scholarly journals INVESTIGATION ON THERMAL DEFORMATION IN LASER ADDITIVE MANUFACTURING

2021 ◽  
Vol 2021 (3) ◽  
pp. 4584-4590
Author(s):  
Y. Kuroiwa ◽  
◽  
D. Kono ◽  
Y. Oda ◽  
◽  
...  
Keyword(s):  
Finite Element ◽  
Additive Manufacturing ◽  
Heat Source ◽  
Deformation Theory ◽  
Thermal Deformation ◽  
Finite Element Simulations ◽  
Laser Additive Manufacturing ◽  
Shape Accuracy ◽  
Metal Material ◽  
Metal Additive

In metal additive manufacturing, a metal material is melted by a concentrated heat source such as a laser. Therefore, thermal deformation occurs in the fabrication, which causes deterioration of shape accuracy and crack of the workpiece. In this study, a method to systematically reduce the thermal deformation was discussed. The mechanism of thermal deformation caused by stacking and lining up the bead was investigated using finite element simulations and experiments. Based on the obtained results and thermal deformation theory in welding, a method to reduce the thermal deformation was proposed and the validity of the method was demonstrated by simulation.

Structural Optimization and Additive Manufacturing

2014 ◽  
Vol 611-612 ◽  
pp. 811-817 ◽  
Author(s):  
Julen Ibabe ◽  
Antero Jokinen ◽  
Jari Larkiola ◽  
Gurutze Arruabarrena
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Stainless Steel ◽  
Additive Manufacturing ◽  
Structural Optimization ◽  
Finite Element Simulations ◽  
Optimization Process ◽  
Manufacturing Processes ◽  
Complex Geometries ◽  
Additive Manufacturing Technology

Additive Manufacturing technology offers almost unlimited capacity when manufacturing parts with complex geometries which could be impossible to get with conventional manufacturing processes. This paper is based on the study of a particular real part which has been redesigned and manufactured using an AM process. The challenge consists of redesigning the geometry of an originally aluminium made part, in order to get a new stainless steel made model with same mechanical properties but with less weight. The new design is the result of a structural optimization process based on Finite Element simulations which is carried out bearing in mind the facilities that an AM process offers.

scholarly journals Analytical Thermal Modeling of Metal Additive Manufacturing by Heat Sink Solution

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2568 ◽  
Author(s):  
Jinqiang Ning ◽  
Daniel E. Sievers ◽  
Hamid Garmestani ◽  
Steven Y. Liang
Keyword(s):  
Heat Transfer ◽  
Finite Element Method ◽  
Boundary Condition ◽  
Finite Element ◽  
Additive Manufacturing ◽  
Computational Efficiency ◽  
Heat Sink ◽  
Thermal Gradients ◽  
Metal Additive ◽  
Element Method

Metal additive manufacturing can produce geometrically complex parts with effective cost. The high thermal gradients due to the repeatedly rapid heat and solidification cause defects in the produced parts, such as cracks, porosity, undesired residual stress, and part distortion. Different techniques were employed for temperature investigation. Experimental measurement and finite element method-based numerical models are limited by the restricted accessibility and expensive computational cost, respectively. The available physics-based analytical model has promising short computational efficiency without resorting to finite element method or any iteration-based simulations. However, the heat transfer boundary condition cannot be considered without the involvement of finite element method or iteration-based simulations, which significantly reduces the computational efficiency, and thus the usefulness of the developed model. This work presents an explicit and closed-form solution, namely heat sink solution, to consider the heat transfer boundary condition. The heat sink solution was developed from the moving point heat source solution based on heat transfer of convection and radiation. The part boundary is mathematically discretized into many heats sinks due to the non-uniform temperature distribution, which causes non-uniform heat loss. The temperature profiles, thermal gradients, and temperature-affected material properties are calculated and presented. Good agreements were observed upon validation against experimental molten pool measurements.

scholarly journals Assumption of Constraining Force to Explain Distortion in Laser Additive Manufacturing

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2327 ◽  
Author(s):  
Deqiao Xie ◽  
Jianfeng Zhao ◽  
Huixin Liang ◽  
Zongjun Tian ◽  
Lida Shen ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Material Properties ◽  
Contributory Factor ◽  
Sectional Area ◽  
Laser Additive Manufacturing ◽  
Element Analysis ◽  
Cross Sectional ◽  
Fea Model ◽  
Metal Additive ◽  
Distortion Mechanism

Distortion is a common but unrevealed problem in metal additive manufacturing, due to the rapid melting in metallurgy and the intricate thermal-mechanical processes involved. We explain the distortion mechanism and major influencing factors by assumption of constraining force, which is assumed between the added layer and substrate. The constraining force was set to act on the substrate in a static structural finite element analysis (FEA) model. The results were compared with those of a thermal-mechanical FEA model and experiments. The constraining force and the associated static structural FEA showed trends in distortion and stress distribution similar to those shown by thermal-mechanical FEA and experiments. It can be concluded that the constraining force acting on the substrate is a major contributory factor towards the distortion mechanism. The constraining force seems to be primarily related to the material properties, temperature, and cross-sectional area of the added layer.

scholarly journals Residual Stresses Control in Additive Manufacturing

2021 ◽  
Vol 5 (4) ◽  
pp. 138
Author(s):  
Xufei Lu ◽  
Miguel Cervera ◽  
Michele Chiumenti ◽  
Xin Lin
Keyword(s):  
Additive Manufacturing ◽  
Residual Stresses ◽  
Thermal Deformation ◽  
Element Model ◽  
Thermal Gradients ◽  
Part Geometry ◽  
The Core ◽  
Optimal Processing ◽  
Scan Pattern ◽  
Metal Additive

Residual stresses are one of the primary causes for the failure of parts or systems in metal additive manufacturing (AM), since they easily induce crack propagation and structural distortion. Although the formation of residual stresses has been extensively studied, the core factors steering their development in AM have not been completely uncovered. To date, several strategies based on reducing the thermal gradients have been developed to mitigate the manifestation of residual stresses in AM; however, how to choose the optimal processing plan is still unclear for AM designers. In this regard, the concept of the yield temperature, related to the thermal deformation and the mechanical constraint, plays a crucial role for controlling the residual stresses, but it has not been duly investigated, and the corresponding approach to control stresses is also yet lacking. To undertake such study, a three-bar model is firstly used to illustrate the formation mechanism of the residual stress and its key causes. Next, an experimentally calibrated thermomechanical finite element model is used to analyze the sensitivity of the residual stresses to the scan pattern, preheating, energy density, and the part geometry and size, as well as the substrate constraints. Based on the numerical results obtained from this analysis, recommendations on how to minimize the residual stresses during the AM process are provided.

Thermo-Mechanical Analysis of Laser Additive Manufacturing for Metals

2019 ◽  
Vol 825 ◽  
pp. 7-12
Author(s):  
Hsuan Hao Shih ◽  
Chih Kuang Lin
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Additive Manufacturing ◽  
Temperature Gradient ◽  
Mechanical Analysis ◽  
Laser Additive Manufacturing ◽  
Element Analysis ◽  
Analysis Technique ◽  
Moving Direction ◽  
Simulation Results

The aim of this study is to develop a finite element analysis technique to characterize the distributions of temperature and stress in the process of multilayer deposition of metallic powders by laser additive manufacturing (LAM). Simulation results indicate the residual normal stress in the laser moving direction is greater than that in other directions due to a larger temperature gradient, and it increases with number of deposited layers. Highly residual stresses are present in the LAM build and at the base nearby the interface between the build and base.

scholarly journals Finite Element Analysis of the Milling of Ti6Al4V Titanium Alloy Laser Additive Manufacturing Parts

2021 ◽  
Vol 11 (11) ◽  
pp. 4813
Author(s):  
Zhaohui Ren ◽  
Xingwen Zhang ◽  
Yunhe Wang ◽  
Zhuhong Li ◽  
Zhen Liu
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Titanium Alloy ◽  
Additive Manufacturing ◽  
Initial Temperature ◽  
Residual Tensile Stress ◽  
Laser Additive Manufacturing ◽  
Element Analysis ◽  
Finite Element Software ◽  
Ti6al4v Titanium Alloy

This study aimed to analyze the defects of large residual stress in laser additive manufacturing metal parts by establishing a milling numerical simulation of Ti6Al4V titanium alloy thin-walled parts based on the Johnson-Cook constitutive model of Ti6Al4V titanium alloy, a modified Coulomb friction stress model, the physical chip separation criterion and other theories, combined with the finite element software ABAQUS. The influences of milling depth, initial temperature and milling speed on the forming quality of the formed part were analyzed. The results show that milling changes the residual stress distribution of the deposition layer, which can reduce or even change the residual tensile stress on the surface of the deposition layer produced by the additive manufacturing process into compressive stress, and the equivalent Mises stress decreases by 47% compared with the original forming surface. When the initial temperature increases from 20 °C to 400 °C, the maximum equivalent Mises stress of the milling surface decreases by 26%.

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