复合材料结构设计的使用安全系数

 飞机结构设计使用安全系数的研究已有50多年的历史。虽然美国在1934年以后定安全系数为1.5,各发达国家也都先后统一为1.5,但由于航空科技的发展,使用材料的变化,这个问题一直争论到现在。 本文从飞机结构设计安全系数的发展历史及其变化根据出发,阐述其选用的原则,并结合当前碳纤维增强树脂基复合材料在航空结构上的应用情况,提出安全系数选用的一些分析和看法。

APPLIED SAFETY FACTOR IN DESIGN OF COMPOSITE MATERIAL STRUCTURES

The argument about applied safety factor in design of aircraft structures has been disputed for more than fifty years. At the beginning it was oniy considered to select a factor according to experience in practice to guarantee the safety. Some designers took five times as much as the applied load in structural design and test. Obviously this approch is not very reliable. The name' load factory' did not appear untill 1920s. In 1934 some Americans first took 1.5 as the safety factor, then people in other developed countries followed. However, as the aeronautical technology has been developing and various materials are being used, it is necessary that the safety factor be further discussed now.In general, there are two theories in this field. One is olassical, i. e. to take a fixed figure is 1.5 as safety factor. Another is based on probability. The former is simple and easy to ultilize, but not exact. The later is considered to be better, but more complicated and difficult, having to be varified by a great many of tests.This paper will discuss the classical theory of safety factor and make a comparison between the two theories, and then present a principle of selecting the safety factor. Finally, some examples and ideas to analyse the safety factor used in composite material structures will be given.