复合材料层压板的安全系数与可靠度

SAFETY FACTOR AND RELIABILITY FOR COMPOSITE LAMINATES

1.引言 在飞机结构设计中考虑到载荷的特性、材料的特性、设计和制造中的不确定性等因素,通常用一个笼统的安全系数来概括。安全系数可有不同的定义,在飞机结构静强度设计中常用的安全系数f的定义是设计载荷(极限载荷)与使用载荷(限制载荷)之比。安全系数是一个设计系数,它提供了一种保证。

In the aircraft design the safety factor / is a design limit load of struc-turs in the ultimate load of structure. It provides guarantee for certain degree of safety. In fact, from the reliability design point of view, both the strength and load are random variables obeying certain distributions. Therefore, the concept of simple safety factor of reliability fx is introduced. It concerns with coefficient of variation of normal distribution and reliability index and it only adopts to simple elements or a single failure mode of a structure. For composite laminates the concept of comprehensive reliability safety factor based on reliability analysis is presented and its rangs is given. Comprehensive reliability safety factor relates to the disperse degree of strength and load and the value of required reliability. Several failure modes of laminate, different load group and the effect of structural parameters of laminate are also considered. The application of comprehensive reliability safety factor is convenient as general safety factor and its characteristics is better than simple safety factor of reliability.