Analysis of Load-Enhanced Factor(LEF) of MIL-P-25690B Acrylic Glass

MIL-P-25690B acrylic glass is one of the primary materials currently used in transparent structural components of civil aircraft. In order to shorten the time of fatigue tests and reduce the cost, the load-enhanced factor (LEF) method is used for fatigue tests. The fatigue test load multiplies the LEF, which is amplified in the fatigue test. LEF, sample sizes, and fatigue test duration are correlated according to the CMH-17 composite materials handbook. According to MIL-P-25690B acrylic glass, the test scheme of LEF is determined; test results, test data analysis, and processing method are given. The relationship between LEF and the corresponding test duration under certain conditions is obtained, which provides a theoretical basis and analysis support for fatigue tests of transparent parts of civil aircraft.