STUDY ON DAMAGE TORERANT DESIGN OF SHIP STURUCTURES

损伤容限设计是一种在设计阶段综合考虑在役检查、维修和结构监测的结构设计方法。本研究开展了以下五个与损伤容限设计相关的研究项目：(1)用于应力监测的高灵敏度牺牲试件；(2)基于压电式元件的应力历史测量传感器；(3)基于产品模型的船舶检测支撑系统；(4)考虑腐蚀影响的船舶结构检测规划；(5)用于疲劳强度评估的固有损伤区模型。其中，第(1)项和第(2)项取得了显著的效果。第(1)项的高灵敏度牺牲试件是一种小尺寸的疲劳试件，其设计使得当试件固定在结构构件上时，可以充分早地在试件中产生疲劳损伤。在这项研究中，开发了一种用粘结剂固定在结构构件上的试件。The…更多的目的是为了估计结构构件的长期应力分布水平。通过试件的疲劳试验和实际集装箱船的疲劳试验，发现牺牲试件可以预测实际构件的长期应力。该传感器是一个90 mm×60 mm×25 mm的铝薄板矩形盒子，其中包括压电元件、包括积分电路、纽扣式电池、通断开关、使用LED的应力水平仪和应力水平交叉计数器在内的电路。应力水平计可根据应力水平的变化点亮和关闭不同颜色的二极管。应力水平交叉计数器可以显示监测期间超过特定应力水平的循环次数。使用粘合剂将传感器粘接在结构编号上。通过实验室的多次试验，发现该传感器可以监测结构的应力历史。较少

Damage tolerant design is a design method of structures considering in-service-inspections, repair actions and structural monitoring at the design stage. In this study, the following five research items related with damage tolerant design are carried out.(1) high-sensitivity sacrificial specimen for stress monitoring.(2) stress history measurement sensor using piezoelectric element.(3) inspection supporting system of ships by the use of product model.(4) inspection planning of ship structures considering corrosion effects.(5) inherent damage zone model for fatigue strength evaluation.Among them, remarkable results are obtained for the items (1) and (2).High-sensitivity sacrificial specimen of item (1) is a small sized fatigue coupon which is designed so that fatigue damage may be produced in the specimen sufficiently earlier when it is secured to the structural member. In this study, a coupon specimen which is secured onto the structural member by using adhesive agent is developed. The … More purpose is to estimate the level of long-term stress distribution working on structural member. From the fatigue tests using specimens and using a real container ship, it is found that the sacrificial specimens can predict the long-term stress of actual members.Stress sensor using piezoelectric element of item (2) is developed to monitor the stress history of structural member. The sensor is a rectangular box(90mmX60mmX25mm) made of thin aluminum plate, in which piezoelectric element, electric circuit, including integrating circuit, button type battery, make and break swich, stress level meter using LED and stress level cross counter are facilitated. The stress level meter can light on and off different color diodes according to the change of stress level. The stress level cross counter can display the number of cycles which exceeds a specific stress level during the monitoring period. The sensor is bonded onto the structural number by using adhesive agent. Through the several tests in the laboratory, it is found that the sensor can monitor the stress history of structures. Less