基于热成像的薄片材料热扩散率快速无损检测

针对传统热扩散率测量方法对热激励、边界和试样尺寸有严格要求等苛刻条件,提出一种适用于薄片材料的热扩散率测量新方法。该方法采用热成像技术采集受激光激励引起的材料表面温度场变化数据,将其通过曲线拟合对导热微分方程中的微分项进行估测,求取微分方程解析解转化为对代数方程求解以确定热扩散率值,因而无需严格控制边界条件、初始条件和热激励。通过仿真分析验证了理论模型的合理性,并对H62黄铜和304不锈钢材料进行了实测,对比文献参考值表明测量偏差均在6.0%以内,测量重复性为4.3%,可满足快速无损的测量要求。

A Rapid and NondestruCtive DeteCtion on the Thermal Diffusivity of Thin Materials Based on Thermography

A novel measuring method which adapts to the thermal diffusivity of thin materials is proposed. It can solve the defects of traditional measurement method that has strict demands of the thermal excitation,boundary and the size of the materials. The method collects the changing temperature field data which caused by the laser heating on material surface by using the imaging technology,and estimates the differential terms from partial differential equation of heat conduction by curve fitting. The differential equation can be transformed into algebraic equation to determine the thermal diffusivity. The measuring experiment needs not to control the boundary condition,initial condition and thermal excitation strictly. The results of the simulation analysis verified the feasibility of the theoretical model. For measuring of the thermal diffusivity of H62 brass and 304 stainless steel and the deviation is less than 6. 0% in comparison to the literature values and the measurement repeatability is 4. 3%,so the method can satisfy the requirement of the rapid and nondestructive measurement.