scholarly journals Laser Shock Induced Deformation of Copper Foil on Diverse Molds and the Cross-Sectional Microstructure Changes

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1264
Author(s):  
Di Huang ◽  
Jiaxiang Man
Keyword(s):  
Copper Foil ◽  
Laser Energy ◽  
Three Dimensional ◽  
Element Model ◽  
Hexagonal Structure ◽  
Residual Stress Distribution ◽  
Laser Shock ◽  
Cross Sectional ◽  
Forming Mechanism ◽  
Pulse Laser Energy

The microscale structures prepared on copper foil by laser shock deformation was introduced in the paper. The various sizes of hexagonal structures were successfully fabricated on copper foil with different molds. The influence of laser energy on the deformation depth of a hexagonal structure was studied using experiments. The morphology of the hexagonal structures on copper foil was observed by a three-dimensional profilometer, and mechanical property were characterized by a nanoindenter. A finite element model was established in order to describe the copper foil forming mechanism on mold and calculate the residual stress distribution. The microstructures and cross-section deformation of copper foil on different molds were also observed. The results indicated that the depth of hexagonal structures on 50# mold was higher than that of the structures on 100# mold and 230# mold, and the depth of hexagonal structures increased with the increasing of pulse laser energy. The copper foil above the mold hexagon side was bent and thinned after laser shock, and the grains of copper foil were also refining. The mechanical properties of copper foil were improved after laser shock was performed on the mold.

Crashworthiness performance of concentric structures with different cross-sectional shapes under multiple loading conditions

2020 ◽  
pp. 095440702096188
Author(s):  
Sadjad Pirmohammad
Keyword(s):  
Energy Absorption ◽  
Specific Energy ◽  
Absorption Maximum ◽  
Element Model ◽  
Hexagonal Structure ◽  
Loading Conditions ◽  
Cross Sectional ◽  
Specific Energy Absorption ◽  
Multiple Loading ◽  
Energy Absorbing

This paper evaluates the crashworthiness performance of concentric structures with different numbers of tubes (i.e. one to five) and cross-sectional shapes (i.e. hexagon, octagon, decagon and circle) under the multiple loadings of θ = 0, 10, 20 and 30°. An experimentally validated finite element model generated in LS-DYNA is employed to calculate the crashworthiness parameters including the specific energy absorption, maximum crush force and crush force efficiency. A total of 20 concentric structures are analyzed to explore the effects of number of tubes and cross-sectional shapes on the crushing performance. A multi-criteria decision-making method known as TOPSIS is also used to compare and rank the concentric structures in terms of crushing performance. Based on the results, the hexagonal structure including two tubes and octagonal, decagonal and circular structures including three tubes demonstrate the best results among their corresponding cross-sectional shapes. These structures show 9, 39, 38 and 39% higher specific energy absorption compared to their corresponding single tubal cases, respectively. However, in comparison to single tubal cases, they generate 4, 57, 57 and 58% higher maximum crush force, respectively. As such, the values for the improvement of the crush force efficiency are 3, 26, 25 and 21%, respectively. Furthermore, the decagonal structure including three tubes provides the highest energy absorbing characteristics as compared with all the other structures studied in this research. Meanwhile, taking into account all the multiple loading conditions, this structure shows 50% higher specific energy absorption than the hexagonal structure including single tube (as the weakest structure).

scholarly journals Experimental and Numerical Investigations of a Novel Laser Impact Liquid Flexible Microforming Process

Metals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 599 ◽  
Author(s):  
Fei Liu ◽  
Huixia Liu ◽  
Chenkun Jiang ◽  
Youjuan Ma ◽  
Xiao Wang
Keyword(s):  
Numerical Simulation ◽  
Laser Energy ◽  
Pure Copper ◽  
Three Dimensional ◽  
Element Model ◽  
Force Transmission ◽  
Large Area ◽  
Laser Impact ◽  
Metallic Foils

A novel high strain rate microforming technique, laser impact liquid flexible embossing (LILFE), which uses laser induced shock waves as an energy source, and liquid as a force transmission medium, is proposed by this paper in order to emboss three-dimensional large area micro arrays on metallic foils and to overcome some of the defects of laser direct shock microembossing technology. The influences of laser energy and workpiece thickness on the deformation characteristics of the pure copper foils with the LILFE process were investigated through experiments and numerical simulation. A finite element model was built to further understand the typical stages of deformation, and the results of the numerical simulation are consistent with those achieved from the experiments. The experimental and simulation results show that the forming accuracy and depth of the embossed parts increases with the increase in laser energy and decrease in workpiece thickness. The thickness thinning rate of the embossed parts increases with the decrease of the workpiece thickness, and the severest thickness thinning occurs at the bar corner region. The experimental results also show that the LILFE process can protect the workpiece surface from being ablated and damaged, and can ensure the surface quality of the formed parts. Besides, the numerical simulation studies reveal the plastic strain distribution of embossed microfeatures under different laser energy.

Effect of Friction on Residual Stress Distribution Induced by Split Sleeve Cold Expansion Process

2020 ◽  
Author(s):  
Mithun K. Dey ◽  
Dave Kim ◽  
Hua Tan
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Compressive Residual Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Residual Stress Distribution ◽  
Expansion Process ◽  
Cold Expansion ◽  
Three Dimensional Finite Element

Abstract Residual Stress distribution and parametric influence of friction are studied for the split sleeve cold expanded holes in Al 2024 T351 alloy, by developing a three-dimensional finite element model of the process. Fastener holes in the alloy are necessary for the manufacturing process, but they create a potential area for stress concentration, which eventually leads to fatigue under cyclic loading. Beneficial compressive residual stress distribution as a result of the split sleeve cold expansion process provides retardation against crack initiation and propagation at the critical zones near hole edges. In this parametric study, the influence of friction between contact surfaces of the split sleeve and mandrel is numerically investigated. Hole reaming process after split sleeve cold expansion is often not discussed. Without this post-processing procedure, split sleeve cold expansion is incomplete in practice, and its purpose of providing better fatigue performance is invalidated. This study presents results and an overview of the significance of friction with the consideration of the postprocessing of split sleeve cold expansion. The numerical results show that with increasing friction coefficient, compressive residual stress reduces significantly at the mandrel entry side, which makes the hole edge more vulnerable to fatigue. The different aspects of finite element modeling approaches are also discussed to present the accuracy of the prediction. Experimental residual stress observation or visual validation is expensive and time-consuming. So better numerical prediction with the transparency of the analysis design can provide critical information on the process.

Three-Dimensional Reconstruction of Three Real Roots Included Periodontal Ligament and Implant Study

2014 ◽  
Vol 575 ◽  
pp. 931-934
Author(s):  
Qi Wang ◽  
Ling Chen ◽  
Zhong Zhang ◽  
Xing Hua Niu
Keyword(s):  
Finite Element ◽  
Periodontal Ligament ◽  
Three Dimensional ◽  
Element Model ◽  
Imaging Method ◽  
Element Analysis ◽  
Cross Sectional ◽  
The Real ◽  
Engineering Software ◽  
Ct Data

To investigate the periodontal ligament contains the real root of the three model cases, a combination of different implant and tooth variation of the stress distribution for the subsequent three root implant biomechanics analysis provides digital models. Methods: Mimics and Geomagic reverse engineering software for digital imaging method to obtain CT data processing. And the use of UG assembled in ANSYS workbench in finite element analysis. Results: A consistent with the real situation of three tooth root finite element model which contains periodontal ligament, and found that with the dental implant junction with the cross-sectional area decreases, where the stress amplitude fluctuations increases.

Three-Dimensional Endmill Dynamics: Modal Development and Experimental Validation

2011 ◽  
Author(s):  
Bekir Bediz ◽  
Uttara Kumar ◽  
Burak Ozdoganlar ◽  
Tony L. Schmitz
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Impact Testing ◽  
Cross Sectional ◽  
Macro Scale ◽  
Model Predictions ◽  
Bending Modes ◽  
Milling Tools ◽  
Better Than

In this paper the three-dimensional dynamic behavior of macro-scale milling tools is modeled using the spectral-Tchebychev technique while considering the actual fluted cross-sectional geometry and pretwisted shape of the tools. The bending and torsional behavior of three different fluted endmills is compared to finite element predictions and experimental results obtained using impact testing with free-free boundary conditions. The percent difference between experiment and the spectral-Tchebychev method predictions is shown to be 3% or less for all three tools while considering the first six bending modes and first two torsional modes. For the same modes, the spectral-Tchebychev and finite element model predictions agreed to better than 1%.

scholarly journals Simulation and Experimental Study on Residual Stress Distribution in Titanium Alloy Treated by Laser Shock Peening with Flat-Top and Gaussian Laser Beams

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1343 ◽  
Author(s):  
Xiang Li ◽  
Weifeng He ◽  
Sihai Luo ◽  
Xiangfan Nie ◽  
Le Tian ◽  
...  
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Stress Distribution ◽  
Energy Distribution ◽  
Laser Energy ◽  
Residual Stress Distribution ◽  
Laser Shock Peening ◽  
Laser Beams ◽  
Laser Shock ◽  
Shock Peening

The residual stress introduced by laser shock peening (LSP) is one of the most important factors in improving metallic fatigue life. The shock wave pressure has considerable influence on residual stress distribution, which is affected by the distribution of laser energy. In this work, a titanium alloy is treated by LSP with flat-top and Gaussian laser beams, and the effects of spatial energy distribution on residual stress are investigated. Firstly, a 3D finite element model (FEM) is developed to predict residual stress with different spatial energy distribution, and the predicted residual stress is validated by experimental data. Secondly, three kinds of pulse energies, 3 J, 4 J and 5 J, are chosen to study the difference of residual stress introduced by flat-top and Gaussian laser beams. Lastly, the effect mechanism of spatial energy distribution on residual stress is revealed.

Study on Technology of Flexible Forming of Sheet Metal Based on Laser Shock Waves

2004 ◽  
Vol 471-472 ◽  
pp. 453-456 ◽  
Author(s):  
Yong Kang Zhang ◽  
Jian Zhong Zhou ◽  
Dun Wen Zuo ◽  
Judith C. Yang ◽  
Lan Cai
Keyword(s):  
Shock Waves ◽  
Sheet Metal ◽  
Three Dimensional ◽  
Processing Parameters ◽  
Laser Shock ◽  
Forming Process ◽  
Element Analysis ◽  
Flexible Forming ◽  
Forming Mechanism ◽  
Fea Simulation

The conventional forming of sheet metal is realized by the Die and Mould, this method usually give rise to high cost, long production periods and little flexibility. In order to adapt to the changing requirements of the market and make small batch production of three-dimensional parts of shallow stretching economically, a flexible forming technique of sheet metal based on laser shock waves is presented in this paper. After the forming mechanism and process are introduced, a finite-element analysis method is applied to simulate the shock forming process to obtain the optimized laser parameters and the shocking tracks. The experimental are carried out for the overlapped shock-forming, and the forming contour is measured and compared with the FEA simulation. The investigation provides the theoretical foundation for the selection of forming locus and processing parameters of flexible forming of sheet metal.

scholarly journals Flexible GMR Sensor Array for Magnetic Flux Leakage Testing of Steel Track Ropes

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
W. Sharatchandra Singh ◽  
B. P. C. Rao ◽  
S. Thirunavukkarasu ◽  
T. Jayakumar
Keyword(s):  
Sensor Array ◽  
Spatial Information ◽  
Three Dimensional ◽  
Element Model ◽  
Axial Component ◽  
Cross Sectional ◽  
Dimensional Finite Element ◽  
Gmr Sensor ◽  
Three Dimensional Finite Element ◽  
Induced Defects

This paper presents design and development of a flexible GMR sensor array for nondestructive detection of service-induced defects on the outer surface of 64 mm diameter steel track rope. The number of GMR elements and their locations within saddle-type magnetizing coils are optimized using a three dimensional finite element model. The performance of the sensor array has been evaluated by measuring the axial component of leakage flux from localized flaw (LF) and loss of metallic cross-sectional area (LMA) type defects introduced on the track rope. Studies reveal that the GMR sensor array can reliably detect both LF and LMA type defects in the track rope. The sensor array has a fast detection speed along the length of the track rope and does not require circumferential scanning. It is also possible to image defects using the array sensor for obtaining their spatial information.

scholarly journals Stress Analysis of a Maxillary Central Incisor Restored with Different Posts

2007 ◽  
Vol 01 (02) ◽  
pp. 067-071 ◽  
Author(s):  
Necdet Adanir ◽  
Sema Belli
Keyword(s):  
Stress Distribution ◽  
Glass Fiber ◽  
Gold Alloy ◽  
Three Dimensional ◽  
Element Model ◽  
Von Mises Stress ◽  
Maxillary Incisor ◽  
Central Incisor ◽  
Cross Sectional ◽  
Maxillary Central Incisor

ABSTRACTObjectives: To evaluate the effects of different post materials on the stress distribution in an endodontically treated maxillary incisor.Materials and Methods: A pseudo 3-dimensional finite element model was created in a labiolingual cross-sectional view of a maxillary central incisor and modified according to five posts with different physical properties consisting stainless steel, titanium, gold alloy, glass fiber (Snowpost), and carbon fiber (Composipost). A 200 N force was then applied from two different directions; a) vertical load on the incisal edge, b) 45 degree diagonal load above the cingulum location. Stress distribution and values were then calculated by considering the pseudo three dimensional von Mises stress criteria.Results: Under two loading conditions, post made of steel showed greatest stress concentration at the post/dentin interface followed by titanium, gold alloy, Snowpost and Composipost. However, Composipost, which elastic modulus was closer to the dentin, produced highest stress values at 1/3 cervical area.Conclusions: Within the limitation of this simulated mechanical analysis, we can conclude that the physical characteristics of posts were important on stress distributions in post and core applications. Glass fiber post revealed more balanced stress distribution under functional forces. (Eur J Dent 2007;2:67-71)

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