysis (FMEA) were compared to show that improvements have been made. A four step process is presented to show how the FFRDM is used during conceptual design.

Failure Evaluation and Analysis of Mechatronics-Based Production Systems during Design Stage Using Structural Modeling

2016 ◽  
Vol 852 ◽  
pp. 799-805 ◽  
Author(s):  
M.K. Loganathan ◽  
Priyom Goswami ◽  
Bedabrat Bhagawati
Keyword(s):  
System Reliability ◽  
Failure Modes ◽  
Production Systems ◽  
System Structure ◽  
Design Stage ◽  
Structure Modeling ◽  
Effective Manner ◽  
Digraph Model ◽  
Probable Failure ◽  
Failure Evaluation

A method based on structural modelling is developed for failure evaluation and analysis of mechatronics-based production systems. Majority of the elements in production systems are mechatronics-based, which includes various elements such as; electrical, electronic and mechanical. Each of these may have different failure types that may be interdependence/interactive. The reliability of the system mainly depends on how well the failures are taken care of during design stage. In general, individual failures are generalized into probable failure modes and early identification of these helps to reduce their probability. However, consideration of failures and their interdependence / interactions will help to evaluate and analyse the failures of complicated systems in an efficient and effective manner and increase the inherent system reliability. The system structure modeling helps in this regard. Digraph model, in conjunction with matrix method, is employed for failure evaluation and analysis of a mechatronics-based production system based on its structure.

Resilience Allocation for Early Stage Design of Complex Engineered Systems

2016 ◽  
Vol 138 (9) ◽  
Author(s):  
Nita Yodo ◽  
Pingfeng Wang
Keyword(s):  
Distribution System ◽  
Failure Modes ◽  
Early Stage ◽  
Design Stage ◽  
Early Design ◽  
Early Design Stage ◽  
Complex Engineered Systems ◽  
Operating Environments ◽  
Early Stage Design ◽  
Critical Components

The continuous pursuits of developing a better, safer, and more sustainable system have pushed systems to grow in complexity. As complexity increases, challenges consequently arise for system designers in the early design stage to take account of all potential failure modes in order to avoid future catastrophic failures. This paper presents a resilience allocation framework for resilience analysis in the early design stage of complex engineering systems. Resilience engineering is a proactive engineering discipline that focuses on ensuring the performance success of a system by adapting to changes and recovering from failures under uncertain operating environments. Utilizing the Bayesian network (BN) approach, the resilience of a system could be analyzed and measured quantitatively in a probabilistic manner. In order to ensure that the resilience of a complex system satisfies the target resilience level, it is essential to identify critical components that play a key role in shaping the top-level system resilience. Through proper allocation of resilience attributes to these critical components, not only target could resilience requirements be fulfilled, global cascading catastrophic failure effects could also be minimized. An electrical distribution system case study was used to demonstrate the developed approach, which can also be used as a fundamental methodology to quantitatively evaluate resilience of engineered complex systems.

scholarly journals Set Theoretical Variants of Optimization Algorithms for System Reliability-based Design of Truss Structures

2021 ◽  
Author(s):  
Ali Kaveh ◽  
Kiarash Biabani Hamedani ◽  
Mohammad Kamalinejad
Keyword(s):  
Design Optimization ◽  
System Reliability ◽  
Failure Modes ◽  
Optimization Problems ◽  
Optimization Algorithms ◽  
System Level ◽  
Truss Structures ◽  
Jaya Algorithm ◽  
Reliability Based Design Optimization ◽  
Reliability Based Design

In this paper, recently developed set theoretical variants of the teaching-learning-based optimization (TLBO) algorithm and the shuffled shepherd optimization algorithm (SSOA) are employed for system reliability-based design optimization (SRBDO) of truss structures. The set theoretical variants are designed based on a simple framework in which the population of candidate solutions is divided into some number of smaller well-arranged sub-populations. In addition, the framework is applied to the Jaya algorithm, leading to a set-theoretical variant of the Jaya algorithm. So far, most of the reliability-based design optimization studies have focused on the reliability of single structural members. This is due to the fact that the optimization problems with system reliability-based constraints are computationally expensive to solve. This is especially the case of statically redundant structures, where the number of failure modes is so high that it is impractical to identify all of them. System-level reliability analysis of truss structures is carried out by the branch and bound method by which the stochastically dominant failure paths are identified within a reasonable time. At last, three numerical examples, including size optimization of truss structures, are presented to illustrate the effectiveness of the proposed SRBDO approach. The results indicate the efficiency and applicability of the set theoretical optimization algorithms to solve the SRBDO problems of truss structures.

scholarly journals Failure Modes and Effects Analysis (FMEA) for evaluation of a sugarcane machine failure

2018 ◽  
Vol 204 ◽  
pp. 01012
Author(s):  
Hilma Raimona Zadry ◽  
Dendi Adi Saputra ◽  
Agung Budiman Tabri ◽  
Difana Meilani ◽  
Dina Rahmayanti
Keyword(s):  
Failure Modes ◽  
Design Stage ◽  
Preliminary Treatment ◽  
Risk Priority Number ◽  
Ergonomic Design ◽  
Machine Maintenance ◽  
Machine Failure ◽  
Potential Failure ◽  
Fmea Method ◽  
Causes Of Failure

The Failure Modes and Effects Analysis (FMEA) method has been widely recognized as a tool that systematically identifies the consequences and failures of the system or process, and reduces or eliminates the chances of the failure. This study applies that method to evaluate the causes of failure in the use of sugarcane machine that have been designed in the previous studies. FMEA approach anticipated the failures at the design stage, so that a more reliable and ergonomic design can be produced for future sugarcane machine. The potential failure identified from the machine consists of capacity issues, machine maintenance, preliminary treatment, and procedures of use. The study found that capacity issues are the priority problems that cause the machine failure. Then, this study proposed some actions to reduce the risk priority number (RPN) on 12 failures.

A Clustering-Based Approach for Failure Mode Identification

2002 ◽  
Author(s):  
Srikesh G. Arunajadai ◽  
Robert B. Stone ◽  
Irem Y. Tumer
Keyword(s):  
Quality Control ◽  
Failure Modes ◽  
Functional Approach ◽  
Product Launch ◽  
Design Stage ◽  
Mode Identification ◽  
Detail Design ◽  
Potential Failure ◽  
Failure Mode Identification ◽  
Statistical Clustering

Research has shown that nearly 80% of the costs and problems are created in product development and that cost and quality are essentially designed into products in the conceptual stage. Currently failure identification procedures (such as FMEA, FMECA and FTA) and design of experiments are being used for quality control and for the detection of potential failure modes during the detail design stage or post-product launch. Though all of these methods have their own advantages, they do not give information as to what are the predominant failures that a designer should focus on while designing a product. This work uses a functional approach to identify failure modes, which hypothesizes that similarities exist between different failure modes based on the functionality of the product/component. In this paper, a statistical clustering procedure is proposed to retrieve information on the set of predominant failures that a function experiences. The various stages of the methodology are illustrated using a hypothetical design example.

Enhancement of Safety and Design in Cargo Handling Spaces to Prevent Accidental Fire or Explosion in Oil Tankers and FPSOs

2019 ◽  
Vol 35 (4) ◽  
pp. 299-308
Author(s):  
Duo Ok
Keyword(s):  
Design Stage ◽  
Environmental Damage ◽  
Early Design Stage ◽  
Cargo Handling ◽  
Safety Design ◽  
Standards And Guidelines ◽  
Fire And Explosion ◽  
Engineering Practices ◽  
Oil Tankers ◽  
Safety Procedures

Over the last few decades, there have been a significant number of accidents on crude oil tankers, floating production storage and offloading (FPSO) and offshore units due to fire and explosion, which have resulted in loss of lives, assets, and environmental damage. These incidents increase scrutiny and questions on the current level of safety design in hydrocarbon handling spaces and other high-risk spaces in oil tankers and FPSOs. There are many factors which may contribute to these incidents, including; defects of equipment and components, overlook during design, inappropriate maintenance procedure and history, improper workmanship, and lack of company safety procedures and instruction during maintenance and emergency responses. This study is focused on and has discussed all safety aspects and barriers for the enclosed cargo-handling spaces in tankers and offshore units. Various existing regulations, standards, and guidelines have addressed safety design of enclosed cargo-handling spaces. These requirements and guidelines are referred and investigated to identify typical industry gaps in design and to recommend best engineering practices. The proposed key design recommendations may be considered at the early design stage of new building or conversion projects to enhance the overall safety and to reduce the likelihood of critical safety events.

Sign in / Sign up

Export Citation Format

Share Document