面向映射单调性的TC4初生α相晶粒尺寸超声评价方法

An ultrasonic method of evaluation of TC4 primary α-phase grain size towards mapping monotonicity

随着被检对象微观组织结构复杂信息的增加,以误差最小为目标来建立有效的评价曲线越来越难,针对这一问题提出了一种以单调性为目标的TC4钛合金初生α相晶粒尺寸超声评价方法。依据相关性度量从多个超声参数中选取有效参数,经映射函数降成单维参数并归一化处理后与晶粒尺寸进行一次项拟合,构建以单调性(特征参数样本点依次序列差值同时为正或为负)最大为目标的优化问题并结合自适应差分进化(SADE)算法进行求解,寻找最佳的映射函数和拟合函数系数,最终建立映射单调性的多参数超声评价模型。实验结果表明,因考虑了单调性的重要性且与误差为目标的评价模型相比,所建模型的评价效应更显优势。与单一参数的声速模型、衰减系数模型和非线性系数模型对比分析,所建模型误差小、单调性好、性能稳定且有着评价结果精度高等特点。

The addition of complex information in the microstructure of the tested object increases the difficulty to establish an effective evaluation curve with minimized errors.To solve this problem,this paper proposes a monotonicity-oriented method of ultrasonic evaluation ofα-phase grain size of TC4 titanium alloy.Based on the correlation measure,effective parameters are selected from multiple ultrasonic parameters,and the mapping function is reduced to a single-dimensional parameter and normalized to fit the primaryαphase once,constructing a optimization problem of reaching maximized monotonicity where the sample points of feature parameter are successively positive or negative.The problem is solved with the self-adaptive differential evolution(SADE)algorithm to find the most ideal mapping function and fitting function coefficient,finally establishing the monotonicity based on multi-parameter model for ultrasonic evaluation.The experimental results show that the evaluation effect of the established model is more significant than that of the error-oriented evaluation model because it considers the importance of monotonicity.Compared with the single-parameter ultrasonic velocity method,the attenuation coefficient method and the nonlinear coefficient method,the established model contains smaller error,better monotonicity,more stable performance and higher accuracy of evaluation.