Theory of Active Reliability-Based Design for Predetermined Life of Structures

2008 ◽  
Vol 44-46 ◽  
pp. 745-750 ◽  
Author(s):  
Chu Liang Yan ◽  
K.G. Liu
Keyword(s):  
Economic Efficiency ◽  
Structural Reliability ◽  
Reliability Assessment ◽  
Economic Life ◽  
View Point ◽  
Reliability Design ◽  
Reliability Based Design ◽  
Fatigue And Fracture ◽  
Safety And Reliability

The project presents the theory of active reliability-based design for predetermined life targeted at their economic life. The structural reliability is designed from the view point of economic efficiency and maintainability requirements, so that the destruction of products led by fatigue and fracture is eliminated to the highest possible degree to provide the longest life, the highest reliability and the lowest cost. The reliability assessment of conventionally finished product is developed into an active reliability design at preset life, which is implemented before the design of products is finalized, to improve the safety and reliability of structures.

scholarly journals A Practical Nonprobabilistic Reliability Assessment Method on Key Strata Shear Failure in Longwall Mining

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Hebing Luan ◽  
Jiachen Wang ◽  
Guowei Ma ◽  
Ke Zhang
Keyword(s):  
Structural Reliability ◽  
Shear Failure ◽  
Longwall Mining ◽  
Reliability Assessment ◽  
Friction Angle ◽  
Assessment Method ◽  
Mechanical Tests ◽  
Potential Hazard ◽  
Support Design ◽  
Key Strata

Roof cutting has long been a potential hazard factor in longwall panels in some diggings in China. Meanwhile, the key strata structural reliability, which provides an assessment on the stability of overlying roof strata, may be a significant reference for support design in underground coal mines. This paper aims to investigate a practical nonprobabilistic reliability assessment method on key strata. The mechanical tests and the hollow inclusion triaxial strain tests were conducted to measure relevant mechanical parameters and in situ stress. Furthermore, against the typical failure features in Datong Diggings, China, a shear failure mechanical model of key strata is proposed. Then, an allowable-safety-factor based nonprobabilistic stability probability assessment method is given. The sensitivity of geometrical dimensions and uncertainty levels of friction angle and cohesion are further studied. It is found that thickness and span of key strata have more dominative effect on key strata’s stability compared with the other factor and the increase of uncertainty levels results in decrease of stability probability.

Reliability-Based Design Optimization for Nonlinear Energy Harvesters

2015 ◽  
Author(s):  
Sumin Seong ◽  
Christopher Mullen ◽  
Soobum Lee
Keyword(s):  
Energy Harvesting ◽  
Design Optimization ◽  
Reliability Based Design Optimization ◽  
Vibration Energy Harvester ◽  
Reliability Design ◽  
Energy Harvesters ◽  
Reliability Based Design ◽  
Stable Characteristic ◽  
Tip Mass ◽  
Nonlinear Energy

This paper presents reliability-based design optimization (RBDO) and experimental validation of the purely mechanical nonlinear vibration energy harvester we recently proposed. A bi-stable characteristic was embodied with a pre-stressed curved cantilever substrate on which piezoelectric patches were laminated. The curved cantilever can be simply manufactured by clamping multiple beams with different lengths or by connecting two ends of the cantilever using a coil spring. When vibrating, the inertia of the tip mass activates the curved cantilever to cause snap-through buckling and makes the nature of vibration switch between two equilibrium positions. The reliability-based design optimization study for maximization of power density and broadband energy harvesting performance is performed. The benefit of the proposed design in terms of excellent reliability, design compactness, and ease of implementation is discussed. The prototype is fabricated based on the optimal design result and energy harvesting performance between the linear and nonlinear energy harvesters is compared. The excellent broadband characteristic of the purely mechanical harvester will be validated.

GENERALIZED UNCERTAINTY IN STRUCTURAL RELIABILITY ASSESSMENT

1994 ◽  
Vol 11 (2) ◽  
pp. 81-110 ◽  
Author(s):  
KWAN-LING LAI Research Assistant ◽  
BILAL M. AYYUB Member, ASCE
Keyword(s):  
Structural Reliability ◽  
Reliability Assessment

scholarly journals Gradual Reliability Sensitivity Analysis of Mechanical Part Considering Preventive Maintenance

2014 ◽  
Vol 6 ◽  
pp. 829850
Author(s):  
Li Changyou ◽  
Liu Haiyang ◽  
Guo Song ◽  
Zhang Yimin ◽  
Li Zhenyuan
Keyword(s):  
Mechanical System ◽  
Preventive Maintenance ◽  
Gamma Process ◽  
Reliability Model ◽  
Application Process ◽  
Initial State ◽  
Reliability Design ◽  
Mechanical Part ◽  
Safety And Reliability ◽  
Deterioration Process

A lot of mechanical parts are subject to failure due to the deterioration. Usually the preventive maintenance is taken to ensure the safety and reliability. Therefore, it is very important to study the gradual reliability design of the mechanical part for improving the gradual reliability of the mechanical system under the condition of considering the preventive maintenance. Beta distribution is employed to describe the randomness of the mechanical part state after the preventive maintenance. The deterioration process of the mechanical part is modeled using the nonstationary Gamma process. The gradual reliability model before the first preventive maintenance is proposed according to the gradual failure principle and using the initial state distribution and the properties of Gamma process. Then, the gradual reliability model between any two times of preventive maintenance is also derived. Subsequently, the sensitivity equations of the proposed gradual reliability model to each parameter are given. The application process and practicality of the proposed approach are described by a numerical example. This work solved the problem where the maintenance has not been well considered in the reliability design of the mechanical part and contributed to the theory and method of improving the safety and reliability operation of the mechanical system.

FMEDA and FIT-Based Safety Assessment of NPP I&C Systems Considering Expert Uncertainty

2018 ◽  
Author(s):  
Alexander Yasko ◽  
Eugene Babeshko ◽  
Vyacheslav Kharchenko
Keyword(s):  
Emotional Disorders ◽  
Nuclear Power ◽  
Safety Assessment ◽  
Failure Modes ◽  
Reliability Assessment ◽  
Software Tool ◽  
Critical Systems ◽  
System Specification ◽  
Multiple Faults ◽  
Safety And Reliability

The complexity of modern safety critical systems is becoming higher with technology level growth. Nowadays the most important and vital systems of automotive, aerospace, nuclear industries count millions of lines of software code and tens of thousands of hardware components and sensors. All of these constituents operate in integrated environment interacting with each other — this leads to enormous calculation task when testing and safety assessment are performed. There are several formal methods that are used to assess reliability and safety of NPP I&C (Nuclear Power Plant Instrumentation and Control) systems. Most of them require significant involvement of experts and confidence in their experience which vastly affects trustworthiness of assessment results. The goal of our research is to improve the quality of safety and reliability assessment as result of experts involvement mitigation by process automation. We propose usage of automated FMEDA (Failure Modes, Effects and Diagnostic Analysis) and FIT (Fault Insertion Testing) combination extended whith multiple faults approach as well as special methods for quantitative assessment of experts involvement level and their decisions uncertainty. These methods allow to perform safety and reliability assessment without specifying the degree of confidence in experts. Traditional FMEDA approach has several bottlenecks like the need of manual processing of huge number of technical documents (system specification, datasheets etc.), manual assignment of failure modes and effects based on personal experience. Human factor is another source of uncertainty. Such things like tiredness, emotional disorders, distraction or lack of experience could be the reasons of under- and over-estimation. Basing on our research in field of expert-related errors we propose expert involvement degree (EID) metric that indicates the level of technique automation and expert uncertainty degree (EUD) metric which is complex measure of experts decisions uncertainty within assessment. We propose usage of total expert trustworthiness degree (ETD) indicator as function of EID and EUD. Expert uncertainty assessment and Multi-FIT as FMEDA verification are implemented in AXMEA (Automated X-Modes and Effects Analysis) software tool. Proposed Multi-FIT technique in combination with FMEDA was used during internal activities of SIL3 certification of FPGA-based (Field Programmable Gate Array) RadICS platform for NPP I&C systems. The proposed expert trustworthiness degree calculation is going to be used during production activities of RPC Radiy (Research and Production Corporation). Our future work is related to research in expert uncertainty field and extension of AXMEA tool with new failure data sources as well as software optimization and further automation.

scholarly journals Structural reliability under uncertainty in moments: distributionally-robust reliability-based design optimization

2021 ◽  
Author(s):  
Yoshihiro Kanno
Keyword(s):  
Design Optimization ◽  
Optimization Problem ◽  
Structural Reliability ◽  
Reliability Based Design Optimization ◽  
Input Distribution ◽  
Reliability Based Design ◽  
Optimal Value ◽  
Reliability Constraint ◽  
Distributionally Robust ◽  
Robust Reliability

AbstractThis study considers structural optimization under a reliability constraint, in which the input distribution is only partially known. Specifically, when it is only known that the expected value vector and the variance-covariance matrix of the input distribution belong to a given convex set, it is required that the failure probability of a structure should be no greater than a specified target value for any realization of the input distribution. We demonstrate that this distributionally-robust reliability constraint can be reduced equivalently to deterministic constraints. By using this reduction, we can handle a reliability-based design optimization problem under the distributionally-robust reliability constraint within the framework of deterministic optimization; in particular, nonlinear semidefinite programming. Two numerical examples are solved to demonstrate the relation between the optimal value and either the target reliability or the uncertainty magnitude.

scholarly journals Structural reliability assessment based on optical monitoring system: case study

2016 ◽  
Vol 9 (2) ◽  
pp. 297-305 ◽  
Author(s):  
E. Mesquita ◽  
P. Antunes ◽  
A. A. Henriques ◽  
A. Arêde ◽  
P. S. André ◽  
...  
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Structural Reliability ◽  
Extreme Values ◽  
Low Cost ◽  
Reliability Assessment ◽  
Water Reservoir ◽  
Optical Systems ◽  
Structural Health

ABSTRACT Optical systems are recognized to be an important tool for structural health monitoring, especially for real time safety assessment, due to simplified system configuration and low cost when compared to regular systems, namely electrical systems. This work aims to present a case study on structural health monitoring focused on reliability assessment and applying data collected by a simplified optical sensing system. This way, an elevated reinforced concrete water reservoir was instrumented with a bi-axial optical accelerometer and monitored since January 2014. Taking into account acceleration data, the natural frequencies and relative displacements were estimated. The reliability analysis was performed based on generalized extreme values distribution (GEV) and the results were employed to build a forecast of the reliability of the water elevated reservoir for the next 100 years. The results showed that the optical system combined with GEV analysis, implemented in this experimental work, can provide adequate data for structural reliability assessment.

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