Investigation on the strain-path dependency of stress-based forming limit curves

Proceedings of the Institution of Mechanical Engineers, Part L:

Abrinia

Assempour

et al. 2014

In this study, the effect of a compressive normal stress has been considered in the determination of forming limit diagrams and forming limit stress diagrams to predict neck initiation failure in tube hydroforming of T-shaped parts. Computation of the forming limit diagrams and FLSDs is based on the generalized Marciniak and Kuczynski method to consider the existence of through-thickness compressive normal stress. The proposed forming limit diagrams and FLSDs were used in conjunction with ABAQUS/EXPLICIT finite element simulations to predict the onset of necking in tube hydroforming of T-shaped part. The amount of calibration pressure and axial feeding required to produce an acceptable part in finite element method was compared to published experimental data, and a satisfactory agreement between the FEM and test results has been achieved. Therefore, the present approach can be used as a reliable criterion to design tube hydroforming processes and reduce the number of costly trials.

Section: Resultsmentioning

confidence: 99%

Forming limit diagram of tubular hydroformed parts considering the through-thickness compressive normal stress

Proceedings of the Institution of Mechanical Engineers, Part L:

Abrinia

Assempour

et al. 2014

“…The FLD is widely accepted as an efficient tool to analyze the formability of sheet metals. [11][12][13][14][15][16][17][18][19][20][21][22][23][24]…”

Section: Introductionmentioning

confidence: 99%

Forming limit diagrams of fine-grained Al 5083 produced by equal channel angular rolling process

Rahimi

Sedighi

Proceedings of the Institution of Mechanical Engineers, Part L:

2016

The objective of this research is to study the strain forming limits of Al-Mg alloy (5083) sheet, fabricated by equal channel angular rolling process at room temperature. For this purpose, the equal channel angular rolling process was executed at room temperature in three passes. Mechanical properties, microhardness, and microstructure were investigated after the equal channel angular rolling process. Uniaxial tensile tests of the equal channel angular rolling process produced samples and showed that yield and ultimate stresses increase, while the uniform elongation to fracture decreases in comparison with the annealed state. There was a continuous hardness enhancement by increasing the number of the equal channel angular rolling passes. After the third pass, the amount of hardness raised by 73% in comparison with the annealed sample. In the fourth pass, the hardness reduced slightly, that was attributed to the strain saturation in room temperature and was followed by high surface cracks. In the annealed condition, the average grain size was 45 mm, and after the third equal channel angular rolling pass, this amount was reduced to 10 mm. Furthermore, the forming limit diagrams were determined experimentally, using the Nakazima test. The obtained results show that after the third pass, the forming limit diagrams' level move downward, meaning that a reduction occurred in the forming limits of equal channel angular rolled samples.

“…Forming limit curves (FLCs) are applied to determine the sheet metals formability. The laboratory tests results has demonstrated that the FLCs are effected by several factors containing strain rate [5,6], strain hardening index and anisotropy coefficients [7,8], heat treatment [9,10], grain size and microstructure [11], strain path changes [12][13][14] and sheet thickness [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Forming limit diagram of aluminum-copper two-layer sheets: numerical simulations and experimental verifications

Karajibani

Int J Adv Manuf Technol

Sedighi

2016

The aim of this research was to introduce a simulation-based approach for determination of the Forming limit curve (FLC) in two-layer metallic sheets. In this study, the FLC of Aluminum-1100/Copper-C10100 two layer sheets were obtained through numerical simulations and experimental investigations. In order to construct the FLC, two different criterions including the acceleration (i.e., the 2 nd order of derivatives) of equivalent plastic strain and major strain were applied to obtain the onset of necking in the materials. Based on these methods, the localized necking would be started when the acceleration of the equivalent plastic strain or the major strain got its maximum value. To verify the numerical predictions, the experimental works were accomplished on the Aluminum-1100/Copper-C10100 two-layer sheets and a good agreement between the proposed methods and experimental works was observed.