X-ray Computed Tomography has proven its unprecedented objectivity for nondestructive inspection of materials and structures. However, high-resolution nondestructive evaluation of small critical flaws in structures with large in-plane dimensions has been a fundamental challenge for the CT techniques. This work presents a novel Variable Zoom X-ray CT technique that can significantly improve defect resolution for structures with large in-plane dimensions. The details of the scanning technique and the reconstruction method essential for achieving accurate high-resolution results are provided. Superior performance and accuracy of the technique is demonstrated on the dimensional and sharpness measurements of known features in the artificial phantom and in X-ray CT of composite panel with large in-plane dimensions. Application of the new approach is demonstrated on the detection of complex structural damage due to low-velocity impact in large and thin composite laminate panels, which is among the worst-case scenario for the conventional CT methods.

X射线计算机断层扫描已证明其对材料和结构的无损检查具有前所未有的客观性。但是，对平面技术较大的结构中的微小关键缺陷进行高分辨率无损评估一直是CT技术的一项基本挑战。这项工作提出了一种新颖的可变变焦X射线CT技术，可以显着提高平面内大尺寸结构的缺陷分辨率。提供了实现精确的高分辨率结果所必需的扫描技术和重建方法的详细信息。该技术的卓越性能和准确性在人造体模和大平面内复合面板的X射线CT的已知特征的尺寸和清晰度测量中得到了证明。