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.

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.

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.

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.

FEM simulation of laser forming process of shipbuilding steel plate

2004 ◽  
Vol 120 ◽  
pp. 507-512
Author(s):  
Zhang Liwen ◽  
Zhong Qi ◽  
Pei Jibin ◽  
Zhang Guoliang ◽  
Xia Yuanliang
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Thermal Stresses ◽  
Steel Plate ◽  
Fem Simulation ◽  
Laser Forming ◽  
Transient Temperature ◽  
Forming Process ◽  
Shipbuilding Steel ◽  
Finite Element Software

Laser forming has become a promising technique to form sheet metal in recent years. This new forming process can produce plastic deformation by thermal stresses resulted from the irradiation of laser beam scanning. In this paper, a 3-D thermo-mechanical FEM model was developed to simulate the laser forming process of shipbuilding steel plate. The finite-element software MSC.Marc was used to calculate the temperature field, stress field and strain field during laser forming process. The transient temperature field and the final bending angle were predicted. Then the effect of laser forming process technical parameters was studied. To evaluate the accuracy of the simulation, a laser forming experiment was performed. It is demonstrated that the finite element simulation results are in good agreement with experimental results.

Numerical Simulation and Test Research of Continuous Flexible Forming Process for the Spherical Parts

2011 ◽  
Vol 291-294 ◽  
pp. 269-272
Author(s):  
Ying Wu Lan ◽  
Zhong Yi Cai ◽  
Ming Zhe Li
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Longitudinal Deformation ◽  
Forming Process ◽  
Flexible Forming ◽  
Sensing System ◽  
Flexible Forming Process ◽  
The Finite Element Model

The deformation of sheet metal in the continuous flexible forming (CFF) process is complex and the formed result is affected by many factors. In this paper, the finite element model of CFF was founded and the forming processes of spherical parts were simulated with the software ABAQUS. The interaction between transversal deformation and longitudinal deformation in the CFF process is analyzed. Based on results of numerical simulation and forming tests, the process parameters of CFF is revised, and formed surface is measured by three dimensional sensing system, the measured results indicate the precision of formed parts are satisfactory.

Temperature Gradient-Based Laser Bending of Full Plates and Plates With Cutout

2020 ◽  
pp. 270-305
Author(s):  
Paramasivan Kalvettukaran ◽  
Sandip Das ◽  
Sundar Marimuthu ◽  
Dipten Misra
Keyword(s):  
Laser Forming ◽  
Forming Process ◽  
Laser Bending ◽  
Bending Angle ◽  
Aisi 304 ◽  
Thermally Induced ◽  
Bending Process ◽  
Gradient Based ◽  
Different Dimensions ◽  
Different Shapes

The laser bending process, also called the laser forming process, consists of irradiating the surface of a sheet or a plate by means of a moving laser beam with a predefined scanning strategy to generate the desired shape through thermally induced residual stress. This chapter presents the mechanisms of a laser bending process and the technological aspects concerning laser v-bending of rectangular AISI 304 plates for full plates and plates with a central cutout at its middle to highlight the process fundamentals and how processing affects the final bending angle of the workpieces. Laser bending involving plates with a cutout will have numerous applications for car bodies, such as front and rear panels where bending is required to be performed on panels with cutout geometries. To investigate the effects of shape and size of the cutout on temperature distribution, stress distribution, and final bending angle, different shapes such as circular, ellipse, rectangular, and square, as well as different dimensions of cutouts have been chosen.

The Study on Numerical Simulation of Tailor Welded Blanks on Square Cup Stamping

2011 ◽  
Vol 189-193 ◽  
pp. 3932-3935
Author(s):  
Xiao Gang Qiu
Keyword(s):  
Numerical Simulation ◽  
Plastic Deformation ◽  
Strain Distribution ◽  
Weld Seam ◽  
Element Model ◽  
Forming Process ◽  
Tailor Welded Blanks ◽  
Tailor Welded Blank ◽  
Different Thickness ◽  
The Finite Element Model

The stamping process of the tailor welded blank(TWB) was simulated by the software of DYNAFORM. The finite element model of a boxy part was founded, and the forming of different thickness and properties of the material was studied. Meanwhile, the influence of weld seam on forming result was analyzed. The results show that the weld seam model which founded by real properties can describe the plastic deformation and strain distribution more exactly in the forming process.

Stress Analysis for Electric Stop Valve of Nuclear Power Plant Considering Action of Preload and Stem Force

2013 ◽  
Vol 313-314 ◽  
pp. 1210-1213
Author(s):  
Ji Wang ◽  
Jian Hua Zheng
Keyword(s):  
Finite Element ◽  
Power Plant ◽  
Nuclear Power ◽  
Thermal Stresses ◽  
Fluid Pressure ◽  
Element Model ◽  
Stop Valve ◽  
Valve Stem ◽  
Reaction Forces ◽  
The Finite Element Model

The finite element model of electric stop valve with flange bolts preload and valve stem force was established to improve the valve stress calculation method which was based only on action of fluid pressure, thermal stresses and pipe reaction forces. The principle and application of pretension load elements were expounded. By ANSYS, the stresses of this valve with preload and valve stem force were calculated, and the Mises equivalent stresses contour and some values of key position of whole valve were obtained. The results indicate the influence of the stresses on the valve caused by preload of bolt mounted on the flange and valve stem force can not be ignored.

The Effect of Nonconventional Laser Beam Geometries on Stress Distribution and Distortions in Laser Bending of Tubes

2006 ◽  
Vol 129 (3) ◽  
pp. 592-600 ◽  
Author(s):  
Shakeel Safdar ◽  
Lin Li ◽  
M. A. Sheikh ◽  
Zhu Liu
Keyword(s):  
Laser Beam ◽  
Laser Scanning ◽  
Thermal Stresses ◽  
Laser Forming ◽  
Beam Diameter ◽  
Hydraulic Systems ◽  
Tube Bending ◽  
Laser Bending ◽  
Scanning Velocity ◽  
Laser Tube

Laser forming is a spring-back-free noncontact forming method that has received considerable attention in recent years. Compared to mechanical bending, no hard tooling, dies, or external force is used. Within laser forming, tube bending is an important industrial activity with applications in critical engineering systems such as heat exchangers, hydraulic systems, boilers, etc. Laser tube bending utilizes the thermal stresses generated during laser scanning to achieve the desired bends. The parameters varied to control the process are usually laser power, beam diameter, scanning velocity, and the number of scans. The thermal stresses generated during laser scanning are strongly dependent upon laser beam geometry. The existing laser bending methods use either circular or rectangular beams. These beam geometries sometimes lead to undesirable effects such as buckling and distortion in tube bending. This paper investigates the effects for various laser beam geometries on laser tube bending. Finite element modeling has been used for the study of the process with some results also validated by experiments.

The Significance of Experiment in the Finite Element Analysis of a Pulley Forming Process

2005 ◽  
Vol 6-8 ◽  
pp. 615-622
Author(s):  
Xiao Hang Liu ◽  
Mike Daniels ◽  
Bez Shirvani
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Numerical Models ◽  
Metal Flow ◽  
Element Model ◽  
Axial Loads ◽  
Forming Process ◽  
Element Analysis ◽  
Forming Tools ◽  
The Finite Element Model

For reasons of cost and weight, light gauge sheet is used wherever possible for metal fabrications. In sheet metal forming the process is to gather the metal into defined areas. The pulley forming process is no exception and is achieved by superimposing axial loads on top of radial loads using a pressure-controlled tailstock. Whilst the headstock-mounted tooling is fixed, that part held on the tailstock can be powered axially under controlled pressure. This pressure is governed by the width of the workpiece which changes during the forming process. Experiments have been designed to provide an understanding of the pulley forming process and to verify numerical models. The latter has been taken the form of finite element simulations to enable prediction of metal flow, tool forces and potential sources of defects and failures. There are three objectives for conducting the experiments which have been investigated in this paper: 1. providing data to define the movements of the forming tools for the finite element model, including displacements and velocities, 2. understanding the effects of the pulley forming operation on the flow of material, and 3. validating the finite element model.

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