Reliability Bounds based on Universal Generating Function and Discrete Stress-strength Interference Model

A method for estimating the component reliability is proposed when the probability density functions of stress and strength can not be exactly determined. For two groups of finite experimental data about the stress and strength, an interval statistics method is introduced. The processed results are formulated as two interval-valued random variables and are graphically represented component reliability are proposed based on the by using two histograms. The lower and upper bounds of universal generating function method and are calculated by solving two discrete stress-strength interference models. The graphical calculations of the proposed reliability bounds are presented through a numerical example and the confidence of the proposed reliability bounds is discussed to demonstrate the validity of the proposed method. It is showed that the proposed reliability bounds can undoubtedly bracket the real reliability value. The proposed method extends the exciting universal generating function method and can give an interval estimation of component reliability in the case of lake of sufficient experimental data. An application example is given to illustrate the proposed method

Improved Discrete Interval-Valued Stress-Strength Interference Model Based on Extended Universal Generating Function

In practical engineering,sometimes the probability density functions( PDFs) of stress and strength can not be exactly determined,or only limited experiment data are available. In these cases,the traditional stress-strength interference( SSI) model based on classical probabilistic approach can not be used to evaluate reliabilities of components. To solve this issue, the traditional universal generating function( UGF) is introduced and then it is extended to represent the discrete interval-valued random variable.Based on the extended UGF,an improved discrete interval-valued SSI model is proposed, which has higher calculation precision compared with the existing methods. Finally,an illustrative case is given to demonstrate the validity of the proposed model.

Well interference evaluation considering complex fracture networks through pressure and rate transient analysis in unconventional reservoirs

Severe well interference through complex fracture networks(CFNs)can be observed among multi-well pads in low permeability reservoirs.The well interference analysis between multi-fractured horizontal wells(MFHWs)is vitally important for reservoir effective development.Well interference has been historically investigated by pressure transient analysis,while it has shown that rate transient analysis has great potential in well interference diagnosis.However,the impact of complex fracture networks(CFNs)on rate transient behavior of parent well and child well in unconventional reservoirs is still not clear.To further investigate,this paper develops an integrated approach combining pressure and rate transient analysis for well interference diagnosis considering CFNs.To perform multi-well simulation considering CFNs,non-intrusive embedded discrete fracture model approach was applied for coupling fracture with reservoir models.The impact of CFN including natural fractures and frac-hits on pressure and rate transient behavior in multi-well system was investigated.On a logelog plot,interference flow and compound linear flow are two new flow regimes caused by nearby producers.When both NFs and frac-hits are present in the reservoir,frac-hits have a greater impact on well#1 which contains frac-hits,and NFs have greater impact on well#3 which does not have frac-hits.For all well producing circumstances,it might be challenging to see divergence during pseudosteady state flow brought on by frac-hits on the logelog plot.Besides,when NFs occur,reservoir depletion becomes noticeable in comparison to frac-hits in pressure distribution.Application of this integrated approach demonstrates that it works well to characterize the well interference among different multi-fractured horizontal wells in a well pad.Better reservoir evaluation can be acquired based on the new features observed in the novel model,demonstrating the practicability of the proposed approach.The findings of this study can help for better evaluating well interference degree in multi-well systems combing PTA and RTA,which can reduce the uncertainty and improve the accuracy of the well interference analysis based on both field pressure and rate data.

Horizontal Well Interference Performance and Water Injection Huff and Puff Effect on Well Groups with Complex Fracture Networks:A Numerical Study

Well interference has become a common phenomenon with the increasing scale of horizontal well fracturing.Recent studies on well interference in horizontal wells do not properly reflect the physical model of the postfracturing well groups and the realistic fracturing process of infill wells.Establishing the correspondence between well interference causative factors and manifestations is of great significance for infill well deployment and secondary oil recovery.In this work,we develop a numerical model that considers low velocity non-Darcy seepage inshale reservoirs to study the inter-well interferencephenomenon that occurs in theSantanghufield,andconstruct an explicit hydraulic fracture and complex natural fracture network model with an embedded discrete fracture model,focusing on the effect of fracture network morphology on well interactions.The model also considers a multi-segment wellbore model to accommodate the effect of inter-well crossflow on wellbore tubular flow.The changes in formation pressure and water saturation during fracturing are performed by controlling the injection pressure and water injection rate.The result shows that the shape of the fracture network generated by the infill well with the old well determines the subsequent fluid and oil-increasing performance of the disturbed well.The synergistic production or competitive relationship formed by fractures with different connectivity between the two wells determines the positive and negative effects of the interference.The paper also investigates the adaptation study of water injection huff and puff schemes for well groups with different connectivity,and demonstrated a potential yield increase of up to 10.85%under adaptation injection.This method of identifying well interference based on the production dynamics of affected wells and the subsequent corresponding water injection method provides valuable references for the selection of secondary oil recovery measures.

Reliability Analysis of Systems with Common Cause Failure Based on Stress-Strength Interference Model

Many mechanical systems have the characteristics of multiple failure modes and complex failure mech- anisms. On the basis of stress-strength interference （SSI） model, this paper takes the mechanical system with common cause failure （CCF） as the research object. The relationship between the stress distribution and the strength distribution is studied, and the failures of components are independent of each other under the determin- istic stress. Then, the concept of conditional reliability is introduced to build the system reliability models under the action of one-stress and multi-stress for both series and parallel systems. Finally, the corresponding properties of the DrODosed methods are discussed to show their advantages.

FATIGUE RELIABILITY CALCULATION MODEL FOR COMPONENT UNDER RANDOM LOADING

in reliability design of fatigue under random loading, the influence of loading se-quence must be considered. In order to avoid the uneertain hypothesis in the Miner's rule, ie. thatthe sum of damage equals one represents failure, this paper proposes the probabilistic relativeMine's rule. This paper also presents a new method for calculating reliability, ie. the syntheticmethod of Miner's rule and interference model. This model considers not only the influence ofstress concentration, dimension and surface, but also the influence of stress amplitude and se-quence.

基于离散模型的内超环面齿轮干涉检验方法

针对内超环面齿轮齿面加工局部和全局干涉现象,提出一种干涉检验方法,有效地避免了加工干涉。通过干涉检验面簇的引入和干涉检验线簇的构造,将内超环面齿轮齿面和刀具扫掠体离散化。运用内超环面齿轮齿面和刀具扫掠体离散模型,通过截平面处刀具中心的求解,确定内超环面齿轮齿面加工局部和全局干涉区域。通过实例分析进一步验证了内超环面齿轮齿面加工干涉检验方法的可行性。

车铣复合数控加工仿真系统的开发研究

介绍了开发车铣复合数控加工仿真系统的目的,给出了自主开发车铣复合数控加工仿真系统的方案和总体框架、模型建立以及开发过程中的关键性技术.