太子城站钛锌蜂窝板芯层结构高温加速老化试验研究

Experimental Study on High Temperature Accelerated Aging of Titanium-Zinc Honeycomb Core in Taizicheng Railway Station

蜂窝板结构由上下两层面板和中间一层蜂窝芯组合而成,具有整体质量轻、强度高、刚度大等特点,被广泛应用于航空航天、船舶、汽车和建筑领域。由于常用的蜂窝板芯层结构采用胶黏剂连接,胶黏剂的性能对其力学性能影响较大,尤其是胶黏剂的老化对蜂窝板结构性能影响尚不明确。而蜂窝板常被用于建筑外表面,长时间受到外环境影响,对其耐久性提出了很大的考验。结构耐久性评价指标通常需要根据不同的使用要求进行设定,蜂窝板结构根据不同的工作条件关注的对象也不相同,其中力学性能是一个很重要的评价指标,需重点关注蜂窝板的平压强度。主要对钛锌蜂窝板芯层结构进行高温加速老化试验,通过对平压强度变化评价其耐久性。首先根据工程要求的设计使用年限,设定预期寿命为0,25,30 a,并基于阿累尼乌斯方程推导温度变化的反应速率变化公式,从而推导高温加速老化时间。选取典型的4家厂家提供的60 mm×60 mm×20 mm蜂窝芯标准试件,将其分别按照预期寿命0,25,30 a分组并进行高温加速老化,每组预留1个试样仅加速老化不进行准静态压缩,其余各组进行准静态压缩试验,逐件测试试样的准静态压缩力,记录载荷特性曲线,读取压溃荷载,记录压溃形式。分析试样老化后平压强度与峰值强度,与老化前同批次试样对应数值对比,设定老化后试样与同规格件老化前控制指标偏差超过±15%,进行偏差性分析。试验结果表明:蜂窝芯层在平压过程中经过弹性变形、塑性变形和失稳三个阶段。弹性变形阶段Ⅰ:在荷载-位移曲线上为斜直线,蜂窝芯呈现弹性变形。塑性变形阶段Ⅱ:蜂窝芯壁板间发生脱胶脆裂,出现塑性屈曲变形,平压强度迅速降低。失稳阶段Ⅲ:随着加载继续,壁板间约束失效,蜂窝芯逐渐被压合,且周边蜂窝结构逐渐破坏,当结构被压合后,平压强度维持在一个相对较低的平台上。分析表明:4个厂家的蜂窝板在老化年限为30 a以内,平压强度变化范围均没有超过设定的±15%的指标偏差,耐久性表现良好。当蜂窝芯排布更密实时,平压强度提高较为明显,同时平压后整体试件表现更好,能基本保持方形。随着老化时间的提高,蜂窝板的平压强度总体上呈现下降趋势,在老化年限25 a内,各系列强度下降较小,且有部分系列强度甚至提高,设计使用年限定为25 a较为合理。由于不同厂家的产品因胶黏剂成分和制备方法的差异,不同厂家的力学性能表现差异较大。分析方法和试验结果论证了蜂窝芯层结构在实际使用前的使用寿命预测的必要性和可行性。

The honeycomb panel structure is composed of two upper and lower panels and a honeycomb core in the middle.It has the characteristics of light weight,high strength and high rigidity,and is widely used in the fields of aerospace,ships,automobiles and buildings.At present,the structure of honeycomb core is usually connected by cementing agent.The change of cementing agent has a great influence on its mechanical properties and its aging performance is not clear.The honeycomb panel is often used on the outer surface of the building,which is affected by the external environment for a long time,which puts a great test on its durability.The targeted index of structural durability evaluation usually needs to be set according to different use requirements.The honeycomb structure pays different attention to the objects according to different working conditions,among which the mechanical properties are an important evaluation index.This article focuses on the flat compressive strength of honeycomb panels.This paper mainly conducts high temperature accelerated aging test on the structure of Titanium-Zinc honeycomb core,evaluate its durability by changing its flat compressive strength and predicts its service life.The life expectancy is set to 0,25,30 years,and the reaction rate change formula based on the Arrhenius equation to derive the temperature change is used to derive the high-temperature accelerated aging time.Select the standard test pieces of honeycomb core provided by four typical manufacturers,whose size is 60 mm×60 mm×20 mm,group them according to the expected life of 0,25,and 30 years and perform accelerated aging at high temperature.One sample is reserved for each group,only accelerated aging without quasi-static compression,and the remaining groups are tested for quasi-static compression.Test the quasi-static compressive force of the sample piece by piece,record the load characteristic curve,read the crushing load,and record the crushing form.The flat compression strength and peak strength of the sample after aging are analyzed and compared with the corresponding values of the samples of the same batch before aging.Deviation is used for durability analysis,and the performance index of the sample before and after aging is set to not exceed±15%.The test results show that the deformation of the honeycomb core layer during the flattening process passes through three stages of elastic deformation,plastic deformation and instability.Elastic deformation stage I:The load-displacement curve is an oblique straight line,and the honeycomb core shows elastic deformation.Plastic deformation stage II:Degumming and brittle cracking occurs between the honeycomb core wall panels,plastic buckling deformation occurs,and the flat compression strength decreases rapidly.Instability phase III:As the loading continues,the constraints between the wall panels fail,and the honeycomb core is gradually pressed.And the surrounding honeycomb structure is gradually destroyed.When the structure is pressed,the flat compressive strength is maintained on a relatively low platform.The analysis results show that the strength changes of the test specimen within 30 years of aging time did not exceed the deviation of the index of 15%of the quality standards.And as the aging time increases,the flat compressive strength decreases.When the honeycomb cores are arranged denser and in real time,the improvement of flat compression strength is more obvious,and the overall test piece performs better after flat compression,and can basically maintain a square shape.As the aging time increases,the flat compressive strength of the honeycomb panel generally shows a downward trend.Within 25 years of aging,the strength of each series decreased slightly,and some series even increased in strength.Therefore,the design life is limited to 25 years is more reasonable.However,due to the differences in the manufacturing methods,the mechanical properties of the products vary greatly which demonstrate the necessity and feasibility of the life prediction of the honeycomb core structure.