橡胶"O"形密封圈结构参数和失效准则研究

利用大变形、接触的非线性有限元理论建立了某固体火箭发动机密封结构的二维轴对称模型,用有限元软件计算出该结构在工作状态下的变形和应力。通过计算可知,在橡胶“O”形密封圈与上下法兰接触的位置产生最大的接触压应力,在密封槽槽口转角位置产生最大的剪切应力。对密封性能的各结构参数进行了分析,讨论了上下法兰张开间隙、初始压缩率、密封槽槽口及槽底倒角半径、密封槽宽、密封圈材料等典型参数的影响:上下法兰张开间隙、密封圈的初始压缩率对最大接触压应力的影响较大,而密封槽槽口和槽底处倒角半径对剪切应力影响明显。三维壳体结构的有限元分析结果表明,上下法兰在内压作用下产生不均匀的张开间隙,体现了三维结构的特点。不均匀的张开间隙与二维轴对称结果对比可知,以最小间隙作为设计间隙,二维轴对称分析模型可取代三维模型来分析该结构的密封性能。最后,确定了“O”形圈密封结构的最大接触应力和剪切应力失效准则。

Investigation on structure parameters and failure criteria of "O"-type rubber sealing ring

2D axisymmetric model of sealing ring structure f or SRM was derived by using nonlinearity finite element theory of large deformat ion and contact problem.The deformation and the stress of sealing ring structur e were calculated by finite element software.The results show that there exists maximum contact stress at the contact area of "O"-type rubber sealing ring an d upper and lower flange,and there exists maximum shear stress at the notch of s eal groove.Some typical structure parameters of the seal were analyzed,and the e ffects of the typical parameters were discussed,such as the gap breadth between upper and lower flange,initial compressibility,fillet radii of notch and bottom of seal groove,groove width and sealing ring material.The gap breadth and initia l compressibility have great effect on the maximum contact stress,and fillet rad ii of notch and bottom of seal groove have obvious effect on the maximum shear s tress.Finite element analysis results of 3D case structure show that non-unifor m gap appears between upper and lower flange under the internal pressure,which c haracters feature of 3D structure.Based on non-uniform gap and 2D axisymmetric results and taking the minimum gap as design gap,2D axisymmetric model can ratio nally take the place of 3D model to analyze the seal performance.Finally failure criteria of the maximum contact stress and shear stress of "O"-type rubber s ealing ring was determined.