Research on the Forming Limit Diagram Based on Laser Shock Forming

2010 ◽  
Vol 44-47 ◽  
pp. 148-152
Author(s):  
Yin Fang Jiang ◽  
Zhen Zhou Tang ◽  
Zhi Fei Li ◽  
Lei Fang
Keyword(s):  
Sheet Metal ◽  
Strain Path ◽  
Reduction Rate ◽  
Forming Limit Diagram ◽  
Thickness Reduction ◽  
Forming Limit ◽  
Laser Shock ◽  
Maximum Thickness ◽  
Laser Shock Forming ◽  
Strain Paths

Laser shock forming (LSF) of sheet metal is a novel technology in plastic deformation. It is necessary to correctly predict the Forming Limit Diagram (FLD) based on LSF. New failure maximum thickness reduction rate criterion is used to determine the forming limit based on the numerical system during LSF. The relationship model between maximum thickness reduction rate and the strain path is built. In addition, the effects of strain path and strain-hardening exponent on forming limit are considered. The maximum thickness reduction rate under equi-biaxial tensile strain path can be determined easily during LSF and the expression of the criterion is determined finally. Then the limit strains under other strain paths between uniaxial tension to equi-biaxial tension can be determined by the criterion combined with numerical simulation of forming process. The criterion can predict forming limits for sheet metal exactly and makes it possible to determine forming limit strains under different strain paths only through equi-biaxial tensile test during LSF.

Sheet Metal Forming Limit Prediction with Maximum Thickness Reduction Ratio

2011 ◽  
Vol 314-316 ◽  
pp. 999-1004
Author(s):  
Jie Shi Chen ◽  
Jun Chen
Keyword(s):  
Numerical Simulation ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Strain Path ◽  
Reduction Ratio ◽  
Thickness Reduction ◽  
Forming Limit ◽  
Forming Process ◽  
Maximum Thickness

Maximum thickness reduction ratio is used to predict sheet metal forming limit in the numerical simulation of forming process. The maximum thickness reduction ratio under different stain path is not a constant for the same material. The effect of strain path and strain hardening exponent on forming limit is considered. The relationship between the maximum thickness reduction ratio that the material can obtained and the strain path between tensile to equi-biaxial is established. The parameter in the criterion can be determined by tensile experiment combined with numerical simulation of the same forming process. Then the limit strains under other linear strain paths between tensile to equi-biaxial can be determined by the criterion combined with numerical simulation of corresponding forming process. Forming limits of three kinds of sheet metals are predicted with the modified maximum thickness reduction ratio criterion. Good agreement is achieved between the predicted data and the experimental data.

Experimental Investigation on Formability of Cryorolled and Room Temperature Rolled AA 6061 Sheet Metal with 50% and 75% Thickness Reduction

2014 ◽  
Vol 592-594 ◽  
pp. 302-306 ◽  
Author(s):  
Tinu P. Saju
Keyword(s):  
Experimental Investigation ◽  
Sheet Metal ◽  
Cryogenic Temperature ◽  
Room Temperature ◽  
Forming Limit Diagram ◽  
Thickness Reduction ◽  
Forming Limit ◽  
Forming Limit Diagrams ◽  
Short Annealing ◽  
Clear Idea

This paper deals with the formability of AA 6061 sheet metal. The forming limit diagram of precipitation hardenable Al–Mg–Si alloy namely AA 6061 was evaluated for sheets rolled at two different temperature media namely room temperature and cryogenic temperature. The sheets were subjected to solutionising, rolling either in room temperature or cryogenic temperature with 50% or 75% reduction and short annealing before forming operation. The forming limit diagrams of the rolled sheets were plotted together to obtain a clear idea about their comparative formability.

Forming Limit Prediction of BCC Materials under Non-Proportional Strain-Path by Using Crystal Plasticity

2012 ◽  
Vol 201-202 ◽  
pp. 1110-1116
Author(s):  
Mei Yang ◽  
Xiao Yan Zhang ◽  
Hao Wang
Keyword(s):  
Sheet Metal ◽  
Crystal Plasticity ◽  
Strain Path ◽  
Forming Limit Diagram ◽  
Forming Limit ◽  
Slip Systems ◽  
Plasticity Model ◽  
Forming Process ◽  
Crystal Plasticity Model ◽  
Microstructure Effect

In this paper, the forming limit of a body-centered cubic (BCC) sheet metal under non-proportional strain-path is investigated by using the Marciniak and Kuczynski approach integrated with a rate-dependent crystal plasticity model. The prediction model has been proved to be effective in predicting Forming Limit Diagram (FLD) of anisotropic sheet metal with FCC type of slip systems[1]. The same model has been used to study the FLD under non-proportional strain-path of BCC slip systems numerically and experimentally. The agreement between the experiments and simulations is good. With crystal plasticity model well describing the crystal microstructure effect, our model can be used to predict the FLD of BCC sheet metal under complicated strain path in plastic forming process with good accuracy.

Effect of Bending Strain in Forming Limit Strain and Stress of IN-718 Sheet Metal

2015 ◽  
Vol 830-831 ◽  
pp. 238-241 ◽  
Author(s):  
K.Sajun Prasad ◽  
Sushanta Kumar Panda ◽  
Sujoy Kumar Kar ◽  
S.V.S. Narayana Murty ◽  
S.C. Sharma
Keyword(s):  
Sheet Metal ◽  
Forming Limit Diagram ◽  
Dome Height ◽  
Forming Limit ◽  
Forming Process ◽  
Hardening Law ◽  
Bending Strain ◽  
Multi Stage ◽  
Strain Paths ◽  
Von Mises

The forming limit diagram (ε-FLD) was estimated by deforming IN-718 sheet metal in different strain paths using a sub-size limiting dome height test set-up. The bending strains induced due to the use of smaller punch were estimated in all the strain paths, and the corrected ε-FLD was evaluated. The mathematical models such as Hill localized necking, Swift diffuse necking and Storen-Rice bifurcation theories were implemented to predict the limiting strains. In-order to avoid the path dependency of the ε-FLD during multi-stage forming process, stress based forming limit diagram (σ-FLD) was estimated using von-Mises and Hill-48 anisotropy plasticity theory with incorporation of Hollomon power hardening law. It was found that the bending strain influenced the limiting strains and stresses in the forming limit diagram. However, IN-718 material has encouraging formability in stretch forming process. The plot of the equivalent strains versus triaxiality indicated increasing limiting strain of the material in tension-tension mode.

scholarly journals Influence of the Laser Heat Treatment on the AA5754-H32 strain path during hydraulic bulge tests

2021 ◽  
Author(s):  
Angela Cusanno ◽  
Shanmukha Moturu ◽  
David Carty ◽  
Gianfranco Palumbo
Keyword(s):  
Strain Path ◽  
Forming Limit Diagram ◽  
Local Heat ◽  
Forming Limit ◽  
Bulge Test ◽  
Forming Limit Curve ◽  
Hydraulic Bulge ◽  
Strain Paths ◽  
The Right

The hydraulic bulge test represents an effective experimental method to characterise sheet metals since the equivalent strains before failure are much larger than those measured during tensile testing and there is nearly no frictional effect on the results. Recently this test has been proposed not only for extracting data concerning the equi-biaxial strain condition, but to determine the forming limit diagram (FLD) in the range of positive minor strains. In the proposed methodology, different strain paths can be obtained by merely using a test blank having two holes with a suitable geometry and position to be tested, without the need of dies with elliptical apertures. However, a carrier sheet is necessary, thus implying results may be affected by friction effects. This paper proposes a new methodology for the determination of the right side of the Forming Limit Curve (FLC), based on the adoption of local heat treatments aimed at determining different strain paths on the blank to be tested while using the classical circular die for bulge tests. In particular, the formability of the alloy AA5754-H32 was investigated; 3D Finite Element simulations were conducted setting different laser strategies and monitoring the resulting strain path. Results revealed that the proposed methodology supports obtaining many additional points in the right side of the FLC, thus being effective and friction free.

Optimization of Sheet Metal Process Parameters of a Shield Case Piece Using Computer Simulation

2006 ◽  
Vol 510-511 ◽  
pp. 330-333
Author(s):  
M.C. Curiel ◽  
Ho Sung Aum ◽  
Joaquín Lira-Olivares
Keyword(s):  
Sheet Metal ◽  
Thickness Distribution ◽  
Forming Limit Diagram ◽  
Forming Limit ◽  
Physical Processes ◽  
Forming Process ◽  
Element Analysis ◽  
One Step ◽  
Range Of Values ◽  
Principal Strains

Numerical simulations based on Finite Element Analysis (FEA) are widely used to predict and evaluate the forming parameters before performing the physical processes. In the sheet metal industry, there are basically two types of FE programs: the inverse (one-step) programs and the incremental programs. In the present paper, the forming process of the shield case piece (LTA260W1-L05) was optimized by performing simulations with both types of software. The main analyzed parameter was the blankholding force while the rest of the parameters were kept constant. The criteria used to determine the optimum value was based on the Forming Limit Diagram (FLD), fracture and wrinkling of the material, thickness distribution, and the principal strains obtained. It was found that the holding force during the forming process deeply affects the results, and a range of values was established in which the process is assumed to give a good quality piece.

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