摘要
应用数理统计方法,对钢制薄壁外压球形封头稳定性的不确定性特征进行分析。基于信息熵中模糊性度量与随机性度量相等可实现模糊变量等效随机变量的原理,将钢制薄壁外压容器的模糊临界失稳强度和模糊载荷分别等效为随机强度和随机载荷,讨论按我国标准设计与制造的钢制薄壁外压容器稳定性的模糊可靠度;从控制钢制薄壁外压容器稳定性在正常操作与压力试验时模糊可靠度的角度,对其稳定性安全系数、外压试验压力系数与超压限制系数进行探索。研究表明,(1)薄壁外压球形封头临界失稳强度的实测值与理论预测值之比,是基本符合正态分布的模糊变量。(2)在保持外压差的气压与液压试验时,薄壁外压球形封头稳定性的模糊可靠度分别为0.999 998 714与0.999 998 708;薄壁外压圆筒稳定性的模糊可靠度分别为0.999 999 999 999 997 94与0.999 999 999 999 997 85。在正常操作时,薄壁外压球形封头稳定性的模糊可靠度为0.999 998 631;薄壁外压圆筒稳定性的模糊可靠度为0.999 999 999 999 981 3。(3)从等可靠度的观点认为,薄壁外压球形容器稳定性的模糊可靠度在气压与液压外压试验时应分别不低于0.999 998 714与0.999 990 226,在正常操作时应不低于0.999 998 631;薄壁外压圆筒稳定性的模糊可靠度在气压与液压外压试验时应分别不低于0.999 999 991 40与0.999 990 226,在正常操作时应不低于0.999 999 991 40。(4)薄壁外压球形容器稳定安全系数应不小于14.53;薄壁外压圆筒稳定性安全系数应不小于2.30。(5)薄壁外压球形容器试验压力系数在气压外压试验时等于1.00,在液压外压试验时应不小于1.04但不大于1.30;薄壁外压圆筒试验压力系数在气压外压试验时应不小于1.04但不大于1.19,在液压外压试验时应不小于1.04但不大于1.42。(6)在气压与液压外压试验时,薄壁外压球形容器的超压限制系数在失稳失效准则下应分别不大于0.068 82与0.089 62,薄壁外压圆筒的超压限制系数在失稳失效准则下应分别不大于0.517 78与0.620 26。
By using the method of statistics,the non-definitive characteristic of the steel thin wall external pressure spherical heads stability was analyzed.The fuzzy critical strength in buckling and fuzzy load variables were transferred into related random ones of steel thin wall external pressure vessels,respectively,based on the information entropy theory that fuzzy entropy was equal to probability entropy.The fuzzy buckling critical strength reliability was quantitatively analyzed of steel thin wall external pressure vessels under pressure tests keeping external pressure quantitative difference and normal operation.The fuzzy stability reliability,buckling safety factor,external testing pressure coefficient and overpressure confining coefficient of steel thinness wall external pressure vessels during normal operation and pressure tests were quantitatively analyzed based on the information entropy theory.The researching results show that：（1） For the steel thin wall external pressure spherical vessels or spherical heads,the rate is a fuzzy variable with normal distribution that between the testing data of critical strength in buckling and the theoretical expected.（2） When keeping external pressure quantitative difference of barometrical or hydraulic pressure tests,for the steel thin wall external pressure spherical vessels or spherical heads,the fuzzy reliability of stability is equal to 0.999 998 714 or 0.999 998 708,and for the steel thin wall external pressure cylinders,the fuzzy reliability of stability is equal to 0.999 999 999 999 997 94 or 0.999 999 999 999 997 85.Under normal operation,for the steel thin wall external pressure spherical vessels or spherical heads,the fuzzy reliability of stability is equal to 0.999 998 631,and for the steel thin wall external cylinders,the fuzzy reliability of stability is equal to 0.999 999 999 999 981 3.（3） From the equal-reliability point of view,for fuzzy stability reliability of steel thin wall external pressure spherical vessels or spherical heads,the desirable value should be not less than 0.999 998 631 during normal operation,and the desirable values not less than 0.999 998 714 or 0.999 990 226 under barometrical or hydraulic pressure tests.For fuzzy buckling critical strength reliability of steel thin wall external cylinders,the desirable values should be not less than 0.999 999 991 40 during normal operation and not less than 0.999 999 991 40 or 0.999 990 226 under barometrical or hydraulic pressure tests,respectively.（4） For spherical vessels or spherical heads,the buckling safety factor should be not less than 14.53;and for the cylinder vessels,the buckling safety factor should be not less than 2.30.（5） The external testing pressure coefficient of spherical vessels or spherical heads should be not less than 1.04 and not greater than 1.30 for hydraulic pressure tests,and equal to 1.00 for barometrical pressure tests;the external testing pressure coefficient of cylinder vessels should be not less than 1.04 and not greater than 1.19 for barometrical pressure tests,and not less than 1.04 and not greater than 1.42 for hydraulic pressure tests.（6） Under barometrical or hydraulic external pressure tests,for the spherical vessels and spherical heads,the overpressure confining coefficient should not be greater than 0.068 82 or 0.089 62,and for the cylinder vessels,the overpressure confining coefficient should not be greater than 0.517 78 or 0.620 26.
出处
《机械强度》
CAS
CSCD
北大核心
2011年第2期217-224,共8页
Journal of Mechanical Strength
基金
湖北省教育厅科研项目(B20087301)的部分内容
武汉市教育局重点科研项目(2008K027)
武汉市创新人才开发资金重大创新专项资助项目~~
关键词
薄壁外压容器
稳定性
临界失稳强度
模糊可靠度
外压试验压力系数
稳定安全系数
超压限制系数
Thin wall external pressure vessels
Stability
Critical strength in buckling
Fuzzy reliability
External testing pressure coefficient
Buckling safety factor
Overpressure confining coefficient
