Experimental and Numerical Investigation of Laser Forming of Closed-Cell Aluminum Foam

Author(s):  
Min Zhang ◽  
Chang Jun Chen ◽  
Grant Brandal ◽  
Dakai Bian ◽  
Y. Lawrence Yao

Aluminum foams are generally very attractive because of their ability of combining different properties such as strength, light weight, thermal, and acoustic insulation. These materials, however, are typically brittle under mechanical forming, and this severely limits their use. Recent studies have shown that laser forming is an effective way for foam panel forming. In this paper, the laser formability of Al–Si closed-cell foam through experiments and numerical simulations was investigated. The bending angle as a function of the number of passes at different laser power and scan velocity values was investigated for large- and small-pore foams. In the finite element analysis, both effective-property and cellular models were considered for the closed-cell foam. Multiscan laser forming was also carried out and simulated to study the accumulative effect on the final bending angle and stress states. The maximum von Mises stress in the scanning section was on the order of 0.8 MPa, which was lower than the yield strength of the closed-cell foam material. This paper further discussed the reasonableness and applicability of the two models.

1999 ◽  
Vol 66 (3) ◽  
pp. 772-779 ◽  
Author(s):  
G. Chen ◽  
X. Xu ◽  
C. C. Poon ◽  
A. C. Tam

Laser forming or laser bending is a newly developed, flexible technique which modifies the curvature of sheet metal by thermal residual stresses instead of external forces. The process is influenced by many parameters such as laser parameters, material properties, and target dimensions. In this work, a pulsed Nd:YLF laser was used as the energy source. The laser beam was focused into a line shape irradiating on the stainless steel specimen to induce bending. The bending angle was measured at various processing conditions. A finite element analysis was performed with the use of a two-dimensional plane strain model to calculate the thermoelastoplastic deformation process. Experimental measurements and computational results were in good agreement. Numerical sensitivity studies were performed to evaluate the effects of the unavailable material property data at high temperature. It was found that both optical reflectivity and thermal expansion coefficient influenced the bending angle significantly, while other extrapolated material properties at high temperature yielded acceptable results.


2012 ◽  
Vol 504-506 ◽  
pp. 1213-1218 ◽  
Author(s):  
Loredana Santo ◽  
Denise Bellisario ◽  
Ludovica Rovatti ◽  
Fabrizio Quadrini

Laser forming tests have been performed on open-cell aluminum alloy foams with different pore size. Laser power was fixed at 150 W, a total of 150 laser scans led to a bending angle up to 60°, depending on the laser scan rate. At the end of the laser bending, the foams were left to cool and samples were extracted for analysis by means of an optic microscope. The alloy microstructure was investigated in different points of the samples and correlated with the processing conditions. Image analysis was also carried out to extract the percentage of melted area due to laser heating.


2013 ◽  
Vol 554-557 ◽  
pp. 1864-1871 ◽  
Author(s):  
Fabrizio Quadrini ◽  
Denise Bellisario ◽  
Daniele Ferrari ◽  
Loredana Santo ◽  
Anna Santarsiero

Laser forming of open-cell aluminum foams has been modeled by means of a 3D finite element model which is able to take into account the real foam geometry as well as the main process variables. A parametric procedure has been defined for the geometry construction and meshing, and the simulation run. In order to calibrate and validate numerical modeling, compression and flexure tests were performed on a closed-cell aluminum foam. The simulation of mechanical tests allowed a correct modeling of the aluminum alloy behavior under plastic deformation. The same material behavior was implemented in a complex thermo-mechanical model for laser bending simulation. The final model is able to predict the shape evolution during forming and the correlation between process variables and final bent angles.


Author(s):  
Nurullah Türker ◽  
Hümeyra Tercanlı Alkış ◽  
Steven J Sadowsky ◽  
Ulviye Şebnem Büyükkaplan

An ideal occlusal scheme plays an important role in a good prognosis of All-on-Four applications, as it does for other implant therapies, due to the potential impact of occlusal loads on implant prosthetic components. The aim of the present three-dimensional (3D) finite element analysis (FEA) study was to investigate the stresses on abutments, screws and prostheses that are generated by occlusal loads via different occlusal schemes in the All-on-Four concept. Three-dimensional models of the maxilla, mandible, implants, implant substructures and prostheses were designed according to the All-on-Four concept. Forces were applied from the occlusal contact points formed in maximum intercuspation and eccentric movements in canine guidance occlusion (CGO), group function occlusion (GFO) and lingualized occlusion (LO). The von Mises stress values for abutment and screws and deformation values for prostheses were obtained and results were evaluated comparatively. It was observed that the stresses on screws and abutments were more evenly distributed in GFO. Maximum deformation values for prosthesis were observed in the CFO model for lateral movement both in the maxilla and mandible. Within the limits of the present study, GFO may be suggested to reduce stresses on screws, abutments and prostheses in the All-on-Four concept.


2021 ◽  
Vol 160 ◽  
pp. 107278
Author(s):  
Erdong Wang ◽  
Guangyong Sun ◽  
Gang Zheng ◽  
Qing Li

2021 ◽  
Vol 11 (6) ◽  
pp. 2547 ◽  
Author(s):  
Carlo Prati ◽  
João Paulo Mendes Tribst ◽  
Amanda Maria de Oliveira Dal Piva ◽  
Alexandre Luiz Souto Borges ◽  
Maurizio Ventre ◽  
...  

The aim of the present investigation was to calculate the stress distribution generated in the root dentine canal during mechanical rotation of five different NiTi endodontic instruments by means of a finite element analysis (FEA). Two conventional alloy NiTi instruments F360 25/04 and F6 Skytaper 25/06, in comparison to three heat treated alloys NiTI Hyflex CM 25/04, Protaper Next 25/06 and One Curve 25/06 were considered and analyzed. The instruments’ flexibility (reaction force) and geometrical features (cross section, conicity) were previously investigated. For each instrument, dentine root canals with two different elastic moduli(18 and 42 GPa) were simulated with defined apical ratios. Ten different CAD instrument models were created and their mechanical behaviors were analyzed by a 3D-FEA. Static structural analyses were performed with a non-failure condition, since a linear elastic behavior was assumed for all components. All the instruments generated a stress area concentration in correspondence to the root canal curvature at approx. 7 mm from the apex. The maximum values were found when instruments were analyzed in the highest elastic modulus dentine canal. Strain and von Mises stress patterns showed a higher concentration in the first part of curved radius of all the instruments. Conventional Ni-Ti endodontic instruments demonstrated higher stress magnitudes, regardless of the conicity of 4% and 6%, and they showed the highest von Mises stress values in sound, as well as in mineralized dentine canals. Heat-treated endodontic instruments with higher flexibility values showed a reduced stress concentration map. Hyflex CM 25/04 displayed the lowest von Mises stress values of, respectively, 35.73 and 44.30 GPa for sound and mineralized dentine. The mechanical behavior of all rotary endodontic instruments was influenced by the different elastic moduli and by the dentine canal rigidity.


Author(s):  
Osezua Obehi Ibhadode ◽  
Ishaya Musa Dagwa ◽  
Akii Okonigbon Akhaehomen Ibhadode

Calibration curves of a multi-component dynamometer is of essence in machining operations in a lathe machine as they serve to provide values of force and stress components for cutting tool development and optimization. In this study, finite element analysis has been used to obtain the deflection and stress response of a two component cutting tool lathe dynamometer, for turning operation, when the cutting tool is subjected to cutting and thrust forces from 98.1N to 686.7N (10 to 70kg-wts), at intervals of 98.1N(10kg-wt). By obtaining the governing equation, modeling the dynamometer assembly, defining boundary conditions, generating the assembly mesh, and simulating in Inventor Professional; horizontal and vertical components of deflection by the dynamometer were read off for three different loading scenarios. For these three loading scenarios, calibration plots by experiment compared with plots obtained from simulation by finite element analysis gave accuracies of 79%, 95%, 84% and 36%, 57%, 63% for vertical and horizontal deflections respectively. Also, plots of horizontal and vertical components of Von Mises stress against applied forces were obtained.


2014 ◽  
Vol 618 ◽  
pp. 433-437 ◽  
Author(s):  
Zhibin Li ◽  
Zhijun Zheng ◽  
Jilin Yu ◽  
Jie Yang ◽  
Fangyun Lu

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