Characterization of fracture loci in metal forming

Martins, P.A.F.; Bay, Niels; Tekkaya, A. Erman; Atkins, A.G.

doi:10.1016/j.ijmecsci.2014.04.003

Cited by 122 publications

(86 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In ISF processes, as it was discussed above, failure by direct ductile fracture might be attained within a range of process parameters depending on the material to be deformed. Besides, in most of usual testing geometries such as truncated cones and pyramids, fracture occurs under in-plane tension (see Figure 12a) corresponding to the mode I of fracture mechanics (see the recent unified vision of Martins et al [25]). In these cases, the non-coupled damage criterion of McClintock [26] based on void growth applies as follows in Equation (3).…”

Section: Numerical Resultsmentioning

confidence: 99%

Revisiting Formability and Failure of AISI304 Sheets in SPIF: Experimental Approach and Numerical Validation

Centeno

Martínez-Donaire

Bagudanch

et al. 2017

Metals

View full text Add to dashboard Cite

Single Point Incremental Forming (SPIF) is a flexible and economic manufacturing process with a strong potential for manufacturing small and medium batches of highly customized parts. Formability and failure in SPIF have been intensively discussed in recent years, especially because this process allows stable plastic deformation well above the conventional forming limits, as this enhanced formability is only achievable within a certain range of process parameters depending on the material type. This paper analyzes formability and failure of AISI304-H111 sheets deformed by SPIF compared to conventional testing conditions (including Nakazima and stretch-bending tests). With this purpose, experimental tests in SPIF and stretch-bending were carried out and a numerical model of SPIF is performed. The results allow the authors to establish the following contributions regarding SPIF: (i) the setting of the limits of the formability enhancement when small tool diameters are used, (ii) the evolution of the crack when failure is attained and (iii) the determination of the conditions upon which necking is suppressed, leading directly to ductile fracture in SPIF.

show abstract

Section: Numerical Resultsmentioning

confidence: 99%

Revisiting Formability and Failure of AISI304 Sheets in SPIF: Experimental Approach and Numerical Validation

Centeno

Martínez-Donaire

Bagudanch

et al. 2017

Metals

View full text Add to dashboard Cite

show abstract

“…For the offset or misaligned workpiece simulation, it was observed that D increased rapidly in the region of high strain, where less material was available. Hence, the change in equivalent plastic strain was higher, implying that in Equation (6), the ratio would reach 1.0 more quickly, compared to the other regions. Therefore, failure occurred in this region.…”

Section: Effect Of Offsetmentioning

confidence: 98%

“…A large number of techniques is used to make sheet metal parts. In recent years, many aspects of sheet metal forming processes have been widely studied using electromagnetic forming, especially with regard to the behavior of materials under a high strain rate, the possible future applications and numerical modeling of the process, with several works dedicated to these topics [1][2][3][4][5][6][7]. Moreover, a detailed review of numerical simulations in sheet metal forming and potential developments is presented by Tekkaya [8].…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Studies of Sheet Metal Forming with Damage Using Gas Detonation Process

Patil

Prajapati

Jenkouk

et al. 2017

Metals

View full text Add to dashboard Cite

Abstract:Gas detonation forming is a high-speed forming method, which has the potential to form complex geometries, including sharp angles and undercuts, in a very short process time. Despite many efforts being made to develop detonation forming, many important aspects remain unclear and have not been studied experimentally, nor numerically in detail, e.g., the ability to produce sharp corners, the effect of peak load on deformation and damage location and its propagation in the workpiece. In the present work, DC04 steel cups were formed using gas detonation forming, and finite element method (FEM) simulations of the cup forming process were performed. The simulations on 3D computational models were carried out with explicit dynamic analysis using the Johnson-Cook material model. The results obtained in the simulations were in good agreement with the experimental observations, e.g., deformed shape and thickness distribution. Moreover, the proposed computational model was capable of predicting the damage initiation and evolution correctly, which was mainly due to the high-pressure magnitude or an initial offset of the workpiece in the experiments.

show abstract

“…The equivalent strain at the fracture decreases with the stress triaxiality in the range of negative stress triaxiality (between -1/3 and 0, compression), reaches a minimum at the zero of the stress triaxiality (pure shear), increases with the low stress triaxiality in the rage of low stress triaxiality (between 0 and 1/3), it reaches its peak value at the value of stress triaxiality 1/3 (tension), and decreases with the stress triaxiality in the range of high-stress triaxiality (between 1/3 and 2/3). Hence, it was found that the fracture lines are curved if the triaxiality space was used [24,27]. The distribution of stress triaxiality during the punching process for the material thickness of 1.6 mm and punch diameter of 10 mm is shown in the Figure 9.…”

Section: Resultsmentioning

confidence: 99%

Determination of the Values of Critical Ductile Fracture Criteria to Predict Fracture Initiation in Punching Processes

Myint

Hagihara

Tanaka

et al. 2017

JMMP

View full text Add to dashboard Cite

Punching processes are widely used for producing automobile parts, mechanical components, and other parts. To produce highly accurate parts, it is important to estimate the ratio of the sheared surface to the cut surface. Many researchers have applied the finite-element method (FEM) to analyze the ratio of the sheared surface to the fracture surface on cut surfaces by using ductile fracture criteria. However, it is difficult to determine the fracture criteria on the cut surface by tensile tests or bending tests because the punching process involves many complicated steps. In this study, FEM was applied to the punching process to determine the values of critical fracture criteria (C) by using the ductile fracture criteria proposed by Cockcroft and Latham, Oyane, and Ayada. The ductile fracture criteria were compared with the boundary between the shear surface and the fracture surfaces using experiments performed with a simple punching system. The values of the ductile fracture criteria for the fracture initiation of the formed cut surface were predicted under various clearances between the punch and the die with various punch diameters. The influence of stress triaxiality and the effect of punch diameter on the sheared surface length are also discussed.

show abstract

Characterization of fracture loci in metal forming

Cited by 122 publications

References 26 publications

Revisiting Formability and Failure of AISI304 Sheets in SPIF: Experimental Approach and Numerical Validation

Revisiting Formability and Failure of AISI304 Sheets in SPIF: Experimental Approach and Numerical Validation

Experimental and Numerical Studies of Sheet Metal Forming with Damage Using Gas Detonation Process

Determination of the Values of Critical Ductile Fracture Criteria to Predict Fracture Initiation in Punching Processes

Contact Info

Product

Resources

About