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.

System Reliability Analysis With Dependent Component Failures During Early Design Stage

2015 ◽  
Author(s):  
Yao Cheng ◽  
Xiaoping Du
Keyword(s):  
System Reliability ◽  
Reliability Prediction ◽  
Design Stage ◽  
Early Design ◽  
Early Design Stage ◽  
Design Concepts ◽  
Lack Of Information ◽  
Dependent Component ◽  
Reliability Bound ◽  
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 bound of the system reliability can be estimated, but is usually wide. This wide reliability bound makes it difficult to make decisions, such as evaluating and selecting design concepts, during the early design stage. This work develops a new methodology that makes the system reliability prediction more accurate by considering the dependence between component failures. 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 a narrow bound of the system reliability can be generated. Two examples demonstrate that the proposed methodology produces a narrower system reliability bound than the traditional reliability bound, thereby better assisting decision making during the early design stage.

scholarly journals Metrics for Measuring Sustainable Product Design Concepts

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3469
Author(s):  
Ji Han ◽  
Pingfei Jiang ◽  
Peter R. N. Childs
Keyword(s):  
Product Design ◽  
End Of Life ◽  
Environmental Impacts ◽  
Conceptual Design ◽  
Design Stage ◽  
Sustainable Product Design ◽  
Early Design ◽  
Design Concepts ◽  
Concept Evaluation ◽  
Sustainable Product

Although products can contribute to ecosystems positively, they can cause negative environmental impacts throughout their life cycles, from obtaining raw material, production, and use, to end of life. It is reported that most negative environmental impacts are decided at early design phases, which suggests that the determination of product sustainability should be considered as early as possible, such as during the conceptual design stage, when it is still possible to modify the design concept. However, most of the existing concept evaluation methods or tools are focused on assessing the feasibility or creativity of the concepts generated, lacking the measurements of sustainability of concepts. The paper explores key factors related to sustainable design with regard to environmental impacts, and describes a set of objective measures of sustainable product design concept evaluation, namely, material, production, use, and end of life. The rationales of the four metrics are discussed, with corresponding measurements. A case study is conducted to demonstrate the use and effectiveness of the metrics for evaluating product design concepts. The paper is the first study to explore the measurement of product design sustainability focusing on the conceptual design stage. It can be used as a guideline to measure the level of sustainability of product design concepts to support designers in developing sustainable products. Most significantly, it urges the considerations of sustainability design aspects at early design phases, and also provides a new research direction in concept evaluation regarding sustainability.

Identification of Human Errors During Early Design Stage Functional Failure Analysis

2018 ◽  
Author(s):  
Lukman Irshad ◽  
Salman Ahmed ◽  
Onan Demirel ◽  
Irem Y. Tumer
Keyword(s):  
Failure Analysis ◽  
Human Error ◽  
System Level ◽  
Design Stage ◽  
Human Factors Engineering ◽  
Human Errors ◽  
Functional Failure ◽  
Early Design ◽  
Early Design Stage ◽  
Early Design Stages

Detection of potential failures and human error and their propagation over time at an early design stage will help prevent system failures and adverse accidents. Hence, there is a need for a failure analysis technique that will assess potential functional/component failures, human errors, and how they propagate to affect the system overall. Prior work has introduced FFIP (Functional Failure Identification and Propagation), which considers both human error and mechanical failures and their propagation at a system level at early design stages. However, it fails to consider the specific human actions (expected or unexpected) that contributed towards the human error. In this paper, we propose a method to expand FFIP to include human action/error propagation during failure analysis so a designer can address the human errors using human factors engineering principals at early design stages. To explore the capabilities of the proposed method, it is applied to a hold-up tank example and the results are coupled with Digital Human Modeling to demonstrate how designers can use these tools to make better design decisions before any design commitments are made.

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