Preparation And Life Prediction Of Aerospace Seals Under Extreme Conditions

During high-speed flight and landing,the aircraft needs to experience a temperature difference of hundreds of degrees Celsius,which is a huge challenge for seals.Silicone rubber has excellent high and low temperature resistance and weather resistance,so it is widely used in the aerospace field.For the seal of the landing gear door,this paper selects silicone rubber as the base rubber,which can ensure its high temperature resistance,and then adjust the formula to finally produce high tear strength silicone rubber.Finally,the fatigue life of high tear strength silicone rubber is predicted by finite element method.In order to prepare products with stable performance,this paper firstly characterizes the molecular weight and molecular weight distribution of raw rubber,cold resistance and thermal stability of raw rubber,in order to establish a more perfect characterization system for raw silicone rubber.This experiment hopes to provide technical support for the preparation of silicone rubber products with stable performance.In the process of preparing high tear strength silicone rubber,the effect of the combination ratio of vinyl content of 0.08% and 0.22% on the properties of silicone rubber was studied.It was found that with the increase of vinyl content in the combined rubber,the t90 of silicone rubber was reduced,the crosslinking density of the vulcanizate is increased,the tensile strength and elongation at break are gradually decreased,and the tear strength is decreased.In addition,this experiment studied the effects of DBPMH,silica,hydrogen-containing silicone oil and their levels on the mechanical properties of silicone rubber through orthogonal experimental design,and found that hydrogencontaining silicone oil had the greatest impact on the tear strength of silicone rubber.On the basis of this experiment,raw rubber with vinyl content of 0.04%,0.05% and 0.08%was selected,and 3phr hydrogen-containing silicone oil was added respectively.It was found that hydrogen-containing silicone oil can significantly improve the tear strength of silicone rubber,and the tear strength of silicone rubber with a vinyl content of 0.08%reached 45 k N/m.At the same time,adding hydrogen-containing silicone oil can improve the hardness,tear strength and elongation at break of the vulcanizate,but the tensile strength of the vulcanizate was reduced.Finally,silicone rubber with a vinyl content of 0.08% was selected to study the effect of the amount of hydrogen-containing silicone oil on the properties of silicone rubber.It was found that the G2 compound with1.5 phr hydrogen-containing silicone oil had the best comprehensive performance,with a tensile strength of 10.41 MPa and an elongation at break.The rate is 496%,the tear strength reaches 49 k N/m,and it has good low temperature resistance.Based on the fatigue crack growth theory of rubber materials,the fatigue crack growth test platform built by this research group is combined with finite element to predict the fatigue life of the prepared high tear strength silicone rubber.It is found that the fatigue life of G2 is the largest,reaching 643.4 million seconds,it is the most excellent anti-fatigue crack growth among the prepared high tear strength silicone rubbers.