热膨胀性能对炭/炭复合材料在制动摩擦过程中热应力场的影响

Effect of thermal expansion on stress field of C/C composites during braking

测量以纯树脂炭、粗糙层热解炭和光滑层热解炭为基体的3种炭/炭复合材料的热膨胀系数,并采用有限元分析软件,模拟这3种炭/炭复合材料在飞机正常着陆能量条件下的热应力场,研究热膨胀系数对炭/炭复合材料热应力场及其摩擦性能的影响。结果表明:3种炭/炭复合材料在z方向上的热膨胀系数大于在x和y方向的,且热膨胀系数均随着温度的升高而逐渐增大,其中,基体为粗糙层热解炭的炭/炭复合材料的热膨胀系数最小,纯树脂炭试样的次之,光滑层热解炭试样的最大;在制动过程中,炭/炭复合材料摩擦表面产生的热应力与材料的热膨胀系数相关,材料的热膨胀系数越大,产生的热应力越大;过大的热应力使纯树脂炭试样具有相对稳定的摩擦曲线,在较大热应力的作用下,光滑层热解炭试样的摩擦曲线不稳定,影响其摩擦性能。

The coefficient of thermal expansion（CTE） of three C/C composites with resin carbon matrix,rough lamination pyrocarbon matrix,and smooth lamination pyrocarbon matrix were measured,the finite element analysis software was applied to calculating the stress field of three different C/C composites under the conditions of normal landing energy,and the influence of CTE on the stress field and frictional behavior during braking was studied.The results show that CTE in direction z is larger than that in directions x and y,and CTE becomes larger with the increase of temperature.CTE of the sample with rough lamination pyrocarbon matrix is the smallest,and that of the sample with smooth lamination pyrocarbon matrix is the largest.Correspondingly,the larger the thermal stress,the larger the CTE.Furthermore,large thermal stress makes the sample with resin carbon have a relatively stable friction curve.But the sample with smooth lamination pyrocarbon matrix has unstable friction curve,which influences its frictional behavior.