scholarly journals Numerical Simulation and Experimental Validation of Sheet Laser Forming Processes Using General Scanning Paths

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1262
Author(s):  
Álvaro Navarrete ◽  
Felipe Cook ◽  
Diego Celentano ◽  
Marcela Cruchaga ◽  
Claudio García-Herrera
Keyword(s):  
Numerical Simulation ◽  
Material Properties ◽  
Experimental Validation ◽  
Piecewise Linear ◽  
Scanning Speed ◽  
Laser Forming ◽  
Element Formulation ◽  
Temperature Dependent ◽  
Modeling Framework ◽  
Good Agreement

This work presents numerical simulations and an experimental validation of sheet laser forming processes using general scanning paths with different laser beam operating parameters (i.e., power, diameter, and scanning speed) in two specific graphite coated stainless steel blanks (i.e., with thicknesses of 0.3 mm and 0.6 mm for the AISI 302 and 304 alloys, respectively). To this end, three specific laser forming tests involving single S-shaped, multiple circular, and single piecewise linear scanning paths are carried out. On the other hand, the numerical simulation of these tests is performed via a coupled thermomechanical finite element formulation, accounting for large viscoplastic strains, temperature-dependent material properties, and convection-radiation phenomena. The final bending angles provided by this model are found to be in good agreement with the experimental measurements for all of the cases studied. Therefore, this modeling framework can be established as a reliable approach to predict the material thermomechanical response during sheet laser forming using general scanning paths.

Numerical and Experimental Study of Strain Rate Effects in Laser Forming

2000 ◽  
Vol 122 (3) ◽  
pp. 445-451 ◽  
Author(s):  
Wenchuan Li ◽  
Y. Lawrence Yao
Keyword(s):  
Strain Rate ◽  
Material Properties ◽  
Peak Temperature ◽  
Laser Forming ◽  
Temperature Dependent ◽  
Strain Rate Effects ◽  
Temperature Method ◽  
Rate Effects ◽  
Forming Efficiency ◽  
Simulation Results

Experimental investigation and numerical simulation of the influence of the strain rate in laser forming are presented. To isolate and effectively study the strain rate effects, which are temperature dependent, a “constant peak temperature” method is developed with the aid of numerical modeling and solution. Under the condition of the constant peak temperature, the effects of strain rate on forming efficiency, residual stress and hardness of the formed parts are studied both experimentally and numerically. In the numerical model, the temperature dependence and strain-rate dependence of the flow stress and other material properties are considered. The simulation results are consistent with the experimental observations. [S1087-1357(00)01004-2]

Experimental and Numerical Analysis of Low Output Power Laser Bending of Thin Steel Sheets

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Vicente Stevens ◽  
Diego Celentano ◽  
Jorge Ramos-Grez ◽  
Magdalena Walczak
Keyword(s):  
Numerical Analysis ◽  
Output Power ◽  
Laser Forming ◽  
Element Formulation ◽  
Temperature Dependent ◽  
Forming Process ◽  
Laser Bending ◽  
Operating Variables ◽  
Steel Sheets ◽  
Thermal Boundary Conditions

This work presents an experimental and numerical analysis of a low output power single-pass laser forming process applied to thin stainless steel sheets. To this end, the proposed methodology consists in four stages respectively devoted to material characterization via tensile testing, estimation of thermal boundary conditions present in laser forming, realization of laser bending tests for two sets of operating variables, and finally, numerical simulation of this process carried out with a coupled thermomechanical finite element formulation accounting for large plastic strains, temperature-dependent material properties and convection–radiation phenomena. The numerical analysis, focused on the description of the evolution of the thermomechanical material response, is found to provide a satisfactory experimental validation of the final bending angle for two laser forming cases with different operating variables. In both cases, the predicted high temperature gradients occurring across the sample thickness show that the deformation process is mainly governed by the thermal gradient mechanism.

Numerical study of the effect of the yield drop phenomenon on the deformation behaviour of a Taylor projectile

2011 ◽  
Vol 226 (8) ◽  
pp. 2053-2062 ◽  
Author(s):  
Raguraman Munusamy ◽  
David C Barton ◽  
Tom H C Childs
Keyword(s):  
Numerical Study ◽  
Piecewise Linear ◽  
Deformation Behaviour ◽  
Three Dimensional ◽  
Yield Drop ◽  
Temperature Dependent ◽  
Target Plate ◽  
The Impact ◽  
Good Agreement ◽  
Modelling Approach

This article deals with the effects of parameters relating to the yield drop phenomenon on the deformation of Taylor projectiles. The numerical modelling approach performed using LS-DYNA was validated by considering a solid cylindrical projectile made of AA7010 aluminium alloy impacted against a massive, rigid target as described in the literature. Both the projectile and target were modelled using three-dimensional brick elements. A popular strain rate and temperature-dependent constitutive relation known as the Johnson–Cook model was used to represent the alloy projectile material behaviour, whilst the target plate was assumed to be rigid. A generally good agreement between test and numerical results was found. A steel projectile was then considered using a simple piecewise linear plasticity model which has provision for introducing the yield drop effect and in which temperature effects were ignored. The impact velocities varied from 200 to 1000 m/s. Significant influence of the yield drop on the deformation behaviour of the projectile at low impact velocities was found. However, the effect was far less significant at higher impact velocities (>400 m/s).

Numerical simulation and experimental validation of angular distortion and residual stresses in a T-joint

2015 ◽  
Vol 57 (7-8) ◽  
pp. 628-634
Author(s):  
Jing Chen ◽  
Liying Wang ◽  
Zhendong Shi ◽  
Zhen Dai ◽  
Meiqing Guo
Keyword(s):  
Numerical Simulation ◽  
Residual Stresses ◽  
Experimental Validation ◽  
Angular Distortion

Modeling of mass transfer in biofilms in oscillatory flow conditions using k-ɛ turbulence model

2003 ◽  
Vol 3 (1-2) ◽  
pp. 201-207
Author(s):  
H. Nagaoka ◽  
T. Nakano ◽  
D. Akimoto
Keyword(s):  
Numerical Simulation ◽  
Mass Transfer ◽  
Turbulence Model ◽  
Uptake Rate ◽  
Oscillatory Flow ◽  
Substrate Uptake ◽  
Flow Conditions ◽  
Mass Transfer Mechanism ◽  
Substrate Uptake Rate ◽  
Good Agreement

The objective of this research is to investigate mass transfer mechanism in biofilms under oscillatory flow conditions. Numerical simulation of turbulence near a biofilm was conducted using the low Reynold’s number k-ɛ turbulence model. Substrate transfer in biofilms under oscillatory flow conditions was assumed to be carried out by turbulent diffusion caused by fluid movement and substrate concentration profile in biofilm was calculated. An experiment was carried out to measure velocity profile near a biofilm under oscillatory flow conditions and the influence of the turbulence on substrate uptake rate by the biofilm was also measured. Measured turbulence was in good agreement with the calculated one and the influence of the turbulence on the substrate uptake rate was well explained by the simulation.

Field Observation and Simulation of Sediment Resuspension in a Shallow Lake

1988 ◽  
Vol 20 (6-7) ◽  
pp. 263-270 ◽  
Author(s):  
K. Otsubo ◽  
K. Muraoka
Keyword(s):  
Numerical Simulation ◽  
Shallow Lake ◽  
Water Wave ◽  
Field Data ◽  
Sediment Resuspension ◽  
Field Research ◽  
Lake Kasumigaura ◽  
Bed Erosion ◽  
Current Water ◽  
Good Agreement

The dispersion and resuspension of sediments in Takahamairi Bay basin of Lake Kasumigaura were studied by means of field research and numerical simulation. The field data on wind direction and velocity, lake current, water wave, and turbidity were shown. Based on these results, we discuss how precipitated sediments were resuspended in this shallow lake. To predict the turbidity and the depth of bed erosion, a simulation model was established for this lake. The calculated turbidity showed good agreement with the field data. According to the simulated results, the turbidity reaches 200 ppm, and the bed is eroded several millimeters deep when the wind velocity exceeds 12 m/s in the lake.

scholarly journals Numerical Simulation of the Aerosol Particle Motion in Granular Filters with Solid and Porous Granules

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 268
Author(s):  
Olga V. Soloveva ◽  
Sergei A. Solovev ◽  
Ruzil R. Yafizov
Keyword(s):  
Numerical Simulation ◽  
Aerosol Particle ◽  
Particle Deposition ◽  
Particle Diameter ◽  
Deposition Efficiency ◽  
Hydrodynamic Resistance ◽  
Hydrodynamic Properties ◽  
Granular Filters ◽  
Limiting Value ◽  
Good Agreement

In this work, a study was carried out to compare the filtering and hydrodynamic properties of granular filters with solid spherical granules and spherical granules with modifications in the form of micropores. We used the discrete element method (DEM) to construct the geometry of the filters. Models of granular filters with spherical granules with diameters of 3, 4, and 5 mm, and with porosity values of 0.439, 0.466, and 0.477, respectively, were created. The results of the numerical simulation are in good agreement with the experimental data of other authors. We created models of granular filters containing micropores with different porosity values (0.158–0.366) in order to study the micropores’ effect on the aerosol motion. The study showed that micropores contribute to a decrease in hydrodynamic resistance and an increase in particle deposition efficiency. There is also a maximum limiting value of the granule microporosity for a given aerosol particle diameter when a further increase in microporosity leads to a decrease in the deposition efficiency.

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