汽车B柱加强板软硬部过渡特性的磁巴克豪森噪声检测方法

汽车B柱加强板软硬部过渡特性评价的常规方法是通过破坏性取样对局部硬度进行检测，无法直接面向零部件进行便捷、快速的无损测试，且耗时、耗费成本。为克服传统方法的不足，研究利用磁巴克豪森噪声检测方法实现过渡特性的无损评价。利用自主研发的多功能微磁检测仪器开展标定试验，提出过渡区域起止位置及长度范围的估算方法，并建立过渡区域的表面硬度定量预测模型。研究结果表明，磁巴克豪森噪声、切向磁场强度信号的大部分特征参量可以有效评估软、硬部过渡范围，参量x₁、x₅和x₁₇对起始点的估计误差范围处于±14 mm，长度估算的相对误差小于10%。利用单一参量x₁₇建立的线性表征模型对硬度的预测RMSE值为12.38 HV10，融合多项磁参量建立的BP神经网络模型的预测精度更高，RMSE值小于6 HV10。提出一种汽车关键部件软硬部过渡特性的微磁评估方法，研究磁巴克豪森噪声特征参量与硬度的关系，实现汽车B柱软硬区表面硬度和软硬部过渡范围的定量表征，具有重要的工程应用前景。

MBN Measurement for the Transition Characteristics of Hard-to-soft Part of Automobile B-pillar Reinforcement Plate

The conventional method to evaluate the transition characteristics of the hard-to-soft part of B-pillar reinforcement plate used in automobile is to test the local hardness by destructive sampling, which is not convenient and efficient for the parts directly, and is time-consuming and costly. Hence, magnetic Barkhausen noise measurement method is investigated for nondestructive evaluating the transition characteristics to overcome the shortcomings of traditional methods. Firstly, the self-developed multi-functional micro-magnetic instrument is used to carry out calibration experiments. Then, the estimation method of the position where the transition zone begins and ends and length of the transition zone is proposed. Subsequently, a quantitative prediction model of surface hardness in transition region is established. The results show that most of the feature parameters of MBN and TMF can effectively evaluate the transition range of hard-to-soft part. The estimation error for the starting point is ±14 mm, and the relative error of length estimation is less than 10% using parameters of x₁, x₅ and x₁₇. The RMSE of linear characterization model with parameter of x₁₇ is about 12.38 HV10, while BP neural network model established by integrating multiple magnetic parameters has a higher prediction accuracy with a RMSE value less than 6 HV10. Obviously, a micro-magnetic evaluation method for the transition characteristics of the hard-to-soft part of key automotive components is proposed, in which the relationship between feature parameters from magnetic Barkhausen noise and hardness is studied and the quantitative characterization of surface hardness and transition range of hard-to-soft part of B-pillar is realized. The method has broad prospects in engineering application.