考虑检测维修更新的船体梁时变可靠性分析

目前对服役期内船舶时变可靠性的分析,主要考虑疲劳和腐蚀这两类损伤随时间累积对剖面模数的影响,但很少考虑检测维修因素对损伤的修复作用.本文以某疏浚船为例,通过Matlab软件编程,以船体梁总纵强度为分析对象,建立极限状态方程,定量计算疲劳和腐蚀随时间对剖面模数造成的折减,并定量分析了疲劳裂纹和腐蚀板件检测维修的影响,对船舶的时变可靠性进行分析.计算结果表明,疲劳裂纹和腐蚀损伤随时间累积均会引起船体梁时变可靠度降低,且腐蚀是时变可靠度降低的主要因素;对裂纹和腐蚀板件的检测维修能恢复船舶的可靠度,时变可靠度恢复的效果与裂纹检测精度和腐蚀板件最小允许折减量比率有关.建议在后续研究中将对损伤的检测维修因素纳入分析.

Time-variant reliability analysis of ship hull girder subjected to updating in inspection

Currently, time-variant reliability analysis of ships in service is mainly based on mid-ship section degrada-tion due to fatigue and corrosion, while inspection rarely taken into consideration, which does exist during service life of ships. Taking a dredger as an example, this paper gives the limit state function according to the structural failure of ship hull girder and analyzes its time-variant reliability. Cracks and corroded plates on the ship get inspected and repaired at certain in-tervals during service life. The influences on mid-ship section modulus of such inspection are quantified as well as the sec-tion modulus degradation due to fatigue and corrosion. The program was in Matlab. Results show that fatigue cracks and cor-rosion reduce reliability as time goes by, in which the effect of corrosion is the main factor and that inspection can increase reliability to some extent which is affected by the accuracy of crack inspection and the minimum allowed reduction ratio of corroded plates. It is suggested that inspection should be taken into consideration in further researches on time-variant reliability.