Computational modelling of shaped metal deposition

Abstract

SUMMARYShaped metal deposition (SMD) is a novel process for rapid prototyping that employs tungsten inert gas (TIG) welding controlled by a robot inside an inert gas chamber to build parts by successive layer deposition. This process can be enhanced through modelling and control. Industries are interested in developing systematized models to explain observed phenomena and to predict processing conditions for process planning and optimization. In this work, thermal and mechanical finite element (FE) modelling of SMD is presented. The thermal problem is solved with linear tetrahedral finite FEs that take into account the liquid/solid phase change phenomenon. The mechanical problem is solved with hexahedral elements with tri-linear interpolation of displacements and constant interpolation of mean stresses (Q1-P0). Special techniques to account for material addition were developed, based on activation/deactivation of FEs. Numerical tests were conducted to determine the heat source model parameters. An experiment using Ti-6Al-4V material was developed to validate the formulation. The test consisted of a TIG-wash procedure (arc passing without wire feeding to preheat the plate) followed by a single welding layer. The results, including temperatures and residual displacements, are compared with those obtained with the finite element method (FEM) code. Finally, a multilayer SMD numerical example is presented.

Effect of stress relaxation on distortion in additive manufacturing process modeling

“…A c c e p t e d M a n u s c r i p t 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 Table 3: Temperature dependent mechanical properties of Ti-6Al-4V [8,29] and Inconel R 625 [30] T …”

“…Modeling of AM has primarily focused on predicting thermal response [2][3][4][5][6][7], predicting distortion and residual stress, [8][9][10][11][12], and developing distortion mitigation techniques [13,14].…”

Numerical simulation and experimental calibration of additive manufacturing by blown powder technology. Part I: thermal analysis

“…Many researchers have used the FE method to study additive manufacturing technologies, often taking advantage from the experience acquired in modeling welding processes (Aggarangsi et al 2003), (Labudovic et al 2003), (Jendrzejewski et al 2004), (Jendrzejewski et al 2007), (Zekovic (Yang et al 2010), (Chiumenti et al 2010), (Anca et al 2011), (Marimuthu et al 2013), (Denlinger et al 2014), (Kelly et al 2014) and (Heigel et al 2015).…”

Finite element modeling and validation of thermomechanical behavior of Ti-6Al-4V in directed energy deposition additive manufacturing

“…Chiumenti et al established in-house FE software to simulate the deposition of different layers of filler material using a thermo-elasto-viscoplastic constitutive model coupled with a metallurgical model; they also discussed about the difficulties and the simplified hypotheses [11]. Anca et al introduced a model to simulate shape metal deposition by considering the liquid/solid phase change phenomenon and a concept called the "zero strength temperature", which is defined as the minimum temperature when the strength is zero [20]. Vastola also considered phase transformations between the powder, the liquid and the bulk to track the amount of remelting material [21].…”