Residual stresses in additively manufactured parts: predictive simulation and experimental verification

Abstract

Purpose The purpose of this paper is to investigate a simulation solution for estimating the residual stresses developed in metal fused filament fabrication (MF3) printed parts. Additionally, to verify these estimates, a coupled experimental–computational approach using the crack-compliance method was investigated in this study. Design/methodology/approach In this study, a previously validated thermomechanical process simulation was used to estimate the residual stresses developed in the MF3 printing process. Metal-filled polymer filament with a solids loading of 59 Vol.% Ti-6Al-4V was studied. For experimental validation of simulation predictions, the MF3 printed green parts were slitted incrementally and the corresponding strains were measured locally using strain gauges. The developed strain was modeled in finite-element-based structural simulations to estimate a compliance matrix that was combined with strain gauge measurements to calculate the residual stresses. Finally, the simulation results were compared with the experimental findings. Findings The simulation predictions were corroborated by the experimental results. Both results showed the same distribution pattern, that is, tensile stresses at the outer zone and compressive stresses in the interior. In the experiments, the residual stresses varied between 1.02 MPa (tension) and −2.28 MPa (compression), whereas the simulations were predicted between 1.37 MPa (tension) and −1.39 MPa (compression). Overall, there was a good quantitative agreement between the process simulation predictions and the experimental measurements, although there were some discrepancies. It was concluded that the thermomechanical process simulation was able to predict the residual stresses developed in MF3 printed parts. This validation enables the printing process simulation to be used for optimizing the part design and printing parameters to minimize the residual stresses. Originality/value The applicability of thermomechanical process simulation to predict residual stresses in MF3 printing is demonstrated. Additionally, a coupled experimental–computational approach using the crack-compliance method was used to experimentally determine residual stresses in the three-dimensional printed part to validate the simulation predictions. Moreover, this paper presents a methodology that can be used to predict and measure residual stresses in other additive manufacturing processes, in general, though MF3 was used as demonstrator in this work.

Research on an Ultrasonic Longitudinal Critically Refracted Wave Detection Method for the Depth Distribution of Stress

“…Using the method of time for the flight difference, we obtained the change in time of flight for a certain sound range by measuring the time of flight for a certain sound range. Thus, the stress could be obtained more accurately by using Equation (5). When L CR is used for the detection of internal stress for aluminum alloy components, the sound has to be refracted from a medium with a slower sound speed into a medium with a faster sound speed, and the refraction angle is determined by Snell's law [35].…”

“…Therefore, in situ non-destructive testing of internal residual stress in parts is a challenging problem that the aerospace manufacturing industry tries to solve. Currently, mature destructive residual stress detection methods mainly include the blind-hole drilling and crack compliance methods [5,6], which cannot be applied to finished aluminum alloy components, while the non-destructive X-ray diffraction method does not meet the detection requirements of internal residual stresses of aluminum alloy components [7,8]. Ultrasound offers good penetrability in metallic aluminum alloy materials [9,10], and especially longitudinal waves have been shown to be very sensitive to the macroscopic residual stresses inside the component and are less sensitive to material microstructure [11].…”

Long-Term Thermal Stress Analysis and Optimization of Contraction Joint Distance of Concrete Gravity Dams

“…The conducted analysis did not take into account the impact of different monolith lengths on the stress field (SF) in the dam's body. Thermal stresses can present a big issue in many engineering topics, as well as additive manufacturing and other manufacturing processes [25][26][27][28].…”