船用铝合金与复合材料用防火材料导热系数研究

Thermal conductivity coefficient agorithm of fireproof materials for aluminum alloy and composite material structure on ships

[目的]随着铝合金和复合材料结构件规模化上舰,原有防火材料已无法满足新需求。鉴于此,研制的新型防火材料需获得合适的导热系数。[方法]以标准耐火试验样件为研究对象,建立防火材料导热系数的算法。首先,使用无限大平板非稳态传热模型,进行空间-时域离散,实现耐火分隔传热过程的计算。其次,建立火场传热模型,对材料表面传热系数和发射率2个参数进行近似处理,并验证该近似处理对背火面温度的计算结果不产生明显影响。最后,通过分析铝合金、复合材料与钢材的高温力学差异,确定防火材料背火面温度的限值。通过导热系数的迭代,计算防火材料背火面温度,得到满足要求的导热系数。以陶瓷棉为例计算背火面温度,并与前人试验结果对比。[结果]背火面温度的计算结果与试验结果相符,验证了所提算法的可靠性。利用此算法,得到该防火材料用于铝合金结构时,导热系数应不大于0.032 W·m^-1·K^-1;用于复合材料结构时,应不大于0.020 W·m^-1·K^-1。[结论]得到的导热系数可以为铝合金和复合材料结构用新型防火材料研制提供参考。

[Objectives]With the development of aluminum alloy and composite material structure on surface ships,fireproof materials nowadays are not able to meet the new requirements.Appropriate thermal conductivity coefficient is necessary in the design process of new fireproof materials aiming at such situation.[Methods]The algorithm of thermal conductivity coefficient is established according to the overall design method and the background of standard fire resistance test.First,the heat-transfer calculation process is realized on the base of the theory resolution of unsteady heat-transfer calculation on infinite plate by using discrete method.Then the fire ground calculation model is established.The low sensitivity of surface coefficient of heat-transfer and surface emissivity to the calculation result is tested and proved in order to do approximate process on these parameters.After the analysis of mechanical behavior under high temperature of aluminum alloy and composite material,the temperature on the back side of fireproof materials is obtained.The qualified thermal conductivity coefficient can be found by iterative computations and comparison.Taking ceramic wool as example,its temperature on back side is calculated and compared to the public experiment data.[Results]It is proved that the proposed algorithm is credible by comparing the example of ceramic wool with public experiment data.The results show that the thermal conductivity coefficient of the fireproof materials which is used on aluminum alloy and composite material structure should be lower than 0.032 and 0.020 W·m^-1·K^-1.[Conclusions]The obtained thermal conductivity coefficient and the algorithm can provide reference for the development of new fireproof materials.