共查询到19条相似文献,搜索用时 238 毫秒
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应用COMSOL Multiphysics软件建立了交变电磁场检测缺陷的有限元模型,基于仿真模型分析了不同几何尺寸的磁芯对被检工件表面感应电流的均匀分布和工件缺陷检测效果的影响。研究了磁芯腿部高度、截面宽度和上部长度3个参数变化对工件感应电流均匀性分布和感应磁场信号分布的影响特征,得到了不同几何参数下的激励线圈对缺陷检测灵敏度的影响结果。在不同几何参数的U型探头激励下,得出了工件缺陷电磁场信号的特征分布情况以及检测缺陷时的最优磁芯几何参数,为U型交变电磁场激励探头的优化设计提供了依据。 相似文献
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感应加热时,工件在线圈中的填充情况和温度变化会对线圈磁场产生影响.线圈端部的磁力线逸散,使工件在未进入线圈时加热已经开始,因此,在感应加热模拟的时候,考虑工件运动和磁力线逸散是十分必要的.本文在考虑工件与线圈相对运动和线圈端部磁力线逸散的情况下,对45钢坯锻前双感应炉加热做了有限元模拟分析.得到了钢坯的心表温度分布曲线,并对感应加热的温升过程特点与影响因素进行了分析. 相似文献
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板坯电磁成形载荷计算方法及分布特性 总被引:25,自引:0,他引:25
用平面螺旋和多叠式线圈加工平板毛坯是电磁成形的一种基本方式,其理论研究包括电路分析和动态变形分析两个方面,其中电路分析的目的是确定作用在工件上的脉冲电磁力,并用于变形分析。通过分析板坯电磁成形中工作线圈在强脉冲电流激励下的动态响应过程,建立了线圈磁场、工件表面感应涡流及磁场的计算公式,给出了成形载荷的计算方法。通过数值分析讨论了载荷的分布特性,数值求解结果与相关实验研究结论一致。将成形载荷数值求解结果用于变形分析时,成功地预测了铝板毛坯的自由胀形过程。 相似文献
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针对零件加工生产线对工件完好性的要求,研究利用感应加热热成像检测技术对流水线上移动的工件进行在线检测。首先分析了脉冲涡流热成像对移动工件缺陷的检测机理;使用COMSOL5.2有限元软件进行二维建模,分析了磁性材料(钢)工件当存在和感应线圈相平行的缺陷时,线圈匀速运动经过工件缺陷所产生的温度场分布,并通过分析附近温度曲线、归一化曲线和差值曲线的变化,指出检测磁性材料内平行缺陷的最佳观测区域。为运动工件感应加热热成像缺陷定量检测提供理论指导。 相似文献
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Thin-skin analysis technique for interaction of arbitrary-shape inducer field with long cracks in ferromagnetic metals 总被引:7,自引:2,他引:7
In using the AC field measurement (ACFM) technique for non-destructive evaluation (NDE) of metals, a current-carrying wire structure is used to induce eddy current within a thin layer of the metal and a magnetic field sensor to measure the field perturbations in the vicinity of the metal. The sensitivity of ACFM crack detection and sizing relies on an appropriate design of the wire structure geometry together with a dully placement of the sensor. This paper presents an analytical modeling technique for evaluating the electromagnetic field interaction of an ACFM probe with a long uniform crack in a ferromagnetic metallic slab. The probe in the proposed model can have an arbitrary-shape wire inducer with no restrictions on its relative sensor position. The technique is accurate and very efficient computationally. It first uses the two-dimensional Fourier transform to obtain the field distribution at the metal surface. The Laplacian field distribution above the metal is then determined by satisfying the so-obtained boundary condition at air–metal interface. To demonstrate the accuracy of the model, we consider the special case of a rhombic wire inducer. The comparison of our results with those obtained using the conventional algorithm in the literature validates the accuracy of the model introduced in this paper. To show the generality of the model, we also present theoretical and experimental results associated with a solenoid inducer with a three-dimensional geometry for which no analytical solution is available in the literature. The theoretical prediction of crack signal supported by experimental results is used to develop a model-based method for inverting crack signal into crack depth. 相似文献
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Alternating current field measurement (ACFM) technology has been used for sizing underwater structure cracks. However, conventional ACFM is more sensitive to cracks perpendicular to the induced current than cracks with other angles. In this paper, a rotating alternating current field measurement (RACFM) method and underwater test system are present for the detection of arbitrary-angle cracks with high sensitivity. The RACFM is proved by simulations and experiments. Arbitrary-angle cracks detection results obtained from ACFM and RACFM have shown that the RACFM method overcomes the limitation of directional detection of ACFM and effectively achieves high detection sensitivity for arbitrary-angle cracks on underwater structures. 相似文献
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飞机发动机叶片基体出现裂纹时表面反映不明显,孔探仪检查表面裂纹实际判别的难度较大,因此用交变磁场非接触式探测法探测。介绍探伤原理、特点以及与其它无损检测方法的比较,最后给出了发动机叶片的检测实例。检测结果表明,该方法检出的大小裂纹的波形与实际裂纹相符甚好,因此较传统涡流法和孔探仪法更具优越性,具有实际应用价值。 相似文献
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Structural optimization of 2-D array probe for alternating current field measurement 总被引:1,自引:0,他引:1
A double U-shaped orthogonal inducer for the alternating current field measurement (ACFM) is presented, which could extend the limitation of the direction of tested cracks and decrease the loss of magnetic flux compared to the single rectangular inducer. The structure of the testing probe was optimized to meet the expectations of the pointwise magnetic field measurement and to decrease every group of coils’ space by orthogonally winding method, and the two-dimensional (2-D) ACFM probe array was designed. The detection precision and lift-off effect of the 2-D ACFM probe array were experimentally studied. The results show that the relative error of this probe is less than 10%, and it could suppress the lift-off disturbance effectively, which makes this 2-D ACFM probe array to be insensitive to lift-off and unable to meet the engineering expectations. 相似文献
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According to the principle of the alternating current field measurement (ACFM), the inducing frequency has a significant influence on the signal acquisition and the measurement accuracy of an ACFM system. To design an ACFM prototype system with a U-shaped probe, the inducing frequency of the ACFM system is determined through simulation analysis and an experimental study in this paper. A large number of simulations are designed and run to analyze the influences of the inducing frequency on characteristic vectors of the induction electromagnetic field. By analyzing the simulation results, 6 kHz is selected to be the optimal inducing frequency for the U-shaped probe of an ACFM prototype. This frequency is tested by real crack inspection experiments using the U-shaped probe of the ACFM prototype in laboratory. The results show that 6 kHz is appropriate to realize the crack inspection and sizing with reasonable accuracy. The result in this paper will benefit the design and manufacturing of the prototype for the U-shaped probe ACFM system. 相似文献
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EFFECT OF ROTATING MAGNETIC FIELD ON MACROSTRUCTURE OF A CENTRIFUGAL CASTING Al-1%Cu ALLOY 总被引:1,自引:0,他引:1
1. IntroductionCelltrifugal casting has been broadly used as it offers many advantages over the conventional casting methods. In a celltrifugal casting process, liquid metal is introduced intoa die that is spinning at a high rotational speed. The metal will take the shape of the dieand be subjected to a force 40 to 50 times of gravityg which then usually makes the castmore dense. The cast is also very clean, since the non-metallic inclusions that are presentin the liquid metal are celitrifuged… 相似文献
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This paper presents a wavelet-network-based technique for reconstructing the crack depth profile of a fatigue crack in a metal from the output signal of an alternating current field measurement (ACFM) probe. The main feature of this technique is that it requires only the ACFM probe output signals along the crack opening. The database for training the network is established by developing a random crack-depth generator, using a fast pseudo-analytic ACFM probe output simulator. The validity of the proposed technique is demonstrated by comparing the actual and reconstructed depth profiles of several simulated and machine-made cracks with no predetermined geometries. 相似文献