Multi-failure Modes Research Articles

A failure-path independent method for analysis of structural system reliability

In order to overcome the disadvantages of traditional system reliability methods in the identification of significant failure modes and calculation of joint failure probability, a failure-path independent method is presented for structural system reliability analysis by combining the elastic modulus reduction method and the stochastic finite element method (SFEM). The stochastic responses by the SFEM were employed to define the element bearing ratio and the reference EBR, based on which an efficient dynamic criterion was developed for identification of highly stressed elements. The stochastic elastic modulus reduction method was proposed for simulation of internal force redistribution and damage evolution based on the principle of deformation energy conservation. The significant failure modes of structural system were identified according to the elastic modulus of the highly stressed elements in the limit state, while structural system reliability was calculated based on the joint failure probability of multi-failure modes. Investigation demonstrated the advantages of the proposed method over the traditional system reliability methods and its high accuracy and efficiency.

MDD-Based Method for Efficient Analysis on Phased-Mission Systems With Multimode Failures

Many practical systems are phased-mission systems with multimode failures (MFPMSs) where the mission consists of multiple nonoverlapping phases of operation, and the system components may assume more than one failure mode. In MFPMSs, dependence arises among different phases and among different failure modes of the same component, which makes the reliability analysis of MFPMSs difficult. This paper proposes a new analytical method based on multivalued decision diagrams (MDDs) for the reliability analysis of nonrepairable MFPMSs. MDDs have recently been applied to the reliability analysis of single-phase systems with multiple component states. In this paper, we make the new contribution by proposing a novel way to adapt MDDs for the reliability analysis of systems with multiple phases and multimode failures. Examples show how the MDD models are generated and evaluated to obtain the mission reliability measures. Performance of the MDD-based method is compared with an existing binary decision diagram (BDD)-based method for MFPMS analysis through several examples and a comprehensive benchmark study. Empirical results show that the proposed MDD-based method can offer lower computational complexity and simpler model construction and evaluation algorithms than the BDD-based method, and it can be effectively applied to large practical cases.

Multi-Mode Failure Models for Attribute Test Data in Reliability Systems, a Bayesian Analysis Approach Using Multi-Nomial Distribution Model

This paper describes the extending model of Multi-mode Failure Models by using the Weibull and Gamma distribution models presented in a conference [1,2]. Different than the models in the previous papers which are for variable test data, in this paper we will describe the use of attribute test data for our model. In reliability theory, the most important problem is to determine the reliability of a complex system from the reliability of its components. The weakness of most reliability theories is that the systems are described and explained as simply functioning or failed. In many real situations, the failures may be from many causes depending upon the age and the environment of the system and its components. Another problem in reliability theory is one of estimating the parameters of the assumed failure models. The estimation may be based on data collected over censored or uncensored life tests. In many reliability problems, the failure data are simply quantitatively inadequate. The Bayesian analyses are more beneficial than classical analyses in such cases. The Bayesian estimation analyses allow us to combine past knowledge or experience in the form of an apriori distribution with life test data to make inferences of the parameter of interest. In this paper, we have investigated the application of the Bayesian estimation analyses to multi-mode failure systems for attribute test data. The cases are limited to the models with independent causes of failure. We select our investigation by using the Multi-nomial distribution as our model. This distribution is widely used in reliability analysis for attribute test data. This model describes the likelihood function and follows with the description of the posterior function. A Beta prior is used in our analysis for each model and it is followed by the estimation of the point, interval, and reliability estimations.

Multi-Failure Mode Assessment of Buried Concrete Pipes Subjected to Time-Dependent Deterioration, Using System Reliability Analysis

This article presents a reliability-based methodology for assessment of corrosion-affected, reinforced concrete sewers, considering serviceability and ultimate strength as limit state functions for multi-failure mode assessment. A stochastic model for system failure analysis is developed, which relates to key factors that affect concrete corrosion in a concrete sewer system in Harrogate in the United Kingdom. A time-dependent Monte Carlo simulation method is employed to quantify the probability of failure of concrete sewers with 70-cm diameter due to two categories of failure modes (serviceability and ultimate strength). Factors that affect the failure due to concrete corrosion are also studied by way of parametric sensitivity analysis.

Reliability Calculation Method for Mechanical Components with Dependent Failure Modes

A mechanical component may fail in many modes that are usually not independent. There is generally not a joint probability density function to describe these correlated failure modes. Thus, it is difficult to compute the reliability with considering the correlations between the failure modes. It is supposed that three or more failure modes arise synchronously to be a very small probability event. The relationship between ultimate state functions in different failure modes is established by utilizing linear regression method. A double integration modal for reliability of mechanical components with dependent failure modes is built according to stress-strength interference model. In case of square, cube or exponential relationship between two ultimate state functions, a linear transformation is made. An example of pin is discussed. Its reliability is compared with that obtained using Monte Carlo method, which represent that the reliability model with multi-failure modes proposed is correct.

Equivalent analysis and failure prediction of quasi-isotropic composite sandwich cylinder with lattice core under uniaxial compression

Sandwich cylindrical shells are the major components of aerospace structures. In this paper, an analytical investigation was carried out to examine the response of carbon fiber reinforced composite (CFRC) sandwich cylinders with lattice cores. An equivalent monocoque shell theory, was developed in this paper to predict mechanical behaviors of the quasi-isotropic sandwich cylinder, including the deformation and the multi-mode failure criterion. Five failure modes were suggested for the sandwich cylinder, including global buckling, face sheet mono-cell buckling/dimpling, face sheet local buckling, lattice rib crippling and strength failure. Using the suggested criterion, failure mode maps of the sandwich cylinder were acquired to instruct the design of the hierarchical sandwich cylinder with five geometrical variables. The method also correctly predicted the failure modes of the tested sandwich cylinder within acceptable errors.

Multi-mode failure of form-fitting timber connections – Experimental and numerical studies on the tapered tenon joint

Traditional carpentry joints with tapered tenons have been used widely in timber structures all over Europe to connect two structural parts under compression loads that concur at a somehow diagonal angle. When a change of use is required or when damages are obvious, then an analytical model is needed to prove the structural safety even for non-engineered connections. Experimental investigations and numerical modelling were carried out for the tapered tenon to back up the basic understanding of failure modes and strength. Three types of failure were considered: rolling shear failure, failure of the front side and failure of the bottom face. The influence of friction was examined systematically. Based on the results of the experimental studies, numerical studies were carried out using a cohesive zone model. Practical suggestions for the engineering design were derived from the research results.

Analysis of steel–concrete composite column subject to blast

The single-degree-of-freedom method is commonly used to approximate the dynamic response of structures subjected to blast loading. One of the limitations of this method is that it cannot capture the multi-failure modes of the structural members. The rigid–plastic method is thus, proposed in this paper as an alternative analytical approach to estimate the blast response of concrete-filled steel composite columns. The rigid–plastic results are compared with single-degree-of-freedom calculations as well as numerical simulations in order to assess the competency of the proposed method. Due to the assumption of rigid–plastic material behaviour in the rigid–plastic analysis, the accuracy of this method is influenced by the extent of plastic deformation of the structural member. For the case of impulsive blast loading, the rigid–plastic estimations are found to be closer to the numerical results than those obtained using the single-degree-of-freedom method. Numerical analysis was also conducted to compare the performance of concrete-filled steel composite column to a reinforced concrete column. A significant improvement in the blast resistance of the composite column was observed from the comparison.

Model enrichment: concept, measurement, and application

Simplicity and validity are recognized as important attributes of an effective simulation model. However, some disagreement exists both on the definitions of these concepts and on quantitative measures for them. This paper introduces Enrichment Level (EL) for (simulation) models. The EL is a quantitative measure to compare the effectiveness of alternative models when used in a particular project. While there is no conceptual restriction on expanding the EL, it currently captures the bias, speed, variance, and scope of a model as the main contributing enrichment factors. This paper explores these factors and suggests a utility-based method to combine them according to the relative importance of each enrichment factor. Model effectiveness measures currently used in academic and industrial studies are discussed and compared to the proposed EL. In order to show the usability of EL as a model comparison tool, we study an example of a queue with multi-failure mode servers and apply our method to facilitate decisions about choosing the most suitable model among a set of three.

Lightweight Analysis of Torsion Spring Based on Reliability Constraint in Multi-Failure Modes

The generalized stress and strength distribution interference theory is introduced to establish the reliability model of torsion spring in multi-failure modes. Using it as constraint condition, the lightweight optimization model of torsion spring based on reliability constraint in multi-failure modes is presented. And then an optimization design for a given structure of torsion spring is made to use the theoretical model under operating conditions and the reliability constraint. The weight of the opti-mized torsion spring is lighter than that of non-optimization. This verified the validity of the opti-mization method. The optimization method may contribution to design of aerospace equipments which demand strictly in weight.

An extended replacement policy for a deteriorating system with multi-failure modes

In this paper, the maintenance problem for a deteriorating system with k + 1 failure modes, including an unrepairable failure (catastrophic failure) mode and k repairable failure (non-catastrophic failure) modes, is studied. Assume that the system after repair is not “as good as new” and its deterioration is stochastic. Under these assumptions, an extended replacement policy N is considered: the system will be replaced whenever the number of repairable failures reaches N or the unrepairable failure occurs, whichever occurs first. Our purpose is to determine an optimal extended policy N ∗ such that the average cost rate (i.e. the long-run average cost per unit time) of the system is minimized. The explicit expression of the average cost rate is derived, and the corresponding optimal extended policy N ∗ can be determined analytically or numerically. Finally, a numerical example is given to illustrate some theoretical results of the repair model proposed in this paper.

Seismic FRP retrofit of circular single-column bents using a ductility wrap envelope to alter failure modes

The target displacement ductility requirements for circular reinforced concrete (R/C) single-column bridge bents are considered using a proposed multi-failure mode algorithm to determine the required thickness of fiber reinforced polymer wraps (FRPs). The procedure is developed using two in-house computer algorithms, PACCC (Plastic Analysis of Circular Concrete Columns) and PACCC-FRP, to generate a moment-curvature analysis using circular segments and subsequent failure mode predictions in single-column bents for both FRP-wrapped and unwrapped circular R/C sections. The results of the study were verified against published experimental tests at the ultimate force-deflection states of R/C sections and also against three commercial “software test beds”. The study uses PACCC-FRP to show that single-columns experiencing a brittle failure may be retrofitted with FRP wraps in order to increase the displacement ductility and satisfy target ductility values within the Ductility Wrap Envelope (DWE), or wrap-saturation level, as established herein.

다중파괴모드를 고려한 사면안정해석

최저 안전율 또는 최대 파괴확률을 기반으로 하는 기존의 사면안정해석에 대하여, 지반물성과 해석모델이 갖는 고유 불확실성을 최소화하고, 사면안정해석에서 다양한 안정해석모델과 그에 따른 파괴형상을 반영할 수 있도록 다중 파괴모드에 대한 동시 파괴확률을 고려한 사면의 신뢰성해석기법을 제안하였다. 붕괴현장조사를 통하여 현장에서 가장 빈번하게 발생하는 파괴형식을 다파괴모드로 정의하였다. 동시 파괴확률의 산정에는 체계 신뢰성해석분야에서 최근 도입된 선형계획법에 의한 최적화를 이용하였으며, 이를 통하여 여러 가지 해석모델을 신뢰성 기반으로 동시에 고려하여 해석할 수 있다. 이 방법의 적용성 평가를 위하여 기존 문헌에서 나타난 제방에 대한 신뢰성해석 결과와 비교하였다. 다중 파괴모드에 대한 동시 파괴확률을 고려한 사면의 신뢰성 해석을 적용한 결과, 전체 시스템에 대한 대한 안정성을 정량적으로 산출할 수 있음을 확인하였다. Conventional slope stability analysis is focused on calculating minimum factor of safety or maximum probability of failure. To minimize inherent uncertainty of soil properties and analytical model and to reflect various analytical models and its failure shape in slope stability analysis, slope stability analysis method considering simultaneous failure probability for multi failure mode was proposed. Linear programming recently introduced in system reliability analysis was used for calculation of simultaneous failure probability. System reliability analysis for various analytical models could be executed by this method. For application analysis for embankment, the results of this method shows that system stability of embankment calculate quantitatively.

Computing Method of Reliability Sensitivity under Independent Multi-Failure Modes

To improve the reliability effectively, the reliability sensitivity method is researched with considering that a mechanical system or component may fail in many modes, which is simplified to be a series system model. It is supposed that all ultimate state functions in multi-failure modes are normal distribution. A computation module for total reliability is established. A kind of computation method for reliability sensitivity in multi-failure modes is built based on that in single failure mode. A pin connection component that may fail in shear fracture, bruise on pin or hole surfaces, or in any assemble with two different modes is computed, and the reliability and sensitivity of the component are estimated. Consequently, it is found that the most effective method to enhance the reliability was to enhance the crushing strength of the pin.

Analytical Models and Guidelines for the Ductility Enhancement of Circular Reinforced Concrete Single-Column Bents Using Fiber-Reinforced Polymers

The target displacement ductility requirements for circular RC single-column bridge bents are considered using a proposed multifailure mode algorithm to determine the required thickness of fiber-reinforced polymer wraps FRPs. The procedure is developed using two in-house computer algorithms, PACCC plastic analysis of circular concrete columns and PACCC-FRP, to generate a moment- curvature analysis using circular segment slices and subsequent failure mode predictions in single-column bents for both FRP-wrapped and unwrapped circular RC sections. The results of the study showed good comparison to published experimental tests at the ultimate force-deflection states of RC sections and against three commercial software test beds. The study uses PACCC-FRP to show that single columns experiencing a brittle failure may be retrofitted with FRP wraps in order to increase the displacement ductility and satisfy target ductility values within the ductility wrap envelope, or wrap-saturation level, as established herein. DOI: 10.1061/ASCEBE.1943-5592.0000136 CE Database subject headings: Brittle failures; Failure modes; Concrete columns; Column beams; Fiber reinforced polymer; Lateral displacement; Ductility. Author keywords: Brittle failure; Failure modes; Concrete columns; Fiber-reinforced polymers; Lateral displacement; Ductility.

A multi-component and multi-failure mode inspection model based on the delay time concept

The delay time concept and the techniques developed for modelling and optimising plant inspection practices have been reported in many papers and case studies. For a system comprised of many components and subject to many different failure modes, one of the most convenient ways to model the inspection and failure processes is to use a stochastic point process for defect arrivals and a common delay time distribution for the duration between defect the arrival and failure of all defects. This is an approximation, but has been proven to be valid when the number of components is large. However, for a system with just a few key components and subject to few major failure modes, the approximation may be poor. In this paper, a model is developed to address this situation, where each component and failure mode is modelled individually and then pooled together to form the system inspection model. Since inspections are usually scheduled for the whole system rather than individual components, we then formulate the inspection model when the time to the next inspection from the point of a component failure renewal is random. This imposes some complication to the model, and an asymptotic solution was found. Simulation algorithms have also been proposed as a comparison to the analytical results. A numerical example is presented to demonstrate the model.

Estimation of reliability using failure-degradation data with explanatory variables

We consider semiparametric estimation of characteristics of degradation and failure process using degradation and multi-mode failure time data with covariates under the assumption that the component of hazard rate related to observable degradation is an unknown function of degradation and may depend on covariates. Bibliography: 17 titles.

Variable Ordering to Improve BDD Analysis of Phased-Mission Systems With Multimode Failures

Recently, Z. Tang, and J. B. Dugan proposed a new algorithm (DEP-BDD) based on binary decision diagrams (BDD) for reliability analysis of phased-mission systems (PMS) with multimode failures. Although the variable ordering is very important from a practical point of view, it has not been treated directly. This paper develops four ordering heuristics for DEP-BDD based on two ordinary schemes, and evaluates these schemes & heuristics with hundreds of randomly generated fault trees having different sizes and structure properties. As a synthesis of the obtained performance results, we propose a heuristic selection strategy.

Reliability Analysis of Structure System Considering Failure Modes of Strength, Fatigue and Buckling

There could be multi-failure modes in the course of working of the structure system including slender bar members. For example, strength failure, fatigue failure and buckling failure, especially sudden buckling failure would bring large disaster to structure. In this paper, according to Fatigue and Damage Mechanics theory, safe margin expression of the different failure mode of structure (static strength, fatigue and buckling) is given firstly, then by analyzing different failure mode of structural element under static and fatigue loads, and failure mode of the calculating element is confirmed by comparing the failure probability value of different failure mode. In the course of searching for significant failure paths, not only is failure mode that stiffness matrix of structure is zero considered, but also buckling failure mode of compressed residual structure is considered too, so that failure analysis is more reasonable. In the end, the reliability calculating method of the structural system is given, and the validity of the method proposed in this paper is explained combining an example.

Progressive failure analysis for advanced grid stiffened composite plates/shells

Abstract A progressive failure methodology is developed to simulate the initiation and propagation of multi-failure modes for advanced grid stiffened (AGS) composite plates/shells on the basis of a stiffened element model. Failures of both skin and ribs are taken into consideration, which are matrix cracking, fiber failure, fiber–matrix shear failure, delamination in skin and fiber failure in rib. All these failures are defined using a set of 2-D stress-based polynomial failure criteria wherein the transverse shear stresses at centroid of the stiffened element are calculated by employing an integrated approach of finite element and finite difference method. Corresponding material and stiffness degradation behavior is introduced after the initiation of individual failure mechanisms. The progressive failure behavior of a composite orthotropic-grid curved panel with a centrally located cutout under compressive load is evaluated using the method.