Multi-Defect Detection in Additively Manufactured Lattice Structures Using 3D Electrical Resistance Tomography

Abstract

Cellular lattice structures possess high strength-to-weight ratios suitable for advanced lightweight engineering applications. However, their quality and mechanical performance can degrade because of defects introduced during manufacturing or in-service. Their complexity and small length scale features make defects difficult to detect using conventional nondestructive evaluation methods. Here we propose a current injection-based method, electrical resistance tomography (ERT), that can be used to detect damaged struts in conductive cellular lattice structures with their intrinsic electromechanical properties. The reconstructed conductivity distributions from ERT can reveal the severity and location of damaged struts without having to probe each strut. However, the low central sensitivity of ERT may result in image artifacts and inaccurate localization of damaged struts. To address this issue, this study introduces an absolute, high throughput, conductivity reconstruction algorithm for 3D ERT. The algorithm incorporates a strut-based normalized sensitivity map to compensate for lower interior sensitivity and suppresses reconstruction artifacts. Numerical simulations and experiments on fabricated representative cellular lattice structures were performed to verify the ability of ERT to quantitatively identify single and multiple damaged struts. The improved performance of this method compared with classical ERT was observed, based on greatly decreased imaging and reconstructed value errors.

Roadmap on measurement technologies for next generation structural health monitoring systems

“…The image position errors1 for the two states are 0.1702 and 0.0683, respectively [151]. The predicted values were then employed in the k-nearest neighbors algorithm to find the damaged strut in the two cases.…”

An Electrical Resistance Diagnostic for Conductivity Monitoring in Laser Powder Bed Fusion

“…Here, we utilize electrodes with tapered tips that can provide high current over a uniform area (5 A), along with the capability to measure small voltage fluctuations (up to 0.1 V). Finally, the prior literature on resistance measurements has relied on invasive techniques such as directly soldering electrodes onto the part [ 47 ] or additional connection support built onto the part [ 48 , 49 ] to reduce contact impedance mismatch and provide efficient electrical contact. Here, in an attempt to be minimally invasive, we utilize magnetic arms that help maintain a strong electrical connection along with high degree of mechanical flexibility.…”