Study on overlapping of two sequential scans in laser forming

2007 ◽  
Vol 221 (9) ◽  
pp. 993-997 ◽  
Author(s):  
H Shen ◽  
J Zhou ◽  
Z Q Yao
Keyword(s):  
Plastic Strain ◽  
Material Properties ◽  
Structural Model ◽  
Three Dimensional ◽  
High Strength ◽  
Laser Beams ◽  
Laser Forming ◽  
Numerical Investigations ◽  
Localized Heating ◽  
The Difference

Laser forming can utilize localized heating for the forming of high strength alloys and use combinations of straightandcurved lines to produce three-dimensional formedcomponents, which are of significant value to industries of aerospace, shipbuilding, and microelectronics. A three-dimensional non-linear, indirectly coupled thermal—structural model for the overlapping ratio of two sequential laser beams scanning is established, accounting for temperature dependency of material properties. Numerical results are verified by experimental data. Numerical investigations are carried out to examine the difference in plastic strain distributions under different overlapping ratios. The results show that the bending angle is larger when the size of plastic zone on the top surface is wider, although the plastic strain is smaller.

Laser Forming for Flexible Fabrication

2000 ◽  
Vol 16 (02) ◽  
pp. 97-109
Author(s):  
Koichi Masubuchi ◽  
Jerry E. Jones
Keyword(s):  
Three Dimensional ◽  
Low Carbon Steel ◽  
High Strength Steels ◽  
Cost Benefit ◽  
Network Models ◽  
High Strength ◽  
Laser Forming ◽  
Low Carbon ◽  
Flat Plates ◽  
Neural Network Models

A 36-month program supported by the Defense Advanced Research Projects Agency (DARPA) was conducted to demonstrate the feasibility to predictably laser form a variety of ferrous and non-ferrous metals of different thickness. Laser forming provides a method of producing complex shapes in sheet, plate, and tubing without the use of tooling, molds, or dies. By heating a localized area with a laser beam, it is possible to create stress states that result in predictable deformation. This research program has developed, refined and demonstrated constitutive and empirical, and neural network models to predict deformation as a function of critical parametric variables and established an understanding of the effect of laser forming on some metallurgical properties of materials. The program was organized into two, time-phased tasks. The first task involved forming flat plates to one-dimensional (I -D) shapes, such as, hinge bends in various materials including low-carbon steel, high-strength steels, nickel-based super alloys, and aluminum alloys. The second task expanded the work conducted in the first task to investigate three-dimensional (3-D) configurations. The models were updated, 3-D specimens fabricated and evaluated, and cost benefit analyses were performed.

scholarly journals Multiscale Characterization of An Oxide Scale Formed on the Creep-Resistant ATI 718Plus Superalloy during High-Temperature Oxidation

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6327
Author(s):  
Adam Kruk ◽  
Aleksander Gil ◽  
Sebastian Lech ◽  
Grzegorz Cempura ◽  
Alina Agüero ◽  
...  
Keyword(s):  
Phase Distribution ◽  
3D Visualization ◽  
Three Dimensional ◽  
High Strength ◽  
Temperature Oxidation ◽  
Near Surface ◽  
Cr2o3 Scale ◽  
Surface Areas ◽  
The Difference ◽  
Original Insight

The ATI 718Plus® is a creep-resistant nickel-based superalloy exhibiting high strength and excellent oxidation resistance in high temperatures. The present study is focused on multiscale 2D and 3D characterization (morphological and chemical) of the scale and the layer beneath formed on the ATI 718Plus superalloy during oxidation at 850 °C up to 4000 h in dry and wet air. The oxidized samples were characterized using various microscopic methods (SEM, TEM and STEM), energy-dispersive X-ray spectroscopy and electron diffraction. The 3D visualization of the microstructural features was achieved by means of FIB-SEM tomography. When oxidized in dry air, the ATI 718Plus develops a protective, dense Cr2O3 scale with a dual-layered structure. The outer Cr2O3 layer is composed of coarser grains with a columnar shape, while the inner one features fine, equiaxed grains. The Cr2O3 scale formed in wet air is single-layered and features very fine grains. The article discusses the difference between the structure, chemistry and three-dimensional phase distribution of the oxide scales and near-surface areas developed in the two environments. Electron microscopy/spectroscopy findings combined with the three-dimensional reconstruction of the microstructure provide original insight into the role of the oxidation environment on the structure of the ATI 718Plus at the nanoscale.

Numerical investigation of temperature field of different mechanisms in laser forming

2011 ◽  
Vol 226 (8) ◽  
pp. 2118-2125 ◽  
Author(s):  
Yongjun Shi ◽  
Peng Yi ◽  
Yancong Liu
Keyword(s):  
Temperature Field ◽  
Temperature Distribution ◽  
Process Parameters ◽  
Material Properties ◽  
Industrial Applications ◽  
Laser Forming ◽  
Temperature Zone ◽  
Numerical Investigations ◽  
Distribution Features ◽  
Plate Size

In laser forming, deformation of a plate is different when different mechanisms play dominant roles. A deformation field depends on a temperature field that is related to process parameters, material properties and plate size. Numerical investigations of temperature distribution with different process parameters were carried out when different mechanisms were active. A critical temperature for generating plastic deformation was investigated. Four temperature feature parameters were defined based on the temperature distribution characteristics of the high-temperature zone. The numerical results show that the temperature gradient is obviously different under different mechanism conditions. The temperature distribution features for the different mechanisms have a larger difference, which is helpful for the discrimination of different mechanisms according to the temperature field in real industrial applications.

Application of Ductile Cracking Criterion to the Assessment of Girth Weld Integrity for High Strength Linepipe

2005 ◽  
Author(s):  
Nobuyuki Ishikawa ◽  
Shigeru Endo ◽  
Satoshi Igi ◽  
Teruki Sadasue
Keyword(s):  
Crack Initiation ◽  
Plastic Strain ◽  
Large Deformation ◽  
Material Properties ◽  
Equivalent Plastic Strain ◽  
High Strength ◽  
Small Scale ◽  
Pipeline System ◽  
Ductile Crack ◽  
Notch Tip

Fracture behavior of high strength linepipes with weld defects is of great interest for the integrity of pipeline system. Especially, in the seismic or permafrost area, where large ground displacement can be expected, linepipe materials need to have sufficient resistance against brittle and ductile fracture under large deformation. Wide plate tensile test with surface flaw in the girth weld metal of X100 linepipe demonstrated that tensile limit is dominated by ductile crack initiation and its propagation. Conditions for ductile crack initiation for the base materials and girth weld joints of Grade X80 and X100 linepipes were investigated in this study. It was shown that ductile cracking occurs in the notch tip region of the wide plate specimen when notch tip equivalent plastic strain reaches the same critical value as determined by the small-scale tests. Therefore, “the equivalent plastic strain” in the critical regions can be used as a transferable parameter to predict ductile crack initiation behavior. Assessment methodology for tensile limit of high strength linepipe girth weld with respect to preventing ductile cracking was proposed. The effect of strength matching of girth weld and base metal Y/T ratio on limit remote strain as well as allowable defect size was investigated analytically. Increasing strength matching and lowering Y/T ratio of base material can lead to higher limit strain to ductile cracking of girth weld. These effects of material properties were validated by weld wide plate tensile tests. Therefore, careful selection of material properties should be important to improve resistance against ductile cracking of linepipe girth welds under large deformation field.

scholarly journals Experimental Study on Uniaxial Compression of Bamboo Nodes Using 3D Scanning Technique

2019 ◽  
Vol 275 ◽  
pp. 01022
Author(s):  
Xinmiao Meng ◽  
Han Sun ◽  
Yuyang Cao ◽  
Peng Feng
Keyword(s):  
Three Dimensional ◽  
High Strength ◽  
Experimental Results ◽  
High Yield ◽  
Cross Sectional ◽  
Modeling Technology ◽  
Cross Section Area ◽  
Bamboo Nodes ◽  
The Cross ◽  
The Difference

Bamboo is a kind of ecological building material for its physical and mechanical characteristics, such as fast growth, high yield, high strength, high toughness and good environmental performance. However, there are few studies on the influence of bamboo node structure about the mechanical properties of bamboo, and it is difficult to accurately determine the cross-section area of the bamboo node. In this paper, the three-dimensional scanner was combined with the reverse modeling technology to accurately obtain the cross-sectional area of the bamboo node. The bamboo node was subjected to axial compression test. Based on the experimental results, it was confirmed that the compressive strength of the bamboo node increased from the bottom to the top. The experimental results also showed that the difference in the degree of cracks has an effect on the bamboo break mode. Bamboo nodes with severe cracks and uneven distribution on the surface had the largest degree of expansion at the original deep cracks or the original surface through cracks. Bamboo nodes with slight cracks and even distribution or without cracks on the surface were uniformly expanding at the lower part when they were broken.

scholarly journals Biochemical Analysis of Phytolacca DOPA Dioxygenase

2015 ◽  
Vol 10 (5) ◽  
pp. 1934578X1501000
Author(s):  
Kana Takahashi ◽  
Kazuko Yoshida ◽  
Kei Yura ◽  
Hiroshi Ashihara ◽  
Masaaki Sakuta
Keyword(s):  
Biochemical Analysis ◽  
Structural Model ◽  
Specific Activity ◽  
Three Dimensional ◽  
Single Amino Acid ◽  
Phytolacca Americana ◽  
Conserved Motif ◽  
Single Amino Acid Residue ◽  
The Difference

The biochemical analysis of Phytolacca americana DOPA dioxygenases (PaDOD1 and PaDOD2) was carried out. The recombinant protein of PaDOD1 catalyzed the conversion of DOPA to betalamic acid, whereas DOD activity was not detected in PaDOD2 in vitro. While the reported motif conserved in DODs from betalain-producing plants was found in PaDOD1, a single amino acid residue alteration was detected in PaDOD2. A mutated PaDOD1 protein with a change of 177 Asn to Gly showed reduced specific activity compared with PaDOD1, while DOPA dioxygenase activity was not observed for a mutated PaDOD2 protein which had its conserved motif replaced with that of PaDOD1. A three-dimensional (3D) structural model of PaDOD1 and PaDOD2 showed that the conserved motif in DODs was located in the N-terminal side of a loop, which was found close to the putative active site. The difference in stability of the loop may affect the enzymatic activity of PaDOD2.

Defocus ramp correction in spot-scan imaging

1992 ◽  
Vol 50 (1) ◽  
pp. 130-131
Author(s):  
Kenneth H. Downing
Keyword(s):  
Computer Control ◽  
Three Dimensional ◽  
Sufficient Accuracy ◽  
Objective Lens ◽  
Electron Crystallography ◽  
Contrast Transfer Function ◽  
Tilt Axis ◽  
Specimen Height ◽  
The Difference ◽  
Envelope Functions

Three-dimensional structures of a number of samples have been determined by electron crystallography. The procedures used in this work include recording images of fairly large areas of a specimen at high tilt angles. There is then a large defocus ramp across the image, and parts of the image are far out of focus. In the regions where the defocus is large, the contrast transfer function (CTF) varies rapidly across the image, especially at high resolution. Not only is the CTF then difficult to determine with sufficient accuracy to correct properly, but the image contrast is reduced by envelope functions which tend toward a low value at high defocus.We have combined computer control of the electron microscope with spot-scan imaging in order to eliminate most of the defocus ramp and its effects in the images of tilted specimens. In recording the spot-scan image, the beam is scanned along rows that are parallel to the tilt axis, so that along each row of spots the focus is constant. Between scan rows, the objective lens current is changed to correct for the difference in specimen height from one scan to the next.

Pavement Damage Due to Conventional and New Generation of Wide-Base Super Single Tires

2005 ◽  
Vol 33 (4) ◽  
pp. 210-226 ◽  
Author(s):  
I. L. Al-Qadi ◽  
M. A. Elseifi ◽  
P. J. Yoo ◽  
I. Janajreh
Keyword(s):  
Carrying Capacity ◽  
Material Properties ◽  
Three Dimensional ◽  
Fe Analysis ◽  
Load Carrying Capacity ◽  
Inflation Pressure ◽  
3D Finite Element ◽  
Load Carrying ◽  
Pavement Damage ◽  
New Generation

Abstract The objective of this study was to quantify pavement damage due to a conventional (385/65R22.5) and a new generation of wide-base (445/50R22.5) tires using three-dimensional (3D) finite element (FE) analysis. The investigated new generation of wide-base tires has wider treads and greater load-carrying capacity than the conventional wide-base tire. In addition, the contact patch is less sensitive to loading and is especially designed to operate at 690kPa inflation pressure at 121km/hr speed for full load of 151kN tandem axle. The developed FE models simulated the tread sizes and applicable contact pressure for each tread and utilized laboratory-measured pavement material properties. In addition, the models were calibrated and properly validated using field-measured stresses and strains. Comparison was established between the two wide-base tire types and the dual-tire assembly. Results indicated that the 445/50R22.5 wide-base tire would cause more fatigue damage, approximately the same rutting damage and less surface-initiated top-down cracking than the conventional dual-tire assembly. On the other hand, the conventional 385/65R22.5 wide-base tire, which was introduced more than two decades ago, caused the most damage.

scholarly journals Compressive behaviours of octet-truss lattices

2020 ◽  
Vol 234 (16) ◽  
pp. 3257-3269 ◽  
Author(s):  
Yifan Li ◽  
Huaiyuan Gu ◽  
Martyn Pavier ◽  
Harry Coules
Keyword(s):  
Failure Modes ◽  
Density Ratio ◽  
Three Dimensional ◽  
Compressive Load ◽  
High Strength ◽  
Detailed Comparison ◽  
Compressive Response ◽  
Beam Elements ◽  
Structural Applications ◽  
Octet Truss

Octet-truss lattice structures can be used for lightweight structural applications due to their high strength-to-density ratio. In this research, octet-truss lattice specimens were fabricated by stereolithography additive manufacturing with a photopolymer resin. The mechanical properties of this structure have been examined in three orthogonal orientations under the compressive load. Detailed comparison and description were carried out on deformation mechanisms and failure modes in different lattice orientations. Finite element models using both beam elements and three-dimensional solid elements were used to simulate the compressive response of this structure. Both the load reaction and collapse modes obtained in simulations were compared with test results. Our results indicate that three-dimensional continuum element models are required to accurately capture the behaviour of real trusses, taking into account the effects of finite-sized beams and joints.

scholarly journals Study on improving three-dimensional dynamic simulation model and equation of flexible fabric

2019 ◽  
Vol 11 (6) ◽  
pp. 168781401985284
Author(s):  
Meiliang Wang ◽  
Mingjun Wang ◽  
Xiaobo Li
Keyword(s):  
Simulation Model ◽  
Dynamic Simulation ◽  
Material Properties ◽  
Three Dimensional ◽  
Equation Solving ◽  
Study Results ◽  
Essential Properties ◽  
Dynamic Simulation Model ◽  
Novel Model ◽  
Simulation Equation

The use of the traditional fabric simulation model evidently shows that it cannot accurately reflect the material properties of the real fabric. This is against the background that the simulation result is artificial or an imitation, which leads to a low simulation equation. In order to solve such problems from occurring, there is need for a novel model that is designed to enhance the essential properties required for a flexible fabric, the simulation effect of the fabric, and the efficiency of simulation equation solving. Therefore, the improvement study results will offer a meaningful and practical understanding within the field of garment automation design, three-dimensional animation, virtual fitting to mention but a few.

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