The effect of normal stress on the formability of sheet metals under non-proportional loading

Nurcheshmeh, Morteza; Green, Daniel E.

doi:10.1016/j.ijmecsci.2014.03.015

Cited by 22 publications

(12 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Very recently, new original theoretical works have been published on this very open issue, like the study on the effect of a double strain path change [18] on formability of AA6016 or the study of the effect of normal stress on the formability of sheet metals under non-proportional loading [19]. An alternative methodology to the use of the M-K model has been proposed by Uppaluri et al [20] which work focussed on the developing of a simple analytical tool based on the modified maximum force criterion (MMFC).…”

Section: Introductionmentioning

confidence: 99%

Investigations of the effect of strain path changes on forming limit curves using an in-plane biaxial tensile test

Leotoing

Guines

2015

International Journal of Mechanical Sciences

View full text Add to dashboard Cite

International audienceOptimization of sheet metal forming processes requires a very good knowledge of material forming ability, more especially for aluminum alloys which generally exhibit a poor formability at ambient temperature. During the forming of industrial parts, very complex strain paths are usually observed and can affect the formability of the sheet. In this work, in order to investigate strain path effects on formability, an innovative one-step procedure is proposed to control the strain path changes with a single test, without unloading. The test is based on the use of a cruciform shape loaded with a planar biaxial tensile device. Strain path is controlled by the displacements in the two main directions of the cruciform specimen. For a given non-linear strain path type, experimental forming limit points are greatly influenced by the level of prestrain which can either improve or reduce formability. The same tendency is observed when using a predictive tool based on a finite element model of the same cruciform shape and a rather good correlation is observed between experimental and numerical results

show abstract

Section: Introductionmentioning

confidence: 99%

Investigations of the effect of strain path changes on forming limit curves using an in-plane biaxial tensile test

Leotoing

Guines

2015

International Journal of Mechanical Sciences

View full text Add to dashboard Cite

show abstract

“…Though in the literature of Nurcheshmeh and Green (2014), the effect of normal stress on the formability of aluminum alloy sheets under non-proportional loading was studied in detail, it should be noted that the normal stress was kept constant during the non-linear strain paths in their study. However, for some cases, the normal stress may Forming limit prediction be different for the two stages of non-linear strain paths, so the true influence of normal stress in the first forming stage or the second forming stage on the formability of aluminum alloy sheets should be studied and discussed in detail.…”

Section: Influence Of Normal Stress On Formability Of Aluminum Alloy mentioning

confidence: 99%

“…They found the loading condition during the transitional stage of strain path changes is important for the nonlinear strain path effect on forming limits, and the path dependence of forming limits is determined by the pre-strain level. Nurcheshmeh and Green (2014) investigated the effect of normal stress on the formability of sheet metals under non-proportional loading. They found the influence of normal stress on the formability of sheet metals decreases with increased pre-strain.…”

Section: Introductionmentioning

confidence: 99%

Forming limit prediction for two-stage aluminum alloy sheet forming process considering the effect of normal stress

Zhang

Chen

2016

Engineering Computations

View full text Add to dashboard Cite

Purpose – The purpose of this paper is to analyze theoretically the influence of normal stress on the formability of aluminum alloy sheets in non-linear strain paths. Design/methodology/approach – Four loading modes of non-linear strain paths are investigated in detail to consider the effect of normal stress on formability of aluminum alloy sheets. Findings – Results show that the influence of normal stress in the first stage can be ignored. However, the normal stress in the second stage enhances the formability of aluminum alloy sheets obviously. Besides, the normal stress in the second stage is found to have larger effect on forming limit stress than that in the first stage. Research limitations/implications – Maybe more experiment data should be obtained to support the theoretical findings. Originality/value – This current study provides a better understanding of normal stress effect on the formability of aluminum alloy sheets in non-linear strain paths. Since the reacting stage of normal stress play important roles in normal stress effect on the formability of aluminum alloy sheets, the insight obtained in this paper will help to judge the instability of aluminum alloy sheets in complex forming processes with normal stress reacting on the sheet or tube.

show abstract

“…This is an unwanted variable that can cause variations during testing and data collection [9][10][11]. Pressure is the other contact condition that can cause the sample to fail at higher forces or time because of how the pressure makes the material behave while under stress [12][13][14][15][16][17][18][19][20]. All referenced studies show that the through thickness normal stress influences the forming limit curve (FLC).…”

Section: Introductionmentioning

confidence: 99%

Forming Limit Differences in Hemispherical Dome and Biaxial Test During Equibiaxial Tension on Cruciform

Nikhare

Vorisek

Nolan

et al. 2017

Journal of Engineering Materials and Technology

View full text Add to dashboard Cite

Traditionally, the mechanical properties of materials have been characterized using the uniaxial tension test. This test is considered adequate for simple forming operations where single axis loading is dominant. Previous studies, however, have noted that the data acquired from this type of testing are not enough and additional details in other axes under simultaneous deformation conditions are important. To analyze the biaxial strain, some studies have suggested using the limiting dome height test and bulge test. However, these tests limit the extent of using multi-axial loading and the resulting stress pattern due to contact surfaces. Therefore, researchers devised the biaxial machine which is designed specifically to provide biaxial stress components using multiple and varying loading conditions. The idea of this work is to evaluate the relationship between the dome test data and the biaxial test data. For this comparison, cruciform specimens with a diamond shaped thinner gage in the center were deformed with biaxial stretching on the biaxial testing machine. In addition, the cruciform specimens were biaxially stretched with a hemispherical punch in a conventional die-punch setting. Furthermore, in each case, the process was simulated using a three-dimensional (3D) model generated on abaqus. These models were then compared with the experimental results. The forces on each arm, strain path, forming, and formability were analyzed. The differences between the processes were detailed. It was found that biaxial tests eliminated the pressurization effect which could be found in hemispherical dome tests.

show abstract

The effect of normal stress on the formability of sheet metals under non-proportional loading

Cited by 22 publications

References 18 publications

Investigations of the effect of strain path changes on forming limit curves using an in-plane biaxial tensile test

Investigations of the effect of strain path changes on forming limit curves using an in-plane biaxial tensile test

Forming limit prediction for two-stage aluminum alloy sheet forming process considering the effect of normal stress

Forming Limit Differences in Hemispherical Dome and Biaxial Test During Equibiaxial Tension on Cruciform

Contact Info

Product

Resources

About