Image-based techniques have been extensively deployed in the fields of condition assessment and structural mechanics to measure surface effects such as displacements or strains under loading. 3D Digital Image Correlation (3D-DIC) is a technique frequently used to quantify full-field strain measurements. This research uses 3D-DIC to detect interior anomalies of structural components, inferred from the discrepancy in constitutive properties such as elasticity modulus distribution of a three-dimensional heterogeneous/homogeneous sample using limited full-field boundary measurements. The proposed technique is an image-based tomography approach for structural identification (St-Id) to recover unseen volumetric defect distributions within the interior of a 3D heterogeneous space of a structural component based on iterative updating of unknown or uncertain model parameters. The approach leverages full-field surface deformation measurements as ground truth coupled with a finite element model updating process that leverages a novel hybridized optimization algorithm for convergence. This paper presents a case study on a series of structural test specimens with artificial damage. A computer program was created to provide an automated iterative interface between the finite element model and an optimization package. Results of the study illustrated the successful convergence of the selected objective function and the identified elasticity modulus distributions. The resulting updated model at later stages of loading was also shown to correlate well with the ground truth experimental response. The results illustrate the potential to detect subsurface defects from surface observations and to characterize internal properties of materials from their observed mechanical surface response.

基于图像的技术已广泛应用于状态评估和结构力学领域，以测量表面效应，例如负载下的位移或应变。3D数字图像关联（3D-DIC）是一种经常用于量化全场应变测量的技术。这项研究使用3D-DIC来检测结构组件的内部异常，这是根据本构特性的差异推断出来的，例如使用有限的全场边界测量方法来测量三维异质/均质样品的弹性模量分布。所提出的技术是一种基于图像的层析成像方法，用于结构识别（St-Id），以基于未知或不确定模型参数的迭代更新来恢复结构组件的3D异构空间内部看不见的体积缺陷分布。该方法利用全场表面变形测量作为地面真相，并结合有限元模型更新过程，该过程利用新颖的混合优化算法进行收敛。本文以一系列具有人为损坏的结构试样为例进行了案例研究。创建了一个计算机程序，以提供有限元模型和优化程序包之间的自动迭代接口。研究结果说明了所选目标函数和确定的弹性模量分布的成功收敛。还显示了在加载的后期阶段生成的更新模型与地面真实实验响应具有很好的相关性。结果表明，有潜力从表面观察中发现表面下的缺陷，并从观察到的机械表面响应来表征材料的内部特性。