RETRACTED: The effect of power density, scanning velocity, and pulse frequency on residual stress in laser grooving process

Abstract

The purpose of this study is to present three-dimensional (3D) simulations using the finite-element (FE) method of thermo-mechanical stresses developed in the laser cutting process. The CO 2 laser beam is assumed to be in Gaussian mode and the calculation for prediction of material removal rate and stress values in the target was done on St.37 steel. The analysis allows the investigation of groove depth and stress field for a variety of laser power, cutting speed, and pulse frequency. The laser that is used for this study is 0.15 mm in beam radius with a 10.6 mm wavelength at an intensity range of 200-1000 W and repetition rate of 5000-10 000 Hz. The pulse duration is 10 ms and cutting speed varies from 1 to 2 m/min. Thermal properties of the material are assumed to be temperature dependent and the birth and death technique of elements was employed for simulation of material removal. Therefore, during the cutting process, if the temperature of any element is greater than the melting point, then the element is deactivated and does not participate in the calculation. Applicability of the thermal model under consideration was verified by comparing the result of simulation with experimental data in the relevant literature. The results show the validity of the simulation and applicability of the developed FE model for modelling of the laser cutting process.

Laser Discoloration in Acrylic Painting of Visual Art: Experiment and Modeling

“…The thermal analysis uses the traversing heat source along with the associated convective as well as radiative thermal boundary conditions. The spatial and temporally moving heat source representing moving CO 2 laser [ 22 , 23 ] was used. The balance of energy on the substrate in this non-isothermal process is presented in mathematical form as follows: where ρ is the density of the material (kg/m 3 ), K is the thermal conductivity (W/mK), C p is the specific heat capacity (J/kgK), T i is the temperature (K), t is time variable (s), and Q is the heat source.…”

“…The thermal analysis uses the traversing heat source along with the associated convective as well as radiative thermal boundary conditions. The spatial and temporally moving heat source representing moving CO 2 laser [22,23] was used. The balance of energy on the substrate in this non-isothermal process is presented in mathematical form as follows:…”

Review on finite element analysis of welding deformation and residual stress

“…Even the same welding process, deformation and residual stress also exist difference because of different welding conditions. Power density, scanning velocity and pulse frequency all have obviously influences on residual stress in CO 2 laser grooving welding, especially TEP-FEA-based peak value of residual stress was aggravated by a higher power density as shown in Figure 1 [22]. Welding speed was directly connected to the amount of the heat input, and thus an appropriate welding speed was helpful to reduce mechanical distortion and stress (Figure 2) [23].…”

“…With TEP-FEA method, Cozzolino et al reduced the welding residual stress and distortion by using the post-weld rolling process [36].

Figure 1 Axial residual stress with different power density [22].

Figure 2 Von-Mises stress with welding speed of (a) 2.6 mm s −1 , (b) 4.3 mm s −1 [23].

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Development of a novel high-speed dynamic length measurement system for mobile and large-scale cylinder workpiece

“…In practice, error self-correction mode is an imperative part of improving the measurement accuracy online. 29,30 Therefore, identifying and analyzing all the possible errors linked to the measurement process are fully considered. The influence of the errors which may be enclosed in the process of producing VMDP can be eliminated by the use of 2D error separation method.…”