Development of Structural Monitoring and Inspection on Baysian Reliability Analysis

本文讨论了结构监测和检验在贝叶斯可靠性分析中的适用性。主要研究结果如下：(1)疲劳失效结构的寿命具有高度的不确定性和风险性。为了设计这样的系统，有必要考虑几个随机因素。随着结构的老化，初始成本、检测、维修和可靠性水平之间的关系变得越来越重要，必须从成本效益的角度对其进行研究，以实现良好的设计。本文分析了这种关系，并提出了一种基于欠设计和过设计概念的新型贝叶斯损失函数在结构尺寸方案中进行最优决策的方法。(2)对金属结构疲劳监测的两种方法进行了实验研究：疲劳裂纹检测和疲劳寿命预测。作为检测方法，在实验基础上制作了导电薄膜传感器、导电涂料传感器、塑料光纤传感器、玻璃纤维传感器和碳纤维传感器。将传感器粘接在焊接模型和致密试件的表面，通过疲劳试验检验了传感器的性能，并研制了粘结型疲劳试件指示器。票面主体为中心裂纹薄板，长60 mm，宽10 mm，厚0.25 mm，材质为低碳钢。板的中部长度涂有特氟龙膜，整个板夹在两个薄的环氧树脂板之间。用粘结剂将试件粘接在光滑试件上，通过脉动拉伸和全逆疲劳试验研究了试件的性能。(3)对光纤应变测量的可行性进行了研究。

In the present investigation, the applicability of structural monitoring and inspection on Baysian reliability analysis are discussed. The main results are summarized as follows ;(1) Life of structures which are subject to fatigue failures involves high degree of uncertainty and risk. In order to design such systems it is necessary to take into account several stochastic elements. As the structure ages, the relationship among initial cost, inspections, maintenance and reliability level becomes important, and it has to be studied in order to achieve a good design from the costeffectiveness point of view. This paper analyzes this relationship and proposes a method to take the best decision among a set of alternatives structural regarding structural dimensions using a new class of Baysian loss functions that are based on the concepts of under and over design.(2) Two type of fatigue monitoring methods are experimentally examined for metal structures ; fatigue crack detection and fatigue life prediction.As the detection method, five kinds of crack sensors, i.e., conductive film-sensor, conductive-paint sensor, plastic optical-fiber sensor, glass optical-fiber sensor and carbon-fiber sensor are made on an experimental basis. The sensors are bonded on the surface of a welded joint model and a compact specimen by adhesives or painting, and performances of each sensor are examined through the fatigue tests.As the prediction method, a fatigue coupon indicator of adhesive-type is developed. The main body of the coupon is a center cracked thin plate with 60mm-long, 10mm-width and 0.25mm-thickness, madefrom mild steel. The middle part in length of the plate is coated by Teflon film and the whole is sandwiched in between two thin epoxy resin plates. The coupon is bonded on a smooth specimen by adhesives, and the performance is investigated by pulsating tension and fully reversed fatigue tests.(3) We try to investigate on possibility of strain measurement by optical fiber.