A finite element model for the simulation of direct metal deposition

Abstract

The life prediction of components built by additive manufacturing process, such as Direct Metal Deposition (DMD), needs a good characterization of their physical states (including metallurgy, residual stresses…). A robust finite element analysis of the DMD process at a macroscopic scale should then include thermal, metallurgical and mechanical aspects. The present paper shows a comprehensive model, where the metallurgical section is developed in strong connection with the physical process. The model is implemented in the Finite Element Code Z-Set and a specific strategy is introduced to progressively activate the elements and follow a given fabrication route.

Three-dimensional finite element thermomechanical modeling of additive manufacturing by selective laser melting for ceramic materials

“…Roberts et al [16] used a heat source model considering the absorption of laser energy described in [17] and employed the method of element birth and death to simulate the addition of multiple layers, for Ti-6Al-4V material. The same method was used by Marion et al [18] for Direct Metal Deposition.…”

“…The integration by part and Gauss' law are applied to get the fourth term (arising from the compressible behavior) at left, also second and third terms at right in Eq. (18). The second term at right vanishes if we choose to be closed ( vanishes).…”

Predicting Microstructure Evolution During Directed Energy Deposition Additive Manufacturing of Ti-6Al-4V

“…In the current research, several thermal-mechanicalmicrostructural interactions with relatively negligible effects on microstructural behavior are not considered (i.e., weak coupling) in order to simplify the model and optimize computational efficiency [58,59]. On the other hand, the microstructural model can be coupled with the thermal-mechanical models in order to establish a more accurate model and predict the material response (i.e., distortions and stresses) due to microstructure and temperature [17,20].…”

“…Note that stress-induced phase transformations are ignored since the thermal-driven phase changes during the metal deposition processes have dominant effects [17,58]. Similarly, the effects of mechanical deformations on thermal behavior (i.e., plasticity induced thermal dissipation, change in the thermal boundary conditions) are not taken into account in the modeling due to their low contributions to the thermal evolution [17,59]. In addition, the effects of microstructure on thermal properties of material are not directly modeled.…”

“…Model. The microstructure of the solid state Ti-6Al-4V titanium alloy is modeled using the volumetric phase fractions [51][52][53][54][55][56][57][58][59] by considering only the Widmanst€ atten colony and basketweave a-phase fractions during the diffusion controlled transformation of the b-phase due to the negligible grain boundary a phase fractions [38]. The massive and martensitic transformations are not included in the microstructural model due to several reasons.…”