Laser Forming of Varying Thickness Plate—Part I: Process Analysis

2005 ◽  
Vol 128 (3) ◽  
pp. 634-641 ◽  
Author(s):  
Peng Cheng ◽  
Yajun Fan ◽  
Jie Zhang ◽  
Y. Lawrence Yao ◽  
David P. Mika ◽  
...  
Keyword(s):  
Process Analysis ◽  
Scanning Speed ◽  
Spot Size ◽  
Laser Forming ◽  
Thickness Variation ◽  
Complex Structures ◽  
Forming Process ◽  
Forming Mechanism ◽  
Varying Thickness ◽  
Wide Range

High-intensity laser beams can be used to heat and bend metal plates, but the mechanisms of the laser forming (LF) process are not well understood or precisely controllable. The objective of the National Institute of Standards and Technology sponsored project “Laser Forming of Complex Structures” is to develop technologies for a controllable, repeatable laser forming process that shapes and reshapes a wide range of complex structures such as compressor airfoils that are complex 3D geometries with large thickness variation. In order to apply laser forming to complex 3D geometries, the process analysis and process synthesis (design process parameters such as scanning paths and heating conditions for a desired shape) of LF of varying thickness plate are conducted in this paper. In this study, experimental, numerical, and analytical methods are used to investigate the bending mechanism and parametric effects on the deformation characteristics of varying thickness plates. A transition of the laser forming mechanism was found to occur along the scanning path when the thickness varies. The effect of scanning speed, beam spot size, and multiple scanning on the degree of bending was investigated. The proposed analytical model can predict the bending angle and angle variations for laser forming of varying thickness plate.

Numerical and experimental analysis on cold-forming and spring-back of hull plate

2018 ◽  
Vol 233 (3) ◽  
pp. 561-569 ◽  
Author(s):  
Wei Shen ◽  
Renjun Yan ◽  
Shuangying Li
Keyword(s):  
Three Dimensional ◽  
Dimensional Accuracy ◽  
Ship Hull ◽  
Laser Forming ◽  
Successive Approximation Method ◽  
Spring Back ◽  
Forming Process ◽  
Cold Forming ◽  
Thick Plates ◽  
Forming Mechanism

Ship hull structures are fabricated by curved thick plates before they are welded together. There are traditional methods such as, line heating and laser-forming methods for plate bending. However, it is recognized that the hot-forming technology causes a series of troubles on doubly or multiple curved plates. Multi-point forming mechanism with square press heads is a new forming process for three-dimensional ship hull plate. Cold-forming has a high dimensional accuracy but results in spring-back. The spring-back process of curved thick plates in the finite element method is analyzed and the predicted results are compared with the test results in the present paper. To ensure the forming precision, the successive approximation method is also developed and verified to control the spring-back.

Ring Forming: An Upper Bound Approach. Part 2: Process Analysis and Characteristics

1982 ◽  
Vol 104 (3) ◽  
pp. 238-247 ◽  
Author(s):  
B. Avitzur ◽  
C. J. Van Tyne
Keyword(s):  
Process Parameters ◽  
Upper Bound ◽  
Flow Parameter ◽  
Radial Flow ◽  
Process Analysis ◽  
Forming Process ◽  
Wide Range

The generalized ring forming process has been analyzed for a Mises’ material, using an upper bound approach. This analysis allows the motivation for the process to be supplied on any surface and permits the application of external tractions on any other surface of the ring. In this second part of the series, the analytical equations for the relative forming stress and the radial flow parameter are derived for all three modes of deformation. The characteristics of these equations are shown graphically for a wide range of process parameters. The conditions that lead to the newly introduced “imaginary values” of the neutral radius (Rn) are identified.

The Effects of Laser and Mechanical Forming on the Hardness and Microstructural Layout of Commercially Pure Grade 2 Titanium Alloy Plates

2017 ◽  
Author(s):  
Kadephi V. Mjali ◽  
Annelize Els-Botes ◽  
Peter M. Mashinini
Keyword(s):  
Mechanical Properties ◽  
Titanium Alloy ◽  
Scanning Speed ◽  
Grain Structure ◽  
Laser Forming ◽  
Major Influence ◽  
Forming Process ◽  
Commercially Pure ◽  
Profound Influence ◽  
Pure Grade

This paper illustrates the effects of the laser and mechanical forming on the hardness and microstructural distribution in commercially pure grade 2 Titanium alloy plates. The two processes were used to bend commercially pure grade 2 Titanium alloy plates to a similar radius also investigate if the laser forming process could replace the mechanical forming process in the future. The results from both processes are discussed in relation to the mechanical properties of the material. Observations from hardness testing indicate that the laser forming process results in increased hardness in all the samples evaluated, and on the other hand, the mechanical forming process did not influence hardness on the samples evaluated. There was no change in microstructure as a result of the mechanical forming process while the laser forming process had a major influence on the overall microstructure in samples evaluated. The size of the grains became larger with increases in thermal gradient and heat flux, causing changes to the overall mechanical properties of the material. The thermal heat generated has a profound influence on the grain structure and the hardness of Titanium. It is evident that the higher the thermal energy the higher is the hardness, but this only applies up to a power of 2.5kW. Afterwards, there is a reduction in hardness and an increase in grain size. The cooling rate of the plates has been proved to play a significant role in the resulting microstructure of Titanium alloys. The scanning speed plays a role in maintaining the surface temperatures of laser formed Titanium plates resulting in changes to both hardness and the microstructure. An increase in heat results in grain growth affecting the hardness of Titanium.

Research on the Mechanisms of Laser Forming for the Micro-Structural Element

2008 ◽  
Vol 575-578 ◽  
pp. 1145-1150
Author(s):  
Ying Jin ◽  
Jian Hua Wu ◽  
Yong Jun Shi ◽  
Hong Shen ◽  
Zheng Qiang Yao
Keyword(s):  
Thermal Stresses ◽  
Element Model ◽  
Laser Forming ◽  
Forming Process ◽  
Structural Element ◽  
Laser Bending ◽  
Forming Mechanism ◽  
Thermal Transfer ◽  
Conventional Analysis ◽  
The Finite Element Model

Laser forming of a micro-structural element involves a complex thermoplastic process. Numerous efforts had been made on the mechanisms of laser forming for macro-size elements, such as temperature gradient mechanism, buckling mechanism and upsetting mechanism, etc. It is found that the three mechanisms cannot depict fully the process of deformation in the macro-size element forming, let alone meet the needs of the micro-size one. Considering the laser inducing thermal stresses with size factors differing from the conventional analysis, it is essential to reveal the mechanisms dominating the forming process to accurately control the bending angle of a tiny plate. By studying the thermal transfer and elastic-plastic deformation of micro-structural element laser forming, the forming mechanism is explained within the micro size. The finite element model for laser bending is constructed for simulation. The stimulation results are agreement with the experimental data.

scholarly journals Bowl Surface Laser Forming Process of Stainless Steel Composite Plate

2021 ◽  
Author(s):  
Xiaogang Wang ◽  
Yongjun Shi ◽  
Yankuo Guo ◽  
Qin Wang
Keyword(s):  
Stainless Steel ◽  
Composite Plate ◽  
Three Dimensional ◽  
Target Surface ◽  
Scanning Speed ◽  
Laser Forming ◽  
Process Conditions ◽  
Forming Process ◽  
Repeated Heating ◽  
Steel Composite

Abstract In this paper, the three-dimensional bowl surface was obtained by reasonably planning the radial heating path by taking the laser as the heat source and the stainless steel composite plate (06Cr19Ni10/1Cr17Mn6Ni5N/06Cr19Ni10) as the research object, and the forming process of the three-dimensional bowl surface was studied. It was found that the target surface bending forming obtained by inside-outside symmetric scanning strategy (Strategy d) had the highest accuracy. The plate deformation increased with the increase of laser power (P), increased then decreased with the increase of heating line length (L), and decreased with the increase of scanning speed (V). Moreover, the deformation was approximately linear with the number of repeated heating (N), with the optimal process conditions of P = 500W, V = 10 mm/s, L = 20 mm, N = 7. A three-dimensional thermodynamic coupling model of a three-layer composite plate was established and verified experimentally.

Temperature Gradient Mechanism on Laser Bending of Borosilicate Glass Sheet

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Dongjiang Wu ◽  
Guangyi Ma ◽  
Fangyong Niu ◽  
Dongming Guo
Keyword(s):  
Temperature Gradient ◽  
Borosilicate Glass ◽  
Fe Simulation ◽  
Glass Sheet ◽  
Laser Forming ◽  
Thickness Direction ◽  
Forming Process ◽  
Primary Defect ◽  
Laser Bending ◽  
Forming Mechanism

The present work is a research on the laser forming process of borosilicate glass sheet. The laser forming mechanism was analyzed, and the temperature gradient mechanism was considered as the main forming mechanism of glass bending. According to the experimental results, a thermomechanical finite element (FE)-simulation was applied for investigating the temperature distribution and thermal stress in the thickness direction of the specimen. Cracks, as the primary defect, were summarized to three kinds: “Y” cracks, straight cracks, and arc cracks, while their forming mechanisms were proposed.

The Forming Analysis of Inner Straight Groove Copper Pipe under Different Spinning Speed

2014 ◽  
Vol 651-653 ◽  
pp. 133-136
Author(s):  
Shi Gang Wang ◽  
Bo Yu Zhao ◽  
Feng Juan Wang
Keyword(s):  
Process Analysis ◽  
Equivalent Strain ◽  
Forming Process ◽  
Simulation Data ◽  
Forming Mechanism ◽  
Copper Pipe ◽  
Ball Rolling ◽  
Forming Analysis ◽  
Spinning Speed

Aiming to explain forming mechanism of copper pipe workpiece with inner straight groove via ball-rolling at different spinning speeds, the copper pipe workpiece and straight die is modeled in ABAQUS. And the whole simulation includes forming process, analysis of strain and stress. It is concluded that in the process of ball-rolling, the deformation of copper pipe workpiece is mainly the axial and teeth groove radial; with rotary extrusion increasing, the equivalent strain and stress enlarge gradually. Under the premise of keeping the quality of production, the maximum spinning speeds is 24000 r/min, which will not lose steady and complete the whole operation successfully. The simulation data and conclusion supply the basis for the actual processing.

Bending Angle Estimated Based on Inherent Strain Theory during Laser Forming

2010 ◽  
Vol 663-665 ◽  
pp. 947-951
Author(s):  
Jing Zhou ◽  
Hong Shen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Strain Theory ◽  
Laser Forming ◽  
Elastic Analysis ◽  
Forming Process ◽  
Bending Angle ◽  
Forming Mechanism ◽  
Inherent Strain ◽  
Element Method

Laser forming process analyzed under thermo-elasto-plastic finite element method can better understand the forming mechanism. However, it is very time consuming. This paper introduced the prediction of the deformation in laser forming based on the theory of inherent strain by finite element method (FEM). The relations between inherent strains and laser forming parameters based on some experimental curves and the thermo-elasto-plastic analysis can be determined, in which the inherent strains are assumed to be distributed in a rectangle shape. This method is much more convenient because only elastic analysis is involved. The effectiveness of the proposed method is demonstrated through the comparison with the experimental data.

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.

scholarly journals Comparison of Modified Mohr–Coulomb Model and Bai–Wierzbicki Model for Constructing 3D Ductile Fracture Envelope of AA6063

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Jianye Gao ◽  
Tao He ◽  
Yuanming Huo ◽  
Miao Song ◽  
Tingting Yao ◽  
...  
Keyword(s):  
Ductile Fracture ◽  
Fracture Criterion ◽  
Fracture Strain ◽  
Stress Triaxiality ◽  
Ductile Fracture Criterion ◽  
Forming Process ◽  
Tension Tests ◽  
Wide Range ◽  
Round Bar ◽  
Fracture Envelope

AbstractDuctile fracture of metal often occurs in the plastic forming process of parts. The establishment of ductile fracture criterion can effectively guide the selection of process parameters and avoid ductile fracture of parts during machining. The 3D ductile fracture envelope of AA6063-T6 was developed to predict and prevent its fracture. Smooth round bar tension tests were performed to characterize the flow stress, and a series of experiments were conducted to characterize the ductile fracture firstly, such as notched round bar tension tests, compression tests and torsion tests. These tests cover a wide range of stress triaxiality (ST) and Lode parameter (LP) to calibrate the ductile fracture criterion. Plasticity modeling was performed, and the predicted results were compared with corresponding experimental data to verify the plasticity model after these experiments. Then the relationship between ductile fracture strain and ST with LP was constructed using the modified Mohr–Coulomb (MMC) model and Bai-Wierzbicki (BW) model to develop the 3D ductile fracture envelope. Finally, two ductile damage models were proposed based on the 3D fracture envelope of AA6063. Through the comparison of the two models, it was found that BW model had better fitting effect, and the sum of squares of residual error of BW model was 0.9901. The two models had relatively large errors in predicting the fracture strain of SRB tensile test and torsion test, but both of the predicting error of both two models were within the acceptable range of 15%. In the process of finite element simulation, the evolution process of ductile fracture can be well simulated by the two models. However, BW model can predict the location of fracture more accurately than MMC model.

Sign in / Sign up

Export Citation Format

Share Document