1.1 本指南涵盖了适形涡流传感器阵列的使用，用于对导电材料的不连续性和材料质量进行无损检测。不连续性包括表面破裂、亚表面裂纹和点蚀以及近表面和隐藏表面材料损失。材料质量包括涂层或层厚度、电导率、磁导率、表面粗糙度和其他随电导率或磁导率变化的特性。 1.2 本指南适用于非磁性和磁性金属以及具有导电部件的复合材料，如增强碳-碳复合材料或含碳纤维的聚合物基复合材料。 1.3 本指南适用于具有和不具有绝缘涂层的平面和非平面材料。 1.4 单位- 以国际单位制表示的数值应视为标准值。括号中给出的值是英寸-磅单位的数学转换，仅供参考，不被视为标准值。 1.5 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.6 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 涡流方法用于无损定位和表征磁性或非磁性导电材料中的不连续性和几何特性变化。适形涡流传感器阵列允许检查平面和非平面材料，但通常需要合适的夹具将传感器阵列固定在感兴趣的材料表面附近，例如传感器阵列后面的一层泡沫以及刚性支撑结构。 5.2 在操作中，传感器阵列通过在空气或参考零件中或两者中的测量进行标准化。从传感器阵列测量的响应可以转换为物理特性值，例如剥离、电导率或磁导率，或其组合。 通过确保这些测量响应或特性值在规定范围内，验证仪器的正确操作。定期进行性能验证。对无不连续性参考标准或不包含不连续性的受检材料区域进行性能验证，确保导电性、层厚度或剥离或其组合等电气和几何特性适用于传感器阵列。对包含参考标准的不连续性进行性能验证，确保传感器阵列对不连续性的响应是适当的。 5.3 传感器阵列尺寸，包括传感元件的大小和数量，以及工作频率是根据正在执行的检查类型选择的。 涡流渗透到被检查材料中的深度取决于信号的频率、材料的电导率和磁导率以及传感器阵列的一些尺寸。穿透深度等于高频下的传统表皮深度，但也与低频下的传感器阵列尺寸有关，例如驱动绕组的尺寸以及驱动绕组和传感元件阵列之间的间隙距离。对于与传感器阵列相邻的表面上的表面断裂不连续性，如果穿透深度小于受检材料的厚度，则应使用高频。对于地下不连续性或壁厚测量，应使用较低的频率和较大的传感器尺寸，以便穿透深度与材料厚度相当。 5.4 传感器阵列和被检查导电材料表面之间可能存在绝缘层或涂层。测量对不连续性的灵敏度通常随着涂层厚度或剥离或两者的增加而降低。对于具有线性驱动导体和传感元件线性阵列的涡流传感器阵列，驱动导体和传感元件阵列之间的间距应小于或相当于绝缘涂层的厚度。对于其他阵列格式，应根据经验验证灵敏度深度。 5.5 传感器响应模型可用于将传感器阵列测量的响应转换为物理特性值，如升力- off、电导率、磁导率、涂层厚度或基板厚度，或其组合。为了确定两个特性值，可以使用一个工作频率。对于非磁性材料和裂纹状不连续性检查，应确定剥离和电导率。对于磁性材料，当电导率可以测量或假设恒定时，则应确定剥离和磁导率。只有在灵敏度深度大于相关材料厚度的情况下，使用足够低的激励频率才能确定厚度。为了确定两个以上的特性值，应在至少具有两个穿透深度的操作条件下进行测量； 这些不同的穿透深度可以通过使用多个工作频率或多个空间波长来实现。 5.6 可以执行测量响应或特性值数据的处理，以突出不连续的存在，减少背景噪声，并表征检测到的不连续。例如，可以应用相关滤波器，其中将不连续性的参考特征响应与每个传感器阵列元素的测量响应进行比较，以突出不连续性缺陷。必须注意适当考虑干扰的影响，例如边缘和涂层对此类特征的影响。 5.7 本指南中描述的测量和分析方法也可应用于传感器阵列靠着表面安装或嵌入被检查材料中的应用。 在这种情况下，传感器阵列响应将在一段时间内进行监测，而不是在特定位置上扫描传感器阵列。这导致B扫描和C扫描的水平轴对应于时间或与测试相关的一些其他输入，例如加载循环数。

1.1 This guide covers the use of conformable eddy current sensor arrays for nondestructive examination of electrically conducting materials for discontinuities and material quality. The discontinuities include surface breaking and subsurface cracks and pitting as well as near-surface and hidden-surface material loss. The material quality includes coating or layer thickness, electrical conductivity, magnetic permeability, surface roughness, and other properties that vary with the electrical conductivity or magnetic permeability. 1.2 This guide is intended for use on nonmagnetic and magnetic metals as well as composite materials with an electrically conducting component, such as reinforced carbon-carbon composite or polymer matrix composites with carbon fibers. 1.3 This guide applies to planar as well as non-planar materials with and without insulating coating layers. 1.4 Units— The values stated in SI units are to be regarded as standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Eddy current methods are used for nondestructively locating and characterizing discontinuities and geometric property variations in magnetic or nonmagnetic electrically conducting materials. Conformable eddy current sensor arrays permit examination of planar and non-planar materials but usually require suitable fixtures to hold the sensor array near the surface of the material of interest, such as a layer of foam behind the sensor array along with a rigid support structure. 5.2 In operation, the sensor arrays are standardized with measurements in air or a reference part, or both. Responses measured from the sensor array may be converted into physical property values, such as lift-off, electrical conductivity, or magnetic permeability, or a combination thereof. Proper instrument operation is verified by ensuring that these measurement responses or property values are within a prescribed range. Performance verification is performed periodically. Performance verification on a discontinuity-free reference standard or regions of the material being examined that do not contain discontinuities ensures that the electrical and geometric properties, such as electrical conductivity, layer thickness, or lift-off, or a combination thereof, are appropriate for the sensor array. Performance verification on a discontinuity-containing reference standard ensures that the sensor array response to the discontinuity is appropriate. 5.3 The sensor array dimensions, including the size and number of sense elements, and the operating frequency are selected based on the type of examination being performed. The depth of penetration of eddy currents into the material under examination depends upon the frequency of the signal, the electrical conductivity and magnetic permeability of the material, and some dimensions of the sensor array. The depth of penetration is equal to the conventional skin depth at high frequencies but is also related to the sensor array dimensions at low frequencies, such as the size of the drive winding and the gap distance between the drive winding and sense element array. For surface-breaking discontinuities on the surface adjacent to the sensor array, high frequencies should be used where the penetration depth is less than the thickness of the material under examination. For subsurface discontinuities or wall thickness measurements, lower frequencies and larger sensor dimensions should be used so that the depth of penetration is comparable to the material thickness. 5.4 Insulating layers or coatings may be present between the sensor array and the surface of the electrically conducting material under examination. The sensitivity of a measurement to a discontinuity generally decreases as the coating thickness or lift-off, or both, increases. For eddy current sensor arrays having a linear drive conductor and a linear array of sense elements, the spacing between the drive conductor and the array of sense elements should be smaller than or comparable to the thickness of the insulating coating. For other array formats the depth of sensitivity should be verified empirically. 5.5 Models for the sensor response may be used to convert responses measured from the sensor array into physical property values, such as lift-off, electrical conductivity, magnetic permeability, coating thickness, or substrate thickness, or a combination thereof. For determining two property values, one operational frequency can be used. For nonmagnetic materials and examination for crack-like discontinuities, the lift-off and electrical conductivity should be determined. For magnetic materials, when the electrical conductivity can be measured or assumed constant, then the lift-off and magnetic permeability should be determined. The thickness can only be determined if a sufficiently low excitation frequency is used where the depth of sensitivity is greater than the material thickness of interest. For determining more than two property values, measurements at operating conditions having at least two depths of penetration should be used; these different depths of penetration can be achieved by using multiple operational frequencies or multiple spatial wavelengths. 5.6 Processing of the measurement response or property value data may be performed to highlight the presence of discontinuities, to reduce background noise, and to characterize detected discontinuities. As an example, a correlation filter can be applied in which a reference signature response for a discontinuity is compared to the measured responses for each sensor array element to highlight discontinuity-like defects. Care must be taken to properly account for the effect of interferences such as edges and coatings on such signatures. 5.7 The measurement and analysis methods described in this guide can also be applied to applications where the sensor array is mounted against a surface or embedded within the material being examined. In that situation the sensor array response is monitored over a period of time instead of the scanning the sensor array over a specific location. This leads to the horizontal axes for the B-scans and C-scans to correspond to time or some other input associated with the test such as the number of loading cycles.