Process Design of Laser Forming for Three-Dimensional Thin Plates

2004 ◽  
Vol 126 (2) ◽  
pp. 217-225 ◽  
Author(s):  
Jin Cheng ◽  
Y. Lawrence Yao
Keyword(s):  
Process Design ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Thin Plates ◽  
Laser Forming ◽  
Heat Condition ◽  
Bending Strain ◽  
Doubly Curved ◽  
Made In

Extensive efforts have been made in analyzing and predicting laser forming processes of sheet metal. Process design, on the other hand, is concerned with determination of laser scanning paths and laser heat condition given a desired shape. This paper presents an approach for process design of laser forming of thin plates with doubly curved shapes. The important feature of this method is that it first calculates the strain field required to form the shape. Scanning paths are decided based on the concept of in-plane strain, bending strain, principal minimal strain and temperature gradient mechanism of laser forming. Heating condition is determined by a lumped method. Effectiveness of the approach is numerically and experimentally validated through two different doubly curved shapes.

Laser Forming of Varying Thickness Plate—Part II: Process Synthesis

2005 ◽  
Vol 128 (3) ◽  
pp. 642-650 ◽  
Author(s):  
Peng Cheng ◽  
Yajun Fan ◽  
Jie Zhang ◽  
Y. Lawrence Yao ◽  
David P. Mika ◽  
...  
Keyword(s):  
Plane Strain ◽  
Process Design ◽  
Laser Scanning ◽  
Plate Thickness ◽  
Laser Forming ◽  
Forming Process ◽  
Element Analysis ◽  
Varying Thickness ◽  
Bending Strain ◽  
Finite Element Analysis Simulation

Laser forming (LF) is a non-traditional forming process that does not require hard tooling or external forces and, hence, may dramatically increase process flexibility and reduce the cost of forming. While extensive progress has been made in analyzing and predicting the deformation given a set of process parameters, few attempts have been made to determine the laser scanning paths and laser heat conditions given a desired shape. This paper presents a strain-based strategy for laser forming process design for thin plates with varying thickness, which is utilized in determining the scanning paths and the proper heating conditions. For varying thickness plates, both the in-plane membrane strain and the bending strain need to be accounted for in process design. Compared with uniform thickness plate, the required bending strain varies with not only the shape curvature but also with the plate thickness. The scanning paths are determined by considering the different weight of bending strain and in-plane strain. A thickness-dependent database is established by LF finite element analysis simulation, and the heating conditions are determined by matching the ratio of bending strain to in-plane strain between the required values and the laser forming values found in the database. The approach is validated by numerical simulation and experiments using several typical shapes.

A Numerical and Experimental Study of Sheet Metal Bending by Pulsed Nd:Yag Laser with DOE Method

2009 ◽  
Vol 83-86 ◽  
pp. 1076-1083 ◽  
Author(s):  
M. Hosseinpour Gollo ◽  
Hassan Moslemi Naeini ◽  
G.H. Liaghat ◽  
S. Jelvani ◽  
M.J. Torkamany
Keyword(s):  
Experimental Study ◽  
Sheet Metal ◽  
Nd:Yag Laser ◽  
Metal Forming ◽  
Flexible Manufacturing ◽  
Three Dimensional ◽  
Laser Source ◽  
Laser Forming ◽  
Beam Diameter ◽  
Doubly Curved

Metal forming by a laser source is an efficient and economical method for forming sheet metal into straight bend and doubly curved shape. It can be most useful in the automation of sheet metal forming. This paper presents an FEM model for three dimensional thermo-mechanical simulation of the laser forming. The aim of this simulation and experimental study is to identify the response related to deformation and characterize the effects of process parameters such as laser power, beam diameter, scans velocity and pulse duration, in terms of bending angle for a square sheet part. Extensive experimentation, including a design of experiments, is performed to address the above-mentioned aims. From these experiments it has been determined that laser forming using Nd:YAG laser is a flexible manufacturing process for steel sheet bending.

The Mechanics of Ideal Forming

1994 ◽  
Vol 61 (1) ◽  
pp. 176-181 ◽  
Author(s):  
K. Chung ◽  
O. Richmond
Keyword(s):  
Process Design ◽  
Three Dimensional ◽  
Field Equations ◽  
Starting Point ◽  
Deformation Processes ◽  
External Forces ◽  
Minimum Work ◽  
Yield Conditions ◽  
The Ideal

In this paper, the mechanics of ideal forming theory are summarized for general, three-dimensional, nonsteady processes. This theory has been developed for the initial stages of designing deformation processes. The objectives is to directly determine configurations, both initial and intermediate, that are required to ideally form a specified final shape. In the proposed theory, material elements are prescribed to deform along minimum plastic work paths, assuming that the materials have optimum formabilities in such paths. Then, the ideal forming processes are obtained so as to have the most uniform strain distributions in final products without shear tractions. As solutions, the theory provides the evolution of intermediate shapes of products and external forces as well as optimum strain distributions. Since the requirement of ideal forming to follow minimum work paths involves an over determination of the field equations, the theory places constraints on constitutive and boundary conditions. For example, tool interfaces must be frictionless and yield conditions must have vertices to achieve self-equilibrating three-dimensional deformations in most cases. Despite these constraints, the theory is believed to provide a useful starting point for deformation process design.

scholarly journals High Rates of Conjugation in Bacterial Biofilms as Determined by Quantitative In Situ Analysis

1999 ◽  
Vol 65 (8) ◽  
pp. 3710-3713 ◽  
Author(s):  
Martina Hausner ◽  
Stefan Wuertz
Keyword(s):  
Laser Scanning ◽  
Nutrient Concentration ◽  
Three Dimensional ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Bacterial Biofilms ◽  
Conjugative Gene Transfer ◽  
Biofilm Structure

ABSTRACT Quantitative in situ determination of conjugative gene transfer in defined bacterial biofilms using automated confocal laser scanning microscopy followed by three-dimensional analysis of cellular biovolumes revealed conjugation rates 1,000-fold higher than those determined by classical plating techniques. Conjugation events were not affected by nutrient concentration alone but were influenced by time and biofilm structure.

Determination of changes on tooth-colored cervical restorations in vivo using a three-dimensional laser scanning device

2000 ◽  
Vol 108 (3) ◽  
pp. 233-238 ◽  
Author(s):  
Matthias Flowaczny ◽  
Albert Mehl ◽  
Karl-Heinz Kunzelmann ◽  
Reinhard Hickel
Keyword(s):  
Laser Scanning ◽  
Three Dimensional ◽  
Scanning Device

Comparison of Two- and Three-Dimensional Methods for Assessment of Orientation of the Total Hip Prosthesis

1988 ◽  
Vol 29 (3) ◽  
pp. 357-361 ◽  
Author(s):  
K. Herrlin ◽  
H. Pettersson ◽  
G. Selvik
Keyword(s):  
Hip Prosthesis ◽  
Three Dimensional ◽  
Total Hip Prosthesis ◽  
Hip Prostheses ◽  
Total Hip ◽  
Total Hip Prostheses ◽  
Prosthetic Component ◽  
High Degree ◽  
Made In

A comparison of two- and three-dimensional methods for the determination of the orientation of total hip prostheses was made in a group of 57 patients. The acetabular inclination and the collum-diaphyseal angle measured on a.p. projections (2-D) were adequate in most cases for assessing how vertically the prosthetic component was inserted, but in individual cases with a high degree of version these measurements could be misleading. Anteversion measured in the transverse plane (2-D) was more sensitive to errors than planar anteversion measured as a rotation around the longest diameter of the ellipsoid projection of the acetabular opening, but it gave a rough estimate of the relation of the prosthetic components. Determination of the spatial (3-D) orientation of the components provides a precise estimate of the component relations.

scholarly journals Three-Dimensional Reconstruction and Morphologic Measurements of Human Embryonic Hearts: A New Diagnostic and Quantitative Method Applicable to Fetuses Younger than 13 Weeks of Gestation

2005 ◽  
Vol 8 (4) ◽  
pp. 463-473 ◽  
Author(s):  
Jean-Marc Schleich ◽  
Jean-Louis Dillenseger ◽  
Laurence Loeuillet ◽  
Jacques-Philippe Moulinoux ◽  
Claude Almange
Keyword(s):  
Cardiac Development ◽  
Three Dimensional ◽  
Optical Microscope ◽  
Cardiac Volume ◽  
3 Dimensional ◽  
Dimensional Reconstruction ◽  
First Results ◽  
Made In

Improvements in the diagnosis of congenital malformations explain the increasing early termination of pregnancies. Before 13 weeks of gestation, an accurate in vivo anatomic diagnosis cannot currently be made in all fetuses with current imaging instrumentation. Anatomopathologic examinations remain the gold standard to make accurate diagnoses, although they reach limits between 9 and 13 weeks of gestation. We present the first results of a methodology that can be applied routinely, using standard histologic section, thus enabling the reconstruction, visual estimate, and quantitative analysis of 13-week human embryonic cardiac structures. The cardiac blocks were fixed, embedded in paraffin, and entirely sliced by a microtome. One of 10 slices was topographically colored and digitized on an optical microscope. Cardiac volume was recovered by semiautomatic realignment of the sections. Another semiautomatic procedure allowed extracting and labeling of cardiac structures from the volume. Structures were studied with display tools, which disclosed the internal and external cardiac components and enabled determination of size, thickness, and precise positioning of ventricles, atria, and large vessels. This pilot study confirmed that a new 3-dimensional reconstruction and visualization method enables accurate diagnoses, including in embryos younger than 13 weeks. Its implementation at earlier stages of embryogenesis will provide a clearer view of cardiac development.

Optimal Process Planning for Laser Forming of Doubly Curved Shapes

2004 ◽  
Vol 126 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Chao Liu ◽  
Y. Lawrence Yao ◽  
Vijay Srinivasan
Keyword(s):  
Process Planning ◽  
Laser Scanning ◽  
Industrial Applications ◽  
Laser Forming ◽  
Field Calculation ◽  
Heating Condition ◽  
Scanning Velocity ◽  
Optimal Approach ◽  
Doubly Curved ◽  
Practical Constraints

There has been a considerable amount of work carried out on two-dimensional laser forming. In order to advance the process further for industrial applications, however, it is necessary to consider more general cases and especially their process planning aspect. This paper presents an optimal approach to laser scanning paths and heating condition determination for laser forming of doubly curved shapes. Important features of the approach include the strain field calculation based on principal curvature formulation and minimal strain optimization, and scanning paths and heating condition (laser power and scanning velocity) determination by combining analytical and practical constraints. The overall methodology is presented first, followed by more detailed descriptions of each step of the approach. Two distinctive types of doubly curved shape, pillow and saddle shapes are focused on and the effectiveness of the proposed approach is validated by forming experiments.

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