Dynamic reliability evaluation method for coupling faults of middle trough of scraper conveyor

{
  "publication_number": "US11155419B1",
  "country": "US",
  "kind": "B1",
  "title": "Dynamic reliability evaluation method for coupling faults of middle trough of scraper conveyor",
  "abstract": "The present invention discloses a dynamic reliability evaluation method for coupling faults of a middle trough of a scraper conveyor. Approximation precision of a moment-based saddlepoint approximation method and a function attribute of dynamic t-copula are fully utilized, and the dynamic reliability evaluation method for the coupling faults of the middle trough of the scraper conveyor is provided, so that dynamic correlation between failure modes of the middle trough of the scraper conveyor under a small sample condition is more accurately described, and accuracy of dynamic reliability evaluation of the coupling faults of the middle trough of the scraper conveyor is improved.",
  "claims": [
    "1. A dynamic reliability evaluation method for coupling faults of a middle trough of a scraper conveyor, comprising the following steps: step 1: defining a data collection time point, collecting data samples such as a crack length, a middle plate width, a fracture toughness, a yield strength and a fatigue load of the middle trough of the scraper conveyor at different operation time points, and counting first four moment probability information of each category of the data samples; step 2: respectively defining performance functions in two failure modes according to fracture failure criteria and static strength failure criteria of the middle trough of the scraper conveyor; step 3: on a basis of the first four moment probability information of each category of the data samples of the middle trough of the scraper conveyor, building a probability distribution function of each failure mode by using a moment-based saddlepoint approximation method, and calculating failure probabilities of fracture failure mode and static strength failure mode at different time points; step 4: building a dynamic probability correlation structure between the fracture strength mode and the static strength failure mode of the middle trough of the scraper conveyor by using a dynamic copula function, and further building a dynamic joint probability distribution function between the failure modes; and step 5: performing dynamic reliability evaluation on the coupling faults of the middle trough of the scraper conveyor in combination with the probability distribution function and the dynamic joint probability distribution function of each failure mode of the middle trough of the scraper conveyor and by using a system reliability theory.",
    "2. The dynamic reliability evaluation method for a coupling faults of a middle trough of a scraper conveyor according to claim 1, wherein for details in the step 1: the first four moment probability information of all the data samples of the middle trough of the scraper conveyor refers to a mean, a variance, skewness and kurtosis.",
    "3. The dynamic reliability evaluation method for coupling faults of a middle trough of a scraper conveyor according to claim 1, wherein for details in the step 2: the performance function of the fracture failure mode is defined according to whether a maximum stress strength factor of the middle trough of the scraper conveyor exceeds the fracture toughness or not, and the performance function of the static strength failure mode is defined according to whether a structure resistance of the middle trough of the scraper conveyor is greater than the fatigue load or not.",
    "4. The dynamic reliability evaluation method for a coupling faults of a middle trough of a scraper conveyor according to claim 1, wherein for details in the step 3: a form of the probability distribution function built by using the moment-based saddlepoint approximation method is F Y ⁡ (y) = Φ ⁡ [ω ye + 1 ω ye ⁢ ln ⁡ (υ ye ω ye)], wherein ω ye and ν ye are parameters of the function, and may be calculated by the following formulas: ω ye =sign(t e)√{square root over (2[y e t e −K Ys (t e)])} and ν ye =t e √{square root over (K Ys (2) (t e))} wherein y e represents a standardized variable of a performance function state variable, K Ys represents a cumulant generating function of the standardized variable, K Ys (2) represents a second derivative of the cumulant generating function, and t e represents a saddle point value, and may be calculated by the following formulas: t 1 = - (16 ⁢ ⁢ a 2 ⁢ a 3 + (y - a 1) 2) ⁢ b 2 - 4 ⁢ a 2 ⁡ (y - a 1) ⁢ b + 4 ⁢ a 2 2 + (y - a 1) ⁢ b + 2 ⁢ a 2 4 ⁢ ba 2 and t 2 = - (16 ⁢ ⁢ a 2 ⁢ a 3 + (y - a 1) 2) ⁢ b 2 - 4 ⁢ a 2 ⁡ (y - a 1) ⁢ b + 4 ⁢ a 2 2 + (y - a 1) ⁢ b + 2 ⁢ a 2 4 ⁢ ba 2, wherein y is a second-order reliability index of the performance function, t 1 and t 2 represent two solutions of the saddlepoint equations, and a value meeting calculation reasonability is taken as a saddle point value in practical calculation; and a 1 = - 9 ⁢ θ Ys 3 2 ⁢ (η Ys - 3) 2, a 2 = - 3 ⁢ θ Ys 3 + 2 ⁢ η Ys - 6 4 ⁢ (η Ys - 3), a 3 = 27 ⁢ θ Ys 4 4 ⁢ (η Ys - 3) 3, b = η Ys - 3 3 ⁢ θ Ys wherein θ Ys and η Ys respectively represent skewness and kurtosis of the performance function.",
    "5. The dynamic reliability evaluation method for a coupling faults of a middle trough of a scraper conveyor according to claim 1, wherein for details in the step 4: the dynamic copula function uses a dynamic t-copula function in a form: C t ⁡ (u 1, u 2 ❘ ρ, k) = ∫ - ∞ t k - 1 ⁡ (u 1) ⁢ ∫ - ∞ t k - 1 ⁡ (u 2) ⁢ 1 2 ⁢ π ⁢ 1 - ρ 2 ⁡ [1 + s 2 - 2 ⁢ ρst + t 2 k ⁡ (1 - ρ 2)] - (k + 2) / 2 ⁢ dsdt, wherein k and ρ are parameters of the dynamic t-copula function, k is an invariable parameter, and ρ is a time-varying parameter; a value of the time-varying parameter ρ at different time points is obtained in combination with the data samples collected at different time points through a maximum likelihood estimation method; and u 1 and u 2 represent obtained failure probabilities in the fracture failure mode and the static strength failure mode through calculation in the step 3.",
    "6. The dynamic reliability evaluation method for a coupling faults of a middle trough of a scraper conveyor according to claim 1, wherein for details in the step 5: according to an obtained failure probabilities u 1 and u 2 in the fracture failure mode and the static strength failure mode of the middle trough of the scraper conveyor in the step 3, and the obtained dynamic joint probability distribution function between the two failure modes in the step 4, dynamic reliability of the coupling faults of the middle trough of the scraper conveyor is calculated by the following formula, specifically: P f =u 1 +u 2 −P (u 1,u 2 |ρ), wherein P(u 1,u 2 |ρ) is a joint failure probability obtained through calculation according to the dynamic joint probability distribution function in the step 4; and through calculation on reliability at different time points, the dynamic reliability evaluation on the coupling faults of the middle trough of the scraper conveyor is obtained."
  ],
  "description_excerpt": "The present invention relates to the technical field of mine transportation equipment, and particularly relates to a dynamic reliability evaluation method for coupling faults of a middle trough of a scraper conveyor.\n\nDeep resource development and utilization is a national development strategy, a scraper conveyor is key equipment to achieve deep resource development, and safe and stable operation of the scraper conveyor has important significance on realization of coal mining. Operation conditions of underground transportation equipment are complicated, and work conditions are extremely poor, so that the performance degradation process of equipment such as the scraper conveyor is intensified, and the actual service life of the equipment is reduced. Therefore, accurate and reasonable evaluation and prediction on reliability of key components of the scraper conveyor are of great significance on guaranteeing safe operation of the equipment and improving economic benefits. A middle trough of the scraper conveyor is a machine body of the scraper conveyor and consists of a middle plate, trough upper steel and the like, an upper trough is used for transporting coal, and a lower trough is used for returning of a scraper chain. The middle trough of the scraper conveyor is a main body and a main failure part of the scraper conveyor, so that the service life and reliability of the middle trough are very important for safe and efficient coal mining and economic benefits of enterprises.",
  "cpc": [
    "B65G 43/02",
    "B65G 19/28",
    "B65G 2203/0275",
    "B65G 2812/02891",
    "G06F 17/00",
    "G06F 17/17",
    "G06F 17/18",
    "G06F 30/20",
    "G06Q 10/0639"
  ],
  "ipc": [
    "B65G 19/28",
    "B65G 43/02",
    "G06F 17/17",
    "G06F 17/18"
  ],
  "assignees": [
    "China University of Mining and Technology Beijing CUMTB"
  ],
  "inventors": [
    "Hao Lu",
    "Zhencai Zhu",
    "Fan Jiang",
    "Wei Li",
    "Yuxing Peng",
    "Gongbo Zhou",
    "Gang Shen",
    "Dagang WANG",
    "Yu Tang",
    "Xiang Li"
  ],
  "filing_date": "2019-07-26",
  "publication_date": "2021-10-26",
  "grant_date": "2021-10-26",
  "priority_date": "2019-05-21",
  "application_number": "US-201917042952-A",
  "family_id": "68002001",
  "cited_by_count": 1,
  "citations": [
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}