Reliability Analysis Program Research Articles

Modeling of the Time-Dependent H2 Emission and Equilibrium Time in H2-Enriched Polymers with Cylindrical, Spherical and Sheet Shapes and Comparisons with Experimental Investigations.

Time-dependent emitted H2 content modeling via a reliable diffusion analysis program was performed for H2-enriched polymers under high pressure. Here, the emitted hydrogen concentration versus elapsed time was obtained at different diffusivities and volume dimensions for cylinder-, sphere- and sheet-shaped specimens. The desorption equilibrium time, defined as the time when the H2 emission content is nearly saturated, was an essential factor for determining the periodic cyclic testing and high-pressure H2 exposure effect. The equilibrium time in the desorption process was modeled. The equilibrium time revealed an exponential growth behavior with respect to the squared thickness and the squared diameter of the cylinder--shaped specimen, while it was proportional to the squared diameter for the sphere-shaped specimen and to the squared thickness for the sheet-shaped specimen. Linear relationships between the reciprocal equilibrium time and diffusivity were found for all shaped polymers. The modeling results were confirmed by analysis of the solutions using Fick's second diffusion law and were consistent with the experimental investigations. Numerical modeling provides a useful tool for predicting the time-dependent emitted H2 behavior and desorption equilibrium time. With a known diffusivity, a complicated time-dependent emitted H2 behavior with a multi-exponential form of an infinite series could also be predicted for the three shaped samples using a diffusion analysis program.

Erection strategy for main cable based on unstrained length of parallel wire strands

This paper presents a construction scheme aimed at achieving one-time erection of strands through precise control of the unstrained length. The scheme entails correcting system errors through the initial strand erection and reducing the influence of random errors by improving manufacturing conditions and increasing field measurements. The key objective is to control cable erection using cable length. A reliability analysis program was developed to assess the accuracy of the main cable installation. A case study of an actual bridge was conducted to verify the feasibility of the scheme. First, an assessment of the distribution characteristics of the random variables was performed. Subsequently, a comparative analysis was performed to evaluate the reliability of the proposed scheme against conventional erection methods. Finally, the new method was validated by on-site installation of several strands. Results revealed that while the reliability of cable formation shape was comparable between the traditional method and the proposed scheme, the latter exhibited superior uniformity of internal force among cable strands after formation. In addition, the average value of the cable length correction for Nos. 2 to 15 strands closely aligns with that of the reference strand, suggesting that the systematic error correction determined by the reference strand exhibits relatively high accuracy. Furthermore, strands erected with cable length as the control objective effectively maintained sag errors within the range of [− 4 mm, 8 mm], demonstrating a high level of precision.

Analysis of Deterioration in a Plasma Focus Device

The Plasma Focus (PF) is a kind of dense transient plasmas in with high-pulsed voltage. To produce devices for eld application it is necessary to obtain PF equipment able to operate for a long period of time. Thus, a reliability analysis is indispensable. In this work a reliability analysis program for plasma focus devices is presented. The program considers a criticality analysis using Failure Modes and Effects Criticality Analysis (FMECA) to identify the most important failure modes of the system. Said failure modes are studied operating the Plasma Focus for many cycles, obtaining from them the characteristic curves of V(t) and İ(t). Feature Extraction (FE) techniques are applied to obtain a list of parameters that correlate to the degrading process. Furthermore, Machine Learning tools are used to learn from the obtained data, linking the changes in these parameters during its life cycle to the decay of the system in hope for future implementation of a predictive maintenance system and a reference for data analysis and prediction in PFs. The study was applied to a portable plasma focus device operated at 2 joules of stored energy.

Reliability Assessment of Steel-Aluminium Lattice Tower

In the subject of the present study a probabilistic approach to the analysis of steelaluminium lattice tower was used. Structural design parameters are defined as the deterministic values and random variables. Random variables are not correlated. The criterion for structural failure is expressed the limits of functions referring to the serviceability limit state. The description of the limit state of structure implicit forms of the random variables function was used. The study presents a combination of the reliability analysis program with the MES3D external FEM program. The NUMPRESS software, created at the IFTR PAS, was used in the reliability analysis. The Hasofer-Lind reliability index, determined using an iterative procedure of Rackwitz-Fiessler, was used as a reliability measure. The values of reliability index for different cases of the vector of random variables, that is, different descriptions of mathematical model of the structure, were determined. The effect of assumed probability distribution of individual random variables on the value of the reliability index was determined. In the description of random variables, the different types of probability distribution were used and the values of the reliability index for the normal distribution and the distribution chosen according to the kind of a variable were compared. The primary research method is the FORM method. In order to verify the correctness of the calculation Monte Carlo and Importance Sampling methods are used. The relative error of the reliability index was calculated taking the simulation Monte Carlo method as a reference. The effectiveness of the primary research method was performed by comparing the number of calls of the limit state, which is connected with the calculation time. The sensitivity of reliability index to the random variables was defined.

Nondestructive Evaluation and Reliability Analysis for Determining the Mechanical Properties of Old Wood of Ancient Timber Structure

The objective of this study was to evaluate the mechanical properties of ancient wood of Abies fabri (Mast.) Craib based on the nondestructive tests and reliability analysis. Nondestructive tests including resistograph and stress wave test, and destructive tests were conducted on the wood specimens. Results indicated that there were significant linear correlations between the resistance amplitude (F) and green density (ρ), the dynamic modulus of elasticity (ED) and static modulus of elasticity (MOE), modulus of rupture (MOR), and ultimate compressive strength (UCS) of wood specimens. The cumulative distribution of the predicted MOR and UCS based on the nondestructive tests could be well fitted by the normal distribution according to the χ2 test. Moreover, a reliability analysis program based on the first-order second-moment method was developed. Reliability analysis results showed that the reliability index increased nonlinearly with the increase of the live-to-dead load ratio, and decreased nonlinearly with the increase of the design values for all the simulation load cases. According to the minimum reliability index requirements of the Chinese national standard, it is suggested that the design value of MOR and UCS be 14.0 and 10.7 MPa, respectively.

Asymmetrical Common-Cause Failures Analysis Method Applied in Fusion Reactors

Fusion reactors like the International Thermonuclear Experimental Reactor (ITER) are generally complex systems, which demand reliability analysis. Common-Cause Failures (CCF) are increasingly important in the reliability analysis of these systems because of the widespread redundancy or similar components in them. However, despite the wide research in CCF, there has been little research on the handling of asymmetries of CCF that is inevitable in ITER. A concept of Multi-Common-Cause Failures (MCCF) and its key assumptions are discussed in this paper. On the basis of MCCF and the assumptions, a transition method named Common-Cause Breakdown Structure (CCBS) was designed to manage the asymmetrical CCF. The CCBS method can be easily applied to most fault tree analysis codes because the CCF treated by CCBS can be handled by traditional CCF models. A redundant system example was modeled and calculated in the reliability and probabilistic safety analysis program RiskA developed by FDS Team. The analysis results for water pumps redundant system applied in Tokamak cooling water system show that CCBS method is adequate and effective.

The Evaluation Of Algorithms For Determination Of The Reliability Index

AbstractThe study deals with stability and dynamic problems in bar structures using a probabilistic approach. Structural design parameters are defined as deterministic values and also as random variables, which are not correlated. The criterion of structural failure is expressed by the condition of non-exceeding the admissible load multiplier and condition of non-exceeding the admissible vertical displacement. The Hasofer-Lind index was used as a reliability measure. The primary research tool is the FORM method. In order to verify the correctness of the calculations Monte Carlo and Importance Sampling methods were used. The sensitivity of the reliability index to the random variables was defined. The limit state function is not an explicit function of random variables. This dependence was determined using a numerical procedure, e.g. the finite element methods. The paper aims to present the communication between the STAND reliability analysis program and the KRATA and MES3D external FE programs.

Evaluation and comparison of open source program solutions for automatic seed counting on digital images

Seed number quantification is an essential agronomic parameter conducted mostly manually or by mechanical counters, both with obvious limitations. Digital image analysis provides a reliable and robust alternative to accurately calculate many biological features. This study presents and evaluates the performance of four open-source image-analysis programs i.e. ImageJ, CellProfiler, P-TRAP and SmartGrain to count crop seeds from digital images captured by camera and scanner. It also evaluates ImageJ program for automated seed counting using macro containing RenyiEntropy threshold algorithm. Digital images of cereal crop seeds were acquired i.e. wheat, barley, maize, rye, oat, sorghum, triticale and rice. All images contained 200 seeds per image present in an area of approx. 1400cm2. RenyiEntropy threshold increased the seed count accuracy of ImageJ from digital camera images. Generally, seed counts from digital camera images of all crops were accurate, but software–crop combination had significant (p<0.05) difference from reference value. Among image analysis programs, ImageJ produced mostly higher seed count across all observed crops than other programs. Mean seed counts from scanned images of maize were observed only by CellProfiler and P-TRAP, with other programs inappropriate due to high inaccuracy. These results suggest CellProfiler as a reliable image analysis program for seed counting from digital images. Benchmark test was also performed to compare speed of analysis. The automated seed count produced by image analysis programs described here allows faster, reliable and reproducible analysis, compared to standard manual method. To our knowledge this is the first study on using CellProfiler program for crop seed counting from digital images.

Reliability Optimization Design of Composite Transmission Shaft

In order to solve reliability-based optimization design of composite transmission shaft, the parametric finite element model of composite transmission shaft was built by secondary development of ABAQUS. The reliability analysis of composite transmission shaft was carried out with the first order reliability method (FORM). Using python language, the finite element program and reliability analysis program are combined. The reliability-based optimization model of composite transmission shaft was obtained. The feasibility and effectiveness of the optimization model was verified by the results of an example application.

Motion Reliability Analysis of the PUMA560 Series Mechanism

In this paper, we report an effective method for motion reliability analysis of the PUMA560 series mechanism. It firstly builds a Monte Carlo parameterized 3-D virtual model of this mechanism in ADAMS, and uses VC++ to program a pseudo-random number subroutine function that conforms to normal distribution and user defining function to simulate the stochastic error distribution of the mechanism, and a universal reliability analysis program of the PUMA560 series mechanism is then developed. After multiple virtual tests on this parameterized mechanism model, a large mount of test data are obtained and statistically analyzed to calculate the motion reliability; this can evaluate the influence of different stochastic errors on the mechanism dynamic characteristics. The advantages of this new method include simplicity (no need to solve complex mathematic model) and high accuracy which make it highly promising for application in mechanism design.

Probability-Based Research on Sensitivity of Saddle-Shaped Cables Suspended

Performance-based structural analysis is the main trend of the future development of engineering design; probability-based sensitivity can reflect the importance of different parameters in the structural performance-based design. Therefore based on the response surface method, the reliability analysis program has been established, within which the sensitivity analysis of different parameters, such as the prestress, cable sectional area, cable strength and elastic modulus of saddle-shaped cable suspended, was conducted. And the corresponding sensitivity coefficient has been given, which can not only be used as a reference to the design of structure, but also can check the rationality of the structure design.

Life Cycle Reliability Assessment of Concrete Beam Bridges under Atmospheric Environment

The degradation model of reinforced concrete under general atmospheric environment was summarized. The life-cycle reliability assessment method of existing concrete beam bridges was proposed. The probability model of the life cycle resistance and load effect were established. The time-dependent reliability analysis program was compiled. The engineering application shows that the life-cycle reliability assessment method introducing the material degradation model can predict the remaining life of existing bridges scientifically, and ensure safe operation of bridges.

Nonlinear finite element reliability analysis of Concrete-Faced Rockfill (CFR) dams under static effects

The response of concrete slab on Concrete-Faced Rockfill (CFR) dams is very important. This study investigates the reliability of the concrete slab on a CFR dam by the improved Rackwitz–Fiessler method under static loads. For this purpose, ANSYS finite element analysis software and FERUM reliability analysis program are combined with direct coupled method and response surface method. Reliability index and probability of failure of the concrete are computed in the all critical points of the concrete slab by dam height. This study is also expanded for the reliability of CFR dams including different concrete slab thickness. In addition to the linear behavior, geometrically and materially non-linear responses of the dam are considered in the finite element analysis which is performed with reliability analysis. The Drucker–Prager method and the multi linear kinematic hardening method are, respectively, used for concrete slab and for rockfill and foundation rock. Finite element model used in the analyses includes dam–reservoir–foundation interaction. Reservoir water is modeled by the Lagrangian approach. Welded and friction contact based on the Coulomb’s friction law are considered in the joints of the dam. One-dimensional two noded contact elements are used to define friction. The self-weight of the dam and the hydrostatic pressure of the reservoir water are considered in the numerical solutions. According to this study, hydrostatic pressure, nonlinear response of the rockfill and the decrease in the concrete slab thickness reduce the reliability of the concrete slab of the CFR dam. Besides, the CFR dam models including friction are safer than the models including welded contact in the joints.

Research on Long-Span Old Bridge’s Dynamic Reliability under Vehicular Load

From an analysis of random process with modal analysis method, formulas of related parameters for an analysis of structural dynamic reliability have been deduced first in the paper, accordingly, prepares “the PMDK dynamic reliability analysis program” by Fortran programming language. Next, Some parameters for vehicular load probability distribution model have been derived by a method of unconstrained planning, Combining with an observation data for vehicle distribution at a long-span old bridge, the author has obtained the model in this paper. Finally, author has calculated a dynamic reliability for the long-span old bridge under a specific vehiclar load by the program and studied a relationship between dynamic reliability and displacement as well as sectional position and influences of damping and elastic modulus on its dynamic rerliability. Meanwhile the author also has studied a relationship between dynamic reliability and time and influences of structural unilateral and bilateral reliability.At last all aboved conclusions have been confirmed by Monte Carlo method.

Reliability-based optimisation of offshore jacket-type structures with an integrated-algorithms system

Reliability-based optimisation (RBO) is a powerful tool for including uncertainties in the optimisation process, in which structural and reliability analyses and optimisation algorithms based on mathematical or evolutionary computation concepts have to be combined effectively. This process is rather complicated and difficult to carry out for large structural systems such as steel offshore structures. In this paper, a calculation system of integrated algorithms for the RBO of the offshore towers is presented. The calculation process is composed of a structural analysis package (SAPOS) based on the finite element method, a reliability analysis program based on the first-order reliability method and an optimisation program based on sequential quadratic programming using the International Mathematics and Statistics Library. In the RBO analysis, multiple limit states based on different criteria are used to check a probable failure condition and to identify the limit state criterion. An offshore jacket-type structure is considered as an example to demonstrate the applicability of the implemented algorithm to realistic structural systems.

SCRAP: Sequential circuits reliability analysis program

The recent rapid growth in demand for highly reliable digital circuits has focused attention on tools and techniques we might use to accurately estimate the reliability of a proposed circuit on the basis of failure rate of the utilized technology. Reliability analysis has become an integral part of the system design process, especially for those systems with life-critical applications such as aircrafts and spacecraft flight control. In this paper, we present an algorithm to evaluate the reliability of sequential circuits. This approach called ‘multiple-pass’ combines gate failure probability with the propagated errors to calculate the reliability of every nodes of the circuit in an iterative manner. The proposed approach is used to implement and develop the SCRAP program. It computes the reliability of the sequential circuit based on its standard cell library which can be extended to have larger gates such as D flip-flops. The framework is applied to a subset of sequential benchmark circuits and the observed results demonstrate the accuracy and speed of the proposed technique.

An integrated reliability-based design optimization of offshore towers

After recognizing the uncertainty in the parameters such as material, loading, geometry and so on in contrast with the conventional optimization, the reliability-based design optimization (RBDO) concept has become more meaningful to perform an economical design implementation, which includes a reliability analysis and an optimization algorithm. RBDO procedures include structural analysis, reliability analysis and sensitivity analysis both for optimization and for reliability. The efficiency of the RBDO system depends on the mentioned numerical algorithms. In this work, an integrated algorithms system is proposed to implement the RBDO of the offshore towers, which are subjected to the extreme wave loading. The numerical strategies interacting with each other to fulfill the RBDO of towers are as follows: (a) a structural analysis program, SAPOS, (b) an optimization program, SQP and (c) a reliability analysis program based on FORM. A demonstration of an example tripod tower under the reliability constraints based on limit states of the critical stress, buckling and the natural frequency is presented.

System Fatigue Damage Reliability Assessment of Railway Riveted Bridges

According to the fatigue damage failure mechanism of riveted members, a riveted member probabilistic fatigue failure model (RMPFFM) was proposed, and a fracture finite element program is developed to calculate the geometry function of RMPFFM. Furthermore, a system fatigue damage reliability model of riveted bridges was proposed, and based on Monte-Carlo method, a large system fatigue damage reliability analysis program was developed to calculate the system fatigue failure probability. Then the system evaluation model was used to predicate the system fatigue damage reliability of Ganjiang Railway Bridge. According to assessment results, the probabilistic remaining fatigue life, safe inspection intervals and maintenance strategy are determined, which can control and avoid fatigue failure accident and reduce the contingent disaster in bridge service life.

Application of probabilistic fracture mechanics in evaluation of existing riveted bridges

Many existing riveted bridges in China are often required to carry an increasing volume of traffic, usually consisting of vehicles heavier than the original design. Recently Chinese government and engineers have paid more attention to the actual fatigue life and service safety of such infrastructures, and have decided to research evaluation methods using modern technologies. Therefore, based on investigation of fatigue – damage accumulation theory and probabilistic fracture mechanics, the evaluation methods have been developed to calculate the deterministic and probabilistic remaining fatigue life of existing riveted bridges. According to the fatigue failure mechanism of existing riveted bridges, a simple fracture evaluation model and a single-angle probabilistic fracture failure model (SAPFFM) were proposed, and based on Monte-Carlo method, a fatigue reliability analysis program was developed. Finally, as a case study, the fatigue evaluation models were used to predicate the fatigue safety of Zhejiang St...

Fatigue Reliability Evaluation of Old Steel Bridges Based on Probabilistic Fracture Mechanics

There are many old steel bridges on Chinese transportation lines, which keep their normal traffic service function. The old bridges are often required to carry an increasing volume of traffic and heavier vehicles than the original design, so bridge management departments pay more attention to the actual remaining fatigue life of such structures. Based on probabilistic fracture mechanics theory, the member and the system fatigue failure evaluation models for old steel bridges are all proposed, and the fatigue reliability analysis program is developed using Monte-Carlo. As a case study, the evaluation models are used to predicate the fatigue reliability of Zhejiang Street Bridge. According to evaluation results, the probabilistic remaining fatigue life, safe inspection intervals and maintenance strategy are determined.