Numerical Modeling and Mechanism Analysis of Hybrid Heating and Shock Process for Laser-Assisted Laser Peen Forming

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Mingsheng Luo ◽  
Yongxiang Hu ◽  
Dong Qian ◽  
Zhenqiang Yao
Keyword(s):  
Thermal Stress ◽  
Laser Heating ◽  
Laser Peening ◽  
Mechanism Analysis ◽  
Coupled Modeling ◽  
Bending Deformation ◽  
Peen Forming ◽  
Effects Of Temperature ◽  
Capability Improvement ◽  
Thermoelastic Plastic

Laser-assisted laser peen forming (LALPF) is proposed as a hybrid process to combine laser heating and laser peening to improve the bending capability of laser peen forming (LPF) effectively. To predict LALPF-induced bending deformation and mechanism of bending capability improvement, a sequentially coupled modeling approach is established by integrating three models, i.e., a thermoelastic-plastic model to predict the temperature, a dynamic model to obtain the eigenstrain of laser shock, and an eigenstrain model to predict the bending deformation. The effects of temperature, thermal stress, and thermal plastic strain of laser heating and the coupling effects on the bending deformation were investigated. The results show that the interaction of temperature and thermal stress are the dominant factors contributing to the improvement of bending capability.

Finite element modelling of laser peening and laser peen forming of materials

2004 ◽  
Author(s):  
Patrice Peyre ◽  
Marie-Amélie Petit ◽  
Cyril Bolis ◽  
Eric Bartnicki ◽  
Rémy Fabbro ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Laser Peening ◽  
Element Modelling ◽  
Peen Forming

Research on Bending Angels of Laser Peen Forming without Confine Layer

2013 ◽  
Vol 712-715 ◽  
pp. 637-641
Author(s):  
Hua Ding ◽  
Run Zhang ◽  
Yun Long Wang ◽  
Bo Wu ◽  
Ming Zhou
Keyword(s):  
Laser Energy ◽  
New Technology ◽  
Pure Aluminum ◽  
Processing Parameters ◽  
Orthogonal Experimental Design ◽  
Laser Peening ◽  
Scanning Velocity ◽  
Peen Forming ◽  
Plastic Forming ◽  
Radiation Induced

As a new technology in the field of sheet metal plastic forming, Laser peening forming is a new invention which is based on the laser radiation induced shock waves. In the paper, the orthogonal experimental design is adopted to analyze the interaction of different processing parameters with the sample. Laser bending of thin 1060 pure aluminum sheet with the thickness of 0.25mm was studied by changing the laser energy, scanning velocity, and scanning times to understand the effect of process parameters. The results show that the three parameters have different effects on bending angles, scanning velocity ranks first, followed by scanning times and laser power in terms of their effects on the deformation angle.

Numerical Analysis of the Effect of Spot Superposition on Laser Peen Forming of Aluminum Alloy Sheet

2018 ◽  
Vol 765 ◽  
pp. 209-215
Author(s):  
Pei Xu ◽  
Yong Kang Zhang ◽  
Gui Fang Sun ◽  
Zhong Hua Ni ◽  
Bo Yong Su ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Alloy Sheet ◽  
Laser Spot ◽  
Laser Peening ◽  
Aluminum Alloy Sheet ◽  
Analysis Method ◽  
Element Analysis ◽  
Peen Forming ◽  
The Finite Element Analysis ◽  
Better Than

In order to study the effect of laser spot superposition on aluminum alloy sheet forming by laser peening, the finite element analysis method was introduced to simulating the forming of 7075 aluminum alloy with different spot superposition case. The results showed that the forming effect and stress distribution of the metal sheet was effected by the laser spot superposition modes. The forming effect of transverse spot superposition mode was better than the other three spot superposition modes.

Thermal Stress Associated With Non-Fourier Heat Conduction in Femtosecond Laser Heating of Multilayer Metallic Films

2018 ◽  
Author(s):  
Swarup Bag ◽  
M. Ruhul Amin
Keyword(s):  
Thin Film ◽  
Heat Conduction ◽  
Thermal Stress ◽  
Temperature Distribution ◽  
Pulse Laser ◽  
Laser Heating ◽  
Laser Source ◽  
Phase Lag ◽  
Dual Phase ◽  
Fourier Heat Conduction

In the present work, the deformation behavior in metallic film subjected to ultra-short laser heating is investigated. Static thermo-elastic behavior is predicted for 100 nm thin film of either single layer or multiple layers. The temperature distribution is estimated from dual-phase lag non-Fourier heat conduction model. The maximum temperature after single pulse is achieved 730 K. The temperature profile for this pulse laser is used to compute elastic stress and distortion field following the minimization of potential energy of the system. In the present work, the simulation has been proposed by developing 3D finite element based coupled thermo-elastic model using dual phase lag effect. The experimental basis of transient temperature distribution in ultra-short pulse laser is extremely difficult or nearly impossible, the model results have been validated with literature reported thermal results. Since the temperature distribution due to pulse laser source varies with time, the stress analysis is performed in incremental mode. Hence, a sequentially coupled thermo-mechanical model is developed that is synchronized between thermal and mechanical analysis in each time steps of transient problem. The maximum equivalent stress is achieved 0.3 GPa. Numerical results show that the predicted thermal stress may exceeds the tensile strength of the material and may lead to crack or damage the thin film.

scholarly journals Surface Morphology and Bending Deformation of 2024-T3 Thin Sheets with Laser Peen Forming

2018 ◽  
Vol 167 ◽  
pp. 03007
Author(s):  
Junfeng Wu ◽  
Shikun Zou ◽  
Yongkang Zhang ◽  
Shuili Gong
Keyword(s):  
Surface Morphology ◽  
Laser Energy ◽  
Sheet Thickness ◽  
Aluminum Foil ◽  
Bottom Surface ◽  
Thin Sheets ◽  
Bending Deformation ◽  
Peen Forming ◽  
Length Width ◽  
Convex Deformation

Laser peen forming (LPF) is a pure mechanical forming method through accumulated plastic strain, which has been successfully applied in wing components. Experimental investigation has been performed to understand the effect of process parameters such as constraint conditions, sheet thickness and laser energy on surface morphology and bending deformation of 2024-T3 thin sheets of dimensions of 76 mm ×19 mm (length × width). The research results indicated that bulges on the aluminum foil were generated at the bottom surface and not generated at the topmost surface. It was different for transition value of two-way bending deformations of thin sheets after LPF with different constraint conditions. Remain flat thicknesses of thin sheets after LPF were about 1 mm ~ 2 mm for 20 J, 25 J and 30 J. Arc heights and curvatures of 3 mm thickness sheets increased with laser energy and those of 2 mm thickness sheets only made little change. It was found that convex deformation, flat, concave deformation and laser deep drawing for thin sheets with different thicknesses after LPF.

Effects of temperature on the growth of psychrophilic bacteria from glaciers

1976 ◽  
Vol 22 (6) ◽  
pp. 839-846 ◽  
Author(s):  
A. M. Gounot
Keyword(s):  
Cell Wall ◽  
Thermal Stress ◽  
Viable Count ◽  
Optimum Temperature ◽  
Cell Wall Synthesis ◽  
Psychrophilic Bacteria ◽  
Different Temperatures ◽  
Abnormal Cells ◽  
Effects Of Temperature ◽  
Arthrobacter Species

Growth of five strains of psychrophilic bacteria (four Arthrobacter and one Pseudomonas) isolated from glacial deposits was studied at different temperatures. Three strains were facultative psychrophiles, having an optimum temperature for growth at about 25–28 °C and a maximum at about 32–34 °C. The two Arthrobacter glacialis strains were found to be obligate psychrophiles with an optimum at 13–15 °C and a maximum at 18 °C. Arrhenius plots showed that A. glacialis could compete with the facultative psychrophilic bacteria only at 0 °C, that is, the temperature of its natural environment. The psychrophilic Arthrobacter species studied here are more resistant to thermal stress than are marine psychrophilic bacteria.For Arthrobacter, in contrast to Pseudomonas, temperatures above the optimum induced formation of filaments and abnormal cells. The culture turbidity increased 10 to 30 times, whereas viable count tended to decrease. The thermal block seems to prevent cell wall synthesis and septation, but at a different step for each species.

Sign in / Sign up

Export Citation Format

Share Document