scholarly journals A Self-Configuring Membership-Function-Based Approach for Fuzzy Fatigue Reliability Optimization of Welded A-Type Frame Considering Multi-Source Uncertainties

2019 ◽  
Vol 9 (11) ◽  
pp. 2227 ◽  
Author(s):  
Chengji Mi ◽  
Wentai Li ◽  
Xuewen Xiao ◽  
Jinhua Liu ◽  
Xingzu Ming
Keyword(s):  
Weld Metal ◽  
Membership Function ◽  
Failure Probability ◽  
Fuzzy Variable ◽  
Design Stage ◽  
Reliability Optimization ◽  
Fatigue Reliability ◽  
Engineering Structures ◽  
Sample Data ◽  
Use Stage

A large number of sample data is needed to ascertain the characteristic parameters of traditional membership function, so that the calculated fuzzy fatigue reliability based on this method has certain errors for engineering structures without enough samples. A fuzzy fatigue reliability analysis method based on self-configuring membership function is proposed, while considering its multi-source uncertainties in the design, manufacture, and use stage in order to accurately evaluate fatigue reliability of welded A-type frame. In this paper, a novel membership function was presented on account of a small amount of sample data, which some experimental results verified. The mathematical expression for failure probability was deduced from the suggested model, as well as fatigue reliability. Subsequently, the thickness of steel plate defined in design stage, the material properties of weld metal that is produced in manufacture stage, and the loads at different connection sites determined in use stage were all considered as the random variables, which were obtained from Latin hypercube sampling, and the fatigue limit of weld metal was deemed as the fuzzy variable. Based on the response surface method, the fuzzy fatigue reliability performance function was constructed to assess failure probability of welded A-type frame under the condition of downhill and turning braking with full load, while its fatigue reliability was found to be far less than 90%. The fuzzy fatigue reliability optimization that was based on genetic algorithm was implemented, which showed that its reliability varied from 69.47% to 95.12%.

Vibration Fatigue Reliability of Lead and Lead-Free Solder Joint by FORM/SORM

2007 ◽  
Vol 345-346 ◽  
pp. 1393-1396
Author(s):  
Ouk Sub Lee ◽  
Man Jae Hur ◽  
Yeon Chang Park ◽  
Dong Hyeok Kim
Keyword(s):  
Solder Joint ◽  
Failure Probability ◽  
Lead Free ◽  
Lead Free Solder ◽  
Fatigue Reliability ◽  
Probability Models ◽  
First Order ◽  
Reliability Method ◽  
Vibration Fatigue ◽  
Free Solder

It is well-known that the vibration significantly affect the life of solder joint. In this paper, the effects of the vibration on the failure probability of the solder joint are studied by using the failure probability models such as the First Order Reliability Method (FORM) and the Second Order Reliability Method (SORM). The accuracies of the results are estimated by a help of the Monte Carlo Simulation (MCS). The reliability of the lead and the lead-free solder joint was also evaluated. The reliability of lead-free solder joint is found to be higher than that of lead solder joint.

General Fishnet Statistics of Strength: Nacreous, Biomimetic, Concrete, Octet-Truss, and Other Architected or Quasibrittle Materials

2019 ◽  
Vol 87 (3) ◽  
Author(s):  
Wen Luo ◽  
Zdeněk P. Bažant
Keyword(s):  
Failure Probability ◽  
Three Dimensional ◽  
Strength Distribution ◽  
Particulate Composites ◽  
Material Microstructure ◽  
Engineering Structures ◽  
Quasibrittle Materials ◽  
Statistical Behavior ◽  
Octet Truss ◽  
Strength Models

Abstract The fishnet probabilistic model was recently developed to characterize the strength distribution of nacre-like biomimetic materials. It reveals that the unique fishnet-like connectivity of the material microstructure brings about enormous safety gain at the extremely low failure probability level of one out of a million, desired for engineering structures. The gist of the theory is that the material microstructure plays a determining role in its failure probability tail. Therefore, a carefully designed connectivity for a material microstructure not only enhances its mean strength but also significantly reduces its marginal failure risk. Here, we first show that the initially introduced series expansion and the newer formulation based on order statistics are, in the fishnet model, essentially equivalent. From that we develop a neat general form of the fishnet statistics. Then, we extend our theoretical approach to the strength distributions of architected nanomaterials such as the printed octet-truss carbon nanolattices, as well as to quasibrittle particulate composites such as concrete, and formulate a unified general fishnet statistics. We demonstrate that the octet-truss system can be physically seen and statistically treated as a union of three fishnets with three mutually orthogonal orientations. We show that the three-dimensional assembly of fishnets further enhances the tail strength at the 10−6 probability quantile, compared to two-dimensional (2D) fishnet statistics. We compare the performance of different statistical strength models by fitting of the simulated and experimental histograms data for the octet-truss nanolattice. Finally, we argue that, at the extreme lower tail of failure probability, quasibrittle materials such as concrete or fiber composites should partially exhibit the fishnet-type statistical behavior.

Service Information for Product Quality

2010 ◽  
Author(s):  
Kenji Iino ◽  
Masayuki Nakao
Keyword(s):  
Product Quality ◽  
Hard Work ◽  
Design Stage ◽  
Improve Design ◽  
Service Companies ◽  
Service Information ◽  
Design Production ◽  
Use Stage ◽  
Lifecycle Design

Engineering products go through 4 stages of lifecycle; design, production, use, and disposal. Engineers have developed tools for avoiding design flaws that cause troubles in the later stages. Accidents and malfunctions, however, still happen and some are even catastrophic. Once in the market, products require service. Whether scheduled, or unexpected, service is mostly carried out by subsidiaries of the manufacturer or sometimes unrelated specialists. When product troubles occur, service companies tend to seek solutions within their own organization without going back to the design stage. This approach may prove less costly, however, quick fixes may lead to disasters. Industries currently lack effective ways of feeding service information back to design. We analyzed some real accidents that took place in Japan where hard work in the use stage triggered the events. Information from the use stage to design will prevent accidents and also improve design to closely model reality.

Structural Reliability Optimization Design Based on Artificial Neural Network

2013 ◽  
Vol 834-836 ◽  
pp. 1877-1880
Author(s):  
Li Rong Sha ◽  
Yue Yang
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Economic Benefit ◽  
Optimization Design ◽  
Structural Reliability ◽  
Minimum Weight ◽  
Reliability Optimization ◽  
Fatigue Reliability ◽  
Surface Method ◽  
The Relationship

The ANN-based optimization design for considering fatigue reliability requirements on structure was proposed in this paper. The ANN-based response surface method was used to analysis fatigue reliability of the structure. The fatigue reliability requirements were taken as constraints while the structural weight as the objective function, the ANN model was performed to simulate the relationship between the fatigue reliability and geometry dimension of the structure, the optimization result of the structure with a minimum weight was obtained, thus can make economic benefit meanwhile ensure the safety of the structure.

scholarly journals Research on 3R Design of Straw Woven Living Products based on Green Design Concept

2020 ◽  
Vol 179 ◽  
pp. 01023
Author(s):  
Xiao-cong YAN ◽  
Xiu-li WANG ◽  
Dan-lin ZHAO
Keyword(s):  
Product Development ◽  
Implementation Strategies ◽  
Design Strategy ◽  
Green Design ◽  
Practical Significance ◽  
Design Stage ◽  
Development Path ◽  
Weaving Technology ◽  
Use Stage ◽  
Development Resource

Explore the 3R design strategy of straw woven living products from the perspective of green design. By analyzing the characteristics of traditional straw weaving technology, based on the principles of reduction, reuse and recyclability of 3R design, the green design strategy of straw woven living products is put forward, and the product development and life cycle are divided into design stage, use stage and abandoned stage, and the ideas of reduction, reuse and recycling and the implementation strategies of each link are put forward. Traditional straw weaving technology conforms to the idea of green design. The introduction of the 3R design strategy not only opens up the development path for the contemporary inheritance of traditional straw weaving technology, but also provides ideas for the realization of the green design of modern living products. The integration of straw weaving technology and 3R design will have important practical significance for cultural heritage, product development, resource conservation and environmental protection.

Seismic Hazard and Damages—Avoiding Disaster Through Simulation, Experiment, and Experience

1999 ◽  
Vol 121 (1) ◽  
pp. 30-36 ◽  
Author(s):  
H. Shibata
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Mechanical Engineering ◽  
Design Procedure ◽  
Shaking Table ◽  
Test Facility ◽  
Design Stage ◽  
Engineering Structures ◽  
Aseismic Design ◽  
Piping Systems

This paper deals with the role of proving tests and a large shaking test facility for equipment and piping systems in conjunction with the development of aseismic design in the field of mechanical engineering, especially for nuclear power plants in Japan. To avoid seismic disaster and damage of equipment and piping systems as well as liquid storages, we had to differentiate the seismic design procedure in mechanical engineering from that for building and civil engineering structures. For this process, the dynamic analysis in this field is more significant than for other fields. The author has been trying to develop aseismic design since the design stage of the first nuclear power plant in 1958 based on his experience as a specialist of mechanical vibration. In the early 1970s, shaking tables were developed for this purpose in Japan. The largest one in Japan is a 1000-ton 2-D table. After the 1995 Kobe earthquake, we have been developing a new 1200-ton 3-D shaking table. In the paper, the author discusses the necessity of such a facility and presents a new concept of a numerical shaking table.

Rubber fatigue evaluation for antivibration products and an S–N curve with a scatter band of 0.8

2021 ◽  
pp. 146442072110182
Author(s):  
Robert Keqi Luo
Keyword(s):  
Effective Stress ◽  
Fatigue Cracks ◽  
Design Procedure ◽  
Design Stage ◽  
Strong Correlations ◽  
Critical Plane ◽  
Average Standard Deviation ◽  
Engineering Structures ◽  
Fatigue Design ◽  
Fatigue Evaluation

Rubber antivibration products are widely used in engineering structures. An accurate evaluation on fatigue performance is a challenging issue during a design procedure. In this article, an effective stress approach was applied to multi-directional snubbing (MDS) mounts, AE2 and AE42 specimens. It was demonstrated that observed fatigue cracks were initiated at a place where the maximum effective stress was located. There were confirmed strong correlations between the effective stress and the number of failed cycles: R2 = 0.994 for AE2 with eight fatigue cases, R2 = 0.955 for AE42 with 16 cases and R2 = 0.917 for both AE2 and AE42 with 24 cases. A valuable S–N curve (covering from 2 × 102 to 3 × 106 cycles) of rubber (SBR with 67 hardness) was obtained (a scatter-band range of 0.8 with an average standard deviation of 14.3%). The scatter band includes both natural fatigue scattering and criterion accuracy. Less than 10% CPU time, compared with the critical plane search method, would only be required for evaluation on a fatigue case of a two-dimensional solid. These findings have shown that the proposed approach is reliable and can be considered in a suitable fatigue design stage. As the presented criterion was validated in limited contexts, more cases in antivibration design are required to support this approach.

scholarly journals Non-Linear Model Dynamics Analysis for Aerospace Engineering Structures Subjected to Non-Steady-State Random Loads

2020 ◽  
pp. 42-55
Author(s):  
O.N. Tushev ◽  
A.V. Belyaev ◽  
Yizhou Wang
Keyword(s):  
Steady State ◽  
Dynamic Properties ◽  
High Reliability ◽  
Aerospace Engineering ◽  
Design Stage ◽  
Engineering Structures ◽  
Non Linear ◽  
Coordinate Vector ◽  
External Forces ◽  
Non Linear System

In aerospace engineering, it is customary to employ stochastic analysis methods at the design stage to investigate how the mechanical system responds to random external forces. This is relevant due to high reliability requirements for spacecraft. We developed a method for probabilistic estimation of the dynamic properties of a structure subjected simultaneously to external (additive) and parametric (multiplicative) vibrations. An ordinary non-linear vector differential equation describes the vibrations in the elastic structure. Non-linear position and velocity properties of kinematic pairs may have cusps and discontinuities. We assume that the probabilistic dispersions of respective phase coordinates are close to the normal distribution of probability density. The initial non-linear vibration equations are statistically linearised. The system of differential equations is not rewritten in the canonical form, which means that it is possible to carry out the probabilistic analysis of the system for any external non-steady-state effect. The fundamental matrix of the linearised system is used to find the expected value vector and the correlation function matrix of the phase coordinate vector. The solution consists of a matrix integro-power series containing linear and quadratic terms. Using the method makes it possible to assess the contribution of each external force component to the total result. We consider an example of a non-linear system responding to a stepwise non-steady-state external influence.

Method of informational risk range evaluation in decision making

2020 ◽  
Vol 25 (3) ◽  
pp. 38-44
Author(s):  
Zinchenko A.O. ◽  
◽  
Korolyuk N.O. ◽  
Korshets E.A. ◽  
Nevhad S.S. ◽  
...  
Keyword(s):  
Decision Making ◽  
Decision Maker ◽  
Membership Function ◽  
Fuzzy Variable ◽  
Linguistic Variables ◽  
Predictive Values ◽  
Stochastic Uncertainty ◽  
Information Risk ◽  
Qualitative Nature ◽  
Quantitative Nature

Looks into evaluation of information provision probability from different sources, based on use of linguistic variables. Formation of functions appurtenant for its unclear variables provides for adoption of decisions by the decision maker, in conditions of nonprobabilistic equivocation. The development of market relations in Ukraine increases the independence and responsibility of enterprises in justifying and making management decisions that ensure their effective, competitive activities. As a result of the analysis, it is determined that the condition of economic facilities can be described and determined by the decision-maker, in the presence of the necessary information. The confidence of the decision-maker in the information received is different and the decisions made have a correspondingly different level of information risk. It is important to substantiate the procedure for assessing the numerical extent of information risk in decision-making based on the information obtained in conditions of uncertainty. The use of a linguistic variable in the processing of expert data presented in the form of a matrix of binary relations of values of the membership function, which allowed to move to further processing of knowledge to support decision-making in the management of industrial, commercial, financial and other activities. As a mathematical model for estimating the numerical measure of information risk when making decisions based on the information obtained in conditions of non-stochastic uncertainty, a model has been developed to model natural language uncertainties, which differs from existing ones by formalizing knowledge taking into account uncertainty of input information. Making such a clear decision in a fuzzy environment has appropriate values of effectiveness and risk. The paper proposes all the functions and accessories of indicators of both quantitative nature and qualitative nature to bring their values in the field of definition to one scale. Then the indicator of the effectiveness of decision-making will be a measure of the clarity of the cross-section of fuzzy subsets, which correspond to the introduced indicators of information risk. The condition of economic facilities can be described and determined by the decision-maker, if the necessary information is available. Decision-making on thenumerical measure of information risk must be determined by a set of basic indicators (criteria), which can be both quantitative and qualitative in nature. Predictive values of indicators should be determined in conditions of nonstochastic uncertainty. In this case, the indicators of a quantitative nature can be determined by fuzzy triangular numbers, which implement a high level of confidence in the subjective judgments of experts. Indicators of qualitative nature should be presented in linguistic variables. The values of the indicators of qualitative nature that are predicted must be considered for all fuzzy variable terms-sets of linguistic variables introduced into consideration. For any fuzzy variable, the introduction to the consideration of a clear set of values as carriers of the α-level of its membership function allows to reduce to a single interpretation of the predicted values of indicators of quantitative and qualitative nature in terms of non-stochastic uncertainty.

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