Ultrasonic online monitoring of additive manufacturing processes based on selective laser melting

Rieder, Hans L.; Dillhöfer, Alexander; Spies, Martin; Bamberg, Joachim; Hess, Thomas

doi:10.1063/1.4914609

Cited by 53 publications

(28 citation statements)

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“…Optimal design can be searched in a larger space depending on the possibilities offered to select a certain number of available nozzles. Real-time control of AM like the optical tomography [129,130], thermographic analysis [131] or ultrasonic monitoring [132,133] helps in gaining valuable information about the structural defects that develop during AM processing and their direct consequence on failure of the designed part [73]. This is still a challenging issue as it appears that adequate non-destructive techniques are not yet fully available to evaluate properly AM part performance [52].…”

Section: Optimisation In Additive Manufacturingmentioning

confidence: 99%

Challenges of additive manufacturing technologies from an optimisation perspective

Guessasma

Zhang

Zhu

et al. 2015

Int. J. Simul. Multisci. Des. Optim.

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-Three-dimensional printing offers varied possibilities of design that can be bridged to optimisation tools. In this review paper, a critical opinion on optimal design is delivered to show limits, benefits and ways of improvement in additive manufacturing. This review emphasises on design constrains related to additive manufacturing and differences that may appear between virtual and real design. These differences are explored based on 3D imaging techniques that are intended to show defect related processing. Guidelines of safe use of the term ''optimal design'' are derived based on 3D structural information.

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Section: Optimisation In Additive Manufacturingmentioning

confidence: 99%

Challenges of additive manufacturing technologies from an optimisation perspective

Guessasma

Zhang

Zhu

et al. 2015

Int. J. Simul. Multisci. Des. Optim.

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“…Therefore, it can be utilized for online monitoring. By plotting A-Scan signals after each layer-wise melting, discontinuities in the interfaces between adjacent layers can be identified but not quantitatively evaluated [8]. Karthik et al used high-frequency ultrasonic signals to investigate AM parts.…”

mentioning

confidence: 99%

Detection of Internal Holes in Additive Manufactured Ti-6Al-4V Part Using Laser Ultrasonic Testing

Zhang

et al. 2020

Applied Sciences

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For a non-contact, non-destructive quality evaluation, laser ultrasonic testing (LUT) has received increasing attention in complex manufacturing processes, such as additive manufacturing (AM). This work assessed the LUT method for the inspection of internal hole defects in additive manufactured Ti-6Al-4V part. A Q-switched pulsed laser was utilized to generate ultrasound waves on the top surface of a Ti-6Al-4V alloy part, and a laser Doppler vibrometer (LDV) was utilized to detect the ultrasound waves. Sub-millimeter (0.8 mm diameter) internal hole defect was successfully detected by using the established LUT system in pulse-echo mode. The method achieved a relatively high resolution, suggesting significant application prospects in the non-destructive evaluation of AM part. The relationship between the diameter of the hole defects and the amplitude of the laser-generated Rayleigh waves was studied. X-ray computed tomography (XCT) was conducted to validate the results obtained from the LUT system.

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“…In this study, we propose using ultrasonic nondestructive evaluation to evaluate a wider range of process parameters and narrow the optimal range based on process-structureproperty correlations. Ultrasonic in-situ monitoring of L-PBF has been explored by Rieder et al [90,91]. Their system has the ultrasonic transducer below the base plate.…”

Section: Resultsmentioning

confidence: 99%

“…It was observed that the phase velocity during in-situ monitoring reduced by 15% even though the AM component was fully dense. Rieder et al [90,91], proposed that the reduction in velocity might be due to the heat build-up within the sample. Several studies [84,88] have demonstrated using thermocouples, that the average temperature measured on the base is typically under 100 °C.…”

Section: Resultsmentioning

confidence: 99%

“…Several in-situ monitoring approaches have been published in literature with varying degrees of success [84]. For instance, melt pool monitoring and spatter signature [85], X-ray imaging [86], in-situ metrology [87], distortion and temperature measurement [88], eddy current [89], and ultrasonic NDE [90][91][92] Scanning speed and laser power were varied, with constant hatch spacing (0.1mm) and layer thickness (0.03mm). Each specimen density was measured using the Archimedes' method and then compared with the normal density of the Ti-6Al-4V material to estimate porosity (RD).…”

Section: Linear Ultrasonic Nde: Acoustic Microscopymentioning

confidence: 99%

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Ultrasonic nondestructive evaluation of metal additive manufacturing.

Nadimpalli¹

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Metal Additive Manufacturing (AM) is increasingly being used to make functional components. One of the barriers for AM components to become mainstream is the difficulty to certify them. AM components can have widely different properties based on process parameters. Improving an AM processes requires an understanding of processstructure-property correlations, which can be gathered in-situ and post-process through nondestructive and destructive methods. In this study, two metal AM processes were studied, the first is Ultrasonic Additive Manufacturing (UAM) and the second is Laser Powder Bed Fusion (L-PBF). The typical problems with UAM components are inter-layer and inter-track defects. To improve the UAM process, an in-situ quality evaluation technique was desired. Several NDE techniques were tested in a lab environment before ultrasonic NDE was chosen as a practical, robust, and cost-effective NDE tool. An in-situ monitoring setup was designed and built on an UAM system. NDE results showed interesting features that were simulated through analytic and finite element wave-propagation models. AM layers with defects were characterized as an intact layer and a finite interfacial stiffness spring. The spring stiffness vi coefficient is a quality parameter that was used to characterize AM layers through a modelbased inversion method. In-situ and post-process NDE provided an understanding of defect generation and propagation in UAM. A novel solid-state repair mechanism based on Friction Stir Processing (FSP) was proposed and demonstrated. The quality of L-PBF components depends on several factors including laser power, scan speed, hatch spacing, layer thickness, particle shape/size distribution and other build conditions. Developing process parameters for a new material is an expensive and complex optimization problem. Post-process ultrasonic NDE tests revealed that the model-based insitu quality monitoring developed for UAM is also applicable to L-PBF Additive Manufacturing. A similar NDE setup was designed and installed on an open-architecture L-PBF system. A layer-by-layer bond quality evaluation demonstrates the ability to detect good-quality bonds hidden behind poor-quality regions for Inconel 625 alloy. A costeffective, process parameter development methodology has been proposed and demonstrated. vii TABLE OF CONTENTS

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Ultrasonic online monitoring of additive manufacturing processes based on selective laser melting

Cited by 53 publications

References 0 publications

Challenges of additive manufacturing technologies from an optimisation perspective

Challenges of additive manufacturing technologies from an optimisation perspective

Detection of Internal Holes in Additive Manufactured Ti-6Al-4V Part Using Laser Ultrasonic Testing

Ultrasonic nondestructive evaluation of metal additive manufacturing.

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